| Summary: | 碩士 === 東海大學 === 畜產與生物科技學系 === 93 === The changes of lactose in milk are through two routes after heating. One is the isomerization to form lactoluse, another one is the Maillard reaction in which lactose and its heat derivative interact with protein-bound amino acid to form lactulosyllysine.
This study was using HPLC with LiChroCART 100 NH2 column and a mixture of acetonitrile-phosphate buffer (81:19) as mobile phase (1.0mL/min). The changes of glucose, galactose, lactose and lactulose were detected in raw milk and reconstituted milk which were treated with LTLT, HTST, UHT or sterilization heat process.
As the result, after the heat treatment of LTLT, HTST, UHT and sterilization, the glucose with galactose contents increased gradually, and lactose decreased gradually. The lactulose only appeared in sterilization fresh milk. Therefore, wherewith the three carbohydrates content, should possibly be an effective indicator to identify the method of heat processing for fresh milks.
When the powdered milk exited, the more proportion occupied, then the changes of carbohydrate in various heat intensity would be more distinct. The content of glucose with galactose and lactulose would increase signally, and the lactose content tended to decrease. The ratio of glucose with galactose to lactulose decreased with powdered milk proportion increased in reconstituted milk through UHT, but on the counter doctrine when heated through sterilization.
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