Acidity Of Yogurt Research Articles

Yogurt acid whey powder dietary inclusion level modulates broiler cecal microbiota composition and metabolic activity

All over the world, the increasing demand for Greek yogurt generates vast quantities of acid whey as a by-product. The large volume and nutrient composition of yogurt acid whey makes it worthwhile to investigate potential uses in animal nutrition. This study aimed to investigate the inclusion of yogurt acid whey powder (YAWP) in four dietary levels on broiler performance, cecal microbiota composition and metabolic activity. A total of 300 male one-day-old male Ross broiler chickens were randomly assigned into 4 treatments of 5 replicates each. Broilers were fed maize-soybean meal basal diets following a 2-phase feeding program. Depending on the YAWP inclusion level (g kg-1 diet), treatments were no YAWP addition (W0), YAWP at 25 g kg-1 (W25), YAWP at 50 g kg-1 (W50) and YAWP at 100 g kg-1 (W100). Overall body weight gain, feed intake and feed conversion ratio were not affected by YAWP addition. In the ceca, a linear decrease in total bacteria counts and a linear increase in Lactobacillus spp. was noted with increasing YAWP dietary level. A linear reduction of Clostridium cluster I and E. coli species was noted with increasing YAWP dietary level. A linear increase in total volatile fatty acids concentration, acetic acid and butyric acid molar ratios was shown with increasing YAWP level. In conclusion, the addition of YAWP did not affect overall performance but positively modulated the cecal microbiota and metabolic activity of 42-day-old broiler chickens.

Research on the Commercialization of Low-Sugar Yogurt with Carrot Jam in Response to Consumer Demand

A new low-sugar yogurt with carrot jam was developed by reflecting consumers’ demands of yogurt and the characteristics required for the development of new yogurt. To examine the storage stability of yogurt containing carrot jam, the yogurt was stored in a refrigerator at 4°C for 21 days, and changes in pH and titratable acidity were examined at 3-day intervals. Nine nutrient contents of yogurt were analyzed to compare the sugar content of the control and carrot jam-added yogurt. Considering the health functionality of new yogurt, when questioned about the appropriate amount of sugar content in yogurt, numerous respondents indicated that they wanted the sugar content to be reduced by about 1 to 5% (73.3%) compared with existing products and that the taste should remain similar to existing products (32.2%). The pH and titratable acidity of yogurt with 4% carrot jam were measured during storage, and it was found that the yogurt had excellent storage properties up to the twenty-first day of production. According to the result for the nutrient contents of yogurt with 4% carrot jam, it was found that the total carbohydrate content, including the dietary fiber content of carrots, was 9.3% while the sugar content was 4.7% which was lower than the sugar content of the control group of 7.0%. Considering the above results, it is expected that the consumption of Jeonnam regional specialties will be promoted through commercialization research on yogurt with carrot jam, which can meet consumers’ health needs and perceptions toward the new yogurt.

Evaluation of In Vitro Antihypertensive and Anti-Inflammatory Properties of Dairy By-Products

Sweet whey (SW) and yogurt acid whey (YAW) are dairy by-products of the cheese-making process and Greek-style yogurt production, respectively. Both of them are considered pollutants with huge volumes of SW and YAW produced due to the growing demand for dairy products worldwide. Moreover, whey-derived peptides, resulting from fermentation as well as from further hydrolysis during digestion, have been associated with various biological activities. In the present study, the angiotensin-converting enzyme (ACE)-inhibitory activity of 48 SW samples and 33 YAW samples from bovine, ovine, caprine, and ovine/caprine milk obtained were evaluated. Additionally, the SW and YAW digestates and two of their fractions (smaller than 10 kDa, SW-D-P10 and YAW-D-P10, and smaller than 3 kDa, SW-D-P3 and YAW-D-P3), which were obtained after in vitro digestion and subsequent ultrafiltration, were also subjected to evaluation. Our data indicated that the D-P10 and D-P3 fractions exhibited higher ACE-inhibitory activity compared to the corresponding values before digestion. The ACE-inhibitory capacity after in vitro digestion was higher for the ovine SW samples compared to their bovine and caprine counterparts. The effect of the D-P3 fraction on the inhibition of nitric oxide (NO) production and the expression of a selected panel of immune-response-related genes in LPS-stimulated RAW 264.7 macrophages was also evaluated. Fractions from both dairy by-products inhibited NO production in LPS-stimulated RAW 264.7 cells. Especially, ovine SW-D-P3 showed a strong NO inhibitory activity and suppressed inducible nitric oxide synthase (Nos2) mRNA levels. However, YAW-D-P3 could not trigger neither the gene expression of inflammatory macrophage mediators Nos2 and cyclooxygenase-2 (Ptgs2) nor tumor necrosis factor-α (Tnf) and interleukin 6 (Il6) in LPS-stimulated murine macrophages regardless of animal origin. These findings suggest that in vitro digestion could enhance the production of ACE-inhibitory peptides in both dairy by-products, while SW from ovine origin displays higher potential as an anti-inflammatory agent, effectively preventing excessive NO production.

