Development of Technology for Candy Caramel with Barberry Powder and Sugar Substitute Isomaltitol ^†

Abstract

Confectionery products, particularly caramel, often have low nutritional value and a high glycaemic index, necessitating the development of functional alternatives. This study aimed to create candy caramel with a reduced glycaemic index and enhanced nutritional properties by incorporating isomaltitol and invert syrup as sugar substitutes and fortifying it with dried barberry (Berberis vulgaris L.) powder in amounts of 1%, 2.5%, 5%, and 10% (w/w). Barberry powder, rich in bioactive compounds and essential minerals, also acts as a natural colourant. The powder’s microstructural characteristics were assessed using laser diffraction, while its elemental composition was confirmed via atomic adsorption spectroscopy. The samples of caramel were evaluated using physicochemical and sensory analysis methods. The results showed that the addition of barberry powder enriches caramel with sodium, potassium, iron, manganese and zinc. The increase in the content of barberry in sweets was accompanied by an increase in titratable acidity and a decrease in pH. Sensory evaluation identified 2.5–5% barberry powder as optimal, yielding a product with attractive colour and flavour. Higher concentrations resulted in excessive acidity and darker coloration, which were deemed undesirable. The developed formulation demonstrates the potential of candy caramel as a functional food product, offering improved nutritional and sensory attributes. This approach provides a promising solution for addressing the health and dietary concerns associated with traditional confectionery products.

1. Introduction

Wild berries have attracted increasing attention as a promising food source with applications in culinary, medicine, and nutritional science [1,2]. Wild berry plants are found in many parts of the world: Europe, Asia, Africa, and America [3]. They are a source of fibre that promotes digestive system health, contain vitamins and minerals (vitamin C, potassium, magnesium), and are rich in polyphenolic compounds (flavonoids, anthocyanins, tannins) [4,5]. The fibre content in barberry berries of different botanical species is 7.0–8.1% in pulp and 4.4–5.3% in seeds, the protein content in pulp is 4.7–7.2%, and in seeds—5.9–8.5%, fat—2.6–4.0% (pulp); 4.6–5.3% (seeds) [6], berries also contain ascorbic acid (10.70–13.59%), total carotenoids (345. 1–381.69 μg/100 g), total flavonoids (376.93–395.09), total phenolic substances (675.68 and 702.94) and total anthocyanins in the amount of 77.52–83.55 mg/100 ml of fresh berry juice.The antioxidant activity ranges from 71 to 80% [7]. Due to the presence of biologically active compounds, wild berries provide antioxidant effects, antimicrobial properties, antidiabetic effects, and hepatoprotective actions [8,9]. Wild berries have long been an integral part of people’s diets. As berries are a seasonal product, people have been using wild berries even before they were cultivated. They were picked, dried, boiled, and made into jams, teas, and meat sauces [10].

Today, the use of wild fruits as nutraceuticals is gaining popularity again due to their ability to improve the metabolism, boost immunity, and maintain normal cardiovascular functions. In the food industry, berries are used as spices in Asian and Oriental cuisine [11] for making drinks, jams, and pastilles, and are also used as components of energy products due to their high levels of organic acids, fibre, and vitamins (bars, breakfast cereals, drinks) [12]. Barberries can also be consumed as a dried fruit, juice, marmalade, and food additive (soup, stew, and rice dishes), due to its unique, flavourful, and sour taste and fascinating pink colour. Barberry fruit extract and decoction is used as an effective natural antioxidant in the food industry [13,14]. The presence of anthocyanins in barberry opens up the possibility of using this fruit as a natural colouring agent in the food industry [15].

Often, small seeds prevent the effective use of berries. Therefore, a species of barberry (Berberis vulgaris L. var. asperma) is cultivated in South Khorasan Province. The fruits of this species are seedless and are widely used as a food additive in cooked rice and in jams and drinks [16].

Therefore, the aim of this work (Figure 1) was to use barberry powder as a component of lollipop caramel. This additive makes the flavour of the candy richer and more expressive, adds aroma and a beautiful colour, and improves its sensory properties. To reduce the caloric content, sugar was replaced with a mixture of isomaltitol and invert syrup. This combination reduces the energy value of sweets from 390 to 313 kcal/100 g [17].

