Effects of Quality Characteristics and Antioxidant Activity on Yogurt Added With Cold Brew Liquid Coffee Containing Lactobacillus delbrueckii subsp. bulgaricus
2022
Lim, S.Y.
The purpose of this study is to compare the quality characteristics and antioxidant activities of the tagatose yogurt with different contents (6, 8, 10%) of cold brew liquid coffee. Tagatose is a low-calorie food ingredient with putative health-promoting benefits. The tagatose yogurt was fermented with Lactobacillus delbrueckii subsp. bulgaricus at 37±1℃ for 20 h. The changes in acid production (pH and titratable acidity), viscosity, and lactic acid bacteria were determined every 5 h during fermentation. Color value was determined before and after fermentation, and antioxidant activities were performed after fermentation in triplicate. The yogurts containing cold brew liquid coffee had lower pH, higher acidity, and viscosity than the control, regardless of the liquid coffee contents. All samples had increasing levels of lactic acid bacteria over the fermentation period, but lactic acid bacteria of yogurts with the addition of cold brew liquid coffee increased further than the control. The total polyphenol/flavonoid content, DPPH/ ABTS/H₂O₂ radical scavenging activities, and reducing power increased when the liquid coffee content of the yogurt rose. Consequently, the optimal quality of tagatose yogurt was found when 6-8% of cold brew liquid coffee was added according to the overall results of quality properties and antioxidant activity.
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