Impact of water rinsing and perforation-mediated MAP on the quality and off-odour development for rucola

Rucola is an important leafy green salad normally sold in plastic trays wrapped with macro-perforated polypropylene film without modified atmosphere. The objectives of this study were to optimize the packaging system and to investigate the effects of water rinsing prior to packaging of rucola on changes in quality and accumulation of volatile organic compounds (VOCs). Washed and unwashed rucola were packed using different packaging systems: without perforations (MAP-0); optimized 2 micro-perforations of 0.5 mm diameter (MAP-2); and 21 macro-perforations with 5 mm diameter (Control). Gas composition in control packages stayed close to air, while MAP-0 led to anoxia, and for MAP-2 equilibrium modified atmosphere was achieved by day 2 of storage within the range of 2-3% O2 and 10-12% CO2. Browning of cut edges, water loss, and loss of turgor pressure was most severe for samples in the control packages. Degradation of rucola quality attributes was delayed under MAP-2. A total of 33 VOCs were tentatively identified via GC-MS, consisting of 18 primary (detected on fresh samples prior to storage) and 15 secondary (detected on samples during storage) VOCs. Accumulation of secondary VOCs and development of strong off-odour was higher for washed samples in comparison to unwashed samples. MAP-0 led to development fermentative off-odour by day 3 of storage. Perceived development off-odour based on sensory evaluation was observed to be consistent with the accumulation of ethyl esters, benzaldehyde and benzeneacetaldehyde volatiles. This highlights the critical need for integrated packaging and cold chain design for individual fresh produce.