The Impact of Cereal-Based Plant Beverages on Wheat Bread Quality: A Study of Oat, Millet, and Spelt Beverages

Abstract

Cereal-based plant beverages have gained attention as functional ingredients in bakery formulations, offering both nutritional and technological benefits. Replacing water with these beverages may improve the nutritional value of bread by increasing its fiber and unsaturated fatty acid content, while also introducing functional components that affect dough rheology and bread texture. This study examined the effects of substituting water with oat (BO), millet (BM), and spelt (BS) beverages in wheat bread formulations at 25%, 50%, 75%, and 100% levels. Thirteen bread variants were prepared: one control and four substitution levels for each of the three cereal-based beverages, using the straight dough method, with hydration adjusted according to farinograph results. Farinograph tests showed increased water absorption (up to 64.5% in BO100 vs. 56.9% in control) and improved dough stability (10.6 min in BS100). Specific bread volume increased, with BS75 reaching 3.52 cm³/g compared to 3.09 cm³/g in control. Moisture content remained stable during storage, and crumb hardness after 72 h was lowest in BO100 (9.5 N) and BS75 (11.5 N), indicating delayed staling. All bread variants received favorable sensory ratings, with average scores above 3.75 on a 5-point scale. The highest bread yield (149.8%) and lowest baking loss (10.9%) were noted for BS100. Although BO breads had slightly higher fat and energy content, their nutritional profile remained favorable due to unsaturated fatty acids. Overall, oat and spelt beverages demonstrated the greatest potential as functional water substitutes, improving dough handling, shelf-life, and sensory quality while maintaining consumer appeal.

1. Introduction

In recent years, the baking industry has faced a steady decline in bread consumption, prompting a growing need for product innovation and diversification. At the same time, consumer interest has shifted toward clean-label, health-promoting, and functionally enriched foods, particularly within the bakery sector [1]. These trends have spurred the development of novel bread formulations that meet nutritional expectations while maintaining desirable technological and sensory qualities.

One of the key directions in bakery reformulation is the replacement of conventional ingredients—especially dairy—with plant-based alternatives. The exclusion of cow’s milk from the diet—whether due to allergies, lactose intolerance, dietary preferences such as veganism, or environmental concerns—has led to the widespread adoption of plant-based beverages [2]. Among these, cereal-based beverages—particularly those made from oat, millet, and spelt—have gained popularity due to their favorable nutritional profile, including high levels of dietary fiber, unsaturated fatty acids, essential micronutrients, and bioactive compounds [3,4]. The nutritional composition of plant-based beverages varies depending on the raw material and processing methods, which may influence the overall nutrient balance in the diet. Therefore, it is recommended to choose products fortified with calcium, vitamin D, and vitamin B12 [5].

Cereal-based plant drinks—particularly those made from oats, spelt, and millet—are characterized by a high nutritional value and have beneficial effects on human health. Oat-based beverages are rich in soluble fiber, especially β-glucan, which has been shown to reduce cholesterol levels, improve digestive function, and stabilize blood glucose levels [6,7]. Millet- and spelt-based drinks provide bioactive compounds such as polyphenols and plant sterols, which exhibit antioxidant activity and contribute to the prevention of cardiovascular diseases [6]. In addition, these beverages serve as sources of B vitamins, iron, magnesium, and other minerals essential for metabolism and immune function [8]. Regular consumption of such drinks may support a healthy diet, particularly among individuals who limit dairy intake, and may also promote gut health due to their prebiotic properties [6,7].

Beyond their nutritional potential, cereal-based beverages can influence the physicochemical and rheological properties of dough and, consequently, the quality of the final bread. The addition of such beverages may affect dough water absorption, mixing tolerance, gluten network development, and gas retention capacity—factors that are crucial for baking performance and product shelf life. Farinographic analysis and texture profile analysis (TPA) are valuable tools for characterizing these changes and guiding formulation strategies. In this context, cereal beverages function as both dairy alternatives and structuring agents in plant-based food systems.

Recent studies further emphasize the potential of cereal beverages and their by-products to support sustainable food design. For example, Kobayashi et al. [9] highlighted the upcycling potential of oat beverage production residues rich in soluble dietary fiber. Similarly, Rashed et al. [10] demonstrated that the inclusion of oat-based side-streams can influence water absorption and bread crumb texture. These findings underline the dual advantage of cereal beverages—as sources of nutrition and as contributors to resource-efficient food systems. Despite growing consumer interest and market availability of cereal-based drinks, scientific literature on their application in breadmaking—particularly as full or partial water substitutes—is still limited. Most existing studies focus either on compositional analyses or on by-product valorization, with fewer addressing their impact on dough properties, bread quality, and sensory acceptability. This study aims to bridge that gap.

Therefore, the aim of this study was to investigate the effects of substituting water with oat, millet, and spelt-based beverages—at varying levels—on the quality of wheat bread. The research focused on assessing whether these cereal-based beverages could improve selected technological (dough rheology, baking performance, crumb texture, colour) and nutritional parameters (e.g., fiber, protein, energy) in comparison to a control bread prepared with water. By integrating both technological and nutritional aspects, the study addresses the potential of cereal-based beverages as functional ingredients in plant-based bakery products, responding to growing consumer demand for dairy-free formulations and sustainability-oriented innovations.

2. Materials and Methods

2.1. Materials

In this study, wheat flour type 750 was employed as the main ingredient and sourced from a retail store in Lublin, Poland. The flour was analyzed and found to have a moisture content of 12.9% ± 0.5 and an ash content of 0.74% on a dry basis. The gluten-related parameters included a wet gluten content of 25.0% ± 1.1, dry gluten content of 8.9% ± 0.3, water absorption capacity of 16.2% ± 1.1, and a gluten index of 99.0 ± 0.5. The falling number was measured at 290 ± 18 s. The flour particle size was uniform, with 99% of particles passing through a 0.2 mm sieve. According to the manufacturer’s nutritional label (per 100 g), the flour contained 1.8 g of fat (including 0.4 g of saturated fatty acids), 71 g of carbohydrates (with less than 0.5 g of sugars), 2.9 g of dietary fiber, 12 g of protein, less than 0.01 g of salt, and an energy content of 1427 kJ.

The plant-based beverages used in this study included oat (BO), millet (BM), and spelt (BS) beverages, all of which were commercially available products (Hafer Natural, Natumi GmbH, Troisdofr, Germany). The oat (BO), spelt (BS), and millet (BM) beverages were obtained from a retail source in May 2024. The products came from the following batches: oat—batch no. 229/M4, expiry date 15 August 2024; spelt—batch no. 258/M4, expiry date 12 September 2024; millet—batch no. L2:231011, expiry date 10 October 2024. All beverages were analyzed within four weeks of purchase, using unopened packages stored at room temperature in accordance with the manufacturer’s recommendations.

The composition of the oat beverage included water, whole grain oats (15%), sunflower oil, and sea salt. The chemical composition of the oat beverage, as declared by the manufacturer per 100 mL, was as follows: fat—1.3 g (including saturated fatty acids—0.2 g, monounsaturated—0.3 g, polyunsaturated—0.8 g), carbohydrates 7.9 g (including sugars—3.9 g), dietary fiber < 0.5 g, protein—0.8 g, salt—0.13 g, and an energy value of 200 kJ.

The composition of the millet beverage included water, millet (16%), sunflower oil, and sea salt. The chemical composition of the millet beverage, as declared by the manufacturer per 100 mL, was as follows: fat—1.1 g (including saturated fatty acids—0.1 g, mono-unsaturates—0.3 g, polyunsaturates—0.7 g), carbohydrates 11 g (including sugars—5.5 g), dietary fiber < 0.5 g, protein—0.7 g, salt—0.09 g, and an energy value of 240 kJ.

The composition of the spelt beverage included water, whole grain spelt (17%), sunflower oil, and sea salt. The chemical composition of the spelt beverage, as declared by the manufacturer per 100 mL, was as follows: fat—1.0 g (including saturated fatty acids—0.1 g, monounsaturates—0.3 g, polyunsaturates—0.5 g), carbohydrates 8.7 g (including sugars—6.7 g), dietary fiber < 0.5 g, protein < 0.5 g, salt—0.13 g, and an energy value of 190 kJ.

2.2. Bread Making Procedure

Thirteen bread variants were developed, each incorporating different substitution levels of water with cereal-based plant beverages: oat (BO), millet (BM), and spelt (BS). The control bread (CON) was prepared using only wheat flour and water, with no addition of plant-based beverages. For each beverage type, four substitution levels were tested—25%, 50%, 75%, and 100% replacement of water—resulting in a total of twelve experimental formulations. Each formulation was prepared in two independent baking trials, with three loaves produced per trial, yielding six loaves per variant. A randomized design was employed to minimize the influence of potential batch effects and ensure statistical robustness.

