The effects of pre-processing sanitation and modified atmosphere packaging on microbial growth in bulk packs of Atlantic salmon (Salmo salar) fillets

This research was to extend the shelf-life of fresh Atlantic salmon fillets when packaged in bulk food service modified atmosphere packaging trays with low gas to product volume ratios. When head-on-gutted Atlantic salmon were washed in Neutral electrolyzed water sanitizer prior to filleting, the microbial load on the skin of HOGs treated at 20 ppm and 100 ppm chlorine equivalents decreased by 3.5 log CFU/cm² down to 2.0 and 1.5 log CFU/cm², respectively. Further trials washed the HOGs with 100 ppm of NEW before filleting. They were then packed in a different product gas to product (G/P) volume ratios (0.4:1, 1:1 and 2:1) and stored at 0°C or 4°C up to 20 days. The combinations of sanitation pre-processing and high G/P ratio were most effective for controlling the microbial count to 4.5 log CFU/g when stored at 0°C compared to a microbial count of 7.2 log CFU/g for the unwashed fillets after 20 days under 4°C storage. Other variable combinations were between these levels. A combination of improved pre-processing sanitation and a low temperature can therefore raise the hurdles for microbial growth to extend the shelf-life of bulk packed fresh salmon fillets packed at high volumetric densities for storage and shipping efficiency.