The Effects of Sugar Content on Growth of Zygosaccharomyces bailii in Rice-syrup

摘要

Spoilage yeast was isolated from spoiled rice-syrup and identified by Microbial Identification system (MIDI) as Zygosaccharomyces bailii based on composition of fatty acids exhibiting carbon skeleton of 16:0, 16.1 (Acis 7), 18:2 (Acis 9), 18:1 (Acis 9), and 18:1. Increase in sugar content (Fbrix) resulted in decreased moisture concentration (1%), and water activity decreased from 0.72 to 0.63 when sugar concentration increased from 77 to 83°brix. Yeast showed very slow growth during three weeks post-inoculation in rice-syrup at 77 and 79°brix, and maximal level of Z. bailii was found at 6 and 10 weeks storage at 15 and 25°C, respectively. At over 81°brix its growth slowly decreased at beginning of storage, indicating rice-syrup could be preserved safely at above 81°brix sugar content without Z. bailii contamination.