HCl-extractability of zinc and copper as affected by soaking, dehulling, cooking and germination of high yielding pigeon pea cultivars

The unprocessed seeds of four high yielding cultivars of pigeon pea namely ICPL-87, ICPL-151, UPAS-120 and Manak contained 2.06 to 2.64 and 1.45 to 2.14 mg per 100 g zinc and copper, respectively. Various domestic processing and cooking viz. soaking in water (6, 12, 18 h), soaking (12 h)–dehulling, ordinary (cooking done in crude fibre beakers containing water (80°C) until soft as felt between the fingers) as well as pressure cooking of unsoaked, soaked (12 h) and soaked (12 h)–dehulled seeds and germination (24, 36 and 48 h) enhanced the HCl-extractability of zinc and copper, an index of their bioavailability to a remarkable extent. Among all the methods, soaking and dehulling could bring about maximum improvement (21–28%) in HCl-extractability of zinc followed by germination for 48 h (18–19%) and germination for 36 h as well as pressure cooking of soaked–dehulled seeds (16–18%) in descending order. Copper extractability could be enhanced to the maximum extent i.e. 3–4% over the control when the seeds of all the four cultivars were germinated for 36–48 h (3–4%) or soaked–dehulled seeds were cooked in an ordinary way or pressure-cooked (3–4%). A significant (P<0.05) negative correlation was noticed with antinutrients viz. phytic acid, polyphenols, saponins and trypsin inhibitors with copper and zinc extractability in the processed and cooked pigeon pea seeds.