Investigation of yogurt analogue production possibilities using transglutaminase enzyme from peanut milk (extract) and two different starter cultures

Purpose: In this study, it was aimed to investigate the producibility and some quality characteristics of a fermented product of vegetable origin by using transglutaminase enzyme and two different starter cultures (EPS-producing-YoFlex and non-EPS-producing-YC 350) to the peanut extract selected as raw material. Materials and Methods: Yogurt analog production was carried out by using the response surface method by adding mTGase enzyme, peanut pulp and two different starter cultures to the peanut extract. According to the results obtained from the experimental design, three points where pH decrease is rapid, % lactic acid concentration and relative viscosity are high were determined and a total of six yogurt analogues were produced using three YC350 starter cultures and three YoFlex starter cultures. Produced yogurt analogues samples were stored at +4°C for 21 days. The effects on pH decrease, relative viscosity and % lactic acid during fermentation of yogurt analogues were investigated. SDS-PAGE in samples taken at 0 and 4 hours of fermentation, microstructure, analysis of volatile components on the 1st day of storage, textural properties (texture analysis, water holding capacity, syneresis) in yogurt analogues during 1st, 7th, 14th, 21st days of storage), microbiological analyzes and sensory analyzes were used to characterize the product. Results: When the data obtained at the end of the storage period were examined, similarities were observed in the pH, lactic acid and relative viscosity data, and it was determined that the yogurt analogues containing 0.26% starter culture and 7.5 U/g protein mTGase enzyme had better structural properties compared to the others. When the two cultures were compared, there was no significant difference in water holding capacity and syneresis in storage analysis of yogurt analogs produced with YoFlex Advance 2.0 compared to yogurt analogs produced with YC350 starter culture. According to the results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis performed on yogurt analog samples produced with the addition of mTGase, the decrease in bant intensities and a faint image with the increase of enzyme concentration was interpreted as more cross-linking of proteins. The appearance of the gel structure as loose and irregular holes in the obtained microstructure images was associated with low mTGase concentration, and the dense and tight observation of the gel structure was associated with high mTGase concentration. When the images of gel using YoFlex starter culture are examined, the gel structure appears to be less porous, tight matrix and creamy. In addition, in the sensory analyzes of the same samples, it was determined that the amount of firmness and the feeling of the physical structure and consistency were high. As a result of the volatile component analysis, 34 volatile components were detected in the samples, and it was observed that the most dominant volatile components were acetaldehyde and hexanal from aldehydes, diacetyl from ketones, and 2-4 dimethylpentane and isobutane from alkanes. It was determined that the numbers of Streptococcus thermophilus changed in the range of 5,04-8,46 log cfu/g,. Lactobacillus bulgaricus numbers in the range of 7,04-8,34 log cfu/g during the storage period in the yogurt analog samples, and the number of microorganisms decreased periodically during the storage period. Yogurt analogues produced with YC350 culture scored higher in sensory analysis, especially in terms of appearance, odor and consistency. Conclusion: Within the scope of this study, the integration of mTGase enzyme and peanut pulp into the yogurt analog matrix by drying, grinding and converting it into a fermented product has been successfully carried out, and it has been shown that it can be produced as an alternative for vegan/vegetarian diets. Keywords: Peanut Milk, Transglutaminase, Yogurt Analog, Syneresis, SDS-PAGE, Volatile Components, Microstructure