Quality Of Yogurt Research Articles

Effect Pineapple Extract (Ananas comosus L, Merr) To Dadih Quality During Cold Temperature Storage

The objectives of this research were to study the effect of storage temperature and pineapple extract on physicochemical, organoleptic, and total bacterial colony of curd. This study used factorial completely randomized design with 2 factors, with two replications. The results showed that storage temperature, pineapple extract and interaction affected significantly fat and protein content, total bacterial colonies, and organoleptis. Storage temperature significantly affected pH, while pineapple extract did not affect pH. The highest fat content wat at room temperature storage without the addition of pineapple extract, namely 12.91%, the highest protein content was at room temperature storage with the addition of 10% pineapple extract, namely 4.74%. Storage at cold temperatures with the addition of 2.5% pineapple extract produced the highest total colonies, namely 2.6 x 106 CFU. At room temperature storage, panelists tended to dislike the color, aroma, and texture of the curd. However, at refrigerator temperature storage, panelists preferred the color of the curd and really liked the taste. Panelists tended to like the curd both without pineapple extract and with pineapple extract. The addition of 7.5% pineapple extract and storage at cold temperatures resulted in a protein content of 4.78% and a fat content of 10.67% which met the National Yoghurt Quality Standard. Keywords: Lactic Acid Bacteria; Curd; Pineapple; Total Bacterial Colonies

Fortification of yogurt with cloves extract: Quality characteristics, sensory attributes, and antioxidant evaluation

The purpose of the current study was to evaluate the impact of different concentrations of clove extract (CE: 0%, 0.5%, 1.0%, and 2.0%) on the viscoelasticity, viscosity, syneresis, texture, sensory quality, and antioxidant properties of set yogurt up to 21 days in cold storage. The addition of CE enlarged the total suspended solids (TSS) and mineral contents while reducing whey separation. On the other hand, CE existence dropped the consistency index (k) and elastic modulus (G’) of yogurt gels and further lessening was observed with prolonged storage period. Moreover, the textural firmness remained unaffected whereas gels that are more cohesive were attained with integration of CE. Similarly, total phenolics and free radical scavenging activity increased significantly (p < 0.05) by CE supplementation, and amplified lipid oxidation was observed with increased storage time. Addition of CE lowered the lightness (L*) index and manipulated the organoleptic properties whereas the sample with 1% CE showed improvement in texture and flavor; however, the overall acceptability reduced for samples with higher concentration of CE.

Utilizing pomegranate extracts for enhancing yogurt quality and preservation

As consumers become increasingly conscious of synthetic preservatives, the demand for natural antioxidant and antibacterial agents is rising. This study investigates the potential of pomegranate (Punica granatum) extracts to control yogurt spoilage. Methanolic and ethanolic extracts of pomegranate peel, seed, and leaf were analyzed for total phenolic content (TPC), antioxidant activity, and inhibitory effects on ‘yogurt starter strains’ and selected food-related bacteria (Bacillus cereus, Staphylococcus aureus, Staphylococcus sciuri, Escherichia coli, Salmonella enterica subsp. enterica serovar Typhi, and Shigella flexneri). Yogurt samples treated with pomegranate extracts were stored at 4 °C for 28 days. Sensory evaluation was performed on fresh yogurt samples. Physicochemical properties (pH, titratable acidity (TTA), and antioxidant activity) and microbiological changes (aerobic plate count (APC), coliform count, lactic acid bacteria (LAB) count, and total yeast and mold count (TYMC)) were examined weekly. Among the extracts tested, methanolic and ethanolic extracts of peel had the highest TPC (603 and 576.9 mg GAE/g) and the strongest antioxidant activity with the lowest IC50 (141.8 and 183.43 µg/mL). Overall, pomegranate peel, seed, and leaf extracts inhibited foodborne bacteria more effectively than probiotic strains, indicating significant antibacterial potential against spoilage microorganisms. Based on a minimum inhibitory concentration (MIC) test, ethanolic pomegranate extracts were incorporated into lab-made yogurt at 8 mg/mL. Throughout the storage period, all yogurt samples maintained a standard pH (≤ 4.6) and TTA (> 0.5 %). Yogurt fortified with pomegranate peel and leaf extracts exhibited greater antioxidant activity and a significantly lower aerobic plate count while retaining LAB probiotic levels (≥ 106 CFU/g), ensuring safety for consumption (TYMC ≤ 102 CFU/g) and acceptability in terms of five selected quality attributes. Consequently, pomegranate peel and leaf extracts present a promising natural alternative to potassium sorbate in yogurt preservation, maintaining probiotic properties without compromising quality.

