Effect of plant Lactobacillus P-8 on fermented milk flavor and storage stability.

plant Lactobacillus P-8 is a probiotic strain with excellent properties that can significantly reduce lipid levels, enhance immune function and improve gut flora. Plant Lactobacillus P-8 is widely used in dairy products and has been proven to be used in fermented goat's milk and fermented soybean milk, which can make it have excellent flavor characteristics. Therefore, this experiment will further explore the effects of plant Lactobacillus P-8 and yogurt fermentation agent in combination with fermentation on fermented milk flavor and a series of storage properties.experimental design homogeneity of milk, yogurt fermentation agent (hot streptococcus IMO40133 and German Lactobacillus Bulgarian subsequent IMO20401 by 1:1000 ratio; The ratio of plant lactobacillus to yogurt fermentation agent is added to the milk to prepare fermented milk according to 6 proportions, such as 1:1, 1:5, 1:100, 1:50, 1:1000, etc. The chemical and chemical properties of prepared fermented milk were determined (volatile flavor compounds, pH, TA, live cell count, viscosity, dehydration contraction, etc.).
1: Details of the experimental design . Results 1. Volatile flavor compounds in fermented milkThe plant Lactobacillus P-8 and yogurt fermentation agents were inoculated in 6 proportions, such as 1:1, 1:5, 1:10, 1:100 and 1:1000, respectively. We identified a total of 66 volatile flavor compounds from different proportions of probiotic fermented milk, mainly aldehyde, ketones, carboxy acid, alcohol, esters and aromatic hydroxyl.analysis of the main components of volatile compounds, it was found that there were differences between the volatile components of different proportions of plant Lactobacillus P-8 fermented milk. Fermented milk with ratios of 1:100 and 1:1000 is gathered together on the positive axis. The 1:1, 1:5, 1:10, 1:50 ratio of fermented milk is gathered together on a negative axis (Figure 2A). Aldehyde, ketones, alcohols, esters, and aromatic compounds are located on the positive axis, while acidic compounds are located on the negative axis (Figure 2B). This shows that the ratio of 1:100 and 1:1000 ratio of probiotic fermented milk in aldehyde, ketone, alcohol content is higher, compared to other proportions of probiotic fermentation milk samples have a better flavor.. Figure 2: Analysis of the main components of volatile compounds detailsThe aroma activity value (OAV) of fermented milk is measured, Table 1 shows the OAV values of each component of fermented milk in various proportions, of which the OAV values of 1:100 and 1:1000 ratio fermented milk are the results of the determination, while the OAV values of other ratios are from the literature reference. Six characteristic compounds were detected in 1:100 and 1:1000 ratio fermented milk, namely 3-methylbutylaldehyde, hexaldehyde, (E)-2-synol, acetaldehyde, 2-etone and 2-oxycodone. At 1:100 ratio, the OAV value of the main compounds in fermented milk is greater than the level of 1:1000 ratio, and the OAV values of healdehyde in fermented milk under these two ratios are found to be 10.99 and 10.69, respectively, indicating that hexaldehyde may be the main component of fermented milk cheese aroma, 1:100 may be the best match between plant Lactobacillus P-8 and yogurt fermentation agent.. Table 1: Details of the OAV values of each proportion of fermented milk 2. Table 2 of fermented milk pH and TA valuesshows changes in pH and TA values during fermentation and storage, and we find that after 2 hours of fermentation, the pH value drops rapidly, reaching 4.5 pH in less than 6 hours. At the end of the 14-day storage period, fermented milk pH containing Plant Lactobacillus P-8 can reach 4.01, at which point the TA value can be increased to 93.28.. 3. Fermented milk live cell countThe addition of probiotics at a scale of 1:100 had no significant effect on the count of live cells during fermentation and storage (Table 2). During the fermentation period (0-4 hours) and storage period (0-3 days), the count of live cells of fermented milk increased rapidly, reaching 5.25x109 CFU/mL after 3 days of storage, and then decreasing significantly. Similar results were found in fermented milk at a ratio of 1:1000, with the live cell count peaking at 2.82x109 CFU/mL on the second day of storage.. 4. Fermented milk viscosity and dehydration shrinkage valuesTable 2 also lists the viscosity of fermented milk after the addition of probiotics at 1:100 during fermentation and storage periods. We found that during fermentation and storage, the viscosity of fermented milk increased significantly over time and peaked at 1280 mPas at 1 day of storage. After the addition of plant Lactobacillus P-8, the viscosity increased steadily, reaching 1166 mPas at 3 days of storage. Fermented milk added to Plant Lactobacillus P-8 is more prone to dehydration contraction than other yogurts during the refrigeration phase, with a shrinkage value of 31-36%.. Table 2: Details of the properties of fermented emulsification (pH, TA, live cell count, viscosity and dehydration shrinkage values Sensory assessment of fermented milkThe team members conducted a sample taste sensory assessment of fermented milk with different proportions of probiotics and yogurt fermenters stored on the 0th, and found that the ratio of plant lactobacillus P-8 to yogurt fermentation agent was considered to have better flavor characteristics than other fermentation creams.conclusion After measuring the quality of fermented milk prepared by the ratio of plant Lactobacillus P-8 to yogurt fermentation agent, a total of 66 volatile flavor compounds were identified. According to the difference between plant Lactobacillus and fermentation agent, there are obvious differences in volatile compounds, and 6 characteristic compounds were detected in 1:100 and 1:1000 ratio fermented milk. The addition of plant Lactobacillus P-8 does not affect the physical and chemical properties of fermented milk itself. In addition, we found that the 1:100 ratio of fermented milk flavor quality is better, and through sensory evaluation found that its yogurt characteristics are better than ordinary fermented milk, which also shows that the control of the ratio of probiotics to fermentation agents for regulating the volatile characteristics of fermented milk and the overall flavor is very important.
.