Process Optimization And Storage Quality Analysis Of Brown Yogurt

Brown yogurt,also known as char-grilled yogurt,is a new type of yogurt product that is fermented by using a Maillard reaction of protein and reducing sugar in milk at a high temperature for a long time and then adding a starter.Because of its unique caramel flavor and color,it is favored by consumers.Now the process of factory-produced brown yogurt is browning temperature 95 ° C,browning time 180 min,glucose addition 4%,Sucrose addition 7%,but long-term browning reaction is easy to form a large number of brown-black macromolecular substances,affecting product quality and bring Security risks.In this experiment,the brown yogurt process was optimized by changing the added ingredients and shortening the browning time.The optimized product was analyzed during shelf life and the antioxidant capacity was determined,and the headspace solid phase microextraction-gas chromatography-mass spectrometry was adopted.To study the composition of flavor substances in brown yogurt.The main results are as follows:1.Optimized the production process of brown yogurt.The sensory score and browning index were used as indicators to determine the optimal range of five factors: sucrose,glucose,amino acid,whey protein and p H.The five-factor four-level orthogonal experiment was used to determine the most brown yogurt.The browning process is browning temperature 95 °C,browning time 120 min,browning reaction 7% sucrose addition,7% glucose addition,p H 7.3,whey protein addition 2%,amino acid addition 0.3%.The quality of the brown yogurt produced by the optimized process is superior,and the browning index reaches 10.95.2.The flavor component of brown yogurt was studied.The difference of the species,composition and content of the flavor substances in the test group and the control group(browning temperature 95 °C,browning time 180 min,glucose 4%)was analyzed by headspace solid phase microextraction-gas chromatography-mass spectrometry.The types of compounds in acids,alcohols,esters and alkanes in the test group were significantly higher than those in the control group.A total of 44 volatile flavor substances were detected in the test group,and 32 volatileflavors were detected in the control group.substance.The acid content and the content of alkanes in the test group were also significantly higher than those in the control group.Compared with the control group,acetone,2-pentanone,2-hexanone,hexyl hexanoic acid,butanediol,hexamethylcyclotrisiloxane,octamethylcyclotetrasiloxane and acetic acid in the test group The ammonium content is significantly increased,which is the root cause of the difference in flavor between the two yogurts.3.The physicochemical,sensory and antioxidant properties of brown yogurt during storage were analyzed.The changes of p H value,acidity,viscosity,total number of colonies,water holding capacity and browning index of brown yogurt during storage were investigated.It was found that p H,viscosity,water holding capacity and browning index decreased gradually with the prolongation of storage time.The sensory index showed a trend of increasing first and then decreasing.On the 7th day,the sensory quality was the best.The browning index,viscosity and sensory quality of the experimental group were significantly higher than those of the control group.By measuring the scavenging ability of ABTS free radicals,DPPH free radical scavenging ability and total reducing ability,it was found that brown yogurt had certain antioxidant activity during storage,and the antioxidant capacity of the experimental group was higher than that of the control group in the later storage stage.