Juniper Publishers-Nutrition Food Science International Journal

  Nutrition and Food Science International Journal - Juniper Publishers Abstract Lactic acid bacteria (LAB) play an important role as natural food preservatives. However, the characterization of the variety of their metabolites is limited. The aim of this study was to determine specific metabolites produced by  Lactobacillus gasseri  ATCC 33323 by an optimized liquid chromatography with an ultraviolet/diode detection (HPLC-UV/DAD) method and to investigate their potential antimicrobial activity against specific food pathogens ( Salmonella enterica ATCC14028; Staphylococcus aureus ATCC 29213; Escherichia coli ATCC 25922 and Klebsiella pneumoniae ATCC 700603 ). At the same time, the possible antioxidant activity of metabolites of L. gasseri was tested using the free radical DDPH• (a, a-Diphenyl-β-Picrylhydrazyl). Based on the results of this study, the major metabolites detected in L. gasseri were 6.0 ppm OH-PLA, 3.73 ppm 1,2-dihydroxybenzene, 2.31 ppm benzoic acid in 5 days. This study

  Nutrition and Food Science International Journal - Juniper Publishers Abstract Black tea quality depends on chemical composition of tea leaves and physical and chemical processes involved in its manufacturing. Different literature reports indicated that the main constituents of tea leaves belong to the polyphenol group and also various chemical constituents including methylxanthines, amino acids, chlorophyll, carotenoids, lipids, carbohydrates, vitamins, and more than 600 volatile compounds. This study investigated the effect of withering conditions (time and temperature) on thearubigins (TRs) and theaflavins (TFs) content in seedling and vegetatively propagated tea leaves. Tea leaves were withered at different times (14, 16, 18, and 20hours) at constant temperature (25°C) and different temperatures (23, 25, 27, and 29°C) at constant duration (18hours), prior to HPLC determination of TFs and TRs concentration. Parameters measured included, TFs, TRs, taste, liquor appearance and aroma