Color stability of fruit yogurt during storage

Encapsulation of debittered pomelo juice using novel Moringa oleifera exudate for enrichment of yoghurt: A techno-functional approach

Debittering of pomelo juice was conducted using 3.7 g of activated resin, resulting in a 36.8% reduction in bitterness without affecting the bioactive properties of juice. The debittered juice was then encapsulated with Moringa oleifera exudate at various ratios (1-5%), yielding a powder with a slightly rough surface. Total phenol content (TPC) increased by 46-56% compared to the debittered juice. Functional yoghurt containing encapsulates at concentrations of 1% and 2% demonstrated that the 2% concentration led to longer storage duration, resulting in increased acidity and syneresis compared to the control. TPC of the yoghurt (161.89-198.22 μg Gallic acid equivalent (GAE)/g) remained significantly higher (p < 0.05) than that of the control (47.15 μg GAE/g) and acacia gum-based yoghurt (141.89-171.37 μg GAE/g), decreasing with storage duration. Addition of encapsulates significantly altered the yoghurt's texture, resulting in lower firmness (0.57 to 0.64 N) compared to the control, while adhesiveness values remained comparable (6.33 to 6.25 g.s). The highest values of G' and G" were observed in samples containing 2% encapsulates with moringa compared to those with acacia gum. This study suggests potential avenues for further exploration in functional foods with enhanced health benefits.

Quality Assessment of Greek-Style Set Yoghurt Fortified with Extracted and Dried Australian Native Fruit, Illawarra Plum

The Illawarra plum (IP) is native to Australia and has been used as a bush food for centuries. With rich phytochemicals and natural pigments, IP has the potential to be an added ingredient to improve the physicochemical properties of food, including yoghurt. This study prepared dried IP powders through vacuum drying (VD) and freeze drying (FD), produced extracts from these dried powders, and fortified them into Greek-style set yoghurt. The changes in colour, pH, titratable acidity (TA), syneresis, total soluble solids (TS), and phytochemicals were measured throughout a chilled storage period of 28 days. The results showed that FD and FD extract could provide a stable, distinct pink colour to yoghurt. IP powders and their extracts improved TS content and, thus, the consistency of yoghurt. Compared to the control, VD, FD, and FD extract of IP did not significantly affect the level of acidity or syneresis after 28 days of chilled storage. Yoghurt fortified with FD and FD extract had the greatest level of phenolics, anthocyanins, and radical scavenging antioxidant activities. This study revealed that IP powders and their extracts can positively improve the physicochemical properties of Greek-style set yoghurt. FD powder is recommended over its extract to fortify this yoghurt, as it can be cost-effectively prepared by freeze drying and then grinding the fresh fruit into powder. Future studies are needed to evaluate other variables in yoghurt preparation, including the concentration of IP and strains of yoghurt culture. Further, the consumer perception of sensory quality and acceptability of yoghurt fortified with FD IP powder should be investigated.

Effect of red beet cooking water on yoghurt's physico-chemical, textural and antioxidant characteristics

This study aimed to evaluate the effect of red beet cooking (Beta vulgaris L.) water on the quality properties of yoghurts prepared with different levels (2, 4, 8, and 10% w/w) compared to the nature sample. Results showed a decrease in pH value and an increase in titratable acidity (TA), fat content, and dry matter with the increasing red beet cooking water concentration. Consumer test revealed that incorporating 4% (w/w) red beet cooking water into yoghurt influences the product's overall acceptability compared to the other formulations. The addition of red beet cooking water at the level of 4% induces significant increase in gel firmness with a decrease in syneresis compared to the control sample. The lightness and yellowing of the product decreased while the redness increased. Furthermore, the effect of red beet cooking water addition was significant (p < 0.05) on total phenolic contents (0.369 ± 0.024) as well as antioxidant activity (0.140 ± 0.008). Beet cooking water may be a potential ingredient in the formulation of functional products.

