Wheat-based breads with slowly digestible starch properties by increasing the amylose content: an in vitro approach

BACKGROUND: Previous experiences revealed that increasing the amylose content through the substitution of normal amylose (NA) with high amylose (HA) flours can improve slowly digestible starch properties of cereal-based foods. However, data for wheat-based breads are not clear, since HA sources are frequently used in combination with organic acids and/or specific baking conditions know to reduce rate and extent of starch digestion. OBJECTIVE: The aim was to conduct an in vitro evaluation of starch digestibility of wheat-based breads characterised by increasing amylose levels. METHODS: Wheat-based breads were formulated with increasing amylose levels derived from the substitution of NA white wheat (NAWW) flour with HA maize starch (HAMS) represented by substitution ratio of 0%, 15% and 30% on a total flour basis. RESULTS: Dietary fibre increased (p < 0.05) whereas crude protein decreased (p < 0.05) when the level of HAMS increased in the recipe. The resistant starch and slowly digestible starch fractions increased (p < 0.05), whereas the predicted glycaemic index and the in vitro rate of starch hydrolysis decreased (p < 0.05) when HAMS increased in the formulation. CONCLUSIONS: Present findings suggested that the use of HA ingredients could contribute to formulate wheat-based breads with overall slowly digestible starch properties.