Potential of Pigmented Rice in Bread, Bakery Products, and Snacks: A Narrative Review of Current Technological and Nutritional Developments

Abstract

Rich in bioactive compounds, pigmented rice offers superior antioxidant capacity compared to non-pigmented rice. Processing methods like milling, parboiling, thermal treatments (e.g., extrusion cooking), and biobased approaches (e.g., germination and fermentation) impact the technological and nutritional properties of pigmented rice. All products with added pigmented rice showed improved total phenolic content and antioxidant capacities. Extrusion cooking improved technological properties of dough, bread, and bakery products by modifying the pasting properties of rice. Germination and fermentation enhanced bakery products’ nutritional value by increasing gamma-aminobutyric acid (GABA) levels. Pigmented rice flour can enhance the volume, crumb firmness, and elasticity of gluten-free (GF) bread, especially with ohmic heating. It improved sensory qualities and consumer acceptance of various baked products and extruded snacks. While pigmented rice-based pasta and noodles had compromised cooking qualities, germination improved noodle cooking qualities. Pre-processing techniques like parboiling and micronisation show potential for improving pigmented rice’s technological properties and warrant further study. In conclusion, pigmented rice can enhance the technological and nutritional qualities of bread, bakery products, and snacks. Future researches should focus on agronomic advancement, optimization of pre-processing and processing techniques, exploring varietal differences among pigmented rice cultivars, and promotion of consumer awareness and market potentials.

1. Introduction

Rice (Oryza sativa L.) is one of the most important cereal crops and food in the world. Global milled rice production was 532.87 million metric tons in the crop year 2024/25 [1]. It is cultivated in more than 120 countries, spanning latitudes from 35° S to 53° N, with the majority of production concentrated in the tropical and subtropical regions of Asia [2]. Regarding human nutrition, rice accounts for over one-fifth of the global caloric intake. In Asia, more than two billion people derive 60–70% of their daily caloric intake from rice. Worldwide, most consumed rice is long grain and polished white rice, but there are many cultivars that contain pigments known as coloured or pigmented rice. Pigmented rice is consumed with its seed coat (bran) and has a nuttier flavour compared to polished white rice, where the exterior seed coat has been removed. However, pigmented rice can still be considered as niche product in most parts of the world. Due to poor consumer awareness, its lower yield and staggered market potential, production of pigmented rice is only 0.1% of total rice production [3]. Meanwhile, several studies have shown that pigmented rice has superior nutritional quality compared to polished white rice and non-wholegrain cereals due to the presence of flavonoids and other bioactive compounds [4]. Historically, pigmented rice has been a dietary staple in China, Japan, and Korea for a long time, and still today traditional Chinese medicine includes pigmented rice to improve eyesight, kidney function, blood circulation, remove blood stasis, and treat diabetes. Bioactive substances in pigmented rice possess antioxidant and free radical scavenging, anti-tumour, antiatherosclerosis, hypoglycaemic, or anti-allergic activities [5]. Pigmented rice is also known for its health benefits, including regulation of high blood pressure, anti-obesity effects, anti-diabetic effects, antioxidant activities, anti-inflammatory properties, anti-cancerous properties, and skin anti-aging properties [3]. Overall, pigmented rice is now gaining a lot of attention due to its nutritional value largely attributed by high phenolic compounds, micronutrient content, and high resistant starch content [6].

Bread and pasta are an essential part of the global human diet. The expected average volume per person consumption of bread and pasta in 2025 are 25.5 kg and 7.4 kg, respectively [7,8]. Both can contain functional ingredients or be fortified with bioactive components. Much work has been conducted to improve not only the technological processing, but also the nutritional properties to increase the health benefits of these foods. This includes the use of functional ingredients and innovative technologies. Studies have shown that the use of wholegrain cereals can improve the nutritional properties of bread and pasta (wheat-based and GF), particularly when pigmented varieties are used.

Currently, polished white rice is predominantly utilized as an ingredient in food products due to its GF nature and mild flavour. However, limited research has explored the potential of pigmented rice. This review aims to enhance the knowledge of the potential applications of wholegrain pigmented rice for bread, bakery products, and snacks, and focused on the effects of pigmented rice on the technological, nutritional, and sensory properties of the food products. A review by Tiozon et al. [6] compared the phenolic acids and flavonoids of various pigmented rice varieties (including non-pigmented rice and rice bran) and examined the effects of post-harvest processing. As this topic has already been addressed, it will not be the focus of this review.

2. Methodology

This review specifically aims to identify and discuss the effects of pigmented rice on the technological, nutritional, and sensory properties of bread, bakery products, and snacks. Data collection was conducted in March 2025. A narrative review was used in this study.

2.1. Inclusion Criteria

Research articles that focused on used wholegrain pigmented rice in bread, bakery products, and snacks.

2.2. Exclusion Criteria

Book chapters and research articles that used pigmented rice bran and/ or extracts in product development.

2.3. Data Extraction

A total of 33 research articles were identified through literature searches conducted in electronic databases such as Scopus, ScienceDirect, Google Scholar, and PubMed. Research studies published from 2010 to 2025 were included using the key words, pigmented rice, coloured rice, pasta, bakery products, and snacks.

2.4. Analysis

Studies were evaluated and tabulated based on the type of food product, pigmented rice, additives/ingredients and processing conditions, pigmented rice ratio, effects on technological properties of dough, bread, and bakery products, and nutritional and sensory qualities of the end product. The findings were summarized to provide an overview of the potential and challenges in using pigmented rice in bread, bakery products, and snacks.

2.5. Limitations

This narrative review focused exclusively on research articles that utilized wholegrain pigmented rice in bread, bakery products, and snacks, while excluding studies that used pigmented rice bran or isolated compounds from pigmented rice in these food products. Wholegrain cereals are known to exhibit a greater synergistic effect compared to isolated components. Furthermore, the extraction of specific functional compounds would require additional processing steps that could have an impact on the economic viability of the end products.

3. Origin, Taxonomy, Description, and Types of Rice

Rice domestication occurred independently in China, India, and Indonesia, leading to three races of rice: Sinica (also known as Japonica), Indica, and Javanica (also known as “bulu” in Indonesia). Recent molecular evidence suggested that rice was first domesticated in China around 8000–13,500 years ago. The first domestication gave rise to the Japonica-like varieties from which the Indica types afterwards diverged [9]. Meanwhile, it was reported that rice was cultivated in India between 1500 and 2000 B.C. and in Indonesia around 1648 B.C [10]. Rice has been grown in Europe since the eighth century in Portugal and Spain and by the ninth to the tenth century in southern Italy through European colonization [11].

The genus Oryza L. belongs to the tribe Oryzeae within the subfamily Oryzoideae of the grass family Poaceae (Gramineae). This genus includes two cultivated species, O. sativa L. and O. glaberrima Steud., along with over 20 wild species found across tropical and subtropical regions [10]. Most countries cultivate Oryza sativa based on ecogeographic races Indica, followed by Japonica and Javanica varieties. In Africa, a small amount of Oryza glaberrima is grown. On the other hand, a so-called “wild rice” (Zizania aquatica) is grown in the Great Lakes region of the United States, which is more closely related to oats than to rice [11].

Indica and Japonica can be differentiated based on grain shapes and texture. Indica is long grained and less sticky while Japonica is usually short grained and sticky. They also differ in several other agronomic traits [12]. Japonica rice plants are shorter in height, have darker leaves, better cold tolerance, as well as stronger resistance to lodging and non-shattering grains. However, it tends to have fewer tillers and a slower germination rate compared to Indica rice [12]. More than 40,000 rice species are available in the world and are classified based on kernel size and length, reflecting different cooking characteristics and flavours. On the other hand, with respect to their ecology, rice have different heading (when panicle emerges from the leaf sheath), days to maturity, and disease resistance [12]. Additionally, rice grains exhibit a range of colours, including yellow, green, brown, red, purple, and black. These colours are derived from the deposited anthocyanins, which can be in different layers of pericarp, seed coat, or aleurone [13]. Pigmented rice has been recognized for its nutraceutical benefits, leading to its continued cultivation as niche rice in various regions worldwide. It is known to contain high amounts of total anthocyanin, total phenols, and polyphenols, which translates to their notable antioxidant potential.

Most pigmented rice varieties, though highly nutritious, are traditional landraces that typically possess less favourable agronomic characteristics and produce lower yields than white rice, largely due to limited exposure to intensive selective breeding. In addition to this, pigmented rice varieties have longer cooking times, hard texture, and insufficient viscoelasticity, thus further limiting production. Lower agronomic traits (e.g., longer life cycle and lower yield) and quality traits (e.g., cooking and eating qualities) must be further improved to increase production and consumption [14]. Several methodologies are being developed and studied to improve the agronomic quality of pigmented rice. Sedeek et al. [15] provided multi-omics resources for targeted agronomic improvement of Asian pigmented rice. The study showcased comprehensive phenotypic and genotypic evaluation of both pigmented and white rice germplasm, combined with the integration of desirable traits—such as high yield, optimal growth duration, and superior nutritional value. This can be effectively achieved through allele pyramiding using genomic molecular design. These targeted strategies offer significant potential to improve the accuracy and efficiency of pigmented rice breeding efforts allowing higher yield for food consumption and product development. Meanwhile, Lang et al. [14] stated that it is more feasible to introduce pigmentation into modern cultivars than to improve the quality and yield of pigmented rice landraces and that to date there are no studies that have examined the impact of incorporating specific chromosomal segments from pigmented rice into white rice on its nutritional composition. This agronomic and quality improvements are warranted to improve production and consumption of wholegrain pigmented rice.