Exploring the Biological Value of Red Grape Skin: Its Incorporation and Impact on Yogurt Quality.

The study was conducted to study the sustainability and enhanced nutrition gains obtained from incorporating grape skin powder (GSP) extracted from both Fetească Neagră and Rară Neagră grape varieties into yogurt. Grape skins are major leftovers from wineries, having high amounts of phenolic compounds and dietary fiber responsible for their ability to improve the characteristics of food. The research aimed to evaluate the effect of GSP addition at varying concentrations (0.5%, 1.0%, and 1.5%) on the yogurt's physicochemical properties, antioxidant activity, color parameters, and sensory attributes. Analysis revealed that both Fetească Neagră and Rară Neagră GSP increased the total phenolic content and antioxidant activity; however, Fetească Neagră showed greater improvements, with TPC reaching 1.52 mg GAE/100 g and DPPH inhibition up to 26.63%. Although slightly lower, TPC rose to 1.43 mg GAE/100 g and DPPH inhibition increased to 18.93% with Rară Neagră enhancing these parameters conversely. Color changes were observed in fortified yogurts where lightness decreased (L*) and redness increased (a*) due to the pH-dependent anthocyanin stability. Syneresis, indicative of yogurt's water-holding capacity, was reduced at higher concentrations of GSP from both varieties, suggesting improved textural integrity. Sensory evaluation indicated that consumers generally favored yogurts with lower concentrations of GSP. Yogurts fortified with Fetească Neagră GSP received higher overall preference, while those with Rară Neagră GSP were also well-received for their distinct flavor profiles when used at suitable levels. These results show that GSP from both types of grapes improves the nutritional value of yogurt and complies with the principles of sustainable food production through reutilizing agro-industrial waste.

Improving the sensory and chemical characteristics of functional yogurt fortified with cardamom extract (<i>Elettaria cardamomum</i> L.)

Abstract: This study aimed to assess the effects of aqueous cardamom extract on chemical and sensory qualities of yogurt fortified with cardamom extract. Four different concentrations of cardamom extract (100, 150, 200, and 250 μg.L-1) were incorporated into yogurt, along with a control group without adding cardamom. The moisture content, total protein, carbohydrates, pH, peroxide value, and sensory properties (taste, flavor, and smell) were evaluated. The results show that cardamom extract had no significant effect on the moisture, protein, or carbohydrate content of yoghurt when compared to the control. However, a drop in lipid, pH and peroxide value was seen in cardamom-fortified yoghurt, indicating enhanced lipid quality. Treatments supplemented with 200 and 250 μg.L-1 of extract showed the highest sensory scores. Overall, this study suggests that aqueous cardamom extract holds promise as a functional ingredient to improve yogurt quality and sensory qualities, potentially providing health benefits to consumers. Background: Yogurt is typically processed from cream, milk, or partially or completely skimmed milk, and may include additional ingredients such as vitamins, skimmed milk powder, lactose, lactalbumin, lactoglobulin, or modified whey. Cardamom encompasses two plant varieties, Elettaria and Amomum, belonging to the ginger family. These types are triangular in cross-section, bear seeds in bundles, and possess a thin outer membrane encasing black seeds. Whole milk yogurt was fortified with four different concentrations of aqueous cardamom extract. A control group of plain whole milk yogurt without additives was also prepared. The chemical and sensory properties of yogurt types were analyzed immediately after manufacturing and storage for 1, 3 and 7 days at 5 ±1 °C. Objective: This study aimed to explore the effects of aqueous cardamom extract on chemical and sensory qualities, which are critical for functional foods, of functional yogurt made from raw, whole cow's milk. Four concentrations (100, 150, 200, and 250 μg.L-1) of cardamom extract were incorporated into yogurt, along with a control group without added cardamom. The moisture content, total protein, carbohydrates, pH, peroxide value, and sensory properties (taste, flavor, and smell) were evaluated. Materials and Methods: Raw, whole cow's milk was used to make yogurt production in the laboratory. Five kilograms of raw, full-fat cow's milk was heated for 10 minutes at 90 °C, then cooled to 42 °C and divided into two parts. The first was divided into four fractions, each receiving a different concentration of cardamom extract: 100, 150, 200, and 250 μg/L, representing treatments T1, T2, T3, and T4, respectively. The second part remained untreated and served as the control treatment (C) for yogurt production.