Technology of Enrichment of A2 Dairy Products with Carrot Powder Carotinoids

Topicality. Milk is an available for consumption, popular and nutritious food product, which contains a variety of important macronutrients and biologically active compounds, including carotenoids. Carotenoids contained in food products have low bioavailability, solubility and stability. A high fat content and a unique fat composition of dairy products can be used in order to overcome the problem of low carotenoid bioavailability which is common to fruits and vegetables. Therefore, the usage of fortified dairy products can be a potential means of increasing the supplyof carotenoids to the human body. The aim of the article is to eleborate a technology for enriching A2 dairy products with carrot powder carotenoids. Experimental samples of A2 milk with a mass fraction of fat (3.2%) were produced: control (without additives); sample 1 (enriched with carrot powder in the amount of 10%); sample 2 (enriched with carrot powder in the amount of 20%). The carrot powder was added to milk, thoroughly mixed for 10 minutes, and subjected to homogenization under a pressure of 100-110 MPa, after which it was filtered. The carrot pulp separated during milk filtration, in the amount of 10 and 20% by weight of the product, was used to enrich yogurts. Research methods. Using standard methods, in experimental milk samples organoleptic, physico-chemical indicators were determined according to DSTU EN ISO 1211:2022 (Ukrainian Research and Training Centre for Problems of Standardisation, Certification and Quality, 2023), as well as microbiological indicators were defined according to DSTU 7357:2013 (Ministry of Economic Development of Ukraine, 2014), DSTU 7089:2009 (State Consumer Standard of Ukraine, 2011), and carotenoid content (by chemical method). Additionally, the change in the active acidity of yogurts during their storage was studied by the method of direct potentiometry. Results. It was established that the addition of carrot powder had a positive effect on organoleptic quality indicators of milk, and caused an increase in the protein mass fraction within their composition by 0.03–0.04%. When adding 10% of carrot powder, the concentration of carotenoids increased by 0.163 mg/100 ml, and when adding 20%, then by 0.553 mg/100 ml accordingly. In the case of applying homogenisation under high pressure, and when enriching milk with carrot powder, its microbiological stability was ensured. Enrichment of yogurts with carrot pulp led to a significant increase of dietary fibers content in their composition, and allowed to raise the pH level of the finished product. During the entire storage period, the active acidity of enriched yogurts was within the normal range. Conclusions and discussion. Enrichment of milk with carrot powder and using homogenisation under high pressure leads to an increase in the concentration of carotenoids in milk, which provides almost 5% of the daily needs.

Consumer Acceptance and Physicochemical Properties of a Yogurt Beverage Formulated with Upcycled Yogurt Acid Whey

Drinkable yogurts are low-viscosity beverages often created by diluting yogurt with water or high-value-fluid milk. Yogurt acid whey, a typically discarded byproduct of the Greek yogurt industry, may serve as an upcycled ingredient for these types of products with minimal processing. In this study, differing concentrations of acid whey (35%, 40%, and 45% w/w) were added to a mango yogurt beverage with 0.2% and 0.4% w/w stabilizer and analyzed for physicochemical properties over a 40-day period. The analysis indicated that the percentage of acid whey was positively correlated with both viscosity and water-holding capacity. A hedonic sensory analysis of the beverages indicated positive consumer acceptance of such upcycled products, with enhanced acceptance at 25–35% addition. This study demonstrates the potential for consumer acceptance of yogurt beverages upcycled with native-acid whey, providing insights into sustainable practices within the food industry.

Effect of Milk Origin and Seasonality of Yogurt Acid Whey on Antioxidant Activity before and after In Vitro Gastrointestinal Digestion.