4. Rice Grain Morphology and Nutritional Composition

4.1. Rice Grain Morphology

Most cultivated rice are considered as a semiaquatic annual grass, but can grow in the tropical areas as perennial plant. Mature rice plants have a main stem and tillers with each tiller producing a panicle. Plant height varies from 0.4 to 5 m depending on variety and environmental conditions. Rice morphology includes vegetative phase (germination, seedling, and tillering) and reproductive phase (panicle initiation and heading) [16]. Rice grains consist of an edible rice caryopsis or fruit (also known as brown, cargo, dehulled, or dehusked rice), which is surrounded by the hull or husk [17]. The hull consists of multiple layers of distinct tissues that surround the kernel, as seen in Figure 1. The hull of Indica rice is composed of palea, lemmas, and rachilla while Japonica rice has a hull that includes rudimentary glumes and portion of pedicel. Grain length, width, and thickness differ among varieties. A single grain weighs 10–15 mg (dry weight basis). Hull weight is about 20% of total grain weight [17]. Brown rice consists of 1–2% pericarp, 4–6% aleurone layer, 1% embryo, 2% scutellum, and 90–91% endosperm [17]. The composition and properties of brown rice and its fractions greatly depend on varietal, environmental, and processing conditions. Brown rice, when milled to remove the bran fractions, results to polished white rice or milled rice.

Bran contains the aleurone layer, which is the primary tissue responsible for accumulating various phenolic compounds. These phenolic compounds play a crucial role in crosslinking non-starch polysaccharides with other cell wall components, such as lignin, thereby enhancing the structural integrity of the cell walls while providing defence against invading pathogens. The rice phenolic content is linked to variation in thickness of the bran. Still, the specific mechanisms of phenolic accumulation in different fractions of rice are yet to be understood [6].

4.2. Nutritional Composition

4.2.1. Starch

Starch is the main constituent of rice. Rice starch is composed of amylose and amylopectin and its ratio can vary significantly between species (65–85% amylopectin). Amylopectin is a branched molecule with branch points α-(1,6) bonds while amylose is composed of long-chained α-1,4 linked glucose molecules, but it also may contain a few α-1,6 branch points. Accordingly, rice is classified as low (<20%), intermediate (20–25%), and high (25–30%) amylose [18]. Indica species have higher apparent amylose content than Japonica species. Apparent amylose is inversely correlated to glycaemic index of rice [17]. A study conducted by Pradipta et al. [19] on 10 varieties of Indonesian pigmented rice revealed that amylose content ranged from 2.85% to 26.14%, suggesting that the ratio of amylose to amylopectin is varietal dependent.

4.2.2. Proteins

Protein is the second major component of rice with amounts of approximately 7%, which is relatively low as compared to other cereal grains. However, rice contains a more balanced amino acid profile as it contains more lysine (3.5–4%) as compared to wheat, corn, millet, and sorghum [20]. Rice protein is mainly stored in the aleurone layer, embryo and smaller amounts in the endosperm. Rice storage proteins are classified into albumins, globulins, prolamins, and glutelins depending on their solubility. Glutelins are the most abundant protein followed by prolamins. Pigmented rice protein amount and quality differ from brown rice as pigmented rice has higher levels of proteins necessary to synthesize sugars and flavonoids. It is also found to have higher proteinogenic (histidine, threonine, valine, iso-leucine, methionine, phenyl alanine, lysine, proline, and tyrosine) and non-proteinogenic (glutamic acid, aspartic acid, asparagine, citrulline, and GABA) amino acids as compared to non-pigmented rice [21]. Red rice contains higher enzymes for synthesizing carotenoids, amylopectin, and storage proteins (prolamins and glutelins), while black rice contains significant amounts of glycoproteins and enzymes needed to synthesize thiamine and anthocyanin. Brown rice, on the other hand, contains enzymes needed to synthesize essential amino acids (methionine and arginine), vitamin B, and unsaturated fatty acid [22].

4.2.3. Lipids

Lipids in rice are mainly confined in the bran (20%, dry weight basis). Rice lipids are composed primarily of triglycerides, phospholipids, and free fatty acids, and could be free or bound lipids. Major fatty acids are linoleic, oleic, and palmitic acids [23]. Free lipids, also known as non-starch lipids, are adsorbed on the surface of starch granules while bound lipids or starch lipids are inside the starch granules. The lipid content of rice grains varies depending on genotypes and planting environments. The total lipid contents ranged from 1.72% to 3.84% in brown rice and from 0.09% to 1.52% in polished white rice, while there are no significant differences in lipid content and composition of Indica and Japonica rice. On the other hand, Frei and Becker [24] stated that the black/purple rice varieties have higher lipid content than red/brown and non-pigmented varieties.

4.2.4. Vitamins, Minerals and Dietary Fibres

Rice grains contain a wide array of micronutrients that are beneficial for human health such as iron, zinc, copper, and selenium. Brown rice specifically contains vitamins like thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate (B9), and α-tocopherol (E); however, it lacks vitamins A, D, and C [25]. Arabinoxylans and β-d-glucan are the primary components of soluble dietary fibre in rice; insoluble dietary fibre consists of cellulose, hemicellulose, insoluble β-glucan, and insoluble arabinoxylans. However, the composition and quantity of dietary fibre vary depending on the varieties, the extent of milling, and their water solubility [26]. According to Rebeira et al. [27], the dietary fibre content of pigmented rice is higher than non-pigmented rice.

4.2.5. Phytochemical Composition

Plants contain secondary metabolites such as flavonoids and phenolics that play a significant role in plant development, fertilization, pigmentation, UV protection, and defence against pathogens and environmental conditions. Coloured flavonoids (flavanols, isoflavonoids, flavones) are responsible for plant pigmentation. Due to the presence of flavonoids, pigmented rice exhibits cytotoxic, anti-tumour, anti-inflammatory, antioxidant, and neuroprotective activities [28]. Specifically, proanthocyanidins (red pigments) and anthocyanins (purple to blue pigments) are the two principal flavonoids present in pigmented rice [29]. The darker the grain colour, the higher the anthocyanin level, and therefore the higher the flavonoid content [30]. However, at present, colour measurement cannot be used as an indirect method to determine the phenolic content of cereal grains. Techniques such as high-performance liquid chromatography (HPLC) or spectrophotometric assays are still required for accurate quantification.

The pigmented rice varieties contain various phenolic acids, such as ferulic acid, p-coumaric acid, sinapic acid, and hydroxybenzoic acid. Among these, ferulic, protocatechuic, and p-coumaric acids are mostly cell wall-bound phenolic acids, while sinapic, ferulic (28%), and vanillic acids are the main soluble phenolic acids in black rice [31]. P-coumaric acid and ferulic acid are predominantly found in red rice bran, while gallic acid, protocatechuic acid, p-coumaric acid, and ferulic acid are accumulated in black rice bran. Phenolic compounds in rice exist in three forms: free, insoluble-bound phenolic attached to sugars and other molecules, and insoluble-conjugated phenolic compounds [32]. The majority of the phenolic compounds in pigmented rice is present in an insoluble-bound form; they are not easily discharged in the gut during digestion, and therefore not easily absorbed by the body (low bio-accessibility). Additionally, phenolic compounds often bind with dietary fibres in the bran layer through non-covalent or covalent bond interactions, resulting in lower bio-accessibility [33]. Phenolic compounds in rice reduce risk of developing chronic diseases and prevent oxidative stress-related diseases [29]. In a study conducted by Ponjanta et al. [34], pigmented rice (three varieties per pigment of red and purple) was determined to contain more total phenolic compounds (7.83–47.3 mg/L) and resistant starch (2.44–10.50%) than white flours.

5. Pasting Properties of Pigmented Rice

Determining the pasting properties is crucial in product development, especially for rice-based products, as they influence the texture, consistency, and overall sensory quality. These properties describe how starch behaves when heat is applied in the presence of water. It shows how the starch swells, gelatinizes, breaks down, and retrogrades upon cooling. These behaviours are correlated with key qualities of food products such as stickiness, firmness, viscosity, and cohesiveness. The composition of rice grain and the processes involved also directly influence the pasting properties of rice flour.

