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The
degradation of lectins, phaseolin and trypsin inhibitors during germination of
white kidney beans, Phaseolus vulgaris L.
Plant Foods Hum Nutr 1994 Apr;45(3):213-22
Savelkoul FH, Tamminga S, Leenaars PP, Schering J, Ter Maat DW.
Department of Animal Nutrition, Agricultural University, Wageningen, The
Netherlands.
White kidney beans (Phaseolus vulgaris), cv Processor, contain a relatively high
content of phaseolin (storage protein), lectins and a special group of
glycoproteins as well as a considerable amount of protein-type trypsin
inhibitors. Protein digestion of raw 'Processor' beans in monogastrics, for
example pigs, is disturbed by poorly digested, phaseolin lectins, which can bind
to carbohydrates in brush border membranes of the small intestinal epithelium,
and trypsin inhibitors. The effect of the germination of white kidney beans on
lectins, phaseolin and trypsin inhibitors was studied in order to achieve a
degradation of lectins, phaseolin and trypsin inhibitors and an increase of in
vitro enzymatic hydrolysis of the protein of bean flour. Therefore, whole bean
extracts were examined throughout a germination period of up to seven days for
their lectin and phaseolin pattern, lectin content, binding capacities of
functional lectins towards brush border membranes and trypsin inhibitor content.
In addition the in vitro enzymatic hydrolysis by pepsin and pancreatin of the
protein from flours of (un)germinated white kidney beans was studied. SDS-PAGE
demonstrated a degradation of E-lectins and a disappearance of L-lectins and
phaseolin during germination. Results indicated a decrease of the lectin content
by 85%, a loss of binding capacities of functional lectins towards brush border
membranes by 91%, and a decrease of trypsin inhibitors by 76%, in bean flour
after germination for seven days. A maximum in in vitro enzymatic hydrolysis of
protein from bean flour was already established after germination for half a
day.
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