The efficacy of electrolyzed oxidizing (EO) and acidified chlorinated water (45 ppm residual chlorine) was evaluated in killing Escherichia coli O157:H7 and Listeria monocytogenes on lettuce. After surface inoculation, each leaf was immersed in 1.5 L of EO or acidified chlorinated water for 1 or 3 min at 22 Њ Њ Њ Њ ЊC. Compared to a water wash only, the EO water washes significantly decreased mean populations of E. coli O157:H7 and L. monocytogenes by 2.41 and 2.65 log 10 CFU per lettuce leaf for 3 min treatments, respectively (p Յ Յ Յ Յ Յ 0.05). However, the difference between the bactericidal activity of EO and acidified chlorinated waters was not significant (p Ն Ն Ն Ն Ն 0.05). Change in the quality of lettuce subjected to the different wash treatments was not significant at the end of 2 wk of storage.

A study was done to determine the survival characteristics of Escherichia coli O157:H7 in potato starch powder as affected by a w (0Á24± 0Á26, 0Á51±0Á52 and 0Á75±0Á78), pH (4Á1 and 6Á7) and temperature (4, 20 and 37 C) over a 33-week storage period. Survival was enhanced as the a w decreased. The rate of death was higher as the storage temperature increased. Survival did not appear to be affected by pH. Since the composition of foods greatly affects the viability of E. coli O157:H7 at reduced a w , development of models to predict patterns of inactivation in a given food should be carried out using data generated from that food or one with very similar composition, a w and pH.

The quality of shrimp thawed using a constant temperature thawing chamber compared with running water was studied. Shrimp thawed in room temperature air was used as the control. Shrimp thawed using the thawing chamber had lower drip loss, higher yield and moisture content than shrimp thawed by running water. However, the diflerences were not statistically significant. There were also no significant differences in press juice and shear force between control and shrimp thawed using either thawing method. Shrimp thawed using the thawing chamber had lower aerobic bacterial counts than either control or shrimp thawed using running water. Shrimp thawed using the thawing chamber did not exceed -1C throughout the thawing experiment. and microbial growth during thawing was also avoided. Results indicated thal the thawing chamber has potential for the foodrenice industry to produce uniformly thawed products under sanitary conditions.