The pasting properties determine the functional properties of starch and are greatly affected by the amylose/amylopectin ratio, lipid content, varieties, and cropping environment [35]. A comparison between brown and polished white rice from five traditional Sri Lankan rice grains showed that brown rice flour had lower swelling power, lower RVA viscoamylograph profile, lower gel hardness, and lower gelatinization enthalpy, but higher gelatinization peak temperature, as compared to polished counterparts [36]. Amylase activity in brown rice also results in reduced peak, setback, and final viscosities, as amylase breaks down starch before it fully gelatinizes. In pigmented rice, variation in amylose content exists. Ten Indonesian pigmented rice varieties exhibited no significant differences in functional and proximate properties, except for crude fibre content [19]. The water absorption index ranged from 4.22–7.63 g/g, water solubility index from 3.62–7.40%, oil absorption index from 0.88–1.36 g/g, and swelling power between 5.31–8.42 g/g. The gelatinization enthalpy ranged from 0.82–1.33 J/g, and the sample with the lowest amylose had the highest peak, trough, and final viscosities.

The protein, lipid, and dietary fibre content of rice grains are negatively correlated with the hardness of rice flour paste and cooked rice, but positively correlated with stickiness [36,37]. Protein and dietary fibre specifically compete with starch for water absorption, lowering swelling power, water binding capacity, and peak viscosity, and hindering retrogradation (a process during which amylose reorganizes and retrogrades through hydrogen bond formation). On the other hand, lipid–amylose complexes restrict starch swelling (low peak viscosity) but improve hot paste viscosity (low breakdown viscosity). Protein, lipid, and dietary fibre interfere with amylose reassociation during cooling preventing retrogradation [36]. If the same amount of water is used for cooking, rice with high protein, lipid, and dietary fibre will result in a harder and more rigid cooked rice or gel [38].

Phenolic compounds are characterized by the presence of hydroxyl and carboxyl groups. Polyhydroxy compounds compete with starch granules for water, thereby inhibiting their hydration and swelling, which results in a reduction of peak viscosity [39]. Wu et al. [40] reported that polyphenols form complexes with starch via hydrogen bonding, with the interaction influenced by the polyphenols’ structure, molecular weight, and the number of hydroxyl and methoxy groups. These factors contribute to the varying physicochemical properties of polyphenol–starch complexes. Additionally, the ratio of amylose to amylopectin significantly affects the binding affinity of polyphenols, with higher amylose content promoting the formation of more ordered polyphenol–amylose crystallites, resulting in a higher degree of crystallinity. The presence of polyphenols such as ferulic acid has been shown to enhance the water-holding capacity of rice starch, leading to the formation of a more porous gel matrix upon gelatinization [41]. Thermal processing plays a crucial role in facilitating starch–polyphenol interactions by disrupting the double-helix structure of starch, thereby exposing more binding sites for polyphenols and promoting complex formation. In particular, extrusion cooking can unravel the amylose double helix and increase rice starch porosity, enhancing its interaction with polyphenols [40,42]. Zhu [43] reported that presence of polyphenols affects pasting properties of starch variably. Polyphenols can either increase or decrease setback viscosity and cool paste viscosity depending on type of starch, structure of phenolic compound, and pH of the food matrix. Phenolic acids can modify the pH of a water–starch suspension, making it more acidic. Since pH is positively correlated with final viscosity, this alteration can influence the pasting properties. In a study on wheat pasting properties with added phenolic extracts, it was observed that phytochemicals interact with leached amylose at hydrophobic regions, binding to the side chains of amylopectin through hydrogen bonding and van der Waals forces. This interaction disrupts the retrogradation and reassociation of amylose during the cooling phase, resulting in a less stable gel network [39]. Phenolic compounds can form strong complexes with both starch and proteins leading to lower breakdown viscosity (stable hot paste viscosity). High gelatinization temperature is also noticeable as disrupting the starch–polyphenol–protein matrix requires more energy.

From a technological perspective, the use of wholegrain pigmented rice, which is higher in fibre, lipids, protein, and phenolic compounds, generally leads to lower pasting parameters. This can pose some challenges when incorporating it into bread and bakery products. However, pigment alone does not solely determine the technological qualities of rice, as genetics (e.g., indica and japonica rice), varietal differences (e.g., Basmati and Nero), and environmental factors play a major role and must be carefully considered.

6. Effects of Processing on Pasting Properties, Phenolic Compounds, and Antioxidant Capacities in Pigmented Rice

6.1. Dehulling, Parboiling, and Milling

Pigmented cereal grains undergo physical and chemical transformations as a result of processing. Considerations must be given to minimize losses of cereal grains nutritional integrity and bioactive contents. Processing pigmented cereals can be categorized into primary (parboiling, dehusking/dehulling, milling, and fractionation) and secondary processing (e.g., heat treatment and biobased approaches). Dehulling and degree of milling determine the microstructural grain content, and thereby the nutritional value of rice grain fractions. Milling processes may reduce the nutrient quality of rice as nutrients are mainly present in the outer layers of rice grains. In the studies of Luh [44] and Dexter [45], the nutrient content of rice flour was reduced by milling as follows: thiamine (68–82%), riboflavin (B2) by (57%), niacin (64–79%), pantothenic (51–67%), pyridoxine (43–86%), folic acid (60–67%), biotin (86%), vitamin E (82%), lipids (77–82%), proteins (10–16%), and fibres (63–78%). Milling techniques such as dry and wet grinding processes affect the type, concentration, and anti-inflammatory properties of proanthocyanidins present in pigmented corn grains [46]. On the other hand, milling increased the starch content and starch digestibility of the rice grain.

Parboiling is a heat-moisture treatment wherein paddy rice is soaked in water until the moisture percentage reaches 30–40%, then steamed or boiled until the rice starch gelatinizes. The rice is then dried (moisture <14%) and dehulled. Parboiling increases the nutritional value of rice as nutrients from the hull seep into the grain during soaking and steaming. Parboiling increases grain hardness, and thus improves milling and results in fewer broken grains [47]. During the process, water-soluble micronutrients like B vitamins, essential minerals such as iron, and phytochemicals like phenolic acids are transferred from the rice bran to the starchy endosperm, thus increasing the nutritional content of the rice grain. Additionally, the starch in rice undergoes gelatinization during steaming and retrogradation during cooling, leading to a reorganization of starch molecules into a more ordered structure, which can increase starch crystallinity. This, in turn, raises the levels of slowly digestible starch (SDS) and resistant starch (RS) in parboiled rice, potentially resulting in a lower blood sugar response compared to regular white rice [48]. Parboiled rice can also be germinated to further increase the nutrients such as γ-aminobutyric acid (GABA), fibre, vitamins, and phenolic acids. Additionally, it inactivates lipase for better storage and process, preventing undesirable microorganisms during the soaking and germination process. Free phenolic acids, p-coumaric acid, and bound vanillic acid increased with parboiling [49].

In a study conducted by Pinta et al. [50] in eleven varieties of rice (two white, five black, four red) grouped into two groups; one was dehulled (wholegrain) while the other group was parboiled (24 h soaking, 48 h germination ~0.5 cm root, steamed at 95–97 °C, sundried for 2 days, moisture at 11 ± 1%). The results showed that parboiling decreased dietary fibre, total phenolic content, and antioxidant activity (DPPH) in rice, while non-parboiled rice retained higher levels of these components. However, it did not significantly alter ash and protein content of the rice. Two black rice landraces were found to be nutritionally the most favourable genotypes for both parboiled and non-parboiled rice. The research concluded that parboiling influenced the nutritional content of rice, with the impact varying based on genotype differences. On the other hand, Hu et al. [49] stated that parboiling for >5 min increased free phenolic content and ABTS antioxidant activity, but decreased the bound phenolic content and antioxidant activity of germinated red rice. Paiva et al. [51] compared parboiling of black and red rice genotypes, and reported that red rice had higher protein migration compared to black rice during the process but there was reduced ash content. Parboiling resulted in partial preservation of free phenolics and lower relative crystallinity (crystallites disruption). In addition, parboiling affected the levels of bioactive compounds in black (Venere brown and Violet brown) and red (Ermes brown and Orange brown) Italian pigmented rice varieties; however, they still retained higher antioxidant activity in the final product compared to non-pigmented rice [52]. Hu et al. [49] described that germination and parboiling treatments significantly increased the viscosity and thermal properties of germinated red rice and decreased heat enthalpy. Germination alone decreased viscosity profiles of red rice while parboiling improved the pasting profile of germinated red rice. All viscosity parameters (except breakdown value) increased with 0 to 2 min parboiling. The authors argued that during the parboiling process, gelatinization, and re-crystallization of starch take place in a starch–water mixture, where dispersed amylose chains create double-helical structures consisting of 40–70 glucose units through hydrogen bonding. Thus, retrogradation of the outermost branches of starch granules can result in increased pasting viscosity of germinated rice. This could be attributed to disruption of hydrogen bonds or breaking of covalent linkages of the double helices. The authors concluded that a short time parboiling can improve the viscosity characteristics of germinated red rice. Germination and parboiling increased thermal properties (T₀, T_p, and T_c), while change in enthalpy decreased, which further indicated that the rice granule structure was destroyed by parboiling. Parboiling (rice paddy, 24 h soaking, 1 h steaming, sundried, and oven dried, 12–14% moisture) increased the resistant starch (five-fold) of intermediate and high amylose pigmented rice. The linear helical chains of amylose can form tightly packed structures with high crystallinity, which restricts enzymatic access [53]. On the other hand, Marti et al. [54] concluded that extrusion cooking promoted cooked pasta firmness when applied to parboiled white rice flour. They reported that pasta using parboiled white rice showed the lowest starch enzymatic susceptibility, indicating that the pasta-making process for parboiled rice flours resulted in significant rearrangement of starch macromolecules, effectively reducing cooking losses. High extrusion cooking temperatures led to greater starch gelatinization and increased retrogradation and further decreased enzymatic susceptibility.

