Quality Characteristics and Antioxidant Activity of Yogurt with Different Tomato Pomace Powder

This study examined the quality characteristics, bioactive compounds and antioxidant activities of yogurt prepared by replacing skim milk powder with 0%, 3%, 6%, and 9% tomato pomace powder.The pH and sugar content decreased, and the total acidity in the control and experimental groups increased as the fermentation time and tomato pomace powder content increased.Lactic acid bacteria increased rapidly as the fermentation time of yogurt increased, and partially decreased as the amount of tomato pomace powder added was increased.The viscosity increased proportionately to the fermentation time and the amount of tomato pomace powder added.Colorimetry of the fermented yogurt showed that lightness decreased, and the redness and yellowness increased as the amount of tomato pomace powder added.The total polyphenol and total flavonoid content of the yogurt increased as the amount of tomato pomace powder added was increased, and the carotenoid content showed that lutein, lycopene and -carotene all increased as the tomato pomace powder content was increased.The antioxidant activity, as measured by the DPPH and ABTS radical scavenging activity and reducing power, also increased as the amount of tomato pomace powder added was increased.Therefore, adding 6% or more tomato pomace powder to yogurt, considering the acidity, lactic acid bacteria proliferation pattern, bioactivity and antioxidant activity of yogurt, can produce yogurt that utilizes the functional properties of tomato pomace.