2. Materials and Methods

2.1. Materials

The berries of Berberis vulgaris (Berberidaceae), ground into powder, were used in this study. The berries were collected in Chernivtsi, Western Ukraine; were separated from the seeds; dried to an air-dry state; and ground in a household mill at RAF 300 W. For the formation of the caramel base, granulated isomaltitol (BENEO GmbH, Mannheim, Germany) and invert syrup (TM LAPED SRL, manufactured in Ospedaletto, Italy) were used. The ingredients of the developed sample formulation were purchased at the local supermarket (Chernivtsi, Ukraine). All reagents used in the analysis were of analytical grade.

2.2. Sample Preparation

A series of five samples were prepared for the analysis. A sample without barberry was used as a control. Four samples contained barberry powder at 1 to 10% of the total mass of raw materials. The concentrations of barberry powder (1%, 2.5%, 5%, and 10%) were selected based on preliminary trials to cover a technologically feasible range and were sensorially relevant for evaluating its effect on product quality. It was established that at lower concentrations, the powder is barely perceptible, while higher concentrations have a negative impact on the taste and texture of the caramel. The formulation for caramel candy with barberry powder contained, as g/100 g, 17 g of invert syrup, which was the same for all lollipops. The content of isomaltitol and barberry varied depending on the powder content: 12.5–21.5% and 1–10%, respectively. The basic production flow chart for candy caramel based on isomalt–invert syrup with the addition of barberry powder includes the following steps: preparation of a mixture of isomaltitol and invert syrup; boiling the caramel mass at a temperature of 140–145 °C; cooling the caramel to a temperature of 70–75 °C and adding barberry powder; forming the caramel, cooling and packaging (Figure 2).

2.3. Methods

The mineral composition of barberry berries was determined by atomic absorption spectrophotometry using a C-115 M atomic absorption spectrophotometer with flame atomisation. The mineralisation of the samples was carried out in a Multiwave 5000 microwave system (Anton Paar) by dissolving 0.300 g of the powder sample in 6 mL of concentrated nitric acid. The combustion was carried out in four stages. The first one was 10 minutes of heating from 0 to 90 °C, the second―10 minutes of holding at 90 °C, the third―heating from 90 to 200 °C for 10 minutes and holding at 200 °C for 10 minutes.This method ensures the complete decomposition of the sample material.

The moisture content of barberry powder and candies crushed in a mortar was determined by the express method using a Precisa XM-60 humidity metre.

The particle size distribution of barberry powder was determined using a laser diffractometer PSA 1900, Anton Paar (Anton Paar Austria GmbH, Graz, Austria). To prevent the aggregation of barberry powder particles during the measurement, 0.5–1 mL of 80% Tween 80 solution was added and the sample was sonicated for 1 min. The water activity in the powder was determined using an electronic water activity metre ‘LabMasteraw neo’ by Novasina AG (Lachen, Switzerland) at a temperature of 20 °C.

The pH of the samples was measured using a 692 pH/Ion metre (Metrohm, Herisau, Switzerland) with a combined glass electrode. The candy was milled using a mortar. A 5 g sample was dissolved in 50 mL of distilled water and the pH of the solution was measured. The rest of the solution was used to determine the titratable acidity (in terms of citric acid) by titrating with 0.1 N NaOH solution [18].

The ascorbic acid content was quantified through titration using 2,6-dichlorophenolindophenol (DCPIP) as the titrant. A 5 mL aliquot of the liquid sample was transferred to a conical flask, and the sample was titrated with a standard DCPIP solution. The titrant was added gradually until a faint and stable pink coloration indicated the titration endpoint. The volume of the titrant consumed was recorded from the burette to calculate the ascorbic acid concentration [19,20].

The Fehling method was utilised to measure the content of reducing sugars in the candies. This approach is based on the capacity of reducing sugars to reduce copper (II) ions in an alkaline medium, resulting in the formation of copper (I) oxide as a precipitate [21].

