Effect of Extent of Gelatinisation of Starch on the Glycaemic Responses of Carbohydrate Rich Breakfast Meals

ABSTRACT

Introduction: Previous studies have shown that roti and pittu, which are South Asian foods, when prepared with the same composition of wheat flour and coconut scrapings had significantly different (p<0.05) glycaemic index (GI) values. The only difference was in the processing where roti (GI 57) was dry-heated (roasted) and pittu (GI 80) was wet-heated (steam cooked). The present study was carried out to investigate the association between GI and the properties of starch during processing for the observed variations of GI values of roti and pittu prepared with different flour varieties. Methods: The characteristics of isolated starch granules, molecular size distribution pattern of carbohydrates, amylose, amylopectin contents and change in temperature during the cooking of ‘pittu’ and ‘roti’ were analysed. Results: The results indicate that the contribution to GI from starch gelatinisation correlates positively and corroborates with reported data. Thus the significantly low GI values of roti compared to pittu could be mainly attributed to less disintegrated and less swollen starch granules of flour used in the preparation of roti. This was observed irrespective of the variety of flour. Conclusion: This study confirms that wet heat gelatinises starch to a greater extent than dry heat and provides evidence of a possibility that foods processed using dry heat to be associated with lower GI values, than the wet processed foods if other factors are constant.