Microbiological Quality and Shelf Life of Enzyme-peeled Fresh-cut Persimmon Slices Stored in High CO2 Atmospheres

Abstract

The microbiological quality and shelf life of enzyme-peeled fresh-cut persimmon slices were evaluated during storage in a high CO2 controlled atmosphere (CA) and active modified atmosphere packaging (MAP) at 10 °C. Microbial counts of the enzyme-peeled slices were lower in high CO2 atmospheres (10%, 15%, and 20%) than in air during CA storage for 6 days at 10 °C with the 20% CO2 atmosphere being most effective. High CO2 atmospheres did not affect the number of bacterial and fungal species detected in the persimmon slices. The surface color, expressed as C* values, of the peeled side of enzyme-peeled slices was lower in high CO2 than in air after 6 days of CA storage. In contrast, C* values at the cut side were higher for slices stored in 20% CO2 than in air on Day 6. High CO2 atmospheres did not affect other quality of enzyme-peeled slices such as texture, pH, sugar content, and total ascorbic acid content. Based on the optimum 20% CO2 concentration in a CA, enzyme-peeled slices were stored in a MAP flushed with either air or 20% CO2 for 4 days at 10 °C. The CO2 concentration approached an equilibrium of either 5% or 10% after 3 days of storage in packages flushed with either air or 20% CO2, respectively, and the O2 decreased to ≈10% in both packages. Adding 20% CO2 to the MAP was effective in reducing the growth of mesophiles and coliforms but not fungi in enzyme-peeled persimmon slices throughout 4 days of storage. The diversity of bacterial and fungal flora was partially similar between packages flushed with air and 20% CO2. Texture, pH, surface color, sugar content, and total ascorbic acid content of enzyme-peeled persimmon slices were unaffected by air or 20% CO2 as the flushing gas, except that C* values of the enzymatically peeled side on Day 4 were lower for slices flushed with 20% CO2 than air. A 20% CO2 atmosphere is recommended for reducing the microbial population of enzyme-peeled persimmon slices stored at 10 °C and the shelf life of persimmon slices in an active MAP with 20% CO2 is 4 days at 10 °C.