Study On Preparation Technology And Storage Stability Of Tofu Whey Fruit Yogurt

Yogurt is a nutritious and healthy food,but there are few tropical fruit yogurt and unique flavor yogurt with high nutritional value.Tofu whey is discharged as waste water,but it is rich in nutrients and high in content.In this paper,the tofu whey was fermented by lactic acid bacteria,and yogurt was prepared by blending flavor with pineapple jam,and the quality and curdling structure of pineapple jam yogurt in tofu whey were improved by compounding stabilizer,hoping to provide theoretical support and data support for the utilization of tofu whey and the development of flavored fruit yogurt.The main results are as follows:1.Using pH,titrated acidity and reducing sugar as indexes,the utilization of tofu whey by lactic acid bacteria was studied by single factor experiment,and the optimal technological conditions of fermentation tofu whey were determined.It was determined that the addition amount of lactic acid bacteria powder was 0.20%,the fermentation time was 24 hours and the fermentation temperature was 37℃.The fermentation effect of adding soybean polysaccharide was better than glucose,sucrose and lactose,and the addition amount was 1.5%.2.With single factor experiment,the optimum value of tofu whey and lactobacillus powder in yogurt was determined with pH,titrated acidity and water holding capacity as indexes.With pH,titration acidity,water holding capacity,δ-Potential,particle size,texture and microstructure were used to study the main reasons,for the deterioration of the stability of stirred tofu whey yogurt yogurt with the extension of storage time.The results showed that the grain size of tofu whey yogurt and soybean polysaccharide yogurt decreased significantly,and their hydrophobicity remained above 300 after 7 days of storage.The particle size of tofu whey yogurt and soybean polysaccharide yogurt remained below 1 um,and their microstructure was more concentrated.And the viscosity fluctuation of tofu whey yogurt and soybean polysaccharide yogurt decreased and decreased significantly on the 7th and 9th days,respectively,from 16.14 g·sec and 36.33 g·sec on the 1st day to0.74 g·sec and 16.15 g·sec,respectively,the viscosity is almost lost.The amount of tofu whey and lactobacillus powder was determined to be 40% and 0.15%respectively.At the same time,it was found that the key factor affecting the stability of tofu whey yogurt was the significant decrease of viscosity caused by protein adsorption,followed by the change of electrostatic and hydrophobic effects.3.Based on the sensory quality,physical and chemical properties and texture of tofu whey yogurt,the optimal ratio ofacetyldistarch adipate(ADA),propylene glycol alginate(PGA)and guar gum was studied.The effects of stabilizers on the stability of pineapple yogurt with jam(PGS)and tofu whey jam(HGS)were studied by taking pH,titrated acidity,water holding capacity,δ-potential,particle size,texture and microstructure as indexes.The results showed that the stability increased by more than 53%(P<0.05),and the grain size increased gradually with the storage period and significantly increased to 3000 nm on the 9th day(P<0.05).The sensory score of mixed stabilizer tofu whey pineapple yogurt(WHGS)remained stable at more than 70 points during the storage period,and the viscosity was significantly increased(P<0.05).It reached 190 g·sec on the 3rd day and remained at 196 g·sec on the 9th day,showing a visible improvement in the density of the microstructure.The changes in hydrophobicity and δ-potential of WHGS were lower than those of PGS and HGS.Finally,it was determined that the added amount of pineapple jam was 12%,PGA,ADA and guar gum were 0.03%,0.05% and 0.012%,respectively,the yogurt quality was the best.The addition of stabilizer significantly improved the storage stability of pineapple yogurt.