6.2. Innovative Processing to Improve Nutritional Quality of Wholegrain Pigmented Rice (Micronisation, Microfludisation, and Fractionation—Air Classification)

Micronisation is an advanced technique used to valorise bran of cereal grains. It is a process that applies mechanical high shear force to reduce solid materials to the microscale. Mechanical grinder, supercritical fluid technologies and homogenizers can be used for micronisation [55]. On the other hand, microfluidisation—a modified version of micronisation—is a high-pressure homogenization that creates very fine emulsions. By reducing the particle size and microstructure, these processes improve the functional and nutritional properties of rice brans [56]. Reducing the particle size to micron level enhances functional and physicochemical properties such as water-holding capacity, swelling capacity, solubility, and antioxidant activity. It also aids in food preservation by exposing antimicrobial compounds, inactivating microbes, or inhibiting enzymes, thereby increasing food stability. Micronisation delays retrogradation, promotes gelatinization, reduces syneresis, shortens fermentation time, creates stable products, and improves dissolution rates. These effects are attributed to the reduction in particle size and the corresponding increase in surface area [57]. Yin et al. [55] reported that micronisation increased rice bran whiteness, solubility, and nutrient release, while it had no significant effect on oil binding or thermal index and lowered bulk density after extrusion stabilization. Micronisation also improved the release of phenolics, flavonoids, γ-oryzanol, and minerals, enhancing the functional and nutritional properties of rice bran, especially when combined with extrusion stabilization.

Microfluidisation presents a promising approach for forming complexes between starches and fatty acids, which could possibly lead to the development of a novel resistant starch ingredient with enhanced viscosity and water-holding capacity. Additionally, Mert et al. [58] reported that microfluidised cereal by-products contribute unique functional and nutritional benefits to bakery products. In this case, the microfluidisation resulted in more homogenous particle distribution with the formation of the finely separated fibrous structure with greater surface area, thus improving water holding and binding capacity. They stated that the increase in surface area of fibres allowed bran fibre to intertwine and form a strong fibrous matrix, providing higher yield stress and viscoelastic moduli values in batter samples.

Fractionation, on the other hand, is a method used to produce valuable milling fractions of bran with distinct functional and technological characteristics. Dry fractionation is an eco-friendly and cost-effective method that involves the gradual grinding of whole cereal grains to reduce the particle size of the flour [59]. This process then separates fractions that are rich in peripheral tissues, which are abundant in dietary fibre and phenolic compounds. One physical fractionation is air classification, where two main fractions can be obtained: high protein fractions (coarse fraction) and high starch fractions (fine fraction) [60]. These fractions can be used accordingly to further enrich flour with specific components such as protein and starch. Additionally, this process can isolate specific compounds, such as phenolic compounds, which can be used to improve the nutritional and health benefits of food products. Bani et al. [61] highlighted that fractionated bran (below 500 μm) added to milled rice resulted in improved colour and nutritional benefits (total phenolic content >53% and antioxidant activity >60%). However, due to variations in components such as fat, ash, and damaged starch after the fractionations, rheological properties, and thereby end products, are affected.

Air classification can be performed independently or in combination with the micronisation technique, further enhancing the physicochemical and nutritional properties of cereal grains. Spaggiari et al. [62] studied the effects of air classification, both with and without micronisation, on the lipid components of brown rice bran. Their findings revealed that total crude fat content was higher in the fine air-classified fractions, with polyunsaturated triacylglycerols being the most abundant, while the concentration of monoacylglycerols increased in the fine fractions. Given the emulsifying properties of these compounds, this approach could be advantageous for the development of rice-based products. Combining micronisation with air classification has shown promising effects on wholegrain brown rice and could potentially be applied to pigmented rice. However, to date, no studies have specifically examined the use of micronisation, with or without air classification, to enhance the physicochemical and nutritional qualities of pigmented rice for product development, leaving this topic open for further investigation and discussion.

6.3. Thermal Processing of Rice Flours

Heat treatments like baking and extrusion cooking can significantly reduce the total phenolic content of pigmented rice (black, red, brown) due to thermal decomposition of phenolic compounds by high temperature [3]. However, wholegrain bakery products still contain more phenolics compared to those made from refined flour. Baking, a secondary process, was found to liberate bound phenolic acids, thus increasing the free phenolic acids of bread made from pigmented rice [63]. In bread-making, a decrease in anthocyanin content starts in dough preparation due to the addition of other components, air incorporation into the dough, and activation of enzymes such as polyphenol oxidase and peroxidase, which contribute to anthocyanin degradation [64]. Extrusion cooking, on the other hand, is an innovative technology that integrates heating, cooking, and moulding. It is favoured nowadays as it is a rather simple and inexpensive process. By applying short-term high temperature and high pressure, it can alter the texture of food, modify its composition, and enhance the interaction between food components [65]. Although applied temperatures can be high, exposure times are very short, thus the loss of bioactive compounds can be kept at a minimum, retaining the nutritional properties to a large extent, at the same time starch is gelatinised and protein denatured, so their digestibility is increased. Like baking, extrusion cooking impacts the polyphenol content and antioxidant activities of grain by converting bound to free phenolic acids through disruption of the cell walls [66]. Studies have shown that temperatures in the range of 90–110 °C do not consistently reduce anthocyanin levels, while extrusion temperatures exceeding 120 °C result in a slight loss of anthocyanins [67]. To counteract these losses, high feed moisture, increased flow rates, higher screw speeds, and use of citric or ascorbic acid improve anthocyanin retention during extrusion cooking [68,69].

Other thermal processing, such as roasting and puffing, improve the digestibility, nutrient bio-availability, and organoleptic properties of final food products as they can transform or release bound to free phenolic acids, which improves the overall antioxidant capacities [66,70]. Puffing pigmented cereals has been shown to modify texture, increase volume, enhance protein digestibility and nutritional functionality, and promote the development of desirable flavours [71].

6.4. Biobased Processing (Germination and Fermentation)

Germination is an affordable and efficient processing method used to convert grains into more processable forms while enhancing their nutritional value. This process involves exposing grains to moisture, triggering a series of physical and biochemical changes to support the development of shoots. During germination, various enzymes are activated, and nutrients and phytochemicals from the embryo and endosperm are released [72]. Germination of pigmented rice (red and brown) improves water absorption, dough development time, and stability compared to non-germinated counterparts. Bread baked with germinated brown rice had higher volume, lower hardness, and improved phenolic and GABA content with higher antioxidant activities, but uneven porosity and moderate consumer acceptance [73,74]. Like germination, microbial fermentation is an economical method that can further enhance nutritional (release of phenolics and flavonoids during the process) and sensory quality of cereal grains. An increase in flavonoids and polyphenols can be attributed to microbial enzyme activities that lead to plant secondary metabolites that are more freely available [75].

6.5. Stability of Phenolic Compounds and Pigments in Rice

Stability of pigmented rice bioactive compounds can be significantly affected by post-harvest processing, storage conditions and food processing techniques. Ensuring the retention of desirable chemical, physical, and sensory properties is critical for their effective use in novel food products. Pigmented rice bran is highly susceptible to oxidation due to its high lipid content, reducing its shelf life. Anthocyanins, being the main pigments in black rice, were found to be highly affected by several factors such as pH, temperature, light, antioxidants, metal ions, and oxygen. Xue et al. [76] reported the effects of these factors on the stability of anthocyanins. The colour of anthocyanin changed depending on pH, in a range of red–pink–colourless–blue. Anthocyanins were found to be stable in acidic environment (pH 2–3), while stability was poor at neutral or alkaline condition. High temperature readily affected anthocyanin content, while low temperature was more conducive in maintaining the structural stability of anthocyanins (strong stability at 2–4 °C). Light treatment can degrade and shorten the half-life of anthocyanins. The presence of antioxidants like ascorbic acid can disrupt the stability of anthocyanins by condensing with them. Metal ions, on the other hand, enhance self-association of anthocyanins with catechol groups, thus improving their stability. The presence of oxygen can speed up the breakdown of anthocyanins, either through direct oxidation or via the activity of oxidative enzymes.