Yogurt acid whey (YAW) is a by-product of Greek strained yogurt production. The disposal of YAW constitutes an environmental problem, and given the increasing demand of Greek yogurt worldwide, its handling is a challenge. However, whey-derived peptides, resulting from microbial fermentation as well as those resulting from further hydrolysis during the digestion process, have been linked to enhanced biological activities. In this study, the antioxidant capacity of 33 samples of YAW obtained from Greek dairy companies of bovine, ovine or caprine origin was investigated using both cell-free and cell-based assays. The YAW samples, their in vitro digestion products (YAW-Ds) and a fraction of the digests (less than 3 kDa; YAW-D-P3) were assessed using four biochemical assays, namely ORAC, ABTS, FRAP and P-FRAP. Our data revealed a higher antioxidant capacity for digested samples compared with undigested samples, with all four methods. ORAC values after in vitro digestion were higher for the ovine samples compared to their bovine (YAW-D and YAW-D-P3) and caprine (YAW-D-P3) counterparts. Furthermore, the YAW-D-P3 fraction derived from samples collected in the summer months exhibited higher ORAC values when compared to the respective fraction from the winter months' samples. The cellular antioxidant activity of ovine YAW-D-P3 was improved in H2O2-treated HT29 cells compared to the control H2O2-treated cells. However, YAW-D-P3 could not trigger either the pathways involving the transcription factors NF-κB or NFE2L2 or the gene expression of SOD1, CAT and HMOX1 in LPS-challenged THP-1-derived macrophages. These results suggest that YAW, and particularly YAW from ovine origin, could be used as a natural source for its antioxidant potential in human and animal nutrition.

Effect of Yogurt Acid Whey on the Quality of Maize Silage

The increasing popularity of Greek yogurt generates large amounts of acid whey worldwide. The use of yogurt acid whey in animal nutrition is limited. The aim of this study was to determine the effect of a yogurt acid whey powder (YAWP) addition to maize forage prior to ensiling on the nutritional, microbial and fermentation quality of maize silage. Depending on the addition level of the YAWP to maize forage, there were the following four experimental treatments: YAWP 0, 2.5, 5 and 10% w/w. An increasing YAWP inclusion level linearly increased the maize silage dry matter, crude protein and ash concentrations, whereas it reduced the crude fiber, neutral-detergent fiber and acid-detergent fiber concentrations. The silage pH decreased quadratically with the increasing YAWP level, with the lower plateau noted for the YAWP 5% addition. Concentrations of total bacteria in the silage and Lactobacillus spp. decreased linearly with the YAWP increase. The silage acetic acid content decreased linearly, whereas propionic acid, lactic acid and the ratio of lactic to acetic acid increased linearly with the increasing YAWP level. The ammonia-N content decreased linearly with the increasing YAWP level. In conclusion, the incorporation of the 5 and 10% YAWP addition in silage preparation improved the nutritional and fermentative quality of the produced silage.

Yoghurt quality when using probiotic starter cultures and vegetable filler

In order to increase the biological value of yogurt, increase and improve its assortment, it is necessary to continue the search and use of new additives and fillers of natural origin. Such fillers should be well combined with the milk base, contain mineral elements, vitamins and other biologically active substances. The article substantiates the use of bacterial starters and vegetable filler in yogurt technology. The results of studies on the use of dry bacterial starter cultures of direct application of the Ukrainian manufacturer of the “YOGURTON” trademark and the vegetable filler “Black currants dry extract of 30 % anthocyanins” in the production of yoghurt are presented. An evaluation of the prototypes showed that when using the Yoghurt Probio TM «YOGURTON» starter, the product had a more pronounced taste and smell. The time of clot formation, changes in titrated acidity, and organoleptic characteristics of yogurt with filler were studied. It was found that all samples of yogurt on organoleptic parameters meet the requirements of DSTU and high scores on the scoring system of fermented milk products. The tested starter cultures at a fermentation temperature range of 40 ± 2 °C form a clot for 6–8 hours with a titratable acidity of 75 °T. Yogurt with a content of dry currant powder in an amount of 1 % in terms of organoleptic characteristics turned out to be the best; with an increase in the content of currant powder in yogurt up to 1.5 %, an increase in the taste of currants and a decrease in the characteristic sour milk taste of the product were noted. High acidity gives the product a sour taste and smell, which reduces its organoleptic characteristics. The acidity of yogurt with a filler content of 1 % was 116 °T on the first day of storage and increased to 140 °T for ten days. During storage of yogurt at the temperature of +6 ± 2 °C there is a gradual increase in lactic acid microorganisms, which affects the organoleptic characteristics of yogurt. “Black currant extract dry 30 % anthocyanins” enriches yogurt with anthocyanins, flavonoids, organic acids, pectin, which improve the taste and quality of the product.

