Studies On Processing Technology Of The Brown Yoghurt

With the rapid development of China’s economy,people’s consumption level is increased sharply,also to the taste of the food and nutrition requirement is higher and higher,the requirements for tastes and nutrition of food are getting higher and higher.In recent years,Chinese dairy products has maintained rapid growth,in which the fastest growing is yogurt category.With its nutritional value and unique flavor to attract consumers,brown yogurt has risen as a new category in the last two years.Some technical issues of similar products in the market often appear,such as thin taste,water precipitation and so on.Systematic research has lacked in this category.The optimum formulation and processing technology of brown yoghurt was determined by systematic study on raw material,process,stabilizer and strain.This study can provide the guidance and the help to the industrial production of brown yogurt.Selecting three starter to do applied research,the changes of pH,apparent viscosity,gel process,aroma analysis and sensory evaluation of brown yoghourt produced by three fermenting agents during the shelf life were investigated.The results showed that Yo-C571-F had a moderate ability of acid production,strong ability to produce viscous and strong gel strength analyzed by Turbiscan curve.Yo-C571-F is a typical fermented yogurt aroma,and has a good fragrance.The order of sensory evaluation scores is Yo-C571-F>Yo-C351-F>Yo-C342-F.Yo-C571-F is determined as the optimum starter.In the research of the raw material,this paper systematically studied the application of different protein content,fat content and proportions of casein and whey protein in brown yoghurt.The results showed that with the increase of protein and fat content,the water retention and the apparent viscosity of the product increased.The optimal protein content of brown yoghurt is 2.8-3.5% and the fat content is 3.0-4.5%.Yogurt with the increase of water can be realized by increasing the proportion of whey protein to casein,at the same time,the yogurt gel strength is also improved.When the ratio of casein to whey protein is 2:1,the yogurt gel is obviously enhanced.Through the orthogonal test of the concentration of glucose,browning temperature and time,we found the browning temperature affected the quality of brown yoghurt the most.The optimum glucose addition amount was 5%,when browning yoghurt at 95°C for 120 min.Because of Maillard Reaction of reducing sugar and amino acids during the browning,the thermal stability of the proteins reduced and the formation of yoghurt gel structure was affected.The colloid of water-retaining and excellent resistance to high temperature was chosen in priority through a lot of single factor experiment in this part.Then it was compound with emulsifier to determine the optimal scheme of the compound stabilizer.The pH value,apparent viscosity,water-retaining capability,rheological properties and sensory evaluation were monitored among brown yoghurt with stabilizer,blank sample and similar products on the market.The results showed that apparent viscosity,water-retaining capability and elastic modulus of the sample adding compound stabilizer and the commercial sample are higher than those of blank sample.Sensory evaluation of the sample adding compound stabilizer was better than that of blank samples and similar products on the market.The results showed that adding compound stabilizer increased the density of the protein gel and promoted the formation of the milk protein gel,which made the network more closely and enhanced the continuity of system.