Encapsulation of Curcumin With Persian Gum and Its Application to the Production of Functional Yogurt: Physicochemical, Antioxidant, Sensory Properties, and Starter Bacteria Survival Study

ABSTRACTThis study aimed to evaluate the ability of Persian gum to encapsulate curcumin and enhance its stability in dairy products. Given the increasing interest in functional foods, this study investigated the incorporation of nanocapsules containing curcumin (CLN) into functional stirred yogurt (CLN‐Y). CLN was prepared with Persian gum (PG) at different levels and included in the yogurt formula (CLN‐Y1%, CLN‐Y2%, and CLN‐Y3%). The physicochemical properties, rheological characteristics, antioxidant activity (AA), survival of starter bacteria, and sensory properties of the yogurt were evaluated over a 21‐day storage period at 4°C. The results showed that CLN significantly improved AA (reduction of 7.31% in the control vs. 1.85% in CLN‐Y3%), viscosity, hardness, and water holding capacity (reduction of 2.27% in control vs. 1.14% in CLN‐Y3%), while reducing syneresis (an increase of 10.87% in control vs. 3.16% in CLN‐Y3%) during storage (p < 0.05). CLN concentration directly affected AA. Although CLN‐Y exhibited a yellowish color and lower light intensity than the control, the samples were well accepted during storage. Increasing CLN levels led to decreased taste, color, and overall acceptance scores, and a 3% concentration is recommended for yogurt formulation due to its potential to improve yogurt quality, provide antioxidant benefits, maintain probiotic viability, and achieve high consumer acceptance during storage.

Improvement of brown yogurt quality by Lactiplantibacillus plantarum S58 and oat β-glucan: Physicochemical properties, sensory quality, and metabolic changes

The flavor quality of brown yogurt is affected by the different fermentation methods. In this study, we investigated the effects of probiotics (Lactiplantibacillus plantarum S58), prebiotics (oat β-glucan), and synbiotics (Lactiplantibacillus plantarum S58 combined with oat β-glucan) on physicochemical properties, consumer acceptance, flavor substances, and metabolites of brown yogurt. The results showed that the addition of probiotics and synbiotics significantly shortened the curdling time of brown yogurt (30 min and 40 min, respectively), and synbiotics improved the physicochemical properties and flavor components of the yogurt. Compared with the control group, the volatile flavor substances in the synbiotic yogurt, such as acetophenone, 2-decanone, and octanoic acid, were significantly increased. Sensory analysis of 111 consumers showed that the sample of synbiotic brown yogurt was highly accepted and close to the ideal point. Synbiotic fermentation alters the metabolic profile of yogurt, increasing the levels of beneficial metabolites and reducing harmful metabolites. In conclusion, synbiotic brown yogurt achieved the highest quality. This study provides a theoretical basis and data support for the development of brown yogurt with high probiotic activity and a unique flavor.