Incorporation of Yogurt Acid Whey in Low-Lactose Yogurt Ice Cream.

Yogurt acid whey (YAW), a by-product of strained yogurt production, is a strong environmental pollutant because of its high organic load. Hence, efforts are made for its utilization to minimize its disposal in the environment. This study deals with the incorporation of YAW in yogurt ice cream (YIC) by partial replacement of yogurt with simultaneous lactose hydrolysis (LH) of the formulated YIC mix. Six YIC mix formulations were made, two without YAW (non-LH- and LH-control samples, A and AH), two with 12.5% YAW (samples B and BH), and two with 18.75% YAW (samples C and CH). The results showed that the partial replacement of yogurt with YAW decreased significantly (p < 0.05) the total solids of B, BH, C, and CH products (31.72 ± 0.14%, 31.92 ± 0.21%, 30.94 ± 0.14%, and 31.27 ± 0.10%, respectively) compared to the total solids of control products A and AH (33.30 ± 0.36% and 33.74 ± 0.06%, respectively). In contrast, the overruns increased (51.50 ± 2.36%, 58.26 ± 0.09%, 56.86 ± 1.92%, and 65.52 ± 1.30% for the B, BH, C, and CH products, respectively) compared to control samples (42.02 ± 2.62% and 49.53 ± 2.12% for A and AH, respectively). LH significantly decreased the freezing point and the viscosity of the YIC mixes but increased the overruns of the products as shown previously. YAW significantly decreased the hardness of the B and C products (56.30 ± 2.11 N and 43.43 ± 3.91 N, respectively) compared to control A (81.14 ± 9.34 N), and LH decreased it even more, leading to a rather soft scoop YIC. AH, BH, and CH YICs exhibited better melting properties despite the lack of fat destabilization in all samples. After 60 days of storage, counts of yogurt starter microorganisms were still >107 cfu/g and DPPH radical scavenging activity had increased in all products. In the sensory evaluation test, lactose-hydrolyzed samples AH, BH, and CH had less intense sandiness and, as expected, more intense sweetness. In conclusion, in the framework of the circular economy, it is possible for the YAW to be used as a resource material at a ratio of 12.5% to produce a YIC product without leaving behind any new waste.

In vitro evaluation of the effect of yogurt acid whey fractions on iron bioavailability

A side effect of the raised consumption of Greek yogurt is the generation of massive amounts of yogurt acid whey (YAW). The dairy industry has tried several methods for handling these quantities, which constitute an environmental problem. Although the protein content of YAW is relatively low, given the huge amounts of produced YAW, the final protein amount in the produced YAW should not be underestimated. Taking into consideration the increased interest for bioactive peptides and the increased demand for dietary proteins, combined with protein and peptides content of YAW, efforts should be made toward reintroducing the latter in the food supply chain. In this context and in view of the prevalent dietary iron deficiency problem, the objective of the present study was the investigation of YAW fractions' effect on Fe bioavailability. With this purpose, an in vitro digest approach, following the INFOGEST protocol, was coupled with the Caco2 cell model. To evaluate whether YAW digest fractions exert positive, negative or neutral effect on Fe bioavailability, they were compared with the ones derived from milk, a well-studied food in this context. Milk and YAW showed the same effectiveness on both Fe bioavailability and the expression of relative genes (DCYTB, DMT1, FPN1, and HEPH). Focusing further on YAW fractions, by comparison with their blank digest control counterparts, it resulted that YAW 3- to 10-kDa digests fraction had a superior effect over the 0- to 3-kDa fraction on Fe-uptake, which was accompanied by a similar effect on the expression of Fe metabolism-related genes (DCYTB, FPN1, and HEPH). Finally, although the 3- to 10-kDa fraction of bovine YAW digests resulted in a nonsignificant increased Fe uptake, compared with the ovine and caprine YAW, the expression of DCYTB and FPN1 genes underlined this difference by showing a similar pattern with statistically significant higher expression of bovine compared with ovine and bovine compared with both ovine and caprine, respectively. The present study deals with the novel concept that YAW may contain factors affecting Fe bioavailability. The results show that it does not exert any negative effect and support the extensive investigation for specific peptides with positive effect as well as that YAW proteins should be further assessed on the prospect that they can be used in human nutrition.

