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KMID : 0380619890210060795
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Korean Journal of Food Science and Technology
1989 Volume.21 No. 6 p.795 ~ p.799
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Changes of Some Physicochemical Properties of Yoghurt made from β- Galactosidase - treated Commercial Milks
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Abstract
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This study was carried out to hydrolyze lactose in commercial milk by β-galactosidase from Kluyveromyces fragilis and to compare some physicochemical properties of yoghurts made from control and lactase-treated commercial milks. Quantitative analysis of sugars was performed by gas liquid chromatograph (GLC) on trimethylsilyl (TMS) derivatives. In commercial milk, 94.6% of lactose was hydrolyzed after 2 hours incubation at 40℃ with 6.0 units/ml of β-galactosidase. pH, titratable acidity and viable cell number of yoghurt made from lactase-hydrolyzed (LH) commercial milk were 4.1, 1.04% and 6.5 x 10^8/ml of Str. thermophilus, 8.9 x 10^8/ml of L. bulgaricus after 8 hours incubation at 40, respectively. The total contents of amino acid were 2.63% in control and 2.19% in LH yoghurt. The total contents of free amino acid were 26.95 mg% in control and 17.55 mg% in LH yoghurt. Analysis of free fatty acids resulted in that the contents of short chain fatty acids in LH yoghurt were a little higher than those in control. Both in control and LH yoghurt, the palmitic acid content was highest and that was followed by oleic and myristic acid.
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