Role and influence mechanism of different concentration of hyaluronic acid on physicochemical and organoleptic properties of yogurt

Hyaluronic acid (HA) has been approved to be added to milk and other dairy products, it has highly water-binding ability which can combine with a large number of water molecules through intramolecular hydrogen bonding to form high viscous gels. In addition, HA is one of the prebiotics, can provide health benefits like anti-aging, anti-inflammatory, angiogenic, is a potential additive for enhancing the quality of yogurt. Therefore, the aim of this study was to evaluate the effect of 0%, 0.02%, 0.05%, 0.1%, 0.25% and 0.5% HA on rheological properties, functional properties, thermal stability, protein stability, protein structure and protein fractions of yogurt. The addition of HA, storage modulus (G') is always larger than loss modulus (G'') in all the samples, which is a typical characteristic of gel networks, and the microstructures of the yogurt samples showed a continuous and more homogeneous spatial network structure. Overall, the higher concentration (0.5%) had positive effect on the yogurt characteristics, like higher WHC, foam stability, microstructure, and texture. In contrast, the 0.1% concentration HA lead to a very abnormal results, it had a negative effect on yogurt including water-holding capacity, texture, and protein stability, suggesting structural destabilization and disruption of inter-aggregation before protein. These findings provide a valuable fundamental data for commercialized HA adding yogurt development and quality control processes.

Effects of different enzymatic hydrolysis techniques on volatile flavor compounds and nutritional metabolites of soybean meal yogurt

AbstractBACKGROUNDThis study explores enzymatic hydrolysis as a method of modifying soybean meal (SM). It can reduce the particle size, improve flavor, and convert macromolecules into absorbable nutrients. The purpose is to provide technical information regarding the use of SM. Papain alone, and a combination of papain and acid protease, and a mixture of papain, acid protease, and Lactiplantibacillus plantarum were employed for the enzymatic hydrolysis of SM.RESULTSSensory evaluation and nutritional and flavor analyses were performed with yogurt produced after SM enzymatic hydrolysis. The enzymatic hydrolysis improved yogurt quality significantly in comparison with non‐enzymatically hydrolyzed soybean meal yogurt (SMY) by accelerating the decrease in pH and shortening the duration of fermentation. Enzymatic hydrolysis also reduced beany flavors and bitterness and enhanced the aromatic compound, flavor‐related amino acid, and organic acid content, rendering the yogurt more appealing to consumers. Microstructural analysis revealed favorable characteristics that textural and rheological properties of the yogurt produced after enzymatically hydrolyzed SM were improved.CONCLUSIONIn this study, the biotechnological approach was used to demonstrate the efficacy of enzymatic hydrolysis in improving the quality and value of SM, promoting the efficient application of SM in the food industry. © 2024 Society of Chemical Industry.

Effect of the Fermentation Time of Purple Sweet Potato (Ipomea Batatas L) Synbiotic Yoghurt with Probiotic Starter on Product Quality and Antioxidant Activity

Purple sweet potato (Ipomea batatas L) has the potential as a fermentation medium because it has a high carbohydrate content of around 20.1%. The combination of purple sweet potato extract, skimmed milk, and probiotic starter is expected to be a synbiotic yogurt that can help the digestive system. This study aims to determine the effect of long-term fermentation of purple sweet potato synbiotic yogurt with probiotic starter culture on product quality and antioxidant activity. The observed quality was chemical, microbiological, and organoleptic, with variations in fermentation time of 0, 4, 8, and 12 hours. The study's results showed a long-term effect of the fermentation of purple sweet potato synbiotic yogurt with probiotic starter culture on the quality of yogurt. The variation of 0-hour fermentation time did not meet the pH chemical quality standard with a value of 5.16. Still, it met the TAT chemical quality standard with a value of 0.513%, while the variation of fermentation time of 4-12 hours met the pH quality standard with a value of 3.88-4.33 and a TAT of 1.268-1.967%. In the quality of microbiology, there was a total increase in BAL, which was 46.2×107 - 90.61×107. The best organoleptic quality of color, taste, and aroma was obtained in the 8-hour fermentation variation, while the best texture organoleptic quality was obtained in the 12-hour fermentation variation. The best antioxidant activity was received at 12 hours of fermentation with an IC50 value of 62.727 ppm. From this study, it can be concluded that the best yogurt results are obtained with a fermentation time of 12 hours.

