The influence of mucilage-rich flours from diverse Australian Plantago species on the pasting, storage, and gluten-free breadmaking properties of rice flour

Abstract

Plantago seed composition varies with natural variation, particularly regarding their mucilage content and structure, but little is known about how this influences their potential as replacements for conventional food hydrocolloids. We investigated the influence that whole seed flour (WSF) addition from diverse Plantago species had on the pasting, storage and gluten-free (GF) breadmaking properties of rice flour (RF). Despite being starch-less, Plantago WSF significantly altered the pasting profiles of RF with the mucilage conclusively shown to be key. Hastened pasting, stimulation of gelation on cooling and increased storage stability were hypothesised to be related to starch-hydrocolloid interactions. GF RF doughs with WSF added had significantly increased elastic moduli (G’) and with tan δ showing a reduced frequency dependence. Improved dough rheology modulated proofing kinetics and led to collapse resistance which produced GF breads with increased specific volume, improved crumb structure, and improved textural characteristics like lower hardness and higher cohesiveness. WSF from the commercial species, P. ovata (psyllium) produced high quality breads but two Australian native relatives, P. turrifera and P. cunninghamii, produced doughs with improved rheological properties and GF breads with greater volume, improved crumb structure and improved texture. Effects of Plantago WSF addition were partly independent of mucilage content suggesting that mucilage polysaccharide structure is influential and might be related to co-polymer network formation. These data show that Plantago WSF can be used as nutritious and sustainable hydrocolloids in starch-based foods and that natural variation in Plantago seed composition is an untapped resource for selectively manipulating their quality.