Effects on mineral content of different methods of preparing frozen root vegetables.

摘要

Contents of ash and P, K, Ca, Mg, Na, Fe, Zn, Mn, Cu, Cr and Ni were determined in raw carrots, root celery, parsnips and red beets before and after blanching and cooking, and also after 12 months of refrigerated storage. Treatments applied before freezing included washing, peeling, grinding and blanching or cooking, which caused significant decreases in contents of most of the analysed elements in carrots, root celery and parsnips. Red beets were not peeled before thermal processing; this avoided mineral losses, and no significant changes were found between raw and boiled samples. Carrot, root celery and parsnip previously cooked and then frozen had significantly higher contents of Na and Mn, while Cr content did not change. There were no differences in Mn, Zn, Ni or P contents of carrots and parsnips. Contents of some minerals were higher in cooked than in blanched samples before freezing.