Color stability and degradation kinetics of anthocyanins in mulberry stirred yoghurt fermented by different starter cultures

To evaluate the storage stability of anthocyanin in stirred yoghurt, mulberry juice and different starter cultures (S) were added into milk to investigate the color stability and degradation kinetics of anthocyanin. The result showed that the redness value decreased, while the brightness value increased, and the anthocyanin content decreased significantly from 1.47 ~ 1.86 to 1.01 ~ 1.19 mg/g. The degradation kinetics followed a first-order reaction. Principal component analysis showed that S2 and S6 were correlated with anthocyanins, S8 and S4 were correlated with a*. At the later stage, S4, S8 were correlated with a*, while S2, S4, S6 were correlated with anthocyanins. At 28th day, the anthocyanin content of S4 was 1.14 mg/g, which was not the highest, but the total score was the highest. Therefore, S4 was the best choice when the storage period is 28 days. This study provided technical support for the selection of a better starter for stirring yoghurt.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01271-8.

Stability of Phenolic Compounds, Antioxidant Activity and Color Parameters in Colored-Flesh Potato Chips

Potato (Solanum tuberosum) chips are the most consumed snacks worldwide today. Colored potato chips prepared from potato cultivars with red and purple flesh are a novel alternative to traditional potato chips because of their higher phenolic compound content, such as anthocyanins and hydroxycinnamic acid derivatives (HCADs), which might make these chips healthier compared with traditional chips. There is little information on the stability of these compounds. In this study, the nutritional value of these chips was evaluated by determining phenolic profiles, antioxidant activity and color parameters with liquid chromatography diode array and mass spectrometry detection (HPLC-DAD-ESI-MS/MS) and spectrophotometric methods during storage for four months. Five anthocyanins and three HCADs were detected, with the latter compounds being the most abundant, with concentrations on average between the first (97.82 mg kg-1) and the last (31.44 mg kg-1) week of storage. Similar trends were observed in antioxidant activity and stability, with the CUPRAC method showing the highest response among all the methods employed. The color indices were stable throughout the storage time. Based on these results, colored-flesh potato chips are an optimal alternative for consumption because of their high retention of phenolic compounds and antioxidant activity during storage, providing potential benefits to human health.

The effect of addition Eriobotrya japonica L. marmalade on physicochemical, microbiological, and sensory properties of probiotic yogurts

This study investigated the effects of loquat (Eriobotrya japonica L.) marmalade (LM) supplementation in probiotic yogurt during a 21 days storage period. In addition, the viability of Bifidobacterium and its effect on yogurt quality were investigated. Four types of yogurt, including plain yogurt (LM0) and yogurts with 5%, 10%, and 15% LM, were prepared. On days 1, 7, 14, and 21 of storage, physicochemical properties, microbial growth, and textural and sensory properties were investigated. The addition of LM to yogurt significantly affected the total dry matter, fat, pH, titratable acidity, syneresis, water holding capacity, and color parameters (L*, a*, b*). The addition of LM caused a decrease in L* (from 87.52 to 81.78) and an increase in a* values (from -35.42 to -30.14). Yogurts containing 10 and 15% LM demonstrated lower syneresis than control samples during storage. During storage, the pH of yogurts continuously decreased (P < 0.01). The viability of Bifidobacterium in yogurt was not affected by the LM addition. During storage, the viable count of Bifidobacterium ssp. decreased in all yogurt types. Lactobacillus delbrueckii ssp. bulgaricus decreased more than Streptococcus thermophilus did during storage. In all yogurt samples, coliform bacteria stayed below detectable concentrations. When a general evaluation was made by considering the physicochemical quality, sensory, and textural properties of all yogurt samples, it was revealed that LM-added yogurts can be produced and stored for 21 days.