A sensory analysis of the caramel was conducted by a panel of experts following established guidelines to assess its taste, texture, aroma, and overall quality. The evaluation was performed in accordance with ISO 8589 [22], ensuring the consistency and reliability of the results. Key attributes, including sweetness, smoothness, and flavour balance, were critically examined to determine the product’s compliance with quality benchmarks.

All experiments were performed in triplicate, and results were presented as means ± standard deviation. One-way ANOVA with Tukey’s multiple comparison post hoc test was performed to assess significant differences between groups at p < 0.05.

3. Results and Discussions

3.1. Physico-Chemical Properties of Barberry

Understanding the microelement composition of barberry berries is crucial for evaluating their nutritional significance and potential health benefits. Such insights contribute to the advancement of functional confectionery products and the development of high-quality, ingredient-driven formulations.

Table 1. Content of selected elements in barberry powder, mg/100 g.

Element	Element Content, mg/100 g
	[23]	[24]	[6]	[25]	Ukrainian Barberry
K	1183.53	1274.54	392.0–648.9	1225/1380	1536.94 ± 4.67
Na	253.99	10.92	24.0–72.6	18/198	248.81 ± 2.98
Fe	34.21	10.92	12.3–180.8	0/10	8.19 ± 0.58
Mg	119.49	2.33	0.5–5.8	58/109	75.11 ± 1.23
Ca	258.73	37.40	190.2–872.5	160/132	112.25 ± 5.67
P	256.04	203.95		93/109
Mn	0.67	2.27		1/1	1.52 ± 0.12
Ni	2.29	0.58			0.28 ± 0.02
Cu	0.52	1.00	1.5–2.5	0/1	1.79 ± 0.15
Zn	9.47	9.01	1.6–11.2	2/6.4	0.92 ± 0.09
Cd		0.73		0	0

presents a comparative analysis of the elemental content in wild B. vulgaris fruits reported in the literature and the studied sample.

The results show that barberry are rich in potassium and sodium, while the content levels of calcium, magnesium, phosphorus, and zinc are also sufficient to have a beneficial effect on the nutritional properties of caramel (Table 1). Moreover, variations in the mineral composition of wild-grown barberry fruits may be due to different environmental conditions, soil type, and plant genotype [6].

The moisture content of barberry berries is in the range of 60–80%, depending on the variety and ripeness [6,7]. In this study, a powder from dried barberry berries was used. The moisture content of the air-dried powder was 2.28%, which corresponds to the data of other researchers [18]. The powder was a homogeneous free-flowing mass of red colour with a pleasant smell and pronounced taste of barberry (Figure 3a). The acidity of the barberry powder, determined titrimetrically, was 3.3 ± 0.3, and the pH was 3.20 ± 0.04. The results are in good agreement with the literature: the titrated acidities of B. calliobotrys, B. orthobotrys, and B. psedumbellata were 2.26, 2.18, and 1.36 (% citric acid), and the pH, respectively, was 3.91, 3.52, and 3.33 [7]. Such acidity values are due to the presence of a significant amount of organic acids in barberry berries, in particular, phytic acid, the content of which varies depending on the variety: from 2.2 (B. lycium) to 9.9 mg/100 (B. pseudumbellata) [6] and ascorbic acid: 10.70 (B. calliobotrys), 14.92 (B. orthobotrys) and 13.59 mg/100 (B. psedumbellata) [7].

To evaluate the effect of barberry powder on the taste properties of candy caramel, a dispersion analysis of powders obtained from dried barberry berries was carried out. The size of the powder particles affects the homogeneity of its distribution in the caramel, the uniformity of the finished product colour, and the taste properties (smaller particles arebetter distributed in the caramel mass, providing a uniform taste). Figure 3b shows that an increase in the mixing speed leads to a wider distribution. At the same time, the average particle size increases from 37 µm at 150/250 rpm to 79 µm at 450 rpm. In addition, there is an increase in the SPAN factor from 2.9 to 4.8. These factors indicate the formation of the powder into lumps at high mixing speeds.

