Expanding the Shelf-Life of Ready to use Shredded Icebergs by Using Oxidation - Reduction Potential controlled Release of Various Chlorine Concentrations in Washing Water

Abstract

Ready to use (RTU) shredded iceberg lettuce is a perishable product with a short shelf-life. Expanding the shelf life to seven days of this product as an economic need for the producers is the aim of this research. Fresh samples were harvested from the field and prepared according to the standard protocol of minimal processing fresh produce (receiving, removing dribs and pre-washing, washing, de-watering, packaging, and storing). Several concentrations of sodium hypochlorite were precisely optimized by oxidative/ reductive Potential (OPR) automated dozing pump under controlled neutral pH and cold temperature during washing regimen. Samples were vacuumed packed and kept tightly sealed at 4 °C for further analysis. Aerobic plate count and coliform as well as sensory evaluation were performed. Results showed that at a chlorine dose level less than 700 mV ORP, the shredded lettuce deteriorated due to elevated microbial load as well as from a sensory point of view. The level of 700 and 800 mV ORP extended shelf life for 7 days. Washing with chlorine levels higher than 800 mV showed alteration in sensory attributes although the microbial load was under control. Results of this study show that the automated ORP chlorine dozing “in form of sodium hypochlorite” at 700 mV (50 ppm) and 800 mV (100 ppm) within controlled pH and temperature, followed by storing the vacuumed well-sealed packs at 4 °C, were the best measures taken to increase the shelf life of the shredded iceberg lettuce from 5 to 7 days. Furthermore, there was no significant difference between the uses of an ORP reading of 700 mV vs. 800 mV of chlorination. However, it is preferable to use the 700 mV ORP reading because it will release less chlorine in the washing water, hence, it will be healthier and more economical.