Institute of Food & Crop Science, School of Science & Engineering, University of Ballarat, Ballarat, Australia.
Int J Food Microbiol. 2010 May 30;140(1):19-25. doi: 10.1016/j.ijfoodmicro.2010.02.018. Epub 2010 Feb 19.
The aim of this study was to investigate the factors affecting the survival and growth of four food-borne pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus) in sweet and fermenting brewery wort. The Gram-negative pathogens (E. coli and Salm. Typhimurium) were capable of growth during the initial stages of fermentation in hopped wort, although they were quickly inactivated when added during the later stages of fermentation. When the wort was left unpitched, the two Gram-negative pathogens grew unabated. Pathogen growth and survival was enhanced as the pH was increased, and as both the ethanol and original gravity were decreased. Although having no effect on the Gram-negative pathogens, low levels of hop iso-alpha-acids were sufficient to inhibit L. monocytogenes, and a synergistic antimicrobial effect between iso-alpha-acids and pH was observed. S. aureus failed to initiate growth in all of the test worts. There appears to be no reason for concern of the safety of a "typical" wort during fermentation, however due attention should be paid when wort is stored or antimicrobial hurdles are lowered, for example in the production of reduced and alcohol-free beer, and in unpasteurised products.
本研究旨在探究影响四种食源性致病菌（大肠杆菌 O157:H7、鼠伤寒沙门氏菌、单增李斯特菌和金黄色葡萄球菌）在甜型和发酵型啤酒麦汁中生存和生长的因素。在添加麦汁的发酵后期，革兰氏阴性菌（大肠杆菌和鼠伤寒沙门氏菌）很快被灭活，尽管它们能够在添加麦汁的发酵初期生长。如果麦汁不进行接种，两种革兰氏阴性菌则会不受抑制地生长。随着 pH 值的升高以及乙醇和初始比重的降低，病原菌的生长和存活得到增强。尽管对革兰氏阴性菌没有影响，但低水平的酒花异构 α-酸足以抑制单增李斯特菌，并且观察到异构 α-酸和 pH 值之间存在协同抗菌作用。金黄色葡萄球菌未能在所有测试麦汁中开始生长。在发酵过程中，“典型”麦汁似乎不存在安全问题，但应注意麦汁的储存或抗菌障碍的降低，例如在生产低醇和无醇啤酒以及未经巴氏消毒的产品时。