Effect of Red Guava (Psidium guajava L.) Juice Concentration on Product Quality and Antioxidant Activity of Red Guava Synbiotic Yoghurt

Red guava juice has very strong antioxidant activity and has the potential to be processed into synbiotic functional beverage products that have health benefits. This study examined the effect of red guava juice concentration on product quality and antioxidant activity of red guava synbiotic yoghurt. Product quality tested included microbiological quality (total LAB) and chemical quality (pH value and Total Tritable Acid (TTA )value). The concentrations of red guava juice used were 0%, 10%, 20%, 30%, and 40%. Fermentation was carried out for 6 hours at 37⁰C by Lactic Acid Bacteria (LAB) from powdered mixed culture. Then organoleptic testing using the hedonic test, total LAB testing using the Total Plate Count (TPC) method, pH value testing using a pH meter, TTA value testing using the acid-base titration method, and antioxidant activity testing using the DPPH (2,2-diphenyl-1-picrylhydrazil) method. Test data were analyzed using SPSS software to determine the effect of red guava juice concentration on test results. The concentration of red guava juice in red guava synbiotic yoghurt affects the pH value, TTA value, and IC50 value as the result of antioxidant activity testing. Red guava juice concentration did not affect total LAB testing. Organoleptic assessment of red guava symbiotic yoghurt is in the range of like to like very much. The best formulation was red guava synbiotic yoghurt with 30% red guava juice concentration, which had strong antioxidant activity with an IC50 value of 59.637 ppm, pH value of 3.94, TTA value of 1.98%, and total LAB as much as 1.81x10⁸ colonies/g, so it has met the quality requirements of yoghurt according to Indonesian National Standard SNI 2981: 2009.

THE QUALITY AND SAFETY OF GOAT MILK SOUR-MILK PRODUCT

To improve the quality of life of the population, currently a promising direction is the use of functional foods. The article presents the results of the conducted analysis of the quality and safety of symbiotic yogurt from goat milk enriched with a mixture of vegetable raw materials.Purpose of the study: to study the effect of quince syrup on the quality and safety of fermented milk products.This paper presents the results of the study of the developed fermented milk product (yogurt) for functional purposes. The composition of the added ready-made starter includes the cultures Str.thermophiIlus, Lb.bulgaricus, Lb. acidophilus. Quince fruit syrup was used as a natural ingredient of plant origin.Addition of quince syrup in the production of yogurt from goat's milk contributes to obtaining a product enriched with dietary fiber, vitamins, macro-microelements, as well as increasing the range and improving the organoleptic properties of dairy products, including pectin-containing.The presented article provides comprehensive microbiological indicators of the studied yogurt samples and the dynamics of changes in lactic acid microflora during storage.The results showed that according to microbiological indicators, the yoghurts met the requirements of TR CU 033/2013, QMAFAnM did not exceed the specified standards, and coliform bacteria were absent. The growth of lactic acid bacteria in the studied samples was intense on the fifth day – 6.4×109 CFU, then the number of microorganisms decreased. On the seventh day, the number of lactic acid bacteria in the studied sample was – 4.5×108 CFU, the indicator of the control sample for this period was – 2.4×107 CFU.

Process optimization, quality evaluation, and dynamic changes of metabolites in Houttuynia cordata yogurt

Houttuynia cordata Thunb (YXC) is a significant homologous plant valued for its medicinal and culinary properties. However, there are no reports on the study of YXC yogurt. The quantities of YXC liquid, starter culture, and white sugar were used to evaluate their impact on yogurt quality, followed by metabolite profiling analysis. The optimal formula for yogurt consisted of 23 g YXC liquid, 9 g white sugar, and 0.7 g starter culture, resulting in well-balanced coagulation, delicate and smooth taste, and a unique aroma of YXC. Additionally, most differential metabolites were significantly accumulated during the production process of YXC yogurt, of which amino acids, free fatty acids, organic acids, and saccharides were associated with the texture, taste, and flavor of yogurt. Correlation analysis further suggested that saccharides, amino acids, and lipids were positively correlated with sensory quality of YXC yogurt. Collectively, YXC-based yogurt enriches the variety of yogurt products and enhances their nutritional values and flavor properties.

