Microbial and quality changes in minimally processed baby spinach leaves stored under super atmospheric oxygen and modified atmosphere conditions

Abstract

The effect of super atmospheric O2 and modified atmosphere packaging (MAP) on plant metabolism, organoleptic quality and microbial growth of minimally processed baby spinach was studied. Packaging film O2 transmission rates and initial levels of super atmospheric O2 in the packages significantly affected the changes of in-package atmospheres during storage, and consequently quality of baby spinach leaves. In general, a barrier film maintained a higher O2 level for both 80 and 100 kPa O2 treatments during entire storage. Packages with the barrier film also exhibited a more rapid accumulation of CO2 than those with the permeable film, with CO2 levels ranging from 16.2 to 22.5 kPa in the barrier film packages, versus 6.1–10.6 kPa in the permeable film packages at the end of 12 days of storage at 5 °C. Packages prepared with the barrier film with an initial O2 level at 21% accumulated CO2 during storage and exhibited a significant reduction in aerobic mesophilic bacterial growth compared to the perforated film packages (control). However, this treatment also developed strong off-odor and a loss of tissue integrity. Adding super atmospheric O2 to the packages alleviated tissue injury in addition to reducing microbial growth and was beneficial in maintaining quality of fresh-cut baby spinach.