| Summary: | 碩士 === 臺南師範學院 === 自然科學教育學系碩士班 === 92 === The purpose of this study is to investigate the fluorescent difference of the yogurt with different ratio of raw milk by fluorescence spectrophotometer and HPLC.
The raw milk was provided by various dairy plants and reconstituted milk made by one commercial whole milk powder and two skimmed milk powder. 3 ml Lactobacillus bulgaricus and Streptococcus thermophilus were added into yogurt samples which contained different ratio of reconstituted milk, then incubated six hours at 430C for prepareing testing samples.
Seven grams of the above diluted yogurt contained 250μl DEAE-DEXTRAN and 10μl acetic acid, was mixed well, centrifuged and filtrated. The fluorescence intensity of the yogurt was determined by Hitachi F-3000 spectrofluorometer and HPLC with fluorescent detection systems. The results of fluorescent analysis by spectrofluorometer showed that the more reconstituted milk , the more fluorescent intensity and the maximum emission is 415nm correspond to the typical AGEs fluorescence. The results of fluorescent analysis by HPLC with fluorescent detection systems showed that the more reconstituted milk ,the more fluorescence intensity of the peak at 6.33-7.09min .The constituent analysis of the yogurt was determined according CNS and the results showed that the pH , acidity and Ash have no significant difference among samples (p<0.05); the CP, the number of Lactobacillus bulgaricus and Streptococcu thermophilus decrease as the ratio of reconstituted milk increase; the order of theβ-galactosidase of yogurt was not correspond to the quantity of reconstituted milk.
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