Functional and Healthy Yogurts Fortified with Probiotics and Fruit Peel Powders

The application of processing waste by-products along with probiotics is an interesting choice to confer potential functional aspects to food products. This study was designed to investigate the nutritional capacity of freeze-dried mango peel powder (MPP) and banana peel powder (BPP) in the presence of a mixture of three probiotic species (1% of each of three probiotics (Lacticaseibacillus casei (431®), Lacticaseibacillus rhamnosus (LGG®) and Bifidobacterium subsp. Lactis (Bb-12®)) as sources of additional nutrients and prebiotics in fresh and rehydrated freeze-dried (RFD) yogurts for 28 days of refrigerated storage. The net count of probiotics in yogurt fortified with MPP and BPP increased by at least 1 log CFU/g after 4 weeks of refrigerated storage. Adding fruit peel powder (FPP) significantly (p < 0.05) increased fat, ash, and protein contents in both fresh and RFD yogurts in comparison with the control yogurt. Similarly, the total phenolic contents (TPC) and antioxidant activity (AOA) was enhanced significantly (p < 0.05). The TPC reached 2.27 ± 0.18 and 2.73 ± 0.11 mg GAE/g in RFD enriched with BPP and MPP compared to a TPC of 0.31 ± 0.07 mg GAE/g in the control. Additionally, yogurt samples enriched with BPP (Y-5) and MPP (Y-6) demonstrated 12% more sugar contents than non-fortified yogurts (Y-1). Higher titratable acidity and lower pH values were also recorded in the RFD yogurt. Significant differences (p < 0.05) in the color parameters were detected in both fresh and RFD yogurts with reduced brightness (L*) and increased redness (a*) of the product. These findings demonstrated the suitability of MPP and BPP in yogurt formulations to optimize the advantages of such synbiotic products with higher availability of phenolic compounds.

NIR Spectroscopy Assessment of Quality Index of Fermented Milk (Laban) Drink Flavored with Date Syrup during Cold Storage

Fermented milk (laban) with added date syrup can be an excellent candidate for a nutritious drink. Modeling with quality index (Qi) can assist in assessing the quality of the drink’s physiochemical properties. The properties of the laban drink fortified with date syrup were measured and modeled with Qi during shelf life (7 days), and then analyzed with near-infrared spectra (NIR). The aim of this study was to develop a quality index model for the laban drink properties (objective and sensory assessments) and then to predict Qi with a non-destructive measurement of NIR (with partial least-square regression (PLSR) and artificial neural network (ANN) analysis). The results revealed that the developed Qi fits well with measured laban drink properties (viscosity, color, total soluble solids, pH, and sensory assessments during the shelf-life period with R2 = 0.977). The NIR spectrum was efficient to estimate the quality index of the fortified laban drink. It was found that ANN is more appropriate than the PLSR model in estimating the Qi of the Laban drink during cold storage. Thus, non-destructive NIR can predict Qi and can be utilized with great success in the whole chain of production, processing, transportation, storage, and retail market to check the “quality” and “shelf life” of the product.

Aronia Extracts in the Production of Confectionery Masses

The article examines the opportunity to use extracts and Aronia melanocarpa (Michx.) Elliot fruit powders in the production of sugar confectionery for the substitution of synthetic dyes. In the technology of manufacturing confectionery masses, synthetic dyes are used that can cause various allergic reactions, as well as hyperactivity syndrome and lack of concentration in children. The composition of hydroalcoholic extracts was analyzed, and the metabolites of polyphenols, individual anthocyanins and organic acids were quantified. Antioxidant capacity and CIELab chromatic parameters were tested. The technology for manufacturing confectionary masses with extract and powder of aronia was developed. The sensory profile, physicochemical and microbiological quality parameters, antioxidant activity and color characteristics of the confectionary masses with the extract and powder of aronia addition were determined on the 1st and 50th day from the production date. The evolution of DPPH antioxidant activity of confectionery masses during storage was measured in vitro, in the conditions of gastric digestion. The results showed that Aronia melanocarpa (Michx.) Elliot extract is rich in polyphenols, flavonoids and tannins, the main organic acids being represented by malic, citric, acetic and ascorbic acid. During the 50th storage day, the antioxidant activity was higher in confectionery masses containing aronia compared to the control. The sensory and microbiological testing of confectionary masses demonstrated that the combination of extract and aronia powder ensures the optimal shelf life and organoleptic scores. It was demonstrated that during the storage of confectionery masses with aronia, the physicochemical indicators of quality were in accordance with the regulated admissible values. Positive effects of aronia were observed on confectionery masses’ color saturation. These results underline the opportunity to use aronia extract and/or powder in confectionery industry to replace synthetic dyes and obtain products with enhanced functionality.

Quality parameters of natural phenolics and its impact on physicochemical, microbiological, and sensory quality attributes of probiotic stirred yogurt during the storage

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Four types of plant-derived pigments were assessed in stirred yogurt production.

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Yogurts were stable without sedimentation or noticeable decolouration.

