Quality of Irradiated Plain Yogurt During Storage at Different Temperatures (Report‪)‬

INTRODUCTION Yogurt, a sour milk product, is a fermented dairy food originated from the Balkans and the Middle East. Goats', ewes', and cows' milk are used for its manufacture (Teuber, 2000). Yogurt is usually manufactured with or without the addition of some natural derivatives of milk, and with the gel structure being the results of the milk proteins by lactic acid produced from different microorganisms such as Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (Robinson, 2003). It possesses a fresh lactic acid smell and its taste is characteristic, pleasant, full, and slightly to intensely sour (Teuber, 2000). Because yogurt contains an abundant and viable microflora of starter origin at the time of consumption and low pH, it is considered generally safe if possible post-pasteurization recontamination is prevented (Varga, 2006). Antioxidant activity of some yogurt starter cultures also reported (Kim et al., 2005). However, the shelf life of yogurt products is usually 3 weeks or less at refrigerated storage in Korea. In addition, immuno-compromised patients can be suffered from these health-promoting microorganisms present in yogurt.