Bread samples were labeled according to the type of beverage and its substitution percentage, using abbreviations such as BO25, BO50, BO75, BO100, and analogously for BM and BS. All formulations were based on a standard recipe: 600 g of wheat flour, 9 g of salt, 18 g of compressed yeast (Saccharomyces cerevisiae), and an amount of liquid adjusted based on farinographic water absorption (WA) to reach 500 Brabender Units of dough consistency.

The bread-making process followed the straight dough method, adapted from Zarzycki et al. [11]. Mixing was performed using a BEAR Varimixer Teddy 5 L (Varimixer A/S, Denmark), beginning with 3 min at low speed (level 1), followed by high-speed mixing. Total mixing time was determined based on farinograph results to ensure full gluten development. Fermentation was conducted in a proofing chamber (Tefi Klima Pro 100, De-bag, Germany) at 30 °C and 85 ± 2% relative humidity (RH) for 90 min. After 60 min, the dough was degassed by mixing at low speed for 30 s. The dough was then manually portioned into 290 ± 5 g pieces, molded, and placed into baking pans (18 × 7.5 × 7.0 cm). A second proofing step was carried out for 30 min under the same conditions. Fermentation times were recorded individually for each variant.

Baking was performed at 230 °C for 30 min in a Helios Pro 100 oven (Debag, Germany). After baking, loaves were cooled at room temperature for one hour, weighed, packaged individually in plastic bags, sealed, and stored under ambient conditions (20 °C, 50% RH) until further evaluation.

2.3. Farinograph Properties of Dough

Farinograph parameters, including water absorption (WA; the amount of water required to achieve a dough consistency of 500 Farinograph Units, FU), dough development time (DDT; the time needed to reach maximum dough consistency), stability time (ST; the duration for which the dough maintains its maximum consistency), dough softening (DS; the difference in consistency between the peak and 12 min later), and Farinograph Quality Number (FQN; a composite indicator of dough quality), were analyzed to assess the properties of dough made from wheat flour mixed with either water or different proportions of water and plant-based beverages (0%, 25%, 50%, 75%, and 100%). The measurements were conducted using a Farinograph-TS (Brabender, model 816100, Duisburg, Germany) following AACC Method 54-21 [12]. A fixed flour mass of 300 ± 0.1 g (corrected to 14% moisture content) was used for each test. Each formulation was analyzed in triplicate to ensure accuracy and reproducibility of the results.

2.4. Evaluation of Bread Quality Characteristics

Bread quality was assessed based on several parameters, including bread yield (BY; Equation (1)), baking loss (BL; Equation (2)), bread volume, crumb porosity, and moisture content. These parameters were analyzed 24 h after baking, while crumb moisture was additionally measured 72 h post-baking.

The porosity of the bread was assessed using a VHX-7000 microscope (Keyence, Japan) with VHX-7000 software. Observations were conducted on a 4 × 4 cm area located in the central part of the bread slice, at an angle of 0°, using ring illumination and 20× magnification. The analysis was performed with the automatic grain measurement function, based on brightness extraction and with the hole filling option enabled. Only pores with a diameter of at least 0.01 mm were included. For each sample, three measurements were taken. The number and surface area of the pores were recorded. Pore size data (in mm²) were categorized into five ranges: 0.01–0.04 mm², 0.05–0.09 mm², 0.1–0.9 mm², 1–4 mm², and above 4 mm². For each range, both the number of pores and their total surface area were determined, and their percentages relative to the total pore population were calculated.

Moisture content was determined according to AACC Method 44-15.02 [12], by drying the sample at 105 °C for 3 h until a constant weight was achieved. Bread volume was measured using the rapeseed displacement method (AACC Method 10-05.01), and specific volume (cm³/g) was calculated as the ratio of bread volume to bread weight. All measurements were performed in triplicate.

Equations used for calculation of bread yield and baking loss are as follows:

$$BY={(W}_1/W_2)·100\%$$

(1)

$$BL={\displaystyle \frac{W_3-W_1}{W_3}}·100\%$$

(2)

In which W₁ is the weight of baked bread (1 h after removal from the oven), W₂ is the amount of flour used for one loaf, and W₃ is the weight of the proofed dough (measured immediately before baking).

2.5. Evaluation of Colour Parameters of Bread Crumb

Bread crumb colour was assessed using the CIE Lab system, following the protocol by Wirkijowska et al. [13]. A Chroma Meter CR-5 spherical spectrophotometer (Konica Minolta, Sakai, Japan) was employed to determine L* (lightness), a* (red-green), and b* (yellow-blue) values. Standard calibration was performed with black and white reference plates, and each sample was measured 12 times using a D65 light source, a 10° standard observer, and an 8 mm aperture. This evaluation was conducted for breads enriched with cereal-based beverages: BO (oat), BM (millet), and BS (spelt). The total colour difference (ΔE*) compared to the control sample was calculated using Equation (3), where the control’s colour coordinates were used as a reference (L_c*, a_c*, b_c*). Additionally, the whiteness index (WI), yellowness index (YI), and browning index (BI; according to Felisiak et al. [14]) were determined based on the measured L*, a*, and b* values, using Equation (4), Equation (5) and Equation (6), respectively.

$$∆E^{*}=\sqrt{(L_c^{*}-L_i^{*}{)}^2+(a_c^{*}-a_i^{*}{)}^2+(b_c^{*}-b_i^{*}{)}^2}$$

(3)

$$WI=100-\sqrt{\left(\right(100-L^{*}{)}^2+a^2+b^2)}$$

(4)

$$YI=142.83·{\displaystyle \frac{b^{*}}{L^{*}}}$$

(5)

$$\mathrm{B}\mathrm{I}={\displaystyle \frac{\left[\left(\mathrm{X}-0.31\right)·100\right]}{0.17}};\mathrm{w}\mathrm{h}\mathrm{e}\mathrm{r}\mathrm{e}\mathrm{ }\mathrm{X}={\displaystyle \frac{{\mathrm{a}}^{\mathrm{*}}+\mathrm{1,75}·{\mathrm{L}}^{\mathrm{*}}}{5.645·{\mathrm{L}}^{\mathrm{*}}+{\mathrm{a}}^{\mathrm{*}}-3.012·{\mathrm{b}}^{\mathrm{*}}}}$$

(6)

2.6. Texture Profile Analysis (TPA) of Bread

Bread crumb texture was analyzed using the Texture Profile Analysis (TPA) method described by Wirkijowska et al. [13]. After slicing the loaves into 20 mm-thick slices and removing the crusts, cuboidal samples (30 × 30 × 20 mm) were prepared. The double compression test was conducted using a Brookfield AMETEK CTX machine (Middleboro, MA, USA) with a flat cylindrical probe (50 mm diameter), applying a 500 N maximum force. Samples were compressed to 50% of their original height at a speed of 1 mm/s, trigger load 0.98 N. TPA parameters: hardness (N), springiness (-), cohesiveness (-), and chewiness (N) were calculated using the Texture Pro software (v.1.0.19). Measurements were carried out 24 and 72 h after baking, with eight replicate measurements performed for each substitution level.

2.7. Sensory Evaluation of Bread

The sensory evaluation of bread with partial water substitution by cereal-based plant beverages (BO, BM, and BS) was carried out using a five-point hedonic scale, where 1 indicated “dislike extremely” and 5 indicated “like extremely.” The evaluation followed established standards for bread quality assessment, in accordance with ISO 8586:2012 and ISO 8589:2007 [15,16].

The panel consisted of 12 trained individuals (9 women, 3 men) selected from among the employees of the University of Life Sciences in Lublin, based on their regular consumption of bread (at least 4 times per week), good health, and no known gluten intolerance. The study was approved by the Bioethics Committee (Resolution No. UKE/09/2023).

The evaluation was carried out in a dedicated sensory laboratory under controlled conditions [15]. The laboratory provides individual tasting booths with neutral-colored walls, adjustable lighting, and controlled temperature and humidity. Tools to minimize sensory interference, such as nose clips and colored lighting, were available when necessary. These conditions enabled reliable evaluation of specific sensory parameters by minimizing cross-modal influences. Bread samples were sliced into 1 cm-thick slices, wrapped in food-grade polyethylene film, and presented in randomized order using three-digit random codes. Still mineral water was provided to cleanse the palate between samples. Each sample was evaluated in duplicate, and final scores were calculated as the mean of all individual ratings for each parameter. The following attributes were assessed: appearance—judged by loaf shape, degree of crust browning, and surface uniformity; colour—internal crumb color and crust tone; elasticity—assessed by gentle finger pressure on the crumb and observing the rate and extent of spring back; porosity—judged based on size and distribution of air pores; smell—evaluated immediately after unwrapping the sample, considering intensity and characteristic notes associated with cereal-based beverages; taste—assessed for intensity, balance, and the presence of pleasant or specific characteristic notes, overall acceptability—representing an integrated judgment of all assessed features. In this study, a mean score above 3.75 points was considered indicative of high consumer acceptability. This threshold corresponds to an acceptability index (AI) of 75%. According to Lukas et al. [17], products with an AI exceeding 70% can be regarded as acceptable in terms of sensory evaluation. This benchmark was applied to classify bread variants as either acceptable or highly acceptable based on the sensory responses of the panelists.