Ramos et al. [77] showed that drying red rice from 40 to 100 °C and storing it for 12 months resulted in reductions of soluble protein, cooking time, grain integrity after cooking, free and bound phenolics, and total proanthocyanidins. On the other hand, it increased electrical conductivity, grain defects, hardness, and the rehydration index. They recommended drying temperatures below 60 °C to preserve the technological qualities and phenolic content of red pericarp rice during long-term storage. Yamuangmorn et al. [78] and Loan et al. [79] stated that purple and black rice varieties can be preserved by using vacuum-packed containers (polyamide bags) even at room temperature. In a study conducted by Zheng et al. [80], the use of black rice anthocyanin extract in steamed cold noodles improved if food grade chelators were used as the anthocyanins only react with ferrous and ferric iron and copper. The noodles exhibited higher springiness and decreased starch retrogradation, and slightly increased resistant starch content and antioxidant capacity.

7. Applications of Pigmented Rice in Bread, Bakery Products, and Snacks

Polished white rice has been used in bread, bakery product, and snack development due to its market availability and neutral taste while several studies focused on use of pigmented rice in relation to its nutritional benefits. Technological and sensory challenges were experienced by researchers on use of pigmented rice in bread, bakery products, and snacks.

Table 1. Bread, bakery products, and snacks made from pigmented rice.

