Studies on the natural dietary fiber and their functional properties

Abstract

The aim of the present study was to explore novel, natural dietary fibre sources, evaluate their functional properties, dietary fibre profile, isolation of major fibre components and incorporation of these natural fibres in processed foods. In the present study, routinely used vegetables/legumes/spices such as ashgourd, bottlegourd, radish, pea peels, cardamom peels etc, were explored. Screening of the dietary fibre source was done on the basis of the dietary fibre profile (soluble, insoluble and total dietary fibre), flavour, colour, wastage quantum and convenience for incorporating them in different edible products. Thus ashgourd, radish, pea peels and cardamom peels were the promising selected sources for further study. The fibres from the respective sources were isolated wherein the drying kinetics revealed that the rate of dehydration could be positively correlated to the soluble dietary fibre fraction. These fibres were subjected to granulometry (18 to 150 mesh sieves), wherein 60 mesh particles recorded highest yield, followed by 30 and 100 mesh. The exact particle size of fibres from three different mesh i.e. 30, 60 and 100, were analysed using Image Analyzer, wherein the diameters ranged from 280-410 and#61549;m followed by 140-230 and#61549;m and 40-110 and#61549;m, respectively. These fibre particles were also subjected to Scanning Electron Microscopy (SEM), to study the micro structures of fibre particles, before and after hydration. The image as well as micro structural analysis of particles showed distinctive properties. These natural fibres were studied for dietary fibre profile, wherein ashgourd fibre exhibited maximum soluble fibre fraction (22.76%), whereas cardamom peel fibre exhibited maximum insoluble dietary fibre fraction (83.30%). The functional properties such as water holding capacity, water binding capacity, swelling capacity, oil binding capacity, cation exchange capacity and particle density, were also studied at three different mesh sizes i.e. 30, 60 and 100.