Navy bean cotyledon cells : isolation, characterisation and their application in low glycaemic bread : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Palmerston North, Manawatū, New Zealand. ENBARGOED until 29 July 2024.

Abstract

There is an increasing consumer demand for low-glycaemic foods due to the rise in lifestyle diseases such as obesity and type 2 diabetes globally. Reducing the glycaemic response of starch-based foods is a challenge as it leads to a significant change in their texture. Pulses are one of the most popular foods and known to have a low glycaemic index (GI). Recently it has been suggested that their isolated cotyledon cells can play an important role in delaying the digestion rate of starch, due to their unique structure where starch granules are tightly embedded in a protein matrix surrounded by the intact cell walls. Studies have been reported on the lab-scale isolation of gelatinised as well as ungelatinised cotyledon cells from navy beans, but rarely investigated the mechanisms by which their cell structure (cell walls, intracellular proteins) controls the starch digestibility. In the present study, intact cotyledon cells from navy beans were extracted using different processing conditions including acid–alkali treatments, autoclaving and hydrothermal processing, and their properties were compared to their counterpart navy bean starch to understand changes in the starch structure and in vitro digestibility. Furthermore, the effect of partial substitution of wheat flour with isolated cells on physicochemical and textural properties, starch hydrolysis kinetics and digesta characteristics during oral, gastro-small intestinal digestion in vitro was studied.—Shortened abstract