| China's ice cream market is developing at an alarming rate,and per capita consumption of ice cream is growing rapidly.Ice cream has gradually changed from the role of cooling and preventing heatstroke in the past to focusing on hobby and enjoyment.The ice cream industry adheres to the concept of "light maintenance" of health,caters to consumers' health needs,and integrates health and wellness into ice cream.The development trend of the ice cream industry in each country is slightly different,but the general trend is same: the output is constantly increasing,the proportion of high-sugar and high-fat ice cream is constantly decreasing,and the fat-free,low-calorie,and sugar-free ice cream market is developing rapidly.This thesis is mainly divided into two parts:(1)exploring the optimal conditions of lactase hydrolyzed reconstituted milk;(2)completing the replacement of sugar alcohol with sucrose.Finally,the raw milk is lactose-free,and then the sugar alcohol is extended to the application of ice cream products.(1)The ONPG method was used to analyze the selected lactase,and by drawing a standard curve,the lactase activity was measured to be 5600 U/g.A single factor experiment was designed to determine the lactose residue using a lactose meter.Exploring the hydrolysis conditions of whole milk and skimmed milk from the aspects of enzyme amount,temperature and time.Response surface methodology was used to design and optimize the hydrolysis conditions.Several experiments have verified that the best hydrolysis conditions for full fat reconstituted milk lactose are: 35 ?,2.5 h,and enzyme volume 3500 U/L.The optimal hydrolysis conditions for skimmed reconstituted milk lactose are: 35 ?,2.5 h,and enzyme amount 2500 U/L.The lactose content of the hydrolyzed reconstituted milk was verified by high performance liquid chromatography.Compared with a standard curve and a controlling lactose standard chromatogram,the results showed that no lactose was detected in the two hydrolyzed reconstituted milks.It is proved that the hydrolyzed reconstituted milk has reached the lactose-free standard.The electronic nose,electronic tongue,and electronic eye were used to analyze the odor,taste,and color of the reconstituted milk before and after hydrolysis.The results showed that there was no significant difference in the flavor of the reconstituted milk before and after hydrolysis;there was a significant difference in the taste of the milk;the reconstituted milk had a significant increase in sweetness after hydrolysis;the umami and salty tastes also increased;the sour and bitter tastes were almost unchanged;There was no significant change in the color of the reconstituted milk before and after hydrolysis,and the overall milk color of the non-fat reconstituted milk after hydrolysis was changed from pale yellow white to pale yellow.(2)Select maltitol and xylitol for gradient compounding,optimize and determine the best sugar alcohol ratio.Reconstituted milk that meets lactose hydrolysis standards is added together with sugar alcohol in the ice cream mixing stage,and then sterilized,homogenized,aged,frozen,and hardened until the finished product.The mass method was used to measure the expansion ratio of ice cream,TA-XT Plus texture analyzer was used to measure the texture of ice cream,and ZXMP-A1150 constant temperature and humidity box was used to measure the melting resistance.Persons with experience in sensory evaluation performed sensory evaluation on ice cream products.In the form of scoring,the difference between the groups of ice cream is compared with the score.The results show that the expansion rate of ice cream is 70% ~ 90%,the difference between different sugar alcohol ratio groups is obvious.The expansion rate of ice cream with maltitol is significantly better than that of ice cream with xylitol.The hardness and chewiness of ice cream with maltitol is obviously better than that of ice cream with xylitol;the ice cream with maltitol has a fine taste,but the sweetness is slightly weak.The sweetness of xylitol-added ice cream is pure,but the taste is slightly inferior;By comparing the sweetness,frankincense,mouthfeel,and overall coordination of different sugar alcohol groups,the results show that the ratio of maltitol/xylitol is 10%:3%,the two sugar alcohols can complement each other and make the best overall flavor and taste of the ice cream.Based on the existing conclusions,other milks and dairy products can be hydrolyzed and combined with new varieties of sugar alcohol for the development and production of new ice creams.This thesis provides new ideas for the research and development of natural and healthy ice cream. |
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