Polysaccharide substitutes for gluten in non-wheat bread

Abstract

Breads with a specific volume up to, and beyond, that of conventional wheat bread can be made with rice flour (which does not contain gluten) by incorporation of hydroxypropylmethylcellulose (HPMC) and ispaghula husk (isabgol) from Plantago ovata Forsk. Isabgol disperses to a fibrillar ‘weak gel’ network stable over the temperature range of proving (fermentation with yeast) and initial heating in the baking oven. Weakening of the isabgol network at higher temperature is accompanied by thermal gelation of HPMC, so that the overall network strength (storage modulus, G′) remains virtually constant, and the gascell structure developed during proving is retained. Gelation of HPMC (and of methylcellulose) involves two distinct processes which we suggest correspond to partial dissociation and subsequent aggregation of cellulosic ‘bundles’ present in the solution state at low temperature, a mechanism directly analogous to the thermal gelation of globular proteins.