Study On Enzymatic Hydrolysis Of Natural Cream For Preparation Of Milk Flavor Base Material

Milk flavor is one kind of the most popular flavors in food industry.Base material for milk flavor can increase the performance in smell and taste,and help to cover stimulated feeling of synthesized flavoring and uncomfortable taste.Therefore, preparation of flavor base material with enzymatic method has become one of the research focuses nowadays.In this thesis,certain kind of milk was determined as imitation object by market investigation and sensory evaluation.Composition analysis was carried out and main components that may contribute to milk flavoring in base material were decided.A suitable lipase was selected and hydrolysis processing was optimized to hydrolyze cream according to the characteristics of the hydrolysates.Suitable head volatiles were selected and mixed with obtained milk flavor base material to form milk flavor.Among the four commercial milks,one kind of them possesses satisfying flavor characteristics.After analysis of its volatile components by GC-MS,protein content and fat acid composition,the main components in flavoring base material were determined as 9-hexadecenoic acid,9-octodecanic acid and 9,12-octadecadienoic acid.With these three fatty acids as objective,one kind of lipase,which can hydrolyze triglycerides specifically and produce special fatty acids required in milk flavor base material,was selected.Enzymatic hydrolysis conditions were optimized as temperature of 45±2℃,rotating speed of 400 r/m,enzyme addition of 0.1%and buffer addition of 14.2%(buffer was added after 0.5 h hydrolysis and ceased at 3.5 h). The reaction time was 28 h and final pH was obtained as 5.2～5.4 with acid value at 23.75±1.25 mL/g.Suitable head volatile was selected to perfume the flavor base material and their ratio was optimized as 6 g:94 g by sensory evaluation.The flavor and aftertaste of the milk was improved greatly and off-flavors were masked obviously by using 0.05%of the combined flavor in milk.The milk flavor base material produced by enzymatic method in this thesis has been applied to industrial use.