Effect of non-conventional atmospheres and bio-based packaging on the quality and safety of Listeria monocytogenes-inoculated fresh-cut celery (Apium graveolens L.) during storage

Abstract

The increased consumption of fresh-cut celery has led to the need to explore packaging alternatives for fresh-cut celery that can meet consumer, market, and industry needs. In this study, the effect of bio-based packaging and non-conventional atmospheres on the quality and safety of chlorine-sanitized celery sticks stored at 7°C was investigated. Two materials differing in permeability [a bio-based polyester (polylactic acid (PLA)) and a petroleum-based polyolefin (polypropylene/low density polyethylene (PP/PE)] and four initial gas compositions [air (A-PLA or A-PP/PE), 95kPa O2+5kPaN2 (O2-PLA), 99kPaN2+1kPa O2 (N2-PLA), and 6kPa O2+12kPa CO2+82kPaN2 (CO2-PLA)] were evaluated. Changes in headspace composition, weight loss, surface and cut end color, texture, ethanol content, appearance, and growth of Listeria monocytogenes on inoculated celery sticks were assessed during 21d of storage. Active MAP (CO2-PLA) out-performed passive MAP (A-PLA) in maintaining celery stick quality but not safety. Conventional active MAP (CO2-PLA) out-performed non-conventional active MAPs (O2-PLA and N2-PLA) in maintaining celery stick quality throughout storage, but O2-PLA suppressed L. monocytogenes growth while CO2-PLA promoted growth during the first 10d of storage. PLA and PP/PE materials affected celery stick quality but not Listeria growth. This study shows that the initial gas composition and packaging material both impact the quality and safety of celery sticks. Overall, the combination PLA and 95kPa O2 proved most beneficial in maximizing both the safety and quality of celery sticks during one week of storage at 7°C.