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Plant pigment addition did not exert adverse effect on the survival of probiotics.

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Turmeric addition resulted in the highest sensory acceptance, b* value and total phenolic content.

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The use of plant pigments in stirred yogurt production is technologically feasible.

Physicochemical, microbiological, and organoleptic properties were evaluated for probiotic stirred yogurts with plant pigments; 10% Hibiscus, 4% Turmeric, 6% Spinach, and 4% Blue pea, over 14 days at 4℃ compared to the colorless control. The color of yogurts were stable without sedimentation or adverse effect on physicochemical or sensory properties, although an increase of L* value observed over the storage. The microbial analysis confirmed the viability of probiotics (>9 logs CFU/mL) in all yogurts over the storage. Turmeric added yogurt resulted in the highest b* value, total phenolic content (72.6 mg GAE/L) and sensory score for color, while spinach added yogurt ranked the lowest in flavor at the end of storage. Results demonstrated the color stability of studied plant pigments in stirred yogurt with varying physicochemical and sensory properties. Addition of natural colorant in yogurt is recommended. Improved methods for extracting pigments and their health effects should be further examined.

Encapsulation of Different Types of Probiotic Bacteria within Conventional/Multilayer Emulsion and Its Effect on the Properties of Probiotic Yogurt

Microencapsulation of probiotic cells within emulsion is an efficient method to enhance the viability of probiotic bacteria. In the present study, free and encapsulated probiotic cells (Lactobacillus rhamnosus and Lactobacillus plantarum) in simple and multilayer emulsions were used to produce a set of probiotic yogurts. In all samples, an increasing trend in syneresis and acidity values and a decreasing trend in pH and viability of probiotic cells were observed during the storage time. However, the changes in these parameters were more significant for free-loaded probiotic samples. Moreover, the free cells showed poor survival in the yogurt samples by decreasing the viable cell count of probiotics from 7.71–7.59 logs CFU/mL to 6.93–6.82 log CFU/mL during storage, while encapsulation in the multilayer emulsion showed an insignificant reduction from 7.65–7.59 logs CFU/mL to 7.55–7.45 log CFU/mL at the end of storage. The obtained results showed that the type of probiotic bacteria had no significant effects on the physicochemical and structural properties of samples. However, encapsulating probiotics in multilayer emulsion led to a more homogenous structure in yogurt. The sensorial properties were also not affected by the probiotic type and the encapsulation method. Consequently, the multilayer emulsion can provide an ideal delivery carrier for encapsulating probiotic bacteria in dairy products.

Formulation and characterization of yogurt prepared with enzymatically hydrolyzed potato powder and whole milk powder

This study highlights the optimization of a suitable amount of enzymatically hydrolyzed potato powder (EHPP) with whole milk powder (WMP) to produce a quality yogurt. The yogurt was prepared with different levels of EHPP (0, 10, 15, 20, 25, 35 and 50% w/w) with WMP and evaluated after 24 h at 4 °C. The resulted product was analyzed on the basis of physicochemical, sensory, texture, antioxidant activity and microbiological analysis. The prepared yogurt showed a significant (p < 0.05) decrease in pH, protein and fat while acidity, moisture and ash contents were increased compared with control yogurt. In addition, textural parameters like hardness and adhesiveness were decreased while no significant (p < 0.05) change was found in springiness and cohesiveness. Moreover, color parameters such as L ^* and a ^* values decreased while b ^* values were increased. The current study suggested that the yogurt sample supplemented with 25% EHPP of WMP certainly improved the physicochemical, texture, microstructure, color, antioxidant and sensory properties of yogurt with EHPP. The prepared yogurt with EHPP provided an excellent flavor, satisfying sweetness, and homogeneous texture. The yogurt prepared from the EHPP presented potential industrial applications.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-021-05112-6.

