Air Low Temperature-Long-Time Cooking: Feasibility and Food Quality

Background: Low-temperature long-time (LTLT) cooking under vacuum prevents moisture, nutrient, volatile losses and oxidative changes. In addition, aerobic bacteria are inhibited causing shelf-life increasing. The feasibility of under vacuum cooking in convec-tion oven versus classical heating in water bath was investigated through the assessment of different foods quality characteristics. Methods: Two different LTLT cooking appliances were used: a prototype oven using a convective function, and a controlled water bath, both operating within 60 to 90 °C. The tests were conducted on tenderloin beef (2 and 4 cm thick), carrots (200 and 400 g weight), and salmon fillet (1.5 and 3 cm thick); all products were vacuum sealed in plastic bags. Weight loss and moisture were determined. Texture evaluation was assessed by TPA test for beef and salmon, while a cutting test was employed for carrots. To evaluate potential thermal damage, protein carbonyl content in beef, carotenoids in carrots, and lipid perox-idation in salmon were determined. Results: Throughout the cooking process, for all samples heat penetration curves were recorded, demonstrating reproducible tests within each food category and that safe temperature and time thresholds were consistently reached. As expected, time-tempera-ture profiles show that the convection air cavity exhibited a longer cooking time compared to the classical sous vide. Cooking weight losses and moisture content were low and sim-ilar across all food categories and sample sizes. Texture evaluation revealed higher ten-derness for thicker beef and salmon, using both cooking methods. Water cooking led to softer carrots, regardless of the sample weight. Protein carbonyl content, carotenoids and lipid peroxidation indices were low and similar for the various cooking conditions. Conclusions: The results suggest that sous vide LTLT cooking can be effectively per-formed by convective air heating, making feasible the use of common cooking appliances to improve the nutritional value of our meals.