The fermentation-based production of gellan from rice bran and the evaluation of various qualitative properties of gum

Abstract

The potential for the use of rice bran, an agricultural waste, as a substrate in the manufacture of gellan gum was examined. Using a standard strain of Sphingomonas paucimobilis (ATCC 31461) and rice bran substrate, gellan gum was produced under optimized conditions. The optimal yield of gellan gum using rice bran substrate was found to be 11.96 g L−1 with 5% glucose, 10% inoculum, and a mixing speed of 300 rpm. Native gum was found to have a consistency index of 2.00 Pa.sn. The viscosity of the gum was found to be extremely stable when exposed to thermal stress. Concerning the rheological characteristics, the Herschel–Bulkley model offered a more realistic representation of the flow characteristics of gum solutions. The synthesized gums were mostly composed of glucose, rhamnose, and glucuronic acid. The acetic acid content of gellan gums was 2.95%, while the molecular weight was 2.88 × 105 Da. Characterization of native gellan gums by UV–Vis spectroscopy, SEM, TEM and FTIR spectroscopy is also presented.