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J Food Sci Technol (July 2015) 52(7):46524660 DOI 10.1007/s13197-014-1670-6
SHORT COMMUNICATION
Green tea yogurt: major phenolic compounds and microbial growth
Shabboo Amirdivani & Ahmad Salihin Hj Baba
Revised: 7 November 2014 /Accepted: 1 December 2014 /Published online: 11 December 2014 # Association of Food Scientists & Technologists (India) 2014
Abstract The purpose of this study was to evaluate fermentation of milk in the presence of green tea (Camellia sinensis) with respect to changes in antioxidant activity, phenolic compounds and the growth of lactic acid bacteria. Pasteurized full fat cows milk and starter culture were incubated at 41 C in the presence of two different types of green tea extracts. The yogurts formed were refrigerated (4 C) for further analysis. The total phenolic content was highest (p<0.05) in air-dried green tea-yogurt (MGT) followed by steam-treated green tea (JGT) and plain yogurts. Four major compounds in MGTY and JGTY were detected. The highest concentration of major phenolic compounds in both samples was related to quercetinrhamnosylgalactoside and quercetin-3-O-galactosylrhamnosyl-glucoside for MGTY and JGTY respectively during first 7 day of storage. Diphenyl picrylhydrazyl and ferric reducing antioxidant power methods showed highest antioxidant capacity in MGTY, JGTY and PY. Streptococcus thermophillus and Lactobacillus spp. were highest in MGTY followed by JGTY and PY. This paper evaluates the implementation of green tea yogurt as a new product with functional properties and valuable component to promote the growth of beneficial yogurt bacteria and prevention of oxidative stress by enhancing the antioxidant activity of yogurt.
Keywords Yogurt fermentation . Antioxidant activity .
Microbial growth . Green tea
Introduction
Fermented milk products are becoming increasingly popular because of the numerous health benefits associated with highly digestible nutrients especially for individuals with lactose maldigestion, high biochemical (Wu et al. 2008) and antioxidant activities (Kullisaar et al. 2003) and probiotic organism colonisation of intestine after ingestion (Korcznska et al. 2008). The addition of some materials, particularly fruits, into yogurt is practiced to increase the appealing taste of yogurt (Clark and Plotka 2004). This is commercially carried out after fermentation of milk to allow un-interrupted microbial fermentation of milk. However, the presence of additives during the fermentation of milk by starter culture may result in improved end-product (Amirdivani and Baba 2011) particularly when these materials contain phytochemicals that...