The analysis of percentiles at low mixing speeds shows that 10% of the particles are smaller than 4.8 µm (D10) and 10% are larger than 80.7 µm (D90), but 50% are smaller than 25.5 µm. The average particle size at 150 and 250 rpm is 37.5 µm. The presence of a shoulder on the distribution curve, as well as the value of the SPAN factor (2.9 μm), indicates that the system is not highly homogeneous. However, the obtained average value of the barberry particle size (37.40 µm) falls within the limits recommended for use as a biologically valuable components in food [25]. It is also worth noting that intensive mixing during the manufacture of caramel with barberries can induce lump formation and the deterioration of sensory properties.

To avoid the migration of excess moisture from barberry powder into the candies and to identify the shelf life and storage conditions of the finished products, the water activity was measured. The value of AW of freshly prepared barberry powder was 0.3620 ± 0.0012 and that of freshly dried berries was 0.5182 ± 0.0008, indicating the absence of microbiological activity [26]. When stored for 12 months, both the powder and berries change colour from bright red to brown, and their taste and morphology also change. The water activity slightly increases to 0.6230 ± 0.0005 for whole berries and 0.5837 ± 0.0002 for the powder. On the one hand, these changes are not critical and are most likely not related to the development of pathogenic microorganisms but are caused by the adsorption of moisture from the air. Similar patterns have been described for dried berries, such as dried cherries and green coffee beans [27].

3.2. Physico-Chemical Properties of Candies Containing Barberry

A series of samples were produced. Of these, the first caramel candy control did not contain barberry, and samples S1, S2, S3, and S4 contained 1, 2.5, 5, and 10% barberry powder, respectively. Although the powder added to the barberry was air-dried, the moisture content of the lollipops with the additive was slightly higher than that of the control sample. It should be noted that the differences in moisture content among samples S1–S4 were not statistically significant (

Table 2. Physicochemical parameters of candies with barberry and the control sample.

Lollipop Caramel, Sample	Content of Barberry, %	Humidity, %	pH	Titratable acidity, ° (in Terms of Citric Acid)	Ascorbic Acid, mg/100 g	Reducing Substances, %
control	0	0.010 ± 0.002	5.09 ± 0.01	0.010 ± 0.002	0	0.040 ± 0.002
S1	1	0.023 ± 0.001	3.45 ± 0.03	1.024 ± 0.015	0.440 ± 0.022	0.038 ± 0.015
S2	2.5	0.027 ± 0.003	3.25 ± 0.02	2.752 ± 0.023	0.840 ± 0.018	0.041 ± 0.003
S3	5	0.030 ± 0.002	3.18 ± 0.01	5.504 ± 0.013	2.200 ± 0.021	0.041 ± 0.002
S4	10	0.035 ± 0.003	3.12 ± 0.02	10.176 ± 0.031	4.250 ± 0.017	0.042 ± 0.001

). When the lollipops were stored without packaging materials, an increase in moisture content and a deterioration in the appearance of the candies (sticky, deformed shape) were experimentally recorded. The mass fraction of moisture in the caramel when stored in the air without packaging for 10 days increased by 40% and reached 0.035–0.049%. This indicates the necessity of packing the finished product in packaging material.