Bakery Items/Pasta/Snacks	Pigmented Rice	Additives/Ingredients/Other Processing Conditions	Rice Ratio	Technological Properties of Batter, Bread and Bakery Items	Nutritional Properties of Bread and Bakery Items	Sensory Qualities of Bread and Bakery Items	Authors
Bread (gluten-free)	Brown (n = 1) Red (n = 1) Black (n = 1)	Polished rice (as control), yeast, salt, emulsifiers, egg white powder Baking conditions: Conventional (CON) vs. Ohmic baking (OH)	Control: white rice with substitution 20%, 40%,60%, 80%, and 100% of pigmented rice	OH produced GF bread from pigmented rice with higher volume than CON Colour was improved in OH baked bread	GF breads with pigmented rice have improved content of fibre, total phenolic content, and antioxidant activities	Not measured	Evangelista et al. [63]
	Red (n = 1)	Wheat flour (as control), sugar, yeast, salt, shortening, bread improver, xanthan gum, soy protein isolate, low fat dairy milk	Control: 100% wheat bread and 100% red flour; red rice and potato starch ratio (100:0, 90:10, 70:30)	GF bread with lowest amount of red rice flours and highest potato starch had the lowest hardness, highest stickiness and springiness in dough and bread	Not measured	GF bread with lowest amount of red rice flours and highest potato starch were most acceptable compared to other substitution level	Ronie et al. [81]
	Purple (Riceberry) (n = 1)	Polished (Jasmine) rice (as control), salt, yeast, methylcellulose and HPMC, vegetable oil, white egg, milk	Comparison between polished and purple rice in bread (100% substitution)	Purple rice bread had lower cohesiveness, gumminess and adhesiveness than polished rice	Purple rice flour had higher content of total phenolics, anthocyanins, and antioxidant activity. It had lower levels of slowly digestible starch with medium predicted glycaemic index (pGI). Red rice bread demonstrated lower starch hydrolysis and pGI than Jasmine bread	Not measured	Thiranusornkij et al. [82]
Bread (wheat based)	Black (n = 1)	Wheat flour (high gluten) (as control), salt, yeast, sucrose, shortening Equipment: lab-scale single screw extruder Screw speed—180 r/min Diameter of the circular matrix, 8 mm X 3 Temperature: 90 °C Screened sieve: 0.2 mm	10, 20, 30, 40, 50% substitution of black rice flour (BRF) and extruded black rice flour (EBRF) to wheat flour	ERBF substitution resulted in higher water absorption and lower dough development time compared to BRF. ERBF addition resulted in dough, weak gluten structure, and starch gelatinization, low gel stability and slow starch retrogradation than wheat flour dough. BRF and EBRF dough (solid-like behaviour) EBRF dough—more viscous, higher resistance and extensibility, more compact dough) EBRF bread had higher specific volume, lower bake loss and firmness than BRF bread.	Not measured	RBF substituted bread was darker, more yellowish and less red than BRF bread and control	Ma et al. [83]
	Black (n = 1)	White rice (Arborio and Basmati), salt, sugar, lecithin, baker’s yeast,	100% white rice vs. 100% black rice	Bread volume increased while firmness decreased with higher amount of water in dough preparation. Volume and texture better with black rice bread than white bread.	not measured	Black rice substituted bread had darker crumb and crust colour	Banu and Aprodu [84]
	Purple (n = 1)	Wheat flour (as control), sugar, yeast, salt, butter, milk, egg	Control: 100% wheat bread; substituted with 5%, 10%, and 15% purple rice flour and 4% and 8% roselle (flower) flour	Purple rice flour improved dough viscoelasticity Too much roselle disrupts gluten network Substitution of both roselle and purple rice flour resulted in harder bread	Bread with purple rice and roselle flours had increased contents of phenols and anthocyanin	Purple rice and roselle improved aroma (15% purple rice and 8% roselle flour) of bread and changed colour	Qin et al. [85]
	Brown (n = 1)	Wheat flour (control), instant dried yeast, salt, sugar, fresh egg, unsalted butter Germination (24, 48, and 72 h) and temperatures (25 °C and 35 °C).	Control: 100% wheat flour: 30% germinated (GBF) and non-germinated brown flour (NGBF) substituted to wheat flour	GBF flour showed improved water absorption, dough development time, and stability compared to NGBF Wheat-GBF flour had lower peak viscosity and higher alpha-amylase activity compared to control flour Specific bread volume: Control > GBF bread > NGBF bread Hardness: NGBF bread > GBF bread > Control Uneven pore distribution in GBRF bread compared to control There was no difference in springiness and cohesiveness among the bread samples	Germination increased the levels of gamma-aminobutyric acid (GABA), total phenolic content, and antioxidant activity in brown rice	Bread with GBF had better sensory acceptance	Charoenthaikij et al. [73]
	Brown (n = 1)	Wheat flour (control), salt, sugar, alpha-amylase, ascorbic acid, lecithin, DATEM, vegetable oil, instant dry yeast, sourdough (from brown rice) Germination (30 °C for 24 h) and sourdough	Control bread (wheat: germinated brown rice) (90%:10%) Samples: with different sourdough (9% w/w of the dough recipe) containing L. sakei, L. sanfranciscensis, and combination	Not measured	The use of sourdough containing L. sakei resulted in a bread with the highest amounts of bound and total phenolic compounds and antioxidant activity. There was increased in GABA content in breads prepared by L. sakei + L. sanfranciscensis and L. sakei fermented sourdoughs, respectively	The L. sakei + L. sanfranciscensis and L. sanfranciscensis containing sourdough breads gained the highest overall acceptability from sensory panellists’ point of view	Sobhanian et al. [74]
Cake (gluten-free)	Brown (n = 1) Red (n = 1) Black (n = 1)	Brown rice (control), sugar, pasteurized egg, milk, butter, baking powder, salt	100% pigmented rice flours with or without transglutaminase	Only brown rice cake was affected by the addition of transglutaminase, resulting in a decrease in crumb firmness and increase in bread volume Red rice showed good technological properties	The total content of phenolic compounds (specifically ferulic and p-coumaric acids) in the pigmented rice cakes decreased after baking Increased in free phenolics in cake Red rice showed highest levels of bioactive compounds	Not measured	Lang et al. [86]
	Red (n = 1)	Red rice, sugar, sunflower oil, whole eggs, milk, baking powder Equipment: Extruder (co-rotating twin-screw extruder) Screw speed: 100 rpm Moisture: 25% Barrel temperature extrusion: 80 °C, 100 °C, 120 °C, 140 °C, and 160 °C	76.2% extruded red rice flour used in the recipe	Batter viscosity increased by 43% with extrusion. Higher extrusion temperature resulted in cake with higher porosity but lower bulk density and moisture	Phytochemical properties of rice flour and cake decreased with an increase in extrusion temperature	Cake using flour extruded between 120–160 °C had higher appearance scores Higher extrusion temperature had higher texture scores (good mouthfeel and less compact) Most acceptable cake was made using flour extruded at 140 °C	Das and Bhattacharya [87]
Cupcake (gluten-free)	Red (n = 1)	Germinated red rice, sugar, milk, eggs, sunflower oil and baking powder Germination (40 h) used in cupcake)	35% germinated red rice used in cupcake formulation	Use of germinated rice flours resulted in firmer crumb cupcakes	Phenolic acids and individual flavonoids in the free fraction increased as well as caffeic, coumaric, and ferulic acids, and myricetin after 16 h of germination. The content of GABA (gamma-aminobutyric acid) in the flour also increased over time, which further increased after baking the cupcakes	Germinated rice flours resulted in high acceptability ratings (89.65%) and intention of purchase (3.9)	Müller et al. [88]
Cake (wheat-based)	Black (glutinous) (n = 1)	Wheat flour (control), fresh egg, sugar, margarine, evaporated milk, vanillin flavour, emulsifier, baking powder	30, 50, 70, 100% (w/w) substitution to wheat flour	Increased glutinous black rice led to decreased in batter viscosity and increased in batter specific gravity (indicates the amount of air incorporation; lower value, higher air incorporation) Increased in glutinous black rice resulted in cake with lower specific volume, darker crumb and crust colour, and firmer, gummier and chewier texture	Not measured	Hedonic sensory tests showed that the cake prepared with black glutinous rice flour had similar flavour, taste, texture, and overall acceptable scores to that of the control sample	Itthivadhanapong and Sangnark [89]
Chiffon cake (wheat-based)	Black (n = 1)	Wheat flour (control), baking powder, sucrose, sodium chloride, soybean oil, egg yolk, non-fat dry milk	10, 20, 30, 40, 50, 60, 70, 80, 90, 100% (w/w) substitution to wheat flour	Increasing black rice substitution resulted in an increase in specific gravity (lower air incorporation) in cake batter, and crumb a* value (increase redness), hardness, cohesiveness, adhesiveness, gumminess and chewiness, while the reverse was found in moisture in cake batter, cake volume, crust colour crumb L* and b* values, springiness, and resilience	Increasing black rice flour resulted in an increase in total phenols, anthocyanins contents, and scavenging ability of cake	Hedonic sensory results showed control cake was comparable to 10–60% substitution while 70–100% had low sensory results	Mau et al. [90]
Muffins (wheat-based)	Black (n = 1)	Wheat flour (control), coconut butter, salt, brown sugar, eggs, baking powder	50% and 100% (w/w) black rice substitution to wheat flour	Substitution of black rice resulted in an increase in firmness, springiness, and chewiness of muffins, while cohesiveness was lowered	Muffins with black 50% and 100% black rice had higher anthocyanin content Higher retention rate of anthocyanins and antioxidant activities were found	Sensory analysis showed that all samples were appreciated Improved colour and microbial stability	Croitoru et al. [91]
Brownies (gluten-free)	Purple (Riceberry) (n = 1) Red (Jasmine) (n = 1)	Rice flour composites, butter, dark chocolate, white sugar, fresh egg Germination 18 h for 50:50 ratio (purple:red)	Composite rice (purple and red rice) flour ratio (75:25, 50:50, 25:75)	Increased in red jasmine flour resulted in higher specific volume, L*, a*, b* values and decreased the hardness attributed to higher amylose content of red rice Effect of germination led to higher specific volume, L*, a*, and b* values, but decreased in reducing sugar.	Not measured	The sensory characteristics increased with increasing ratio of red jasmine rice flour No significant difference were found in sensory characteristics of non-germinated and germinated pigmented rice flours	Penjumras et al. [92]
Biscuits (wheat-based)	Purple (n = 1)	Refined wheat flour (control), butter, sugar, egg, salt, sodium bicarbonate, xanthan gum	25, 50, 75, 100% (w/w) substitution of purple rice flour to wheat flour	100% purple rice biscuit had highest spread ratio (positive) and darkened the end product	Biscuits substituted with purple rice resulted in an increase in fibre content, phenolic compounds, and antioxidant activities An increase in purple rice resulted in higher protein content and protein digestibility of biscuits but lower starch digestibility 100% purple rice biscuit had lowest predicted glycaemic index	25 and 50% substitution sensory rating were not significantly different from the control	Klunklin and Savage [93]
Cookies	Red rice (n = 1)	All-purpose flour (control), butter, sugar, egg, salt	20, 40, 60, 80, 100% (w/w) substitution to all-purpose flour	Not measured	Not measured	Cookies with 40% red rice flour had similarities with control in terms of sensory properties; they were softer and slightly different in colour than the others	Yee et al. [94]
Crackers (gluten-free)	Black (n = 1) Brown (n = 1)	Brown rice (as control), whey protein, xanthan gum, margarine, sugar, salt, baking powder	25, 50, 75, 100% (w/w) substitution to brown rice	Black rice lowered the spread ratio of crackers but did not influence textural parameters	100% black rice contained higher protein, lipids, ash, crude fibre, polyphenols, proanthocyanidins, and flavonoids	50:50 ratio of black rice and brown rice resulted in nutritional improvement and was widely accepted by consumers	Uivarasan et al. [95]
Pasta (wheat-based)	Black (glutinous) (n = 1)	Semolina (control), water, egg, salt	20, 40, 60% (w/w) black glutinous rice (BGR) substitution to semolina	BGR flour in pasta led to decreased in cooking time, elasticity, and hardness while there was increased in cooking loss and stickiness Pasta with higher moisture content showed lower cooking time Peak viscosities of 0–40% BGR pasta were not different from each other	BGR flour increased fibre, protein, fat, phenolic compounds and antioxidant properties of pasta	Consumer preference peaked at 40% BGR flour substitution; 60% led to decreased acceptance.	Subanmanee et al. [96]
Pasta (gluten-free)	Black (n = 1)	White rice, black rice, tapioca starch, xanthan gum, salt, whole eggs Penne form	2:1 ratio (white rice: black rice)	Optimal cooking time: 7 min. Moisture (raw pasta): 31.9% Water absorption: 68% Cooking loss: 4.8%	Pasta showed lower caloric content compared to commercial pasta	Sensory analysis showed 67–89% acceptance, with 86% purchase intention	Chan et al. [97]
Noodle (wheat-based)	Purple (Riceberry) (n = 1)	Wheat flour (control), salt, sodium carbonate	10, 20, 30, 40%(w/w) purple rice substitution to wheat flour	Increasing the proportion of purple rice flour in the noodles resulted in a decrease in cooking time, water absorption, and elasticity, while cooking loss and hardness increased	Purple rice noodles had lower protein but higher fibre and ash	30% substitution resulted in the same taste, softness, stickiness, and overall acceptability scores as the control	Sirichokworrakit et al. [98]
Noodle (gluten-free)	Red (Jasmine red rice) (n = 1)	White rice (as control)	25, 50, 75, 100% (w/w) red rice substitution to white rice	Optimal quality observed at 75:25 ratio (white rice:red rice). This ratio showed improved tensile strength, elasticity, and cohesiveness Increasing red rice flour in the noodles resulted in a decrease in cooking time and an increase in cooking loss, water absorption, and stickiness.	Increasing substitution of red rice flour increased nutritional value, total phenolic content, and antioxidant activity	Red rice flour substitution had no effect on sensory scores in terms of colour, flavour, and taste of rice noodles	Kraithong et al. [99]
	Purple (Riceberry) (n = 1)	White rice (control) flour (50%), tapioca flour (50%)	10, 20, 30, 40, 50% (w/w) purple rice substitution to white rice	Noodles supplemented with purple rice flour had shorter cooking times, lower cooking loss, and higher cooking yield compared to white rice flour noodles 80:20 (white rice: purple rice) blend showed acceptable cooking quality, texture, and acceptance	Not measured	Noodles with up to 20% purple rice flour were found to have acceptable sensory properties, including good cooking quality, texture, and consumer acceptance. However, higher purple rice flour content led to weaker noodle structures and decreased sensory scores	Thongkaew and Singthong [100]
	Brown (n = 1)	Brown rice Solid state fermentation of rice grain (SFRG) vs. liquid state fermentation of rice grain (LFRG)	100% (w/w) brown rice	SFRG enhanced the hardness, springiness, and chewiness of rice noodles and promoted optimal gel network SFRG noodles had lowest cooking loss and broken strip rate Fermentation resulted in lower pasting parameters	Not measured	Fermented rice noodles exhibited a visually appealing white and translucent appearance, with a desirable chewy texture. They had high acceptability. Aroma and taste had lower rating due to accumulation of lactic acid	Weiling et al. [101]
Extruded snacks (gluten-free)	Brown rice (n = 1)	White rice (as control) and spice mix (sugar, ginger powder, onion powder, cheese powder, garlic powder, chili powder, citric acid) Equipment: Extruder (co-rotating twin screw extruder)	White rice (100%) vs. brown rice (100%)	The optimum extrusion conditions (numerical optimization) were moisture content of 12%, screw speed of 350 rpm, and temperature of 133 °C	Brown rice snack exhibited high vitamin B1 content—0.45 mg/100 (50% of RDA); no vitamin B1 was detected in white-rice-based snacks Vitamin B1 retained up to 85% after extrusion cooking at optimized extrusion conditions	High overall acceptability in optimum conditions	Bhat et al. [102]
	Purple rice (n = 1)	60–70% purple rice, 12–22% corn flour, barbecue seasoning powder, salt, and sugar Simplex-lattice mixture design. Equipment: Extruder (Single screw laboratory extruder)	60–70% purple rice	Optimized recipe ratio: 70% purple rice, 12% corn flour and 18% water Optimized physical characteristics: Lightness (L*) 17.09, redness (a*) 3.09, yellowness (b*) 5.38, moisture 0.79%, water activity (aw) 0.61%, texture hardness 5.76 N	Not measured	The optimized recipe had average score, appearance, colour, flavour, and overall acceptance (n = 250) in moderate levels	Fakfoung (2018) [103]
	Black (n = 1) Red (n = 1) Brown (n = 1) White (n = 1)	White rice as control Pigmented rice used at 100% Equipment: Extruder (co-rotating twin screw extruder) Feed rate (100 kg/h), screw speed (100 rpm), barrel zones temperature (40, 60, 80, 120 °C), feed moisture (10%)	100% pigmented rice	The black rice smack with the highest phenolic content had the lowest peak, final, and setback viscosities and the highest snack porosity The brown rice snack exhibited a high degree of expansion and less porous structure. Higher gelatinization capacity (peak viscosity) of flour (brown rice) led to a more compact structure of extruded snacks with small pores The red rice snack had the highest resistance to breaking and lowest index of expansion The pasting profile of snacks showed loss in viscosity after extrusion due to loss of crystalline order in starch granules Medium rice grain showed higher expansion rate than long grain rice grain	Red and black extruded snacks contained higher antioxidant capacity.	Not measured	Blandino et al. [31]
	Brown rice (n = 1)	Broken brown rice and watermelon seeds Equipment: Extruder (co-rotating twin screw extruder) Feed moisture content (16,17,18%) Barrel screw speed (300, 360 and 420 rpm) Exit barrel temperature (120, 130, 140 °C) Response optimizer: Minitab software version 20.3	90% broken brown rice 10% watermelon seeds	Optimized process conditions (with maximum protein content of 17.71%): 18.0% feed moisture, 140 °C extrusion barrel temperature, and 300 rpm	Brown rice–watermelon seeds extruded snacks have an intermediate glycaemic index	Not measured	Sanusi et al. [104]
Extruded breakfast cereals (gluten-free)	Black rice (n = 1) Red rice (n = 1)	100% pigmented rice Equipment: Extruder (co-rotating twin-screw extruder) Barrel temperature zones: 75 (1st), 100 (2nd), 125 °C (3rd) Feed rate: (15 kg/h) Screw speed: 250 rpm Feed moisture: 15.5% (black rice), 16% (red rice) 4th barrel zone temp: 159 °C (black rice), 150 °C (red rice)	100% pigmented rice	The red rice extrudates presented higher expansion properties, and a fragile structure when immersed in milk, which affecting the water absorption and the viscosity	Black rice extrudates exhibited higher phenolics and antioxidant capacities, higher protein, dietary fibre, ash, lipid, and amylose	Both breakfast cereals were nutritive, gluten-free, hypoallergenic, naturally coloured (no need to add artificial colorants), and presented good sensory acceptance, with higher scores for the attributes shape, size, colour, and crispness	Meza et al. [105]
	Black rice (n = 1) Red rice (n = 1)	Pigmented rice Equipment: Extruder (co-rotating twin-screw extruder) Barrel temperature zones: 75 (1st), 100 (2nd), 125 °C (3rd) Feed rate: (15 kg/h) Screw speed: 250 rpm	100% pigmented rice	Moisture had a higher impact on the extrusion process than temperature. Less expanded, denser, harder, and darker products were obtained at higher moisture levels The optimum points were defined as 15.5% and 16.0% for feed moisture and 159 °C and 150 °C for temperature for black and red rice extrudates, respectively. These conditions resulted in cereal breakfast extrudates with optimal water solubility, volume, texture, and good colour	Not measured	Not measured	Meza et al. [106]
Extruded puffed breakfast cereals	Red rice (n = 1)	Red rice, purple sweet potato and corn flour Equipment: Single screw extruder, Screw speed: 120 rpm, Feed rate: 40 rpm, Barrel temperatures (zones 1–4): 80, 100, 120, and 160 °C, Die type: curricular, Die diameter: 3.00 mm, D-optimal mixture design approach	15–40% red rice flour	Purple sweet potato (55%), whole red rice flour (15%), and corn flour (30%) resulted in an extruded product with satisfactory expansion, texture, and antioxidant properties.	Anthocyanin degradation was observed during extrusion	Not measured	Senevirathna et al. [107]
Nachos	Black rice (n = 1)	Pigmented rice Procedures: Steaming and roasting	100% black rice	The optimized pre-treatment conditions were found to be 30 min of steaming at 100 °C and 13.12 min of roasting at 180 °C. The resultant nachos showed good hardness and fracturability	Optimized recipes retained maximum total phenolic content and antioxidant activities	Steaming lessened the bitter aftertaste of raw and roasted-only nachos	Deka et al. [108]
Popped snacks	Black (n = 2) Red (n = 1) White (n = 1)	White rice (as control) Procedure: Popping	100% pigmented rice	Popped white rice had the highest volume increase, popping percentage, and consumer preference	Pigmented popped rice retained high phytochemicals and oryzanol with high antioxidant potency. All rice genotypes retained insoluble dietary fibre on popping. Popping increased the iron content in all rice genotypes. Total starch decreased in red and black popped rice	Not measured	Itagi et al. [109]