2.8. Chemical Composition of Raw Materials and Bread

The chemical composition of the raw materials and bread produced with various formulations was determined using standardized AACC and AOAC methods [12,18]. The following parameters were assessed: moisture content (AACC Method 44-15A), ash content (AACC Method 08-01), and protein content using the Kjeldahl method (AACC Method 46-08) with a nitrogen-to-protein conversion factor of N × 5.7. Fat content was determined according to AACC Method 30-26. Total, soluble, and insoluble dietary fiber (TDF, SDF, and IDF, respectively) in the bread samples were measured using AOAC 991.43, AOAC 985.29, and the corresponding AACC methods (32-07, 32-21, and 32-05). For the plant-based beverages, fiber content was not determined analytically but inferred from product labels and data provided by the manufacturers. Available carbohydrates were calculated by subtracting the sum of protein, fat, moisture, ash, and total dietary fiber from the total weight of the wet sample. The energy value of the bread and raw materials was calculated using Atwater conversion factors: 4 kcal/g for protein and carbohydrates, 9 kcal/g for fat, and 2 kcal/g for dietary fiber. All chemical analyses were performed in triplicate.

2.9. Statistical Analysis

All analytical results were expressed as mean values ± standard deviations. Statistical differences among samples were evaluated using one-way analysis of variance (ANOVA), followed by Tukey’s post hoc test to identify significant differences at a confidence level of p ≤ 0.05. In addition, for selected parameters Pearson correlation coefficients were calculated to assess the strength and direction of the relationship between the substitution level and the observed effect. All analyses were conducted using Statistica software (version 13.3, StatSoft Inc., USA). Each measurement was performed in triplicate or more to ensure reliability and reproducibility.

3. Results and Discussion

3.1. Farinograph Properties of Dough

The farinographic evaluation of dough with partial or full substitution of water by cereal-based plant beverages is presented in

Table 1. Farinograph parameters of wheat dough with partial water substitution by cereal-based plant beverages (0–100%).

Sample	WA [%]	DDT [min]	ST [min]	DS [FU]	FQN
CON	56.9 ± 0.1 g	4.1 ± 0.4 ef	7.3 ± 0.2 g	61.5 ± 3.5 bc	77 ± 2 g
BO25	59.9 ± 0.4 e	3.8 ± 0.3 f	8.2 ± 0.1 ef	57 ± 1 cde	89.3 ± 1.5 def
BO50	61.7 ± 0.3 c	4.1 ± 0.2 ef	8.6 ± 0.1 cde	55.7 ± 2.1 cde	93 ± 2 cde
BO75	63.6 ± 0.2 ab	5.3 ± 0.2 bc	9.0 ± 0.1 bcd	57 ± 1 cde	100 ± 2 bcd
BO100	64.5 ± 0.4 a	5.8 ± 0.1 ab	9.3 ± 0.1 bc	55 ± 2 def	108 ± 3 b
BS25	60.6 ± 0.8 de	4.7 ± 0.2 d	8.5 ± 0.6 de	53.7 ± 4.5 ef	88.3 ± 11 defg
BS50	61.5 ± 0.2 cd	4.5 ± 0 ed	8.3 ± 0.2 def	54 ± 1 def	96 ± 2 bcde
BS75	63.1 ± 0.4 b	5.6 ± 0.2 abc	9.6 ± 0.1 b	56.3 ± 1.5 cde	103 ± 3 bc
BS100	63.8 ± 0.2 ab	5.9 ± 0.1 a	10.6 ± 0.4 a	49.3 ± 1.5 f	125 ± 5 a
BM25	58.9 ± 0.3 f	3.9 ± 0.2 f	7.2 ± 0.1 g	68 ± 1 a	79 ± 2 fg
BM50	60.2 ± 0.1 e	4.1 ± 0.1 ef	7.6 ± 0.2 fg	66 ± 2 ab	84 ± 3 efg
BM75	61.8 ± 0.1 c	5.0 ± 0.2 cd	8.3 ± 0.2 def	60 ± 1 bcd	91 ± 2 cdef
BM100	63.9 ± 0.2 ab	5.6 ± 0.1 ab	9.4 ± 0.1 bc	57 ± 2 cde	102 ± 4 bc

CON—control sample; BO—dough with oat beverages; BS—dough with spelt beverages; BM—dough with millet beverages (25–100 the numbers indicate the percentage of water substituted with plant-based beverages); mean values (n = 3) ± SD; different lowercase letters (a–g) within a column indicate statistically significant differences (Tukey’s test, p ≤ 0.05); WA—water adsorption; DDT—dough development time; ST—Stability time; DS—Dough softening; FQN—Farinograph Quality Number.

. The results confirm that both the type of beverage and the substitution level significantly influenced the mixing behavior and the quality of wheat dough. Water absorption (WA) increased significantly (p ≤ 0.05) in all tested variants as the proportion of plant-based beverage increased. The control dough (CON) exhibited the lowest WA (56.9%), while the highest values were recorded in BO100 (64.5%), BS100 (63.8%), and BM100 (63.9%). This increase is likely attributed to the presence of dry matter, particularly dietary fiber, which enhances the dough’s water-binding capacity. Similar trends were observed by Rashed et al. [10], who reported increased water absorption in doughs supplemented with oat beverage residue flour. Their results showed that water absorption rose proportionally with both the particle size and the inclusion level of the additive. In the present study, oat and spelt beverages produced the most substantial increases in WA, particularly at substitution levels above 50%, which aligns with the differences in fiber content across the beverages. The effect of fiber on water absorption, regardless of its origin, has been widely documented in the literature [13,19,20,21]. However, some studies have shown the opposite trend. For example, Roozegar et al. [22] and Codina et al. [23] found that the addition of ground whole flaxseed led to a decrease in WA. This was attributed to gluten dilution and the high fat content of flaxseed, which may coat gluten and starch particles, reducing their ability to absorb water.

DDT, indicating the time required to reach maximum dough consistency, also increased with substitution level. The longest development times were recorded for BS100 (5.9 min) and BO100 (5.8 min), suggesting that higher concentrations of cereal-based beverages delay gluten network formation. This effect may be explained by the presence of non-gluten proteins, fiber, and lipids in the beverages, which interfere with gluten matrix formation. Among the tested beverages, spelt had the most pronounced impact on extending DDT. ST increased proportionally with beverage content, with the highest value noted for BS100 (10.6 min), indicating improved dough resistance to mechanical stress. Similar, though less marked, trends were observed in oat and millet-based doughs. Such increases suggest that cereal-based beverages may reinforce the dough structure, potentially through water redistribution or interactions with gluten proteins.

Soluble dietary fibers, such as β-glucans, are known to interact with gluten in several ways: they can compete with proteins for water, delaying hydration and gluten alignment; they may also physically disrupt the continuity of the gluten network, reducing its cohesiveness and elasticity. Moreover, viscous fiber gels can influence dough consistency by increasing the viscosity of the continuous phase and modifying gas retention properties. These interactions likely contribute to the longer development and stability times observed, particularly in formulations with higher fiber content [24,25]. These physicochemical effects may also involve structural rearrangements at the molecular level. Soluble fibers may promote the formation of hydrogen bonds with gluten proteins, leading to partial dehydration and a shift in protein conformation toward more polymerized and stable structures. In some cases, this includes an increase in β-sheet and β-turn structures, which are associated with stronger, more ordered gluten matrices. Additionally, fibers such as arabinoxylans (AX) and β-glucans may form molecular complexes with gluten proteins, improving dough strength and stability at moderate concentrations. However, at higher concentrations, excessive fiber content can cause steric hindrance or promote self-aggregation, weakening the gluten network. These combined effects explain both the beneficial increases in farinograph stability and the formulation-dependent variability in dough behavior [26,27,28,29,30,31].