Lactate content, total polyphenols and antioxidant activity of selected commercial yogurts from the Serbian market

One of the most popular dairy products worldwide is yogurt, which flavor is highly influenced by lactic acid content. Yogurts with fruit preparations contain polyphenols, secondary plant metabolites with proven antioxidant properties. As there is no data regarding neither lactate nor polyphenol content in commercial yogurts in Serbia, this study aimed to determine lactate and polyphenol levels, as well as antioxidant activity in selected yogurts. A total of 15 plain and 5 fruit yogurts with strawberry preparations were analyzed. Lactate contents were from 0.83 to 1.33%. Three plain yogurts in plastic containers differed in lactate content. There was no difference in lactate content among the same plain yogurts packed in plastic and Tetra Pack containers. Fruit yogurts with strawberry preparations differed in total polyphenol content in the range from 6.84 to 29.11mg GAE/100 g and antioxidant properties were determined by reducing power test (from 0.22 to 0.79) and DPPH assay (from 28.13 to 87.23%), while there was no difference regarding lactate. Our results provided new information about the levels of lactate, total polyphenols and antioxidant activity of selected commercial yogurts available on the Serbian market.

Chemical composition, quality attributes and antioxidant activity of stirred-type yogurt enriched with Melastoma dodecandrum Lour fruit powder

Incorporation of Melastoma dodecandrum Lour fruit powder as a promising functional ingredient for stirred-type yogurt (STY) improved physicochemical properties, polyphenol contents, antioxidant activity, microstructure, and texture of STY.

Lactate content, total polyphenols and antioxidant activity of selected commercial yogurts from the Serbian market

One of the most popular dairy products worldwide is yogurt, which flavor is highly influenced by lactic acid content. Yogurts with fruit preparations contain polyphenols, secondary plant metabolites with proven antioxidant properties. As there is no data regarding neither lactate nor polyphenol content in commercial yogurts in Serbia, this study aimed to determine lactate and polyphenol levels, as well as antioxidant activity in selected yogurts. A total of 15 plain and 5 fruit yogurts with strawberry preparations were analyzed. Lactate contents were from 0.83 to 1.33%. Three plain yogurts in plastic containers differed in lactate content. There was no difference in lactate content among the same plain yogurts packed in plastic and Tetra Pack containers. Fruit yogurts with strawberry preparations differed in total polyphenol content in the range from 6.84 to 29.11mg GAE/100 g and antioxidant properties were determined by reducing power test (from 0.22 to 0.79) and DPPH assay (from 28.13 to 87.23%), while there was no difference regarding lactate. Our results provided new information about the levels of lactate, total polyphenols and antioxidant activity of selected commercial yogurts available on the Serbian market.

Effect of Tamarillo Fortification and Fermentation Process on Physicochemical Properties and Nutrient and Volatiles Content of Yoghurt

Bright-red Laird’s Large tamarillo is a unique and under-utilised fruit that is a dietary source of carotenoids, vitamins C and E, and dietary fibre. The effects of the addition of freeze-dried tamarillo powder (5–15%) to milk and yoghurt starter either before (PRE) or after (POS) fermentation on physicochemical properties were examined. Using LC-MS and GG-MS, nutrient and volatile contents of tamarillo yoghurt were also examined. The addition of tamarillo prior to fermentation was associated with a more yellow colour and higher concentrations of tocopherol compared to when tamarillo was added after fermentation. Higher elastic modulus, PUFAs, pro-vitamin A content, and vitamin C retention were observed for POS than PRE. All tamarillo yoghurts showed improvement in syneresis, lower lactose content, and higher concentrations of antioxidant vitamins than the commercial premium-assorted fruits yoghurt from New Zealand Food Composition Data. Yoghurt fortified with tamarillo powder offers the potential for the development of a high-value nutritional product that could be a good source of vitamin C and a source of vitamin E and β-carotene, and maintain the volatiles that give tamarillo its distinctive flavour.

Effect of Two Combined Functional Additives on Yoghurt Properties

The aim of the research was the analysis of yoghurts enriched with blue honeysuckle berries dry polyphenolic extract and new preparation of resistant starch. The additives were introduced individually at concentration 0.1% (w/v) and in mixture at final concentration of 0.1 and 0.2% of both components. Yogurt microflora, pH, and its physicochemical and antioxidant properties were examined over 14 days of storage under refrigerated conditions. Studies showed that both substances can be successfully used in yoghurt production. Yoghurt microflora es. S. thermophilus and Lb. delbrueckii subsp. bulgaricus counts appeared to be higher in samples supplemented with these additives comparing to control yoghurt by 3-8%. More stimulating effect on their growth, especially on S. thermophilus, revealed resistant starch. Addition of this polysaccharide improved also the rheological properties of yogurts, which showed higher viscosity than samples produced without it. Addition of honeysuckle berries preparation significantly influenced the yogurts' color, giving them deep purple color, and their antioxidant potential. During storage, contents of anthocyanin and iridoid compounds were decreasing, but antioxidant activity in the products remained stable.