summarises the studies that investigated the use of pigmented rice in different food products. The food products were mostly prepared using bio-based approaches like germination and fermentation, thermal processing focused on baking, and extrusion cooking.

7.1. Bread

Wheat-based bread can be improved in terms of nutritional quality by substituting it with pigmented wholegrain rice, although this could be challenging as rice is GF and thus bread structure is compromised. As pigmented rice has higher water absorption capacity than wheat due to higher fibre content, adjustment of water (larger amount) in the wheat-based dough can improve the bread volume and lower crumb firmness [84]. On the other hand, use of another ingredient like roselle flower flour (low in starch content, high in vitamins and bioactive compounds) in addition to pigmented rice and wheat resulted in bread with lower volume and higher crumb firmness as the fibre from the roselle disrupted the gluten network in addition to diluting the gluten due to the pigmented rice [85]. However, use of extruded pigmented rice flour may overcome these diminishing effects; its addition resulted in more viscous, highly resistant, extensible, and compact dough, with better gas holding capacity compared to non-extruded pigmented flour. Wheat-based bread substituted with extruded pigmented rice (up to 50% and optimised = higher dough moisture) resulted in higher bread volume, lower bake loss, and lower firmness bread compared to non-extruded pigmented rice flour [83]. In extruded pigmented rice, starch is gelatinised, which can lead to a more continuous dough phase, while the amylose–lipid complexes formed during extrusion cooking lowered water absorption leading to a more compact structure. Biobased approaches such as germination and use of sourdough can further improve technological and nutritional quality of wheat-based bread. Germinated brown rice flour demonstrated improved water absorption capacity, dough development time, and stability, along with a decrease in peak viscosity and an increase in amylase activity. Although bread made with germinated brown rice flour exhibited lower volume and higher firmness compared to wheat bread, it performed better than bread made with non-germinated brown rice flour [73]. Lower firmness in germinated and non-germinated brown rice bread upon storage can be attributed to molecular changes in bread during starch retrogradation and changes in water migration leading to crumb quality deterioration [73]. Additionally, the germination process increased the gamma-aminobutyric acid (GABA) (an inhibitory neurotransmitter that regulates neural activity) content of bread. Use of sourdough (from germinated pigmented rice) further improved the nutritional content of bread by increasing the total phenolic content, antioxidant activities, GABA, and free amino acids [74]. The colour of the bread was significantly influenced by the pigmented rice, which notably enhanced its overall acceptability.

GF bread, being mainly starch based and low in nutritional content, can benefit from the use of pigmented rice as it improves its technological and nutritional quality. Polished white rice is often used in developing GF bread as it is GF, neutral in taste, and readily available; however, it is of low nutritional value. The use of pigmented wholegrain rice thus offers a good potential to improve the quality of GF bread, as several studies have shown. A 100% purple rice bread was found to be comparable to 100% polished white rice bread in terms of bread volume, texture, and springiness, while highlighting a lower predicted glycaemic index and higher total phenolic content and antioxidant activities [82]. The addition of starch at the maximum of 30% (e.g., potato starch) to GF pigmented rice bread can lower crumb firmness, although increasing stickiness and springiness of dough and bread. The application of starch in GF baking has generally been proven to reduce firmness, as in this case potato starch can expand better, improving the ability of dough to trap more air, thus softening bread texture [81]. Evangelista et al. [63] applied ohmic heating for GF bread baking from pigmented rice, and found an increased specific volume, reduced crumb firmness, and enhanced relative elasticity and porosity of GF bread compared to conventional heating. As a rapid volumetric heating method, ohmic heating facilitated quick crumb formation and stabilization, effectively trapping gas and preventing rupture, which led to higher bread volume and softer crumbs [63].

