Research On The Production Technology Of Pasteurized Sour Goat Milk

Pasteurized goat yogurt has high nutritional value and unique flavor,which is very popular among consumers.However,in the pasteurization process,goat yogurt is prone to quality problems such as whey precipitation and water holding capacity decline.In order to solve these problems,this experiment studied the effect of pasteurization conditions,stabilizers,Transglutaminase(TG)and stabilizer with TG complex on the quality of pasteurized goat yogurt,expect to solve the quality problems of goat yogurt in the pasteurization process and improve the quality of goat yogurt.1.Effect of pasteurization conditions on sterilization effect of goat yogurtIn this study,the temperature,time and fermentation pH of pasteurization were optimized to study its effect on the sterilization effect of goat yogurt.The results showed that the microorganisms in goat yogurt were greatly affected by the sterilization temperature,time and fermentation pH.When sterilizing at 70 ?,the longer the sterilization time,the more obvious the sterilization effect.When the temperature was raised to 80 ?,reduced sterilization time required.At the same time,the lower the fermentation pH,the more obvious the sterilization effect.After storage for 10 days at 37 ?,the microbial quantity did not change much,and the pH of goat yogurt remained stable.The sterilization time had a great influence on the precipitation of whey protein in goat yogurt.The longer the time,the more serious the whey precipitation.Comprehensive the results of commercial sterility test and the stability changed,finally determined that when the pH of the goat yogurt fermentation was controlled at 4.3?4.4,the whey precipitation of goat yogurt after sterilization at 80?/5min was less and the stability was good.2.Effect of stabilizer on the quality of pasteurized goat yogurtStudied the effects of pectin,agar,gellan gum,diacetyl tartaric acid esters of mono diglyceride and modified starch on the quality of pasteurized goat yogurt.The results showed that the five stabilizers could improve the viscosity and water holding capacity of'goat yogurt,but the best effect was in a certain range.The optimal combination of five stabilizers was selected by orthogonal test to be A3B1C3D1E1.(0.09%rubber,0.03%agar,1.4%modified starch,0.04%gellan gum,0.06%diacetyl tartaric acid esters of mono diglyceride),the results showed that the effect of stabilizer compounding was better than used alone,and the effect on the quality of goat yogurt was improved.Obviously,the viscosity and water holding capacity of the goat yogurt were significantly increased,the flavor substances acetaldehyde,diacetyl content were increased,the texture characteristics were improved,and no whey precipitated after sterilization.3.Effect of transglutaminase treatment on the quality of pasteurized goat yogurtStudied the effect of TG treatment on acidity,water holding capacity,viscosity and flavor substance,sensory quality and texture characteristics of pasteurized goat yogurt.The results showed that TG treatment had obvious inhibitory effect on the acid production rate of goat yogurt,but there was no significant difference between the groups after treatment with different concentrations of TG.The concentration of TG had significant effect on the viscosity and water holding capacity of goat yogurt,when the concentration was lower than 4u/g,the water holding capacity and viscosity of goat yogurt increased significantly with the increase of TG concentration,after the TG concentration was higher than 4u/g,the water holding capacity of goat yogurt decreased,but the viscosity did not change.At the same time,TG could inhibit the production of flavor substances(acetaldehyde and diacetyl)in goat yogurt,but it has obvious improvement on the texture characteristics of goat yogurt.increasing the viscosity and sourness of goat yogurt.Comprehensive experimental results confirmed that the quality of goat yogurt was the best after 4u/g TG treatment.4.The effect of transglutaminase and stabilizer on the quality of Pasteurized goat yogurtStudied the effect of stabilizers combined with TG on the quality of pasteurized goat yogurt.the results showed that:compound stabilizer,modified starch were used separately together with different concentrations of TG would inhibit the formation of goat yogurt acidity,The higher the concentration of TG,the more obvious the inhibition effect,and the inhibition effect of TG and compound stabilizer was greater than TG and modified starch.The viscosity and water holding capacity of goat yogurt increased significantly after compound stabilizer,modified starch was used together with TG,Compared with the goat yogurt added only compound stabilizer or TG,it was the largest at compound stabilizer with 2u/g TG treatment.After compound stabilizer,modified starch was combined with TG,the content of acetaldehyde in the goat yogurt decreased,and the diacetyl did not change.At the same time,TG combined with compound stabilizer and modified starch had obvious improvement on the texture characteristics of goat yogurt,increaseed the thick thickness and smoothness of goat yogurt,and improved the stability of goat yogurt.Combined with sensory analysis,the quality of goat yogurt after compound stabilizer with 2u/g TG treatment was better than the stabilizer or TG alone.