| Phytate, the major phosphorous-containing compound in grains and legumes, restricts bioavailability of Zn to animals and humans. Phytate reduction in peas (Pisum Sativum L. var. Garfield) and pea enzyme phytase were investigated. Zinc bioavailability was determined by rat weight gain and tibia Zn response from pea seedlings (PS), heat treated peas (HTP) and purified diets (PD1 and 2) supplemented with Zn and phytate for similar phytate:Zn molar ratios (phy:Zn). With diets adequate in Ca (0.75%), weight gains from PS (phy:Zn = 24) and HTP (phy:Zn = 39) were equivalent to a nonphytate control (NPC). Tibia Zn decreased in order from: NPC, PS, PD1, HTP and PD2. At the 1.5% Ca level reduced growth responses from PS and HTP indicated interaction between Ca and phytate. Reduced phytate:Zn ratio, increased phytase possibly hydrolyzing phytate during digestion, and less interaction among phytate, protein, Ca and Zn resulting from germination may explain the enhanced Zn availability from pea seedlings.;Cooking peas 20 min or 2 hr resulted in 13% phytate reduction. Peas soaked 6.5 hr at temperature increments between 25 and 80(DEGREES)C yielded maximum phytate reduction (25%) at 60(DEGREES)C due to phytase activated hydrolysis. Germination (10d) decreased pea phytate 70% and increased phytase activity 12-fold. Germinated pea phytase activity indicated respective temperature and pH optima of 45(DEGREES)C and 5.2, 30% inhibition by 1 mM inorganic P, and substrate preference for pyrophosphate.;The largest proportions of Zn, Mg, K, and Ca, protein-N, and phytate-P were in the raw pea cotyledon. Following germination the major proportions of Zn, Mg, K and protein-N were present in the axis were lowered phy:Zn (1.5) thereby enhancing Zn bioavailability relative to cotyledon and raw pea. Microscopial observation indicated phytate to be uniformly distributed within protein bodies of raw pea cotyledon cells. Germinated cotyledon cells appeared to contain phytate granules within the cytoplasm.;Results suggested Zn bioavailability from germinated peas is superior to that from earlier reported grains, legumes, and purified diets. |
