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Effect of chewing versus mechanical breakdown on in-vitro starch digestibility of grain based foods

K. Germaine1, K.J. Quail2 and S. Samman3

1BRI Australia Ltd, Grain Foods CRC, University of Sydney, North Ryde, Sydney, Australia,
BRI Australia Ltd, Grain Foods CRC, North Ryde, Australia,
University of Sydney, Sydney, Australia


In-vitro starch digestibility methods have been shown to be a good indicator of glycaemic response for high starch foods. There are several in-vitro methods which have been used to predict the glycaemic response to foods. One of the key variables in these in-vitro methods is in the method of the initial food breakdown.

In earlier in-vitro starch digestibility work, foods were typically ground to a fine particle size prior to analysis, using food mills (Ross et al, 1987) and mortar and pestles (Gee and Johnson, 1985). However, work conducted on the effect of food particle size (Heaton et al, 1988) showed that the rate of in-vitro starch digestion was inversely related to particle size. Therefore, as foods are typically not “milled” but chewed prior to digestion, later in-vitro methods focussed on trying to achieve a particle size for in-vitro testing that was representative of chewing using food mincers 1 and the use of human subjects to chew and expectorate the food using human subjects (Granfeldt et al 1992).

In this work a comparison of chewing by human subjects and mincing in the presence of human salivary amylase was conducted to compare the effect of the food breakdown method on in-vitro starch digestibility.


Gee, J.M. & Johnson, I.T. J Sci Food Agric. 1985, 36, 614-620.

Granfeldt, Y et al. Eur J Clin Nut. 1992, 46, 649-660.

Heaton, K.W. et al. Am J Clin Nut.1988, 47, 675-82.

Ross, S.W. et al. Am J Clin Nut. 1987, 46, 631-5.

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