The Effect Of Cooking On Phytochemical Content In Vegetables: A Review.

Cooking induced many chemical and physical modifications in foods: among them also phytochemicals content can change. Many authors studied variations in vegetable nutrients after cooking, and great data variability was reported. In this review more than one-hundred articles from indexed scientific journals were considered in order to assess the effect of cooking on different phytochemical classes. Phytochemical changes upon cooking may result from two opposite phenomena: the thermal degradation reducing their concentration, and the matrix softening effect which increased phytochemical extractability resulting in a higher concentration respect to the raw material. The final effect of cooking on phytochemical concentration depends on the processing parameters, the structure of food matrix, the chemical nature of the specific compound. Looking at the different cooking procedure it can be concluded that steaming will ensure a better preservation/extraction yield of phenols and glucosinolates than other cooking methods: steamed tissues are not into direct contact with cooking material (water or oil) so the leaching of soluble compounds in water is minimized and at the same time thermal degradation is limited. Carotenoids showed a different behavior: a positive effect on extraction and the solubilization of carotenes were reported after severe processing.