Analysis of Plantago species variants for novel functional and in-vitro fermentation properties

Abstract

Food manufacturing and nutraceuticals such as fibre supplements are extensive and ever-growing global industries where research and development are being constantly carried out to manufacture products with better quality, better sensory perception, and improved nutritional and health benefits. Hydrocolloids, which are hydrophilic long-chain polymers (polysaccharides and/or proteins) of various origins, both natural and artificial, are used in the food and fibre industry. Psyllium is one such hydrocolloid derived from the mucilaginous polysaccharides of Plantago ovata seeds and is used widely in the food industry, including as a fibre supplement due to its strong water-holding ability. Although there are many mucilageproducing members in the Plantago genus, P. ovata is the only species currently used commercially in the food and fibre industry as a source of mucilage. Despite the high demand, there are many constraints to obtaining a consistent supply of psyllium with good quality as the species is difficult to breed commercially and there is a little genetic variation to improve production for food functionality purposes. Furthermore, although P. ovata mucilage provides good faecal bulking and laxative properties, it is poorly fermentable thereby providing lesser fermentation-related health benefits and potentially making it a lessthan- ideal fibre source. However, there may be novel sources of Plantago mucilage that can improve these constraints, such as variation generated through induced mutation, through processes such as fractionation, or found naturally, such as in other members of the Plantago genus that may be used as alternatives to P. ovata with similar or improved uses in food and fibre. These alternative options raise questions about the possibility of novel or improved sources of mucilage from different species. Do the differences in mutant mucilage polysaccharide structure and composition caused by gamma irradiation P. ovata seeds provide better forms of psyllium for use as food hydrocolloids? Does whole mucilage of P. ovata provide the best functionality, or could fractionation of mucilage be used to tailor the properties of food? Could alterations to polysaccharide structure by mutation give rise to more fermentable mucilage with superior performance in faecal bulking as well as providing good amounts of beneficial compounds produced by fermentation in the gut? Are there better fermentable species within Australian native Plantago that can be exploited for use in food and fibre applications? These research questions, that have shaped this thesis, are summarized in Figure 1-1.