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흑마늘 농축액을 첨가한 요구르트의 제조와 품질특성

  • 2013-10-18
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Preparation and Quality Characteristics of Yogurt with Black Garlic Extracts

 

Yogurt base was prepared from skim milk added with 0.5, 1.0 and 1.5% (w/v) black garlic extracts(BGE, 60 brix),
fellowed by fermentation with Lactic acid bacteria (the mixed strain of Streptococcus thermophilus, Lactobacillus
delbrueckii subsp. bulgaricus) at 42℃ for 24 hr. The yogurt products were evaluated for acid production (pH, titrable
acidity), number of viable cells, viscosity, color value, and sensory properties. The pH of yogurt with BGE was below
6.0 at 6 hr fermentation, after which it was rapidly acidifies. Aftert 24 hr, the titratable acidity of yogurt with 1.5% BGE
was 0.74%, which was 5.7 times higher than that before fermentation. There was no significant difference in viable cell
count between the samples after 3 hr fermentation. The viscosity of yogurt was decreased by the addition of BGE. As
the percentage of BGE increased, the L value (lightness) decreased while the a value (redness) and b value (yellowness)
increased. The overall sensory score of yogurt with BGE was lower than that of yogurt with only skim milk. Therefore,
moderate addition of BGE was below 1% for the preparation of yogurt.


Key words: black garlic extract(BGE), yogurt, lactic acid bacteria