Quality assessment of ready-to-eat asparagus spears as affected by conventional and sous-vide cooking methods

Asparagus represents a nutritious and refined food being very popular to consumers. The effects on the quality of spears cooked by conventional (boiling, steaming and microwaving) and different sous vide (using hot water or microwave) methods were analyzed. Physical, chemical and sensory traits were compared. Microwaving caused the largest weight change, the highest dry weight increase and the highest Total Color Difference in cooked samples compared to raw asparagus spears. Sous vide-microwaving showed an increase in greenness (the highest value of h°), better than the raw spears, and the lowest reduction in chlorophyll contents. After sous vide microwawing violaxanthin increased by about 42%, while after steaming neoaxanthin decreased by about 57%. Following sensory analysis, all cooked samples generally resulted acceptable (scores > 5 in a 1-9 hedonic scale), nevertheless sous vide-microwaved asparagus satisfied consumer acceptability more than the other cooked samples, especially when compared to steamed samples. Results indicate the sous vide-microwaving technique as optimal to preserve several traits, including the organoleptic ones, essential for the quality of cook-chilled asparagus spears. They also provide product-specific information usually required for cooking process strategies in the industrial area of ready-to-eat vegetables.