Enteric viruses account for most foodborne illness in the United States. The objective of this study was to determine whether the isoelectric point (pI) of viruses such as feline calicivirus (FCV), echovirus 11, and bacteriophages phiX174 and MS2 had any effect on their attachment to butterhead lettuce. The adsorption of virus particles to the lettuce was variable. Bacteriophage MS2 was the only virus that fit the current Derjaguin-Landau-Verway-Overbeek model of virus attachment. Echovirus 11 had the highest affinity to lettuce surface. Echovirus 11 appeared to exhibit reversible attachment above its pI, whereas below its pI strong adsorption was observed. Adsorption of FCV was at its maximum above its pI. Bacteriophage phiX174 exhibited the most complex adsorption pattern, with attachment occurring only at the pH extremes (pH 3.0 and 8.0). These results suggest the current model for virus adsorption to sediment does not adequately explain the attachment of virus to lettuce. Importantly, the results indirectly suggest that current sample processing methods to recover viruses from lettuce may differentially select for the recovery of only certain virus types.

Cooking times and losses were monitored during cooking of ten each of eight kinds of lamb roasts. Roasts were cooked (163OC oven, not preheated) to be rare (6OoC), medium (7OOC) or well done (77OC). Cooking times and cooking losses significantly increased with increasing degrees of doneness. Cooking time recommendations were made based on the data I n a second study, cooking times, cooking losses and energy consumption were monitored during cooking o f 100 each of boneless legs and boneless shoulder roasts. Ovens were either non-preheated or preheated and roasts were fresh, frozen, thawed 12 h at 21 "C, thawed 24 h at 1 O C or thawed by microwaves. Gas consumption was slightly less for boneless shoulders roasted in non-preheated ovens (21.2 cu. ft.) than for those roasted i n preheated ovens (22.6 cu. ft.). Cooking times and losses were lower for fresh boneless shoulders and leg roasts versus those in the frozen or frozenthawed treatments. Statistically significant differences i n gas consump tions for the five treatment groups were observed, but differences i n cost of purchased energy were negligible.