Barberry powder, due to its high acidity caused by the presence of organic acids, should not only change the taste of the lollipop caramel but also its acidity and pH. The barberry powder contains several organic acids, such as citric acid (pKa1 = 3.13, pKa2 = 4.76, pKa3 = 6.40), malic acid (pKa1 = 3.40, pKa2 = 5.11), and tartaric acid (pKa1 = 2.98, pKa2 = 4.30). The pKa1 values for all these acids are relatively low, meaning their presence can influence the pH of the product, and, consequently, the perception of sourness. These findings are supported by the observed decrease in the pH of the candies containing barberry powder to 3.12–3.45 compared to the control at 5.09 (Table 2). At the same time, the presence of at least three acids significantly affects the titratable acidity, which, unlike pH, is strongly dependent on the barberry powder content in the samples and increases from 1.024 to 10.176 with an increase in the content of barberry powder from 1 to 10% (Table 2). The significant content of ascorbic acid in berries depends not only on the region of cultivation but also on the genotype of the plant and can range from 120 to 44 mg/100 g for juice squeezed from berries [28]. The studied barberries in a fresh state contained 184 mg of ascorbic acid per 100 g of wet berries. It is known that vitamin C can be partially destroyed during heat treatment, so the content of ascorbic acid in the finished sweets was determined (Table 2). The content of ascorbic acid in 100 g of candy caramel was 0.44 mg/100 g in S1 and increased with the with the increase in barberry content up to 4.25 mg/100 g in S4. About 75% of the ascorbic acid was destroyed during the caramel cooking process. Potential strategies to reduce these losses could include optimising processing conditions, such as lowering the temperature or reducing the cooking time of the caramel and adding stabilisers or antioxidants to preserve vitamin C during production. Another option is to introduce the barberry powder into the already cooked caramel after it cools to a temperature below 60 °C. This would help avoid thermal degradation; however, it would prevent the creation of a uniformly homogeneous caramel. At temperatures below 60 °C, the caramel and barberry powder cannot be evenly mixed, as the caramel sets quickly, making it difficult to shape the product properly.

Reducing sugars have a negative effect on caramel: with an increase in their content, the shelf life of caramel decreases, it gains moisture and ‘floats’ The source of reducing substances in our case was invert syrup, however, berries also contain 29.4 ± 0.4 mg GLE/g of reducing sugars [29]. Based on our results, it can be seen that the reducing sugars of barberry did not have a significant effect on the total reducing substance content of the lollipop compared to the control (Table 2). Barberry powder can extend the shelf life of caramel due to the presence of organic acids, which contribute to the formation of an acidic environment that inhibits microbial growth, as well as the presence of polyphenols and anthocyanins, which possess antioxidant and bacteriostatic properties.

3.3. Sensory Evaluations of Candies Containing Barberry

Candy caramel containing on isomalt and barberry powder is red in colour, non-sticky, regular in shape, and has a pleasant caramel smell and a delicate sour note of barberry to taste (Figure 4).

The colour of the candy suggests that barberry powder can be used as a natural colouring agent in the production of caramel. Due to the high content of organic acids in barberry berries [30], adding barberry powder to candy should weaken and contrast the sweetness of other ingredients. The evaluation of sensory properties was carried out according to five parameters on a 5-point scale, including acidity (0—not sour/5—too acidic), sweetness (0—not sweet/5—too sweet), texture (0—smooth/5—rough), balance of taste (0—not expressed/5—pronounced), and flavour (0—not expressed/5—pronounced). The taste of the control candy was very sweet and unassuming, while the taste of the S5 sample was excessively sour and sharp, with a pronounced roughness.

The presence of a significant fraction of fine particles (D10 = 4.8 µm) contributes to a smoother and more homogeneous texture. However, the broad distribution range (SPAN = 2.9 µm), along with the presence of larger particles (D90 = 80.7 µm), indicates a heterogeneous system. Such heterogeneity leads to the perception of graininess or unevenness in mouthfeel and may also affect the visual uniformity of the caramel matrix. This effect was observed in candies containing 10% barberry powder. Adding 10% or more barberry powder to the caramel led to a deterioration in the texture of the products due to the large number of powder particles and the appearance of a pronounced sour taste. Samples S2 and S3, with barberry contents of 2.5 and 5%, were optimal in terms of sensory properties (Figure 5).

4. Conclusions

The study investigated the production technology of lollipop caramel with the addition of barberry powder as a source of biologically active components, including minerals, organic acids, and vitamin C. It was found that the optimal concentrations of barberry powder for maintaining high sensory characteristics are in the range of 2.5–5%. An increase to 10% leads to excessive acidity, the deterioration of texture, and particle aggregation. Barberry powder acts as a natural colouring agent. To preserve the quality of caramel with added barberry powder, it is essential to use properly selected packaging materials and maintain controlled storage conditions. The primary goal is to protect the product from moisture, light, oxygen, and temperature fluctuations, which can accelerate the loss of vitamin C, aromatic compounds, and sensory properties. The packaging should be moisture- and oxygen-proof, light-resistant, mechanically strong, and suitable for food products.