Both DDT and ST are essential indicators of flour strength. A longer development time typically reflects greater gluten strength, while a higher stability time suggests better dough tolerance to mixing and enhanced ability to retain CO₂ during fermentation—both characteristics favorable for breadmaking [19,32,33]. These beneficial effects were especially evident in doughs with oat and spelt beverages. Interestingly, Rashed et al. [10] reported contrasting results when using oat beverage residue flour. They observed a significant (p < 0.05) decrease in both dough stability and development time across different particle sizes and inclusion levels. This adverse effect was likely due to the high concentration of solids in the oat residue flour, which may have diluted gluten proteins and weakened the dough matrix.

DS decreased or remained stable in most formulations. The lowest DS value was observed in BS100 (49.3 FU), indicating high resistance to overmixing. In contrast, the highest softening was recorded for BM25 (68 FU), suggesting a weaker gluten structure and lower mechanical stability. A combination of high water absorption and low softening is generally considered favorable, as it reflects doughs that can withstand extended mixing without breakdown [33].

The Farinograph Quality Number (FQN), a composite parameter reflecting overall dough quality, increased with substitution level across all beverage types. The control dough had the lowest FQN (77), while the highest value was observed for BS100 (125). Oat- and millet-based beverages also contributed positively, reaching FQN values of 108 (BO100) and 102 (BM100), respectively. These results confirm the beneficial influence of plant-based beverages—especially spelt and oat—on dough processing characteristics.

In summary, cereal-based beverages significantly influenced farinograph parameters, particularly at higher substitution levels. All tested beverages improved water absorption and dough stability, while also extending development time and enhancing dough quality. Among the tested variants, spelt-based beverages had the most favorable impact on dough performance, followed by oat. These findings highlight their potential as functional substitutes for water in wheat breadmaking, with the ability to improve dough strength and mixing tolerance.

3.2. Chemical Composition of Raw Materials and Bread

The chemical composition of raw materials and resulting bread samples is presented in

Table 2. Chemical composition of raw materials: wheat flour (WF), oat beverages (BO), spelt beverages (BS) and millet beverages (BM), and bread with progressive addition of BH, BW and BA.

Sample	Raw Materials and Bread Compositions [% d.b.]
	Ash	Protein	Fat	TDF	CHO	Energy [kcal/100 g]
Raw materials
WF	0.79 ± 0.01 b	13.43 ± 1.43 a	1.72 ± 0.08 d	3.41 ± 0.51 b	80.64 ± 1.86 a	351.23 ± 2.83 a
BO	1.28 ± 0.03 a	7.70 ± 0.03 b	10.78 ± 0.23 a	5.04 ± 0.24 a	75.20 ± 0.56 b	46.98 ± 1.28 c
BS	1.27 ± 0.07 a	4.91 ± 0.29 c	9.55 ± 0.31 b	4.68 ± 0.07 a	79.60 ± 1.16 a	47.64 ± 0.84 c
BM	0.74 ± 0.07 b	5.19 ± 0.03 c	8.52 ± 0.31 c	3.80 ± 0.07 b	81.81 ± 1.38 a	60.79 ± 3.09 b
Bread
CON	2.30 ± 0.01 b	13.45 ± 1.38 a	1.81 ± 0.07 e	3.58 ± 0.5 a	78.70 ± 1.8 a	222.38 ± 0.75 g
BO25	2.30 ± 0.01 ab	13.35 ± 1.36 a	1.97 ± 0.07 de	3.61 ± 0.48 a	78.64 ± 1.76 a	224.72 ± 0.75 f
BO50	2.31 ± 0.01 ab	13.25 ± 1.33 a	2.13 ± 0.08 bcd	3.63 ± 0.47 a	78.58 ± 1.72 a	229.18 ± 0.75 de
BO75	2.32 ± 0.01 ab	13.15 ± 1.31 a	2.29 ± 0.08 abc	3.66 ± 0.46 a	78.51 ± 1.67 a	229.88 ± 0.74 cde
BO100	2.33 ± 0.01 a	13.05 ± 1.28 a	2.45 ± 0.08 a	3.69 ± 0.44 a	78.45 ± 1.63 a	232.23 ± 0.74 b
BS25	2.30 ± 0.01 ab	13.30 ± 1.35 a	1.95 ± 0.08 de	3.60 ± 0.49 a	78.72 ± 1.75 a	223.03 ± 0.75 fg
BS50	2.31 ± 0.01 ab	13.15 ± 1.32 a	2.09 ± 0.08 cd	3.62 ± 0.48 a	78.73 ± 1.71 a	229.36 ± 0.77 de
BS75	2.32 ± 0.01 ab	12.99 ± 1.29 a	2.23 ± 0.09 abc	3.64 ± 0.47 a	78.75 ± 1.66 a	231.64 ± 0.77 bc
BS100	2.33 ± 0.01 a	12.84 ± 1.26 a	2.37 ± 0.09 ab	3.66 ± 0.46 a	78.76 ± 1.62 a	230.99 ± 0.76 bcde
BM25	2.29 ± 0.01 b	13.27 ± 1.35 a	1.96 ± 0.08 de	3.59 ± 0.48 a	78.77 ± 1.75 a	229.13 ± 0.77 e
BM50	2.29 ± 0.01 b	13.09 ± 1.32 a	2.11 ± 0.08 cd	3.59 ± 0.47 a	78.84 ± 1.7 a	231.43 ± 0.78 bcd
BM75	2.29 ± 0.01 b	12.90 ± 1.29 a	2.26 ± 0.09 abc	3.60 ± 0.46 a	78.91 ± 1.66 a	232.45 ± 0.78 b
BM100	2.29 ± 0.01 b	12.71 ± 1.26 a	2.42 ± 0.09 a	3.60 ± 0.45 a	78.98 ± 1.61 a	235.34 ± 0.79 a

CON—control sample; BO—bread with oat beverages; BS—bread with spelt beverages; BM—bread with millet beverages (25–100 the numbers indicate the percentage of water substituted with plant-based beverages); CHO—catbohydrates; mean values (n = 3) ± SD; different lowercase letters (a–g) within a column indicate statistically significant differences (Tukey’s test, p ≤ 0.05).

. Among the cereal-based beverages, oat (BO) and spelt (BS) beverages exhibited the highest ash content (1.28% and 1.27% d.b., respectively), exceeding that of wheat flour (0.79% d.b.). Millet beverage had a lower ash content than flour, though the difference was not statistically significant (p ≤ 0.05). For comparison, Salama et al. [34] reported ash contents of 0.49% and 0.82% d.b. in oat and barley beverages, respectively.

In the bread samples, ash content remained similar to the control, except for statistically significant increases in BO100 and BS100. Protein content was highest in wheat flour (13.43% d.b.), and lowest in the spelt beverage (4.91% d.b.). Despite these differences, protein levels in bread did not differ significantly across variants, although a slight downward trend was observed with increasing beverage substitution. This likely reflects the lower protein content of the beverages compared to water-based formulations.

Fat content, in contrast, increased with beverage substitution, most notably in breads with oat beverage. BO100 contained 35% more fat than the control, while the lowest increase was observed in breads with spelt beverage. This pattern corresponds with the naturally high fat content of oats, which may reach up to 18% [3]. As cereals are known sources of unsaturated fatty acids—primarily linoleic (omega-6) and oleic (omega-9) acids—the nutritional quality of the fat fraction is considered favourable. The dominant saturated fatty acid in cereals is palmitic acid (Day, 2004), but its proportion remains relatively low compared to the unsaturated fraction [4,35].

Total dietary fibre (TDF) content showed no statistically significant differences across samples; however, a slight increasing trend was noted in breads made with oat beverage, consistent with its higher fibre content (5.04% d.b.). Available carbohydrates (CHO) were similar across all breads, with significant differences only in the BO sample.

The energy value of the breads increased proportionally with the level of beverage substitution, particularly in oat- and millet-based breads. Even a 25% substitution resulted in statistically significant increases in caloric value (p ≤ 0.05). From a consumer perspective, an increase in energy content may be viewed negatively [36]. However, in this case, the rise is primarily due to the increased presence of unsaturated fatty acids—an essential component of a balanced diet with documented health benefits [37].

3.3. Evaluation of Bread Quality Characteristics

The substitution of water with plant-based beverages had a significant impact on the physical properties of wheat bread, including yield, baking loss, loaf volume, crumb moisture, and pore structure.

Bread yield and total baking loss are parameters that indicate the production profitability. Bread yield increased in all experimental groups compared to the control (CON), which achieved a yield of 139.9% (

Table 3. The physical properties of bread with partial water substitution by cereal-based plant beverages (0–100%).

