Optimization of microwave cooking of courgette in terms of nutrient preservation and energy consumption

Abstract

The main objective of this work was to establish the kinetics of spoilage of nutritional and organoleptic criteria of frozen courgette when using microwave and stir-frying cooking but also to evaluate the effect of these cooking methods on these criteria. An optimization of the microwave parameters was also achieved to get the best quality of the courgette after cooking with the lowest energy consumption. The raw and cooked courgettes were analyzed for the total phenols and vitamin C contents, texture, dry matter content and final surface temperature. A remarkable decrease in vitamin C and phenols contents from the first minutes of cooking was noticed for both cooking methods applied. Moreover, these micronutrients seemed to be better preserved at higher power levels with microwave cooking. In addition, a same texture was reached in microwave cooking in a shorter time compared to the conventional process. A two factors Doehlert design was used to find the optimal settings which ensured a cooked product with good nutritional values and energy saving. Adequate levels for the two factors (microwave power and cooking time), were found thanks to the previously established kinetics. The calculated responses given by the quadratic models are quite close to the experimental values. This study will be used in the future for the optimisation of microwave cooking of a mixture of vegetables.