NUTRITIONAL ESTIMATION OF CHANGES IN MINERAL CONTENT DURING FROZEN STORAGE OF WHITE ASPARAGUS

Nine essential elements (copper, iron, zinc, manganese, calcium, magnesium, sodium potassium and phosphorous) were determined in white asparagus (Asparagus officinalis, L.) by flame atomic absorption spectrophotometry in order to examine the possible variations in mineral content caused by frozen storage at ?18C for 45 and 90 days. Statistically significant differences were determined during frozen storage for all the mineral elements investigated, except for Ca, Mg, Na and P which did not exhibit any significant differences (p>0.05) and, together with Zn, showed no significant modifications under frozen storage. A diminution in Cu, Fe, Mn and K concentrations was observed during the frozen storage time. Statistically significant differences were established between thicknesses of the asparagus spear in the content of Cu, Fe, Zn, Ca, Na and K and it was seen that the thickness of the asparagus did not fit any specific model. Between portions, all the elements studied displayed statistically significant differences in their concentrations, except for Ca and K (p>0.05) and, for all the minerals elements analyzed, the highest levels were found in the apical portion of the asparagus spear, except for Na with a higher content in the basal portion. White asparagus is an adequate food source of mineral elements, except for Na, and frozen storage does not cause any great variations in the percentages of mineral RDAs (Recommended Dietary Allowances) supplied.