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- Granfeldt, Y., et al.
(author)
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An in vitro procedure based on chewing to predict metabolic response to starch in cereal and legume products
- 1992
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In: European Journal of Clinical Nutrition. - 0954-3007. ; 46:9, s. 649-660
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Journal article (peer-reviewed)abstract
- A new method for measuring the rate of in-vitro starch digestion in products with a structure 'as eaten' is introduced. An equivalent amount of potentially available starch from each product was chewed by subjects, expectorated into a beaker and incubated with pepsin. The incubate was thereafter transferred to a dialysis tubing and incubated with pancreatic α-amylase for 3 h. Samples were removed from the dialysate at time intervals and the degree of hydrolysis was calculated as the proportion of the potentially available starch degraded to maltose. A hydrolysis index (HI) was calculated as the area under the hydrolysis curve with the product as a percentage of the corresponding area with white wheat bread. The method was applied to 21 cereal and legume products, chosen to cover as wide a range as possible with respect to metabolic response, and to include several of the proposed mechanisms to differences in metabolic behaviour of starch. The accuracy of the in-vitro method was evaluated versus the metabolic responses obtained with the same products in healthy subjects. A significant correlation between HI and glycaemic index (GI) was obtained in cereal as well as in legume products. A significant correlation was also obtained between HI and insulin index (II) with pooled data from all products. However, in the case of II no correlation was obtained with the legume products only. It is concluded that the presently described in-vitro procedure offers a good potential to predict the metabolic behaviour of starchy foods.
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- Tovar, J., et al.
(author)
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Incomplete digestion of legume starches in rats : A study of precooked flours containing retrograded and physically inaccessible starch fractions
- 1992
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In: Journal of Nutrition. - : Elsevier BV. - 0022-3166. ; 122:7, s. 1500-1507
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Journal article (peer-reviewed)abstract
- The digestibility of starch in precooked flours from green coat lentils (Lens culinaris Medik) and red kidney beans (Phaseolus vulgaris L.) was investigated by balance experiments using rats treated with antibiotics to suppress hind-gut fermentation. The legume preparations were rich in intact cells filled with denaturated starch and contained retrograded amylose. Between 8% (beans) and 11% (lentils) of the total starch ingested appeared in the feces, indicating a relatively low starch digestibility. Red bean flours of two different particle sizes were similarly digested. Sixty percent of the fecal starch in the bean-fed animals and 70% in the lentil-fed group was retrograded amylose. The in vitro indigestible starch content of the flours was evaluated with three different methods that gave rather different values. The retrograded amylose fraction, measured after alkaline treatment of a dietary fiber residue obtained by enzymic digestion, was quantitatively recovered in the feces. None of the procedures gave accurate estimates of the total in vivo indigestible starch. Fecal excretion of starch in rats not treated with antibiotics indicated that the indigestible starch in lentils was less susceptible to fermentation than that in the red bean preparations.
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