Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 7, 2004
Publication Date: March 7, 2004
Citation: Allende, A., Luo, Y., Mcevoy, J.L., Artes, F., Wang, C.Y. Microbial and quality changes in fresh-cut baby spinach stored under map and super atmospheric oxygen conditions. Postharvest Biology and Technology 33 (2004) 51-59
Interpretive Summary: A safe, year-round supply of high-quality fruits and vegetables is important to the American consumer. With the growing desire of consumers to have their produce provided in a packaged, ready-to-eat form (fresh-cut) for convenience, there are certain quality and shelf-life challenges faced by the fresh produce industry. For example, fresh-cut baby spinach leaves, which are still alive and breathe, have a high respiration rate and require the presence of oxygen and low levels of carbon dioxide to maintain their freshness. However, the ability of packaging films used today to allow just the right amount of oxygen into the package (oxygen transmission rate) is too low to provide the desired atmospheres for spinach to maintain quality. Therefore, most commercial processors of fresh-cut baby spinach use perforated films in order to avoid low oxygen/high carbon dioxide injury and maintain freshness. This practice, however, raises food safety concerns as bacteria that are harmful to humans may transfer into packages through the perforations causing contamination. In this research, we took a novel approach for improving food safety of packaged fresh-cut baby spinach using a combination of super high oxygen and modified atmosphere packaging (MAP). We found that the addition of very high amounts of oxygen to packages alleviated high CO2 injury and maintained quality without having to use perforated films. These results will be helpful to the produce industry for designing packages to extend shelf-life of fresh-cut produce.
The effect of super atmospheric O2 and modified atmosphere packaging (MAP) on plant metabolism, organoleptic quality and microbial growth of fresh-cut 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 fresh-cut baby spinach. In general, the 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, vs. 6.1 to 10.6 kPa in the permeable film packages at the end of storage. MAP prepared with the barrier film 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. The combination of super atmospheric O2 treatment and MAP alleviated off-odor and was beneficial in maintaining quality of fresh-cut baby spinach.