Sample	Bread Yield [%]	Baking Loss [%]	Specific Volume [cm3 g−1]	Crumb Moisture After 24 h [%]	Crumb Moisture After 72 h [%]
CON	139.9 ± 0.5 h	12.4 ± 0.3 a	3.09 ± 0.04 efg	43.3 ± 0.2 a	42.4 ± 0.9 a
BO25	143.6 ± 0.5 ef	12.1 ± 0.3 a	3.28 ± 0.01 bcde	42.8 ± 0.2 a	41.8 ± 0.8 a
BO50	144.1 ± 0.3 ef	12.0 ± 0.2 a	3.21 ± 0.03 cdefg	41.8 ± 0.1 ab	40.6 ± 0.2 a
BO75	147.6 ± 0.6 b	12.0 ± 0.4 a	3.25 ± 0.02 cdef	41.7 ± 0.1 ab	40.8 ± 0.3 a
BO100	148.1 ± 0.3 b	11.8 ± 0.2 a	3.32 ± 0.03 abcd	41.3 ± 0.1 ab	39.9 ± 0.4 a
BS25	143.2 ± 0.5 f	12.4 ± 0.3 a	3.47 ± 0.01 ab	43.2 ± 0.4 a	42.4 ± 0.1 a
BS50	144.6 ± 1.1 de	12.4 ± 0.7 a	3.39 ± 0.07 abc	41.7 ± 0.4 ab	41.2 ± 0.3 a
BS75	145.6 ± 0.1 d	12.4 ± 0.0 a	3.52 ± 0.05 a	41.3 ± 0.9 ab	40.6 ± 0.3 a
BS100	149.8 ± 0.3 a	10.9 ± 0.2 b	3.27 ± 0.10 bcdef	41.5 ± 0.6 ab	40.0 ± 0.8 a
BM25	141.7 ± 0.1 g	12.4 ± 0.0 a	3.06 ± 0.03 fg	41.7 ± 0.5 ab	40.9 ± 0.2 a
BM50	143.3 ± 0.1 ef	12.4 ± 0.0 a	3.03 ± 0.13 gh	41.2 ± 0.8 ab	40.7 ± 1.4 a
BM75	145.7 ± 0.5 cd	11.8 ± 0.3 a	3.10 ± 0.02 defg	41.1 ± 0.4 ab	40.8 ± 0.0 a
BM100	147.1 ± 0.0 bc	11.8 ± 0.0 a	2.84 ± 0.17 h	40.5 ± 0.1 b	40.5 ± 1.0 a

CON—control sample; BO—bread with oat beverages; BS—bread with spelt beverages; BM—bread with millet beverages (25–100 the numbers indicate the percentage of water substituted with plant-based beverages); mean values (n = 6) ± SD; different lowercase letters (a–h) within a column indicate statistically significant differences (Tukey’s test, p ≤ 0.05).

). The greatest improvements were observed in BS100 and BO100, reaching 149.8% and 148.1%, respectively. The enhanced yield may be attributed to improved water retention in the dough, likely due to the presence of hydrophilic compounds such as β-glucans in oats and soluble dietary fiber in spelt, which are capable of effectively binding water during dough formation and baking [38]. However, it should be noted that the β-glucan content was not directly measured but assumed based on the typical composition of oat-based ingredients.

Baking losses remained relatively uniform across most samples, ranging from 11.8% to 12.4%, similar to the control (12.4%) (Table 3). Only the BS100 sample showed a significant reduction in baking loss, indicating improved moisture retention. This effect may be explained by the higher content of dietary fiber and proteins in the spelt beverage, which support water binding and reduce evaporation during baking [24].

Specific loaf volume, an important quality indicator reflecting gas retention and crumb aeration, varied significantly among the samples. The control reached 3.09 cm³/g, while the highest values were recorded in BS75 (3.52 cm³/g), BS25 (3.47 cm³/g), and BS50 (3.39 cm³/g) (Table 3). Oat beverage also positively influenced loaf volume, particularly at 100% substitution. This improvement may be related to the β-glucans present in oats, which at optimal molecular weights and moderate levels, can enhance gas retention and dough structure [25,38]. However, excessive levels of β-glucans may negatively affect volume by competing with gluten proteins for available water [39]. In contrast, millet beverage may reduce loaf volume due to the lack of gluten-compatible proteins, weakening dough structure and limiting gas retention—an effect similar to that observed in gluten-free bread [40].

Crumb moisture was assessed after 24 and 72 h of storage. The control bread showed a decline from 43.3% to 42.4%. No statistically significant differences were observed in moisture content between the control and the breads enriched with cereal-based beverages (Table 3). However, minor variations may reflect differences in water-binding capacity, determined by the chemical composition of each beverage (Table 2). Spelt and oat beverages, richer in soluble fiber and gelling agents, appeared to retain moisture more effectively than millet beverage. β-glucans from barley, for example, are known for their strong water-holding capacity, which alters water mobility and promotes redistribution within the dough, supporting crumb humidity over time [24]. Millet beverage, containing fewer hydrophilic compounds, may contribute to lower moisture retention and a faster drying rate.

Pore structure was evaluated by analyzing the proportion of pores in specific size classes. The highest share of small pores (0.01–0.04 mm²) was observed in breads containing oat and spelt beverages at substitution levels up to 75%, while the lowest percentages were found in the control and millet-based breads (Figure 1). A similar trend was noted for the 0.05–0.09 mm² range, with the smallest share again in millet-based samples.

Interestingly, millet-enriched breads exhibited a higher percentage of pores in the 0.1–0.9 mm² range, suggesting a shift toward larger pore formation. This pore size class represented the largest proportion of total pores across all samples. For pores between 1–4 mm², the highest percentages were found in BS75 and BS100. Although no statistically significant differences were observed for pores >4 mm², the highest share was also recorded in BS75.

Analysis of total pore surface area (Figure 2) revealed similar patterns. In the control, oat-, and millet-based breads, pores sized 0.1–0.9 mm² contributed the most to the total surface area. In contrast, in breads containing spelt beverage, the largest surface share was associated with pores sized 1–4 mm². As large pores contribute most significantly to total crumb volume [41], the high volume observed in BS75 is consistent with the dominance of large pores in that sample. Furthermore, pores >4 mm² contributed more to total surface area in BS75 than in the control or other variants.

Overall, the higher proportion of large pores in breads with cereal-based beverages may indicate more dynamic yeast activity and fermentation. This could be attributed to the presence of simple sugars in the beverages, serving as nutrients for yeast, as well as native amylolytic enzymes that promote starch breakdown and gas production [42].

3.4. Texture Profile Analysis (TPA) of Bread

The results of the bread crumb texture analysis, including four key parameters—hardness, springiness, cohesiveness, and chewiness—are presented in

Table 4. Texture profile analysis of the bread with partial water substitution by cereal-based plant beverages (0–100%) after 24 and 72 h of storage.

Sample	Hardness [N]		Cohesiveness [-]		Chewiness [N]		Springiness [-]
	24 h	72 h	24 h	72 h	24 h	72 h	24 h	72 h
CON	9.7 ± 0.8 abA	15 ± 4.5 abcB	0.62 ± 0.01 aA	0.42 ± 0.03 aB	5.2 ± 0.5 aA	5.3 ± 1.4 abA	0.86 ± 0.02 aA	0.86 ± 0.01 aA
BO25	8.5 ± 0.9 abA	15.32 ± 1.25 abcdB	0.51 ± 0.01 cA	0.38 ± 0.02 abcB	3.0 ± 0.4 cdB	3.8 ± 0.4 bcdeA	0.69 ± 0.03 dA	0.65 ± 0.02 deA
BO50	9.6 ± 1.6 abA	16.38 ± 1.46 abcB	0.46 ± 0.02 deA	0.34 ± 0.02 cB	2.9 ± 0.5 cdeB	3.2 ± 0.3 cdefA	0.66 ± 0.02 dA	0.59 ± 0.02 efgA
BO75	8.1 ± 0.6 abA	12.66 ± 1.08 bcdB	0.43 ± 0.02 eA	0.33 ± 0.01 cB	1.9 ± 0.2 efB	2.3 ± 0.2 efA	0.56 ± 0.01 eA	0.55 ± 0.01 ghA
BO100	8.2 ± 0.7 abA	9.53 ± 1.02 dA	0.38 ± 0.02 fA	0.35 ± 0.02 bcB	1.6 ± 0.2 fA	1.7 ± 0.2 fA	0.52 ± 0.02 eA	0.51 ± 0.03 hA
BS25	8.8 ± 2.3 abA	13.75 ± 1.55 bcdB	0.58 ± 0.01 bA	0.4 ± 0.02 abB	3.8 ± 1.1 bcA	4.0 ± 1 bcdA	0.75 ± 0.06 cA	0.73 ± 0.07 bcA
BS50	9.1 ± 0.8 abA	14.76 ± 1.26 abcB	0.51 ± 0.03 cA	0.38 ± 0.02 abcB	3.5 ± 0.3 bcdB	3.9 ± 0.3 bcdA	0.76 ± 0.01 bcA	0.70 ± 0.01 cdA
BS75	7.5 ± 0.9 bA	11.45 ± 1.71 cdB	0.51 ± 0.02 cA	0.39 ± 0.01 abB	2.6 ± 0.5 defA	2.6 ± 0.5 defA	0.67 ± 0.04 dA	0.57 ± 0.05 fghB
BS100	10.0 ± 0.3 aA	17.33 ± 2.19 abB	0.44 ± 0.02 eA	0.35 ± 0.02 bcB	3.0 ± 0.2 cdeB	3.5 ± 0.3 cdeA	0.68 ± 0.02 dA	0.58 ± 0.02 efgB
BM25	9.4 ± 0.8 abA	19.44 ± 4.18 aB	0.56 ± 0.03 bA	0.39 ± 0.01 abB	4.3 ± 0.2 abB	6.2 ± 1.2 aA	0.81 ± 0.01 abA	0.82 ± 0.02 aA
BM50	8.9 ± 0.8 abA	14.59 ± 1.33 bcB	0.51 ± 0.03 cA	0.41 ± 0.03 aB	3.4 ± 0.4 bcdB	4.5 ± 0.8 bcA	0.76 ± 0.02 bcA	0.76 ± 0.03 bA
BM75	8.3 ± 0.9 abA	15.78 ± 1.93 abcB	0.49 ± 0.02 cdA	0.35 ± 0.03 bcB	2.9 ± 0.2 cdeB	3.8 ± 0.3 cdA	0.71 ± 0.02 cdA	0.70 ± 0.03 cdA
BM100	9.9 ± 0.4 aA	12.71 ± 1.36 bcdB	0.44 ± 0.02 eA	0.39 ± 0.04 abB	2.9 ± 0.3 cdeA	3.0 ± 0.2 defA	0.67 ± 0.03 dA	0.61 ± 0.01 efB