In Vitro Synergistic Antibacterial and Anti-Inflammatory Effects of Nisin and Lactic Acid in Yogurt against Helicobacter pylori and Human Gastric Cells.

Helicobacter pylori is a bacterium that naturally thrives in acidic environments and has the potential to induce various gastrointestinal disorders in humans. The antibiotic therapy utilized for treating H. pylori can lead to undesired side effects, such as dysbiosis in the gut microbiota. The objective of our study was to explore the potential antibacterial effects of nisin and lactic acid (LA) in yogurt against H. pylori. Additionally, we investigated the anti-inflammatory effects of nisin and LA in human gastric (AGS) cells infected with H. pylori. Nisin and LA combination showed the strongest inhibitory activity, with confirmed synergy at 0.375 fractional inhibitory concentration index. Also, post-fermented yogurt with incorporation of nisin exhibited antibacterial effect against H. pylori. The combination of nisin and LA resulted in a significant reduction of mRNA levels of bacterial toxins of H. pylori and pro-inflammatory cytokines in AGS cells infected with H. pylori. Furthermore, this also increased bacterial membrane damage, which led to DNA and protein leakage in H. pylori. Overall, the combination of nisin and LA shows promise as an alternative therapy for H. pylori infection. Additionally, the incorporation of nisin into foods containing LA presents a potential application. Further studies, including animal research, are needed to validate these findings and explore clinical applications.

Evaluation of Kluyveromyces spp. for conversion of lactose in different types of whey from dairy processing waste into ethanol.

The processing of dairy products currently generates significant amounts of waste, particularly in the form of liquid whey. The disposal of whey poses a challenge to the environment due to its high organic content and biological oxygen demand. Whey contains lactose, soluble proteins, lipids, and minerals. While Saccharomyces cerevisiae can efficiently utilize glucose, they are unable to metabolize lactose. In contrast, Kluyveromyces spp. encode two genes, Lac12 and Lac4 that enable conversion of lactose to other by-products such as ethanol. Here, we selected five Kluyveromyces yeast inoculated into three different types of whey substrates, cheddar sweet whey, cream cheese acid whey, and yogurt acid whey that could be used to convert lactose into ethanol. We demonstrate that differences exist in ethanol production across different whey substrates inoculated with Kluyveromyces yeast. In sweet whey, K. lactis, K. lactis Y-1205 and K. lactis Y-1564 were the highest ethanol producing strains. The highest amount of ethanol produced was 24.85 ± 3.5 g/L achieved by Y-1564 in sweet whey (96.8% efficiency). K. lactis Y-1205 produced 22.39 ± 5.6 g/L ethanol in yogurt acid whey. In cream cheese acid whey, K. lactis strains produced significantly higher ethanol levels compared to S. cerevisiae and K. marxianus (p < 0.05). Outcomes from this study could provide a simple and cheap solution for small-to medium-sized dairy processing facilities to ferment lactose in whey into ethanol using lactose-consuming yeasts.

Functional exploration of taro starch (Colocasia esculenta) supplemented yogurt.

Stabilizers are essential components of manufactured products such as yogurt. The addition of stabilizers improves the body, texture, appearance, and mouth feel of yogurt while also preventing technical defects such as syneresis. A study was conducted to optimize the concentration of taro starch in yogurt. The yogurt was fortified at different concentrations of taro starch. Taro starch levels were 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, and 3%, with different storage times (0, 14, and 28 days). The Tukey honesty test was used for mean comparison (p < .1). The results of the study showed that maximum moisture and protein content was taken by using 0.5% taro starch and stored for 0 days while maximum fat % was attained in 1.5% taro starch treatment and storage time was 0 days. The maximum water-holding capacity was increased by adding 1.5% taro starch under 14 days' storage time. Water-holding capacity started decreasing with the increasing taro concentration. The acidity of yogurt started increasing with the increasing taro starch and the maximum acidity was taken at 2.5% taro starch concentration. The viscosity of the yogurt was maximum at 2% taro starch. As far as it concerned, sensory evolution, aroma, and taste started changing with the increasing taro starch concentration and increasing storage time. The study's goals were to optimize the taro concentration for stabilizing the yogurt synthesis and to probe the impact of taro starch on the physiochemical attributes of yogurt.

