Vibrio parahaemolyticus, enterotoxigenic Escherichia coli, enterohemorrhagic Escherichia coli and Vibrio cholerae

This review highlighted the following: (i) pathogenic mechanism of the thermostable direct hemolysin produced by Vibrio parahaemolyticus, especially on its cardiotoxicity, (ii) heat-labile and heat-stable enterotoxins produced by enterotoxigenic Escherichia coli, especially structure–activity relationship of heat-stable enterotoxin, (iii) RNA N-glycosidase activity of Vero toxins (VT1 and VT2) produced by enterohemorrhagic Escherichia coli O157:H7, (iv) discovery of Vibrio cholerae O139, (v) isolation of new variant of Vibrio cholerae O1 El Tor that carries classical ctxB, and production of high concentration of cholera toxin by these strains, and (vi) conversion of viable but nonculturable (VBNC) Vibrio cholerae to culturable state by co-culture with eukaryotic cells

Enzyme Activity Levels in Beef: Effect of Postmortem Aging and End‐point Cooking Temperature

While it is known that meat flavor varies as a function of end‐point cooking temperature, storage time, and activity of endogenous hydrolytic enzymes, little is known about the interrelationship of these three factors with flavor. Several endogenous enzymes and proteins with potential involvement in meat flavor were investigated. The data indicate two main observations: (1) enzymes are redistributed to new intracellular compartments during postmortem aging. (2) enzyme activity is temperature dependent over the range examined (20‐80°C) with some enzymes such as cathepsins B & L retaining a high level of activity (\u3e20% of that at 20°C) at temperatures above 70°C. Thus, the combined effect of postmortem aging and cooking, via enzyme redistribution and enzyme activity, respectively, influence the production of flavor compounds and precursors. Copyright © 1990, Wiley Blackwell. All rights reserve