Probiotic Yoghurts with Sea Buckthorn, Elderberry, and Sloe Fruit Purees

Elderberries, sea buckthorn, and sloe berries are fruits of wild-grown bushes, valued in folk medicine for their health-promoting properties but still rarely applied in food. The aim of the present study was to produce probiotic yoghurts with a 10% addition of sweetened purees prepared from elderberries (EPY), sea buckthorn (SBPY), and sloe berries (SPY) and to assess their chemical composition, acidity, content of polyphenols and anthocyanins, ferric reducing antioxidant power (FRAP) and antiradical power (ARP), level of starter microbiota, concentration of acetaldehyde and diacetyl, syneresis, instrumentally measured color and texture parameters, and sensory acceptance. The results were compared to those obtained for plain probiotic yoghurt (PPY) and the changes tracked during 1 month of cold storage at 2 week intervals. The addition of elderberry and sloe berries significantly increased the antioxidant capacity of probiotic yoghurts, probably due to a high content of polyphenols, especially anthocyanins. However, anthocyanins were more stable in the EPY when compared to the SPY. All yoghurt treatments were characterized by good sensory quality and viability of starter microorganisms, including probiotic strains during cold storage. Elderberries promoted the evolution of diacetyl in yoghurts during storage and, together with sloe berries, produced increased syneresis and the greatest changes in color profile compared to PPY.

Effect of yogurt-based marinade combined with essential oils on the behavior of Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella spp. in camel meat chunks during storage

The present study evaluated the effect of yogurt-based marinade combined with active essential oil components (EOs) namely: thymol (TH), carvacrol (CA), and cinnamaldehyde (CI) on Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella spp. in camel meat (CM) chunks during storage at 4 and 10 °C. Fresh cocktail mixtures of L.monocytogenes, E. coli O157:H7 and Salmonella spp. strains were inoculated on CM samples. Subsequently, a yogurt-based marinade, with or without 1% or 2% of the added EOs, was mixed with the CM chunks. After treatment, marinated camel samples were stored at 4 and 10 °C for 0, 1, 4 and 7 days. Adding yogurt-based marinade to the CM samples did not cause any significant changes in L.monocytogenes, E. coli O157:H7 and Salmonella spp. numbers at 4 °C, but at 10 °C resulted in a significant decrease in numbers on day 4 and 7 of storage by 1.4-1.5; 2.7-2.1 and 2.5-2.8 log CFU/g, respectively, compared to untreated CM samples. The incorporation of EOs into the CM with marination (CMM) further enhanced the microbial reduction of E. coli O157:H7 and Salmonella. At 10 °C, the synergistic effect of EOs with marinade was greater than at 4 °C. Increasing the concentration of the EOs used in this study from 1% to 2%, enhanced E. coli O157:H7 and Salmonella spp. reduction during storage at 4 and 10 °C while L.monocytogenes numbers were not affected. Increasing active EO component concentrations to 2% caused further significant reductions in Salmonella spp. in the CMM samples during storage by 1.0-2.7 log CFU/g (P ˂ 0.05) at 4 and 10 °C. At 10 °C, increasing the concentration of CI and TH to 2% caused a further reduction (P ˂ 0.05) of E. coli O157:H7 numbers by days 4 and 7 in the range of 3.6-4.4 log CFU/g. Among all tested EOs, 2% TH and 2% CI had the greatest effect against E. coli O157:H7 and Salmonella spp. in CMM during storage at 4 and 10 °C. In comparison to CMM, the highest scores of all examined sensory attributes were found in CMM samples with 1% and 2% CI added. Results indicate that the EO component CI can be used as an effective tool to decrease populations of E. coli O157:H7 and Salmonella spp. in CM with minor sensory changes.