Aerobic Cultivation of Mucor Species Enables the Deacidification of Yogurt Acid Whey and the Production of Fungal Oil.

As the Greek-style yogurt market continues to experience prosperous growth, finding the most appropriate destination for yogurt acid whey (YAW) is still a challenge for Greek yogurt manufacturers. This study provides a direct alternative treatment of YAW by leveraging the abilities of Mucor circinelloides and Mucor genevensis to raise the pH of YAW and to produce fungal biomass with a high lipid content. Aerobic cultivations of these species were conducted in YAW, both with and without the addition of lactase, at 30 °C, and 200 rpm agitation. The density, pH, biochemical oxygen demand (BOD), biomass production, lipid content, fatty acid profile, and sugar and lactic acid concentrations were regularly measured throughout the 14-day cultivations. The data showed that M. genevensis was superior at deacidifying YAW to a pH above 6.0-the legal limit for disposing of cultured dairy waste. On the other hand, M. circinelloides generated more fungal biomass, containing up to 30% w/w of lipid with high proportions of oleic acid and γ-linolenic acid. Additionally, the treatments with lactase addition showed a significant decrease in the BOD. In conclusion, our results present a viable treatment to increase the pH of YAW and decrease its BOD, meanwhile generating fungal oils that can be further transformed into biodiesel or processed into functional foods or dietary supplements.

Physical and Chemical Properties of Cow's Milk Yogurt Added Whey Protein Concentrate (WPC)

The purpose of this research was to examine the physical and chemical characteristics of cow's milk yogurt with the addition of WPC. The physical characteristics observed included color (L*, a*, b*, whiteness index, hue, chroma), texture (firmness, work of penetration, resistance to probe withdrawal), while the chemical characteristics observed included water content, total solids, and titratable acidity. The main research materials are fresh cow's milk, Whey Protein Concentrate (WPC), and starter yogurt. The study was conducted using a Completely Randomized Design (CRD) with 5 treatments and 4 replications. The treatments consisted of control (P0), adding WPC as much as 2% (P1), 4% (P2), 6% (P3), and 8% (P4) of the amount of milk. Data were analysed using analysis of variance and post-hoc orthogonal polynomial test. The results showed that the addition of WPC up to 8% caused a very significant difference to the water content, total solids, titratable acidity, firmness, and work of penetration of yogurt. However, the addition of WPC up to 8% did not cause a significant difference in the color characteristics of yogurt. Total solids of yogurt increased from 12.08% (control) to 17.74% along with the addition of WPC up to 8%. Based on the results of the research, it can be concluded that the addition of WPC up to 8% can decrease the water content, firmness, and work of penetration of yogurt, as well as increase the total solids and titratable acidity of yogurt. However, it did not cause a noticeable change in the color characteristics of yogurt. However, it did not cause a significant change in the color characteristics of yogurt.

Copper inhibits postacidification of yogurt and affects its flavor: A study based on the Cop operon

Yogurt and its related products are popular worldwide. During transportation and storage, Lactobacillus delbrueckii ssp. bulgaricus in yogurt continues to metabolize to form lactic acid, the postacidification phenomenon of yogurt. Postacidification of yogurt is a widespread phenomenon in the dairy industry. Many scholars have done research on controlling the postacidification process, but few report on the molecular mechanisms involved. In this study, we used a molecular-assisted approach to screen food additives that can inhibit postacidification and analyzed its effects on yogurt quality as well as its regulatory mechanism from multi-omics perspectives in combination. The copper ion was found to upregulate the expression of the LDB_RS05285 gene, and the copper transporter-related genes were regulated by copper. Based on the metabolic-level analysis, copper was found to promote lactose hydrolysis, accumulate a large amount of glucose and galactose, inhibit the conversion of glucose to lactic acid, and reduce the production of lactic acid. The significantly greater abundance of l-isoleucine and l-phenylalanine increased the abundance of 3-methylbutyraldehyde (∼1.2 times) and benzaldehyde (∼7.9 times) to different degrees, which contributed to the formation of the overall flavor of yogurt. Copper not only stabilizes the acidity of yogurt, but also it improves the flavor of yogurt. Through this established method involving quantitative and correlation analyses at the transcriptional and metabolic levels, this study provides guidance for the research and development of food additives that inhibit postacidification of yogurt and provide a reference for studying the changes of metabolites during storage of yogurt.