CON—control sample; BO—bread with oat beverages; BS—bread with spelt beverages; BM—bread with millet beverages (25–100 the numbers indicate the percentage of water substituted with plant-based beverages); mean values (n = 8) ± SD; different lowercase letters (a–h) within a column and uppercase letters (A, B) within a row indicate statistically significant differences (Tukey’s test, p ≤ 0.05).

. As expected, storage time had a marked effect on texture characteristics across all samples, with notable differences depending on the type of cereal-based beverage and the level of substitution.

Hardness, a primary indicator of crumb firmness and staling, increased progressively after 72 h in all formulations. At 24 h, hardness values ranged from 7.5 N (BS75) to 10.0 N (BS100), with no statistically significant (p ≥ 0.05) differences compared to the control sample (9.7 N). At 24 h, a weak correlation was found between substitution level and crumb hardness for BM (r = −0.17) and BS (r = −0.11), while the correlation was moderately negative for BO (r = −0.70), suggesting that higher oat substitution may have contributed to slightly lower hardness. After 72 h, a significant increase (p ≤ 0.05) was observed in most variants, particularly in BM25 (19.4 N) and BM100 (12.7 N), suggesting more rapid firming and moisture loss in millet-based breads. Conversely, BO100 and BS75 retained relatively lower hardness values (9.5 N and 11.5 N, respectively), indicating better textural stability during storage. These findings align with the results reported by Rashed et al. [10], who observed increased crumb hardness with oat beverage residue flour—particularly at higher inclusion levels and larger particle sizes—due to gluten network dilution and fiber interference with gas retention. While the present study used whole beverages instead of concentrated residues, a similar trend was observed at higher substitution levels, particularly in millet-based samples. The observed increase in crumb hardness over time may be partially attributed to the presence of dietary fibers in the cereal-based beverages. Dietary fibers—especially insoluble ones—are known to enhance crumb firmness by promoting inter- and intramolecular hydrogen bonding and by increasing the mechanical strength of the dough matrix. This effect stems from their ability to compete for water with gluten proteins, leading to reduced hydration and plasticity of the gluten network and more extensive starch retrogradation during storage [43,44]. Additionally, fibers may act as physical barriers within the protein–starch matrix, contributing to crumb densification and reduced gas cell expansion. Such structural modifications not only increase hardness but also reduce elasticity and springiness. The extent of these changes varies depending on fiber type, solubility, and particle size. For instance, fine wheat bran has been shown to increase hardness more significantly than coarser fractions [45], while some hydrocolloids such as almond gum can soften bread when used at optimal concentrations [46]. Similarly, Bartkiene et al. [7] found that breads containing up to 15% fermented oat beverage by-products exhibited reduced crumb firmness after 96 h, supporting the notion that fiber-rich oat materials can positively influence bread softness during storage.

Springiness, which measures the ability of the crumb to recover after compression, decreased in all samples over time. The control bread retained the highest springiness at both 24 and 72 h (0.86), while the most substantial decrease (p ≤ 0.05) was observed in BO100 (to 0.52). Similar significant (p ≤ 0.05) reductions were noted in BS100 and BM100 (0.58 and 0.61, respectively), indicating gradual weakening of the crumb structure, particularly in high-fiber formulations. According to Dürrenberger et al. [47] and Rashed et al. [10], decreased aeration and increased dough density are associated with reduced crumb springiness. This supports the trend observed in the current study, especially for oat-based breads at high substitution levels. A strong negative correlation (at 24 h) was observed between substitution level and springiness, particularly in BO (r = −0.96), BM (r = −0.99), and BS (r = −0.91), confirming the dose-dependent weakening of elastic recovery.

Cohesiveness, which reflects internal structural bonding, also declined during storage. Initially, the control sample had the highest cohesiveness (0.62), while BO100 and BS100 exhibited the significantly (p ≤ 0.05) lowest values (0.38 and 0.44, respectively). By 72 h, all variants showed further decreases, particularly at high substitution levels. These results suggest that high proportions of cereal-based beverages, particularly those rich in fiber and fat, may interfere with the gluten matrix, reducing structural integrity during prolonged storage. Although these structural changes were inferred from texture and farinographic data, it should be noted that no direct microscopic observations or gluten index measurements were conducted in this study. As reported by Rashed et al. [10], high-fiber residues interfere with gluten continuity, reducing elasticity and cohesiveness—a phenomenon also evident in our study. Bartkiene et al. [7] similarly noted that breads enriched with fermented oat by-products maintained acceptable cohesiveness over four days of storage, especially at moderate (15%) inclusion levels. These effects are likely related to the physicochemical interactions between soluble dietary fibers and the gluten network. Fibers such as β-glucans can compete with gluten proteins for water, thereby limiting protein hydration and network formation. In addition, they may sterically hinder protein–protein bonding and act as structural diluents, weakening the continuity and elasticity of the gluten matrix [24,25,38]. Such mechanisms help explain the pronounced decrease in cohesiveness observed in BO100 and BS100, where fiber content is highest. The strength of this effect is supported by the high negative correlations (at 24 h) between beverage level and cohesiveness, reaching r = −0.97 for both BO and BS, and r = −0.99 for BM.

Chewiness, a compound parameter derived from hardness, springiness, and cohesiveness, mirrored the trends in those variables. At 24 h, the highest chewiness values were recorded in the control (5.2 N) and BM25 (4.3 N). Chewiness also showed a strong negative correlation with substitution level across all beverages (r = −0.93 for BO, −0.89 for BS, and −0.95 for BM), indicating that higher inclusion levels consistently reduced textural resistance. At 72 h, chewiness increased slightly in most samples but remained significantly lower (p ≤ 0.05) in BO100 and BS100 (1.6–3.0 N), suggesting improved resistance to staling. However, the increase was less pronounced in oat- and spelt-based breads, indicating a slower staling rate. These outcomes are consistent with Bartkiene et al. [7], who found that fermented and ultrasonicated oat by-products contributed to softer crumbs and slower texture deterioration, likely due to their moisture-retaining capacity and modified crumb structure. The inverse relationship between aeration and crumb density described by Rashed et al. [10] further explains the reduced chewiness observed in these variants.

Interestingly, the trends observed in our study partially contrast with those reported for dairy-based substitutions. According to Iuga et al. [48], replacing water with milk or acid whey led to significant increases in crumb firmness, gumminess, chewiness, and resilience, particularly at higher substitution levels. Moreover, crumb cohesiveness increased in milk-based samples but decreased in acid whey breads, suggesting matrix-dependent effects. In our study, all cereal-based beverage variants showed reduced cohesiveness at high substitution levels, aligning more closely with the acid whey results. The relatively lower firmness values observed in oat- and spelt-based breads also suggest that these beverages may be less disruptive to crumb softness than dairy ingredients, likely due to their lower protein and sugar content and more favorable fiber composition.