Comparison of the quality of yoghurt produced from milk containing A1 and A2 β-casein

Abstract A2 milk, characterised by the presence of only the A2 β-casein genotype, has recently been of great interest due to its potential health benefits, which are the subject of intensive scientific research. From the dairy industry standpoint, it is crucial to ascertain its functional and technological attributes. The objective of this study was to compare two types of yoghurt (A1 and A2 yoghurts), produced respectively from cows’ milk containing exclusively β-casein (β-CN) A1 (A1/A1) or A2 (A2/A2) genotypes, in terms of basic chemical composition, protein profile, amino acid composition, antioxidant capacity, sensory quality, acidity, instrumental texture and colour profiles, as well as rheological characteristics. The obtained results indicate that the β-CN polymorphism had no significant impact on the basic chemical composition, acidity, DPPH radical scavenging activity, ferric reducing antioxidant power (FRAP) or colour properties of the yoghurts. Nonetheless, the β-CN genotype did affect the textural, rheological, and sensory qualities of the acidic gels, with A2 yoghurt yielding gels exhibiting higher hardness, gumminess, improved consistency and viscosity, and overall sensory quality compared to the corresponding A1 treatment. These results indicate that A2 milk serves as a good raw material for fermented milk production, warranting further investigation.

Enhancement effect of kale fiber on physicochemical, rheological and digestive properties of goat yogurt

This study incorporated kale fiber into goat milk as a functional component to investigate its impact on the quality and functional characteristics of set goat yogurt. Kale fiber content ranging from 0% to 1.5% (w/v) was added to 15% (w/v) defatted goat milk powder dissolved in water to form set yogurt. The addition of fiber increased the particle size and absolute potential of the goat yogurt, with a positive correlation observed between yogurt hardness, cohesiveness, and fiber content. Optimal water retention and thermal stability were achieved at a 0.5% fiber concentration. Microscopic analysis confirmed the successful incorporation of kale fiber into the yogurt gel network, resulting in significant differences in gel structure based on varying fiber content. Oscillatory temperature scan results indicated enhanced resistance to temperature changes due to the inclusion of kale fiber. Additionally, thixotropy results showed a 10% to 30% increase in gel structure recovery rate compared to the control group. In vitro digestion studies confirmed that kale fiber significantly improved protein bioavailability and release rate during digestion. Thus, incorporating kale fiber into goat milk as a natural plant-based functional component can enhance its nutritional value and rheological properties.

Fortification of yogurt with mulberry leaf extract: Effects on physicochemical, antioxidant, microbiological and sensory properties during 21-days of storage

Mulberry leaves are medicinal and edible, with many physiological functions. To improve the potential function of yogurt, the effects of mulberry leaf extract (MLE) incorporation on the fermentation kinetics, physicochemical, antioxidant properties, and sensory parameters of yogurt were evaluated. The results showed that 0.1–0.3 % MLE improved the acidification rate and shortened the fermentation process. The addition of MLE significantly increased the values of total titratable acids, water holding capacity (WHC), total phenolic content and antioxidant capacities of the yogurt (p＜0.05). Specifically, the WHC values of 0.1 % MLE added yogurt were 1.33–1.41 times that of the control over 21 days of storage. In addition, MLE changed the texture and sensory quality of yogurt, resulting in light green, more stable products. Compared to the control, the yogurt with an appropriate concentration of MLE (0.1 % and 0.2 %) showed stable microbiological properties, and the survival of lactic acid bacteria in the yogurt was able to maintain a stable probiotic count of 108 CFU/g over 21 days of shelf life. The yogurt containing 0.1 % MLE achieved a good balance between the physicochemical and sensory qualities of the yogurt, and the use of MLE as an ingredient in yogurt production was a step towards the development of healthier dairy products.