7.2. Cake and Pastries

Cake (wheat-based) substituted with black pigmented rice, whether waxy or non-waxy, exhibited higher phenolic content and antioxidant activities. However, the substitution resulted in lower batter viscosity and a reduced ability to trap air during baking. Consequently, the cakes had higher firmness, chewiness, and gumminess, along with lower volume, moisture, springiness, and resilience [89,90,91]. These outcomes can be attributed to the reduced gluten content in the batter, which limits the formation of an air-trapping structure and facilitates water migration from the crumb to the crust during baking. Additionally, complexes such as amylose–lipid and protein–starch–phenolic compounds, which could have formed during the process, contributed to reduced water absorption and lower batter viscosity. GF cakes, on the other hand, benefited technologically from the use of extruded pigmented rice as the process increased batter viscosity, improving the porosity, while lowering bulk content and moisture. However, phytochemical properties decreased with an increase in extrusion temperature [87]. Germination did not improve physical quality of GF cakes, as use of germinated red rice flour still resulted in firmer crumb texture, while lack of gluten resulted in fast migration of moisture from crumb to crust [88]. However, when added to GF brownies, they showed higher volume and reduced firmness compared to those made with non-germinated pigmented rice flours. In this case, the use of germinated red rice with higher amylose content enhanced the ability of rice starch granules to bind with water molecules, promoting structure formation that expands effectively under the influence of water vapor during oven baking. Nevertheless, sensory acceptability of GF brownies made from germinated red rice showed no significant difference compared to those made from non-germinated red rice [92]. Interestingly, use of protein-linking enzymes like transglutaminase in GF cakes was only effective on brown rice as it contains less phenolic compounds. Phenolic compounds act as reducing agent on disulfide crosslinks produced by transglutaminase, leading to breakdown of dough after mixing, reduced dough stability, and reduced cake volume [86]. Despite these effects on physical product properties, the nutritional quality was improved in biscuits, cookies, and crackers substituted with pigmented rice addition. They showed higher amount of total phenolic content, antioxidant activities, protein, lipids, ash, and crude fibre [93,94,95]. Biscuits substituted with purple rice exhibited higher protein digestibility, lower starch digestibility, and lower predicted glycaemic index. Substitution of at least 25% pigmented rice in these bakery products was considered acceptable by the consumers and even close to the control samples. Overall, the use of pigmented rice in these bakery products is less challenging compared to its use in bread, as volume is not as critical for their quality. Incorporating pigmented rice (at least 25% w/w) can produce acceptable and nutritious biscuits, cookies, and crackers.

7.3. Pasta and Noodles

Pasta and noodles made with pigmented rice showed higher nutritional benefits, such as increased total phenolic content and antioxidant activities, compared to those made from white rice, semolina, or wheat flour. However, the cooking qualities were negatively affected, including decreased cooking time (undesirable for pasta but desirable for noodles), higher cooking loss, and variable water absorption [97,98,99,100]. Increasing substitution of pigmented rice to both pasta and noodles caused an increase in hardness and a decrease in elasticity. Interestingly, GF noodles were found to benefit from addition of pigmented rice. They showed improved cooking qualities (decreased cooking time, higher water absorption, and higher cooking yield), textural properties, and consumer acceptance when substituted with up to 25% pigmented rice (red and purple) containing higher amylose and protein content [99,100]. The higher amylose and protein content lead to lower peak, breakdown, and final viscosities, resulting in a more thermally stable and strong gel network in the pasta, which remained flexible rather than rigid. Application of fermentation techniques could further improve GF noodles. Weiling et al. [101] reported that solid-state fermentation of brown rice used in noodles led to the formation of an optimal gel network structure, improved water absorption, reduced cooking loss and breakage rate, and enhanced sensory quality. Fermentation also resulted in lower peak, breakdown, final, and setback viscosities in both the flour and the noodles [101].

7.4. Snack Products

Extrusion cooking was investigated to produce GF pigmented rice-based snacks. Bhat et al. [102] and Sanusi et al. [104] employed a co-rotating twin screw extruder to produce brown-rice-based snacks with 90–100% brown rice flours. Conditions used were barrel screw speed of 350 and 300 rpm, temperature of 133 and 140 °C, and feed moisture content of 12 and 18%, respectively [102,104]. Brown-rice-based snacks had significantly higher taste and texture scores than white-rice-based snacks due to their crispy crust formed from higher fat content. The colour and appearance of brown-rice-based snacks were perceived better, though not significantly different from the white-rice-based snacks [102]. Brown rice extrudates exhibited high peak and breakdown viscosities, indicating that the extrudates were not fully gelatinized and still had the potential for further gelatinization or hydration, as well as greater resistance to structural breakdown during heating. However, the low final and setback viscosities observed in brown rice extrudates suggest a limited ability to retrograde, form a gel, and develop a strong structure after extrusion cooking [102]. From a nutritional viewpoint, extruded brown-rice-based snacks exhibited an intermediate glycaemic index and enhanced vitamin B1 content (0.45 mg/100 g, 85% retained after extrusion) compared to non-extruded brown rice snacks. A mixture of 70% purple rice and 12% corn flour produced an extruded snack recipe with good physical characteristics (colour and texture) and moderate sensory acceptability [103]. As expected, black and red rice snack extrudates exhibited higher antioxidant capacities compared to brown and white rice extrudates even after extrusion [31]. Rice with a high peak viscosity produced extrudates with a greater degree of expansion and a less porous structure. In contrast, rice with higher phenolic content, such as red rice, resulted in extrudates with a lower degree of expansion and higher porosity, indicating a more compact wall structure with greater resistance to breaking. Additionally, the study concluded that, in terms of grain shape, shorter rice grain varieties undergo greater expansion during extrusion cooking compared to longer grain varieties [31].

In terms of extruded breakfast cereals, black rice extrudates showed higher phenolics and antioxidant capacity (particularly anthocyanins), contained more protein, dietary fibre, ash, lipids, and amylose compared to red rice extrudates. However, red rice extrudates exhibited better expansion properties but had a fragile structure in milk, affecting water absorption and viscosity [105]. It was emphasized that moisture rather than temperature had an impact on the quality of extruded rice-based breakfast cereals. Higher moisture can lead to less expanded, denser, harder, and darker extrudates.

When utilized for popped snacks, pigmented rice varieties (red and black) retained elevated levels of phytochemicals and oryzanol, demonstrated high antioxidant capacities, maintained insoluble fibre, exhibited a reduction in total starch content, and showed an increase in iron content. Conversely, white rice still achieved the highest volume and popping percentage [109]. Black rice used in GF crackers showed higher nutritional content, polyphenols, proanthocyanidins, and flavonoids [95]. Black rice can also be used in preparation of nachos; 30 min of steaming at 100 °C and 13.12 min of roasting at 180 °C were found to produce an acceptable product quality with high phenolic content and antioxidant potentials [108].

8. Conclusions and Future Research Directions

Pigmented rice offers significant potential for enhancing the technological, nutritional and sensory properties of bread, bakery products, and snacks. Substituting a portion of wheat flour with pigmented rice flour in bread formulations enhanced sensory attributes and nutritional quality, although it affected dough rheology and bread volume either positively or negatively depending on the rice ratio and process conditions. All products with added pigmented rice showed improved total phenolic content and antioxidant capacities. Wheat-based bread demonstrated improved volume and texture with the inclusion of extruded pigmented rice as well as germinated and fermented (sourdough) pigmented rice, while the addition of other starch-based ingredients yielded no noticeable benefits. Extrusion cooking improved technological properties of dough, bread, and bakery products, while the processes of germination and fermentation further enhanced the nutritional value of bakery products by increasing the levels of GABA. Additionally, pigmented rice flour can be used to improve GF bread volume, crumb firmness, and relative elasticity compared to white rice bread, especially with application of ohmic heating. Cupcakes, brownies, biscuits, and cookies benefited from pigmented rice’s improved sensory qualities and consumer acceptance. Extruded snacks, breakfast cereals, and snacks from pigmented rice proved to have good sensory qualities and acceptance. Pigmented rice-based pasta and noodles showed compromised cooking qualities but germination of rice grain improved noodle cooking qualities. Short-duration parboiling of pigmented rice, especially when combined with germination, can enhance both its nutritional profile and viscosity properties. Additionally, integrating parboiling with extrusion cooking has been shown to improve the quality of pasta made from white rice, suggesting potential benefits if applied to pigmented rice as well.

However, given the potential of pigmented rice as a functional food and ingredient, significant challenges remain, its lower yield and, consequently, limited production maintaining its niche status. While there are technological hurdles associated with incorporating pigmented rice into bread and bakery products, numerous studies have demonstrated promising strategies to address these challenges. Still, the use of pigmented rice in product development has to be fully scaled up (industrial scale) for widespread commercial application. Future efforts should focus on agronomic advancement of pigmented rice, optimizing pre-processing technologies (e.g., parboiling and milling) and processing techniques by further refinement of extrusion, ohmic heating, fermentation, and germination to maximize the technological properties of pigmented rice. It is also important to explore genetic and varietal differences among pigmented rice to gain valuable insights in identifying best cultivars for specific food and technology applications. Genetic and varietal differences in pigmented rice significantly influence its technological and nutritional properties, and understanding these differences is essential for identifying the optimal processing technologies and conditions. Other areas to be considered are consumer awareness and market potential of pigmented rice to increase utilization. In conclusion, pigmented rice presents a promising ingredient for improving the technological and nutritional properties of bread, bakery products, and snacks, with high potential applications in gluten-free and health-focused food products.