Overall, cereal-based beverages influenced bread texture in a beverage- and dose-dependent manner. At 25% substitution, most samples exhibited textural profiles similar to the control. However, higher substitution levels (75–100%) led to more pronounced effects. Oat and spelt beverages were particularly effective in maintaining crumb softness and elasticity during storage, while millet-based variants exhibited increased firmness and chewiness. These results, supported by Bartkiene et al. [7], Rashed et al. [10], and Iuga et al. [48], highlight the role of fiber structure, gluten interaction, and moisture dynamics in shaping bread texture. Thus, cereal-based beverages—especially oat and spelt—may serve as functional ingredients for extending the freshness and improving the shelf life of wheat breads.

One limitation of this study is that the beverages used were commercial formulations containing not only cereal extracts but also small amounts of non-cereal ingredients such as vegetable oil, salt, or stabilizers. While these additions reflect typical consumer products and enhance practical relevance, they may have contributed to the observed effects on dough rheology, baking performance, or crumb structure. Moreover, the study evaluated each beverage as a whole and did not attempt to isolate the individual contributions of specific components such as fiber, protein, or other bioactive compounds. Future research using simplified or model formulations—allowing controlled variation of ingredient ratios—would help disentangle the effects of cereal-derived compounds from those of added excipients, and provide deeper mechanistic insight into the functional role of these bever-ages in breadmaking.

3.5. Evaluation of Colour Parameters of Bread Crumb

The colour of bread crumb is an important quality attribute that influences consumer perception and product appeal. The lightness (L*) value of breads containing millet and spelt beverages, at substitution levels up to 75%, did not differ significantly from the control sample (

Table 5. Crumb colour of bread with increasing levels of water substitution using cereal-based plant beverages (0–100%).

Sample	L*	a*	b*	∆E*	WI	BI	YI
CON	63.7 ± 2.9 ab	0.7 ± 0.2 ab	14.9 ± 0.6 c	-	60.8 ± 2.7 ab	26.9 ± 2.1 c	33.4 ± 2.2 d
BO25	60.1 ± 2.4 cde	0.6 ± 0.2 ab	15.2 ± 0.7 bc	3.9 ± 2.1 abcd	57.2 ± 2.2 cde	29.3 ± 2.1 bc	36.2 ± 2 bcd
BO50	60.1 ± 2.8 bcde	0.6 ± 0.2 ab	15.3 ± 1.4 abc	4 ± 2.6 abcd	57.2 ± 2.3 bcde	29.5 ± 2.4 abc	36.4 ± 2.4 abcd
BO75	58.1 ± 2.7 e	0.5 ± 0.1 ab	15.4 ± 0.3 abc	5.6 ± 2.7 ab	55.4 ± 2.6 e	30.9 ± 2.5 abc	38 ± 2.6 ab
BO100	57.8 ± 2.1 e	0.6 ± 0.1 ab	15.4 ± 0.5 abc	6 ± 2.1 a	55 ± 1.9 e	31.1 ± 1.5 ab	38.2 ± 1.5 ab
BS25	61.5 ± 1.9 abcde	0.6 ± 0.2 ab	15 ± 0.7 c	2.4 ± 1.8 bcd	58.7 ± 1.8 abcde	28.2 ± 2 bc	34.9 ± 1.9 bcd
BS50	61.4 ± 2.2 abcde	0.7 ± 0.3 ab	15.5 ± 1.2 abc	2.7 ± 2.1 abcd	58.3 ± 2.2 abcde	29.4 ± 3.6 abc	36.2 ± 3.4 abcd
BS75	61.1 ± 1 abcde	0.4 ± 0.2 b	15.4 ± 0.5 abc	2.7 ± 0.8 bcd	58.2 ± 0.9 abcde	28.8 ± 1.3 bc	35.9 ± 1.3 bcd
BS100	59.5 ± 3 de	0.9 ± 0.2 a	16.8 ± 0.8 a	4.8 ± 2.6 abc	56.2 ± 2.6 de	33.5 ± 2 a	40.3 ± 1.8 a
BM25	63.6 ± 1.5 ab	0.6 ± 0.2 ab	15 ± 0.8 c	1.5 ± 0.7 d	60.6 ± 1.5 ab	27.1 ± 2 c	33.8 ± 2 cd
BM50	62.7 ± 2.4 abcd	0.6 ± 0.4 ab	15.4 ± 1.1 bc	2.5 ± 1 bcd	59.6 ± 2.3 abcd	28.3 ± 3.2 bc	35.1 ± 3.1 bcd
BM75	64.3 ± 1.7 a	0.7 ± 0.2 ab	15.8 ± 0.8 abc	1.9 ± 0.9 d	60.9 ± 1.5 a	28.4 ± 1.9 bc	35.2 ± 1.8 bcd
BM100	63.5 ± 1.9 abc	0.8 ± 0.2 ab	16.5 ± 0.7 ab	2.4 ± 0.9 cd	59.9 ± 1.6 abc	30.3 ± 1.7 abc	37.1 ± 1.7 abc

CON—control sample; BO—bread with oat beverages; BS—bread with spelt beverages; BM—bread with millet beverages (25–100 the numbers indicate the percentage of water substituted with plant-based beverages); mean values (n = 12) ± SD; different lowercase letters (a–e) within a column indicate statistically significant differences (Tukey’s test, p ≤ 0.05); ∆E*—total colour difference; WI—whiteness index; BI—browning index; YI—yellowness index.

). This suggests that these beverages had no considerable effect on crumb brightness. In contrast, even a 25% substitution with oat beverage resulted in a noticeable darkening of the crumb. According to Sandvik et al. [49], such colour changes may be positively perceived by consumers, as darker bread is often associated with higher fibre content and greater nutritional value.

No significant changes were observed in the a* parameter (red-green axis) across any of the samples, indicating that cereal-based beverages did not influence red or green tones in the crumb. However, the b* parameter, corresponding to yellowness, increased proportionally with the level of plant-based beverage substitution. This indicates a direct relationship between yellowness intensity and beverage concentration. Nonetheless, the b* values observed in this study were lower than those reported by Marciniak-Łukasiak et al. [40] in gluten-free breads supplemented with cereal beverages, likely due to differences in matrix composition and ingredient interactions.

The most noticeable changes in crumb colour were recorded in samples made with oat beverage, particularly BO75 and BO100. In these variants, the total colour difference (ΔE) exceeded 5 units—a threshold considered visually perceptible—confirming that oat beverage had the strongest effect on crumb colour among all beverages tested. This effect may be attributed to the natural composition of oat beverages, which often contain higher levels of pigments such as carotenoids and phenolic compounds. These compounds can contribute to darker and more yellow crumb coloration upon baking, due to their inherent colour and their participation in Maillard-type reactions. Moreover, the fiber content in oat beverages might also play a role in modulating water activity and heat transfer, thereby influencing browning reactions during baking.

Analysis of the whiteness index (WI) revealed the lowest values in breads containing oat beverage, corresponding with the observed reduction in L* values. In contrast, the browning index (BI) increased with higher levels of water substitution, regardless of beverage type. This trend may be attributed to the presence of simple sugars in cereal-based beverages, which promote Maillard reactions and caramelization during baking [50,51]. In this study, the occurrence of these reactions is supported by significant changes in crust color detected through colorimetric analysis. In addition, the yellowness index (YI) also increased with beverage addition, reflecting the natural beige-yellow hue of the cereal-based drinks. This finding is consistent with the upward trend in b* values observed in samples with higher substitution levels.

Overall, oat beverage had the most pronounced influence on crumb colour parameters, especially in terms of reducing brightness and enhancing yellowness. This tendency may result from the specific raw materials used in oat beverage formulations, which often include whole grain extracts rich in natural pigments and reactive compounds. Although detailed compositional analysis of the beverages was beyond the scope of this study, their known biochemical profile suggests they may promote both non-enzymatic browning and pigment transfer during baking. Spelt and millet beverages had a much milder effect, maintaining crumb colour properties closer to those of the control bread.

3.6. Sensory Evaluation of Bread

The sensory characteristics of bread, including appearance, colour, elasticity, and porosity, are crucial not only for consumer acceptance but also for evaluating functional quality. All bread samples formulated with cereal-based beverages received full consumer acceptance, with mean overall scores exceeding 3.75 points (

Table 6. Sensory evaluation of bread with increasing levels of water substitution using cereal-based plant beverages (0–100%).

