Effects of Lactobacillus fermentum HY01 on the quality characteristics and storage stability of yak yogurt

Abstract

Lactobacillus fermentum HY01 is a probiotic strain screened from traditional yak yogurt, which can effectively relieve enteritis and constipation. This study aimed to evaluate the effects of HY01 as an adjunct starter on the quality and storage of yak yogurt. A total of 36 main volatile flavor substances were detected in all samples. In particular, more aldehydes, esters, and alcohols were detected in yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter MY105 (including Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus). The rheological results showed that the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter MY105 had higher apparent viscosity and lower tan δ value compared with compared with traditional yak yogurt, yak yogurt with only L. fermentum HY01, and cow yogurt with L. fermentum HY01 and starter MY105. Meanwhile, the conjugated linoleic acid in the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter was significantly higher than those in the HY01 group or the yogurt starter group alone. After 28 d of storage at 4°C, the number of HY01 in the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter was still higher than 10 7 cfu/mL, its acidity was lower than 110°T, and its syneresis was the lowest. The results indicated that L. fermentum HY01 could improve the flavor, texture, and storage properties of yak yogurt.

Exopolysaccharide-Producing Lacticaseibacillus rhamnosus Space Mutant Improves the Techno-Functional Characteristics of Fermented Cow and Goat Milks

“…Aldehydes confer a variety of oxidation flavors to fermented milk. The flavor threshold is generally low, and the accumulation and superimposition of these molecules produce a strong flavor effect . Alcohol is another important index that reflects the flavor quality of fermented dairy products, and alcohol production in fermentation processes is associated with the type and quantity of bacterial intracellular enzymes.…”

“…The flavor threshold is generally low, and the accumulation and superimposition of these molecules produce a strong flavor effect. 62 Alcohol is another important index that reflects the flavor quality of fermented dairy products, and alcohol production in fermentation processes is associated with the type and quantity of bacterial intracellular enzymes. The mass fraction of alcohol metabolites detected in fermented goat milks produced by the two bacteria was rather different.…”

Effects of Freezing Raw Yak Milk on the Fermentation Performance and Storage Quality of Yogurt

“…According to the method of Zhang et al [17], the rheological properties of yogurt were tested with the HR-1 rotational rheometer (TA discovery rotational rheometer HR1, New Castle, DE, USA). Before testing, the yogurt samples were rested at 4 • C for 10 min.…”

“…Our research team has carried out some work on improving the quality and shelf life of yak yogurt based on a project of the Key Technology Research and Product Development for Ecological Livestock Products Processing on Qinghai-Tibet Plateau [16,17]. We have further investigated the effects of different raw milk freezing conditions on fermentation performance and the post-acidification, texture and sensory characteristics of yak yogurt based on the current production status of the Yak Dairy Products Processing Cooperative in Yushu Autonomous Prefecture, Qinghai, where raw milk is frozen for a long time, and high-temperature instantaneous sterilization equipment is lacking.…”

Preventive effect of Lacticaseibacillus rhamnosus 2016SWU.05.0601 and its postbiotic elements on dextran sodium sulfate-induced colitis in mice

“…Due to the unique geographical and climatic characteristics of the Qinghai-Tibet Plateau, the microorganisms in yak yogurt have formed a complex microbiota through natural selection and long-term domestication ( Ding et al, 2022 ; Franceschi et al, 2023 ). Yak yogurt is richer in nutrients than regular yogurt and is considered a good reservoir of lactic acid bacteria ( Wei et al, 2022 ), of which Lactobacillus plantarum , Lactobacillus fermentum , and Lactobacillus swissii are the dominant strains, and have a wide range of beneficial properties such as antioxidant and lipid-lowering ( Zhang X. et al, 2022 ). Therefore, yak yogurt is an ideal source for the isolation and screening of excellent lactic acid bacteria.…”