Widely targeted metabolomics analysis reveals the effect of soybean hull polysaccharides on nonvolatile components of plant-based yogurt and its metabolic pattern

Soybean hull polysaccharides (SHPS) enhance the physicochemical properties of plant-based yogurt. However, their effects on the nutritional profile and biochemical mechanisms remain unclear. This study aimed to assess the impact of SHPS addition on the nonvolatile components of plant-based yogurt and its underlying mechanisms through widely targeted metabolomics analysis. The results demonstrated that the addition of SHPS (0.2 %–1.0 % w/v) enhanced the levels of free amino acids, sugars, and organic acids, with the addition of 0.6 % w/v being particularly effective in improving yogurt quality. Widely targeted metabolomics analysis revealed 278 differential metabolites between yogurt supplemented with 0.6 % SHPS (SPY) and the control sample. SHPS increased the content of various metabolites, including amino acids and derivatives, saccharides, organic acids, and flavonoids, among others. Key metabolic pathways affected by SHPS included pantothenate and CoA biosynthesis; valine, leucine, and isoleucine biosynthesis; and benzoate degradation. As the primary component of SHPS, galacturonic acid affected the metabolic products in yogurt by participating in the pentose and glucuronate interconversions and ascorbate and aldarate metabolism pathways. These findings elucidate the role of SHPS in modulating the nutritional composition of plant-based yogurt, offering valuable insights into its functional mechanisms in food processing.

Commodity assessment of the quality of yoghurts sold on the consumer market

Commodity assessment of the quality of yoghurts sold on the consumer market

Valorizing Arthrospira cell residues into polysaccharides: Characterization and application in yogurt

This study aimed to extract and characterize polysaccharides from Arthrospira cell residue and evaluate their application in yogurt. Four Arthrospira polysaccharides (APP-50, APP-60, APP-70, and APP-80) were obtained by different ethanol concentrations. With the increase in ethanol concentration, the component peaks of polysaccharide became less and the components were simpler. The results showed that APP-60 had the highest neutral sugar content and the densest spherical structure. APP-50 had the highest protein content, the strongest antioxidant capacity, the porous structure, and the structure was incomplete. The addition of polysaccharides increased the viscosity, storage modulus, loss modulus, and particle size of yogurt, and improved the stability of yogurt during long-term storage. The microstructure of yogurt with added polysaccharides was tighter and more orderly than that of the control yogurt. This study demonstrated that Arthrospira polysaccharides could be used as functional ingredients to enhance the quality and nutritional value of yogurt.

Effects of optimizing fermentation time and stabilizers using response surface methodology on physicochemical properties of camel milk yoghurt

The objective of this study was to produce camel milk yoghurt with desired qualities using optimized processing conditions (fermentation time) and ingredients (stabilizer and calcium chloride). The conditions were obtained through Response Surface Methodology (RSM) by lactic acid fermentation by inoculating the milk with Lactobacillus delbrueckii subsp. Bulgaricus (YF-L903, CHR Hansen, Denmark. The study also determined the effects of fermentation time and ingredients on the quality of yoghurt. Fermentation time ranged from 2 to 22 h while stabilizer (corn starch) and calcium chloride (salt) ranges were 1.65–3.34 and 0.061–1.23 % respectively. The quality was monitored hourly for a fermentation period of 2–22 h by determining pH, total titritable acidity (TTA) and viscosity. Results indicated that viscosity was influenced by fermentation time, stabilizer and calcium chloride. The viscosity was increased from 0.01 to 0.4 and 0.01 to 0.3 by fermentation time, 0.01 to 0.2 and 0.01 to 0.3 by stabilizer and 0.01 to 0.5 and 0.01 to 0.6 Pa s by calcium chloride. Whereas the combined effects of calcium chloride and stabilizer increased the viscosity of yoghurt to 0.94 Pa s. Prolonged fermentation time, led to an increase in TTA and a decrease in pH. The finding from this study indicated that the optimal conditions required to produce camel milk yoghurt with desired qualities are a fermentation time of 10 h using 2.33 and 0.60 % corn starch and calcium chloride respectively. Under these conditions the produced camel milk yoghurt quality properties were a pH of 4.07, 0.32 % TTA and a viscosity of 0.35 Pa s.