Sample	Appearance	Colour	Elasticity and Porosity	Smell	Taste	Overall Acceptability
CON	4.9 ± 0.3 a	4.8 ± 0.5 a	4.9 ± 0.3 a	4.9 ± 0.3 a	4.9 ± 0.3 a	4.9 ± 0.2 a
BO25	4.9 ± 0.4 a	4.8 ± 0.4 a	4.3 ± 0.8 abc	4.7 ± 0.5 a	4.5 ± 0.8 a	4.6 ± 0.4 ab
BO50	4.9 ± 0.4 a	4.7 ± 0.5 a	4.5 ± 0.7 abc	4.6 ± 0.5 a	4.5 ± 0.6 a	4.6 ± 0.3 ab
BO75	4.9 ± 0.4 a	4.7 ± 0.5 a	4.1 ± 0.7 bc	4.8 ± 0.4 a	4.7 ± 0.6 a	4.6 ± 0.3 ab
BO100	4.7 ± 0.6 a	4.4 ± 0.5 a	3.9 ± 0.8 c	4.7 ± 0.5 a	4.5 ± 0.6 a	4.4 ± 0.3 b
BS25	4.9 ± 0.3 a	4.7 ± 0.5 a	4.5 ± 0.5 abc	4.8 ± 0.4 a	4.8 ± 0.4 a	4.7 ± 0.3 ab
BS50	4.9 ± 0.3 a	4.8 ± 0.4 a	4.9 ± 0.3 a	4.8 ± 0.4 a	4.8 ± 0.4 a	4.8 ± 0.2 a
BS75	4.9 ± 0.3 a	4.4 ± 0.5 a	4.7 ± 0.5 ab	4.8 ± 0.4 a	4.9 ± 0.3 a	4.7 ± 0.2 ab
BS100	4.9 ± 0.3 a	4.4 ± 0.5 a	4.4 ± 0.5 abc	4.7 ± 0.5 a	4.8 ± 0.4 a	4.7 ± 0.2 ab
BM25	4.6 ± 0.5 a	4.5 ± 0.7 a	4.6 ± 0.5 ab	4.9 ± 0.4 a	4.8 ± 0.4 a	4.7 ± 0.4 ab
BM50	4.9 ± 0.4 a	4.7 ± 0.5 a	4.7 ± 0.5 ab	4.9 ± 0.3 a	5.0± 0.0 a	4.8 ± 0.2 a
BM75	4.8 ± 0.4 a	4.6 ± 0.5 a	4.5 ± 0.5 abc	4.9 ± 0.3 a	5.0 ± 0.0 a	4.8 ± 0.2 ab
BM100	4.6 ± 0.5 a	4.3 ± 0.7 a	4.1 ± 0.7 bc	5.0 ± 0 a	4.9 ± 0.4 a	4.6 ± 0.3 ab

CON—control sample; BO—bread with oat beverages; BS—bread with spelt beverages; BM—bread with millet beverages (25–100 the numbers indicate the percentage of water substituted with plant-based beverages); mean values (n = 12) ± SD; different lowercase letters (a–c) within a column indicate statistically significant differences (Tukey’s test, p ≤ 0.05).

), corresponding to an acceptability index (AI) of 75%. According to Lukas et al. [17], products exceeding an AI of 70% may be considered acceptable from a sensory standpoint, confirming the positive reception of all tested breads.

Across all formulations—regardless of beverage type or substitution level—attributes such as appearance, crust color, taste, and smell were consistently rated highly, with mean scores ranging from 4.5 to 5.0. These values did not differ significantly from those of the control sample (CON, which served as the reference), indicating that replacing water with cereal-based beverages did not negatively impact the organoleptic properties. The use of a trained panel ensured precise and consistent sensory assessments, but may not fully reflect the diversity of consumer preferences. The small differences observed suggest that all formulations were well accepted. To improve representativeness, future studies could include untrained consumer testing. In addition, instrumental smell analysis—such as GC-MS or electronic nose techniques—may offer deeper insight into volatile compound profiles and their relationship with cereal-based beverage substitution.

Unlike the findings reported by Iuga et al. [48], where crust browning was intensified through Maillard reactions involving lactose in milk and acid whey, no such effect was observed in this study. This is likely due to the absence of reducing sugars in the cereal-based beverages. Nevertheless, crust colour was still rated favourably, which may be attributed to the presence of natural pigments in the plant beverages.

Elasticity and porosity showed greater sensitivity to formulation differences. Breads with spelt (BS) and millet (BM) beverages at substitution levels up to 75% retained excellent physical properties, with elasticity and porosity scores comparable to those of the control (mean values between 4.4 and 4.8). The BS50 and BM50 variants, in particular, demonstrated sensory profiles closely resembling the control, suggesting that moderate incorporation of these beverages does not compromise the gluten network.

Conversely, breads made with oat-based beverages (BO) exhibited a gradual decline in elasticity and porosity with increasing substitution level. This trend was confirmed by Pearson correlation coefficients between substitution level and the sensory score for elasticity and porosity, which were −0.90 for BO, −0.91 for BM, and −0.55 for BS. These results indicate a stronger negative impact on crumb structure in the oat- and millet-based variants compared to the spelt-based ones. The most pronounced effect was observed in BO100, where porosity dropped to 3.9 ± 0.8. This reduction is likely due to the high content of soluble fibre and β-glucans in oat beverages, which may disrupt gluten matrix formation and alter water distribution, as reported by Rashed et al. [10]. A similar observation was made in breads enriched with oat drink residue flour, where high inclusion levels led to excessive water absorption and reduced crumb elasticity, highlighting the role of both composition and particle size in the physical quality of the final product.

Although the beverages used were commercially available and required no further preparation, broader industrial application may depend on cost structure, supply chain stability, and formulation scalability. Future studies should therefore address cost–benefit considerations and validate the process in a pilot-scale or industrial context.

4. Conclusions

The substitution of water with cereal-based beverages significantly influenced the quality of wheat bread, with effects strongly dependent on both the beverage type and substitution level. All tested beverages—spelt, oat, and millet—enhanced water absorption and dough stability, while higher substitution levels (75–100%) also increased dough development time and strength. Among the tested options, spelt-based beverages demonstrated the most favorable impact on farinograph parameters, followed by oat-based beverages. The type and proportion of the beverage used also played a decisive role in shaping the bread’s physical properties. Spelt beverage improved baking performance by increasing bread yield, reducing baking loss, enhancing specific volume, and promoting crumb moisture retention. Oat beverage positively influenced yield and volume, though full substitution resulted in a decline in crumb structure and sensory texture. Millet beverage, while increasing yield at moderate levels, negatively affected crumb softness and elasticity at higher doses. Texture profile analysis confirmed that bread staling progressed in all samples during storage. However, breads enriched with oat and spelt beverages—especially at higher substitution levels—retained a softer crumb, lower chewiness, and greater springiness compared to both the control and millet-based breads. These improvements are likely linked to the hydration properties and fiber composition of the beverages, which help support gluten network integrity and moisture retention. At 25% substitution, texture characteristics across all beverage types were largely comparable to the control. Sensory analysis further demonstrated that cereal-based beverages can enhance consumer-perceived quality, particularly in terms of elasticity and porosity. The most favorable responses were observed at a 50% substitution level, especially in breads containing spelt and millet beverages. In contrast, full substitution with oat beverage negatively affected texture-related sensory attributes. Nevertheless, all samples scored above the sensory acceptability threshold (AI > 75%), confirming their potential for consumer acceptance. From a nutritional perspective, the use of cereal beverages slightly increased fat and energy content, particularly in oat-based variants. However, due to the presence of unsaturated fatty acids and dietary fiber, the overall nutritional profile may be improved. Additionally, visual and structural enhancements—such as improved crumb porosity and colour—further contribute to consumer appeal. Based on the overall evaluation of technological, textural, and sensory parameters, the optimum substitution level was identified as 75%, particularly for spelt and oat beverages. Although 100% substitution also led to improved water absorption and acceptable product quality, it was occasionally associated with a decline in crumb elasticity, porosity, and cohesiveness—especially in oat-based breads—suggesting a threshold effect beyond which further substitution becomes less beneficial.

The main goal of this study, as stated in the introduction, was to assess whether cereal-based plant beverages could serve as functional alternatives to water in wheat bread production, contributing to improved technological and nutritional properties. The results clearly confirm this objective. Cereal-based beverages—particularly spelt and oat—represent effective functional ingredients for partial or full replacement of water in wheat bread formulations. Their incorporation improves dough handling, enhances baking performance, supports textural and sensory quality, and aligns with the growing demand for sustainable, plant-based, and nutritionally enriched baked products. While the results highlight the functional potential of commercial cereal-based beverages in breadmaking, further research is needed to identify which components are primarily responsible for the observed effects. Studies using simplified or model systems may help clarify the roles of specific nutritional and functional ingredients. In addition, extending the storage period beyond 72 h could provide more insight into long-term staling dynamics and the possible inhibitory role of dietary fiber. Moreover, industrial feasibility and cost–effectiveness should be assessed to determine the practical scalability of such formulations in commercial bakery settings.