ESSENTIAL ELEMENTS IN FRESH AND IN FROZEN SPINACH AND COLLARDS

Abstract

ABSTRACTThe content of 14 essential elements was determined in raw and frozen spinach, and in raw and frozen collards. Atomic absorption spectroscopy (AAS) was used for all the elements except Cl. The effect of commercial freezing on the contents of these mineral elements was also studied. All the elements tested were detected in raw and frozen samples of both vegetables, with the exception of chromium, cobalt and molybdenum which were at levels below the sensitivity limits of the AAS instrument. Statistical analysis of the data showed that commercial freezing caused significant losses of eight elements in spinach and of ten elements in collards at either the 1% or the 5% level of significance. The retention of chloride, copper, magnesium, manganese, nickel, phosphorus and zinc in frozen spinach and frozen collards ranged from 82–97%. The retention of iron, potassium and sodium in frözen spinach was 73%, 74% and 71% respectively. In frozen collards, the retention was 74%, 86% and 73% respectively. Calcium content was higher in the frozen than in the raw samples of both vegetables. The increase was probably caused by absorption of calcium by the raw vegetables from the blanching and cooling waters.