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Hydrothermal treatments of two cowpea ( Vigna unguiculata L. Walp) varieties: effect of micronisation on physicochemical and structural characteristics
Author(s) -
Mwangwela Agnes M,
Waniska Ralph D,
Minnaar Amanda
Publication year - 2005
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2275
Subject(s) - vigna , cotyledon , hydrothermal circulation , moisture , mung bean , starch , chemistry , food science , solubility , horticulture , agronomy , biology , paleontology , organic chemistry
Abstract The effects of a hydrothermal treatment consisting of tempering (to 41% moisture) and heating to 153 °C (micronisation) on the structural and physicochemical characteristics of two cowpea varieties were studied. The untreated varieties had similar cooking times, although cooked Bechuana white cowpeas were significantly ( P ≤ 0.05) softer and had a higher incidence of splitting than Var. 462 cowpeas. This may be due in part to differences in cotyledon structure affecting water uptake during cooking. The hydrothermal treatment changed the physical structure and chemical properties of the cowpea seeds. This led to significant ( P ≤ 0.05) reductions in the cooking time of micronised Bechuana white and Var. 462 cowpeas, by 47 and 36% respectively, as compared with control samples. Micronisation caused physical fissuring of the seed coat and cotyledon and significantly ( P ≤ 0.05) reduced the bulk density of treated seeds. These changes in the physical structure significantly ( P ≤ 0.05) improved the initial water uptake during soaking and cooking, increased the enzyme‐susceptible starch and reduced the protein solubility and hydration capacity of the cowpea seeds. Cooked (60 min) micronised cowpeas also had significantly ( P ≤ 0.05) more splits and a significantly ( P ≤ 0.05) softer texture than control samples. Copyright © 2005 Society of Chemical Industry