Evaluation of instrumental and sensory measurements using multivariate analysis in probiotic yogurt enriched with almond milk

Highlights

Consumers demand the purchase of fortified dairy products.Instrumental (color, texture) and sensorial attributes are critical tests for novel food.Almond milk has high nutritional value with unique textural and sensorial properties.Almond milk is an innovative and attractive additive in probiotic yogurt.

Abstract

In this study, the effect of almond milk addition on color, texture and sensory attributes of probiotic yogurt was investigated. The data generated in combination with instrumental (color and texture parameters) and sensory measurements was analysed statistically to describe a product's attributes scientifically. Statistical analysis illustrated that almond milk rate and storage time had a significant (P < 0.05) effect on the color and textural parameters of yogurt. Compared with the sensorial parameters, generally there were statistically significant differences among samples, whereas insignificant effect was determined among storage days. The results of descriptive statistics (Principle Component and Hierarchical Cluster Analysis) indicated that the relationships among the analysed attributes were determined. In addition, statistical data has demonstrated that almond milk may be used as a novel and functional ingredient in both industrial and research areas for development, innovation, quality, and safety of dairy products.

Application of the "SCOBY" and Kombucha Tea for the Production of Fermented Milk Drinks

For the production of fermented milk drinks, cultures of microorganisms other than traditionally applied can be used. Such possibilities are created by the symbiotic culture of bacteria and yeast (SCOBY), which is used to produce kombucha. The aim of the study was to evaluate the possibility of using kombucha and the SCOBY for fermented milk drink products. The drinks were developed with a lactose-free variant and traditional milk. For the analysis of the obtained beverages, microbiological methods (CFU method), chemical methods (pH method and HPLC method) and the quantitative descriptive analysis (QDA) sensory method were used. As a result of the research, a recipe and the fermentation parameters for fermented milk drinks were developed. In the developed lactose milk drinks, the average lactose content was 4.25 g/100 g. In lactose-free milk drinks, the average glucose content was 2.26 g/100 g. Lactic acid in both types of products was at the highest average level of 0.68 g/100 g. The products had a characteristic pH value for fermented milk drinks and a very good microbiological quality, which followed the FAO/WHO guidelines. Drinks also had a typical sensory profile for this products group. However, slight sensory defects were detected. The developed fermented milk drinks have a potential health-promoting value, thanks to the content of active microflora and organic acids, which have a confirmed positive effect on the human body. The drinks produced require further testing to optimize their cost of production, possible health benefits and sensory quality.

Quality Characteristics and Antioxidant Activity of Yogurt Containing Raw Omija and Sugared Omija during Storage

This study was conducted to determine the quality characteristics and antioxidant properties of yogurt containing omija extract (control, raw omija, and sugared omija) stored at 4°C for 14 days. The pH of all groups decreased, while the titratable acidity increased as the storage period increased. The viscosity of the sugared omija sample was high, while in the syneresis test, the sugared omija sample showed a low value. The total polyphenol content was the highest in the raw omija sample on day 0. DPPH activity was the highest in the raw omija sample for all storage periods; this sample also showed high Fe2+ chelating activity, which did not significantly differ from the sugared omija sample. In sensory evaluation, the sugared omija sample showed the highest overall score. Based on these results, it can be concluded that yogurt containing sugared omija shows improved quality and antioxidant activity.

The Effect of Rosa spinosissima Fruits Extract on Lactic Acid Bacteria Growth and Other Yoghurt Parameters

The aim of the study was to evaluate the effect of purified extract from Rosa spinosissima fruits on the quality characteristics and antioxidant properties of yoghurt. The extract, added to yoghurt at a concentration of 0.1% and 0.2%, contained high quantities of phenolic compounds and exhibited high antioxidant activity due to the presence of anthocyanins flavan-3-ols, flavonols and ellagitannins. Yoghurt physicochemical properties, microbiology and antioxidant properties were evaluated after 1, 7 and 14 days of storage at a temperature of 4 °C. The data revealed a positive influence of rose preparation on yoghurt’s microflora and on its other properties. The highest count of traditional yoghurt microflora was observed in samples with 0.2% of extract. Its addition had a positive effect on the yoghurts’ color, giving them a characteristic pink color of an intensity dependent on additive concentration. It also significantly affected the yoghurts’ antioxidant properties, which were stable during storage, as well as the content of the introduced phenolic compounds.