The effects of packaging method (vacuum pouch vs. plastic tray) on spoilage in a cook-chill pork-based dish kept under refrigeration

The effects of two packaging methods on the spoilage of a cook-chill pork-based dish kept under refrigeration were studied. Raw pork cuts and pre-cooked tomato sauce were packed under vacuum “sous vide” in polyamide–polypropylene pouches (SV) or into translucent polypropylene trays under modified atmosphere (80% N2 + 20% CO2) and sealed with a top film (PT). Samples were cooked inside the pack at an oven temperature/time of 70 °C/7 h, chilled at 3 °C and stored at 2 °C for up to 90 days. Microbial (psychrotrophs, lactic-acid bacteria, Enterobacteriaceae, moulds and yeasts), physical–chemical (pH, water activity and total acidity) and sensory (colour, odour, flavour, texture and acceptance) parameters were determined. Heat penetration was faster in SV (2 °C/min) than in PT (1 °C/min) (core temperature). Both packaging methods were equally effective in protecting against microbial spoilage for 90 day at 2 °C. Minor counts were only detected for lactic-acid bacteria and anaerobic psychrotrophs in SV. No Enterobacteriaceae growth was found. Slight differences between SV and PT in pH and total acidity were observed. SV and PT had similar effects on the sensory preservation of the dishes. A gradual loss of acceptance of the cooked pork and tomato sauce was observed. Rancid flavour in PT and warmed-over-flavour in SV were noted in the final stages of storage. According to acceptance scores, the shelf-life of both SV and PT was 56 days at 2 °C. Both packaging methods can be used to manufacture sous vide meat-based dishes subsequently stored under refrigeration for catering use.