Design of the correct modified atmosphere packaging for fresh-cut broccoli raab

A low-oxygen controlled atmosphere has been reported to be useful in maintaining freshness and qualitative traits of fresh-cut broccoli raab during cold storage, while excessive accumulation of CO2 (10-15%) should be avoided. Starting from these previous findings, the aim of this work was to select the correct modified atmosphere packaging (MAP) for fresh-cut broccoli raab in order to reach, at equilibrium, the target low-oxygen (3%) atmosphere during cold storage. Broccoli raab harvested from a commercial farm was sorted to remove defects and cut from the stalks, obtaining the ready-to-use product. After washing, the product was packaged in plastic trays sealed in bags of different plastic materials. Two commercially available polymeric laminated films [polypropylene/polyethylene terephthalate (PP/PET) and microperforated polypropylene/polyamide (PP/PA)] were used with or without the inclusion of a CO2 absorber (5-g sachet). For each package type, a passive atmosphere (P-MAP) and an active atmosphere achieved by flushing with 5% O2 in nitrogen (A-MAP) were used. Unpackaged samples were used as controls and stored with all packages at 5°C. Quality attributes (overall appearance, odor, color, and weight loss) were evaluated initially and after 3 and 8 days. Gas concentrations (O2 and CO2) inside packages were also monitored. Among the packaging treatments tested, the combination using PP/PA in A-MAP with the use of CO2-absorbing sachets reached an equilibrium condition very close to optimal for broccoli raab (5% O2 and <=5% CO2). Fresh-cut broccoli raab stored under these conditions for 8 days showed negligible reduction of appearance and odor scores, and product was comparable to the fresh samples.