Journal of Food Composition and Analysis 17 (2004) 597–604
HCl-extractability of zinc and copper as affected by soaking,
dehulling, cooking and germination of high yielding
pigeon pea cultivars
Aarti Duhan, Neelam Khetarpaul*, Saroj Bishnoi
Department of Foods and Nutrition, CCS Haryana Agricultural University, Hisar 125004, India
Received 9 October 2002; received in revised form 25 June 2003; accepted 22 September 2003
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 (Po0.05) 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.
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Keywords: HCl-extractability; Soaking; Dehulling; Ordinary and pressure cooking; Germination; Zinc and copper
Pigeon pea is a good source of dietary essential minerals such as calcium, phosphorus, iron, zinc
and copper (Salunkhe et al., 1986; Duhan et al., 1998). Besides these minerals, pigeon pea like
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