Probiotic Incorporation into Yogurt and Various Novel Yogurt-Based Products

Probiotics are commonly added to yogurt to provide many health benefits for the consumer. A description is provided for some commonly used probiotics in yogurt. A GRAS (generally recognized as safe) list of probiotic bacteria that can be added to yogurt or similar types of products is provided. Additionally, prebiotics, synbiotics (combination of prebiotics and probiotics), postbiotics, paraprobiotics, and psychobiotics can be added to yogurt. Probiotic yogurt can come in various forms in addition to spoonable yogurt, and yogurt can be used as an ingredient in other food products. Many useful functional ingredients can be applied to probiotic yogurt. The safety of probiotics must be addressed, especially for critically ill patients and other susceptible populations. Probiotics must survive within yogurt throughout its entire shelf-life and within the gastrointestinal tract after consumption by the consumer to provide health benefits, and many techniques can be used to maintain survival of probiotics in yogurt. Furthermore, probiotics can be added to Greek yogurt acid whey. Many opportunities exist for adding a wide variety of probiotics to a wide variety of yogurt-based products.

Effect of hemp protein on the physicochemical properties and flavor components of plant-based yogurt

The aim of this study was to develop a new formulation of soybean and hemp protein fermented yogurt (SHY) and to evaluate the effects of hemp protein concentration on the physicochemical and flavor properties of yogurts. The results indicated that hemp protein rapidly reduced the pH, and increased total titratable acidity of yogurts due to the propagation of lactic acid bacteria. Stronger influence on the parameters was detected at higher hemp protein concentration. Yogurt with hemp protein has the potential to reduce the whey precipitation and improve texture and rheology compared to those of control yogurt. The key volatile components, including alcohols, esters, alkanes, and aldehydes, may be conducive to the flavor optimization of SHYs. The results of physicochemical properties and flavor substance selection also supported the high liking scores of 10% SHY in sensory evaluation. These findings demonstrated that hemp protein has great development potency as a nutritional source to produce functional dairy products with optimum quality.

CHANGES OF QUALITY CHARACTERISTICS OF FUNCTIONAL FRUIT YOGURTS FORTIFIED WITH HUSK EXTRACTS OF VARIOUS NUTS DURING COLD STORAGE

Walnut, almond, and pistachio husk extracts were used to enrich the peach yogurt. The effects of the extracts on the physicochemical, biochemical, microbiological, and sensory properties of yogurt were investigated during 21 days of cold storage. Husk extracts slowed down the increase in acidity of yogurt and, correlatedly, the syneresis values of extract fortified yogurts were lower than the control yogurt. Inevitably, husk extracts caused a difference in ΔE of yogurts. However, this difference did not affect the sensory appearance scores of yogurts negatively. All extracts, especially those of walnut husk, significantly increased the antioxidant and antidiabetic activities of yogurt, but this effect was partially reduced with prolonged storage. Also, the extracts reduced the lipid oxidation of yogurt by almost half. Although some sensory values of almond and walnut samples were relatively lower than control yogurt, the panelists liked pistachio yogurts at least as much as control yogurt. The findings of this study revealed that husk extracts of various nuts can be used as both a natural preservative and a functional ingredient in fruit yoghurt.

Niacin inhibits post-acidification of yogurt based on the mining of LDB_RS00370 biomarker gene

The post-acidification of yogurt results in short shelf life, undesirable flavor, and sour taste, making it unacceptable to consumers. Many scholars have proposed several solutions to this problem. However, the existing methods of inhibiting post-acidification cannot fundamentally solve this problem. So exploring the molecular mechanism behind post-acidification can be a better approach to finding the solution. Therefore, we first evaluated the correlation between 69 candidate genes for post-acidification and changes in the acidity of yogurt fermented with different Lactobacillus bulgaricus, and mined a biomarker LDB_RS00370 for post-acidification. Subsequently, this biomarker was used for large-scale screening of food additives that could inhibit post-acidification, and niacin was found to be the most representative one. Finally, the mechanism of niacin inhibiting post-acidification of yogurt was analyzed by RNA-seq, which revealed that post-acidification might be inhibited by affecting protein synthesis and glycolysis. This study opens up a novel perspective on molecular prediction of the post-acidification process, which could provide guidance for precautions to be taken in yogurt production.