Sous Vide/Freezing Technology for Ready-Meal Components

Abstract

There is strong buoyancy in the ready-meal sector in Europe due to lifestyle changes and the need for convenience. Sous vide has long been used as a method for cooking catering products and enhancing quality and sensory attributes compared with conventional cooking methods. More recently, sous vide products are being increasingly steered towards the retail market in consumersized packs as ready-meals. However, there are inherent microbiological safety risks with the chill storage of sous vide products. Freezing these products offers greater microbiological safety, longer shelf life and flexible storage logistics, but may adversely affect texture in comparison with chilling. The purpose of this study was to investigate the effects of sous vide cooking followed by freezing on the quality of ready-meal components; carrots were used as a model food. Sensory tests indicated that shear values in the range 1.3 to 2.6 kN represented the ideal texture for steamed carrots. This became the target range for the sous vide freezing tests on carrots. Sous vide cook times of 22 min at 85oC (for carrots cooked from raw) and 11 min at 85oC (for carrots which were blanched or blanched/frozen before cooking) delivered a frozen sous vide product with shear values within the desired texture range. These samples compared favorably with steamed carrots in sensory tests and have an extended shelf-life in comparison with sous vide/chilled samples. Sous vide/freezing resulted in a minimal loss of soluble solids when raw carrots were used as starting material. The test data show that sous vide freezing is a suitable technology for carrots in consumer-sized packs and for inclusion as a component in ready-meals. The procedures used for carrots are currently being applied to a range of carbohydrate and muscle foods, and to sauces and gravies. Sous vide freezing is logistically better than sous vide/chilling and gives a safer product with a much extended shelf-life.