Reduction of chlorine concentration and microbial load during washing-disinfection of shredded lettuce

Disinfection of shredded lettuce by washing is an essential operation to eliminate foreign matter and cellular fluids produced by cutting, and to reduce the initial microbial contamination. The response surface methodology was used to evaluate the effect of initial chlorine concentration (50-150 ppm), water-to-produce ratio (20-50 L kg(-1)) and time (2-8 min) on the depletion of total and available chlorine and also the microbial count reduction on shredded lettuce. The predictive models obtained, validated through additional confirmatory experiments, were shown to be adequate and could be used as a way of improving the operation.