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

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.

Yield and rheological properties of exopolysaccharide from a local isolate: Xanthomonas axonopodis pv. vesicatoria

Background: The aim of the present study was to evaluate gum productivity of a local strain, Xanthomonas axonopodis pv. vesicatoria, isolated from pepper plant, and its rheological behavior for the first time compared to the standard strain, Xanthomonas campestris DSM 19000 (NRRL B-1459). The influence of operational conditions (agitation rate and inoculum volume) on gum production and rheological properties of gums from the Xanthomonas strains were investigated. Results: The isolated strain of Xanthomonas showed similar xanthan yield compared to the standard strain. Furthermore, this study clearly confirmed that gum yield depended on bacterial strain, agitation rate, and inoculum size. The most suitable conditions for the gum production in an orbital shaker in terms of agitation rate and inoculum size were 180 rpm and 5%, respectively, resulting in an average production of 10.96 and 11.19 g/L for X. axonopodis pv.vesicatoria and X. campestris DSM 19000, respectively. Regarding the rheological properties, Ostwald-de-Waele and power law models were used to describe flow and oscillatory behavior of the gum solutions, respectively. Consistency of the novel gum solution remarkably was much higher than the commercial xanthan gum solution. Flow and oscillatory behavior and their temperature ramps showed that weak gel-like structure could be obtained with less gum concentrations when the novel gum was used. Conclusion: Therefore, yield and technological properties of the aqueous solutions of the exopolysaccharide synthesized by X. axonopodis pv. vesicatoria were observed to be more suitable for industrial production.

Effects of xanthan, guar, carrageenan and locust bean gum addition on physical, chemical and sensory properties of meatballs.

This study evaluated the effects of xanthan gum, guar gum, carrageenan and locust bean gum on physical, chemical and sensory properties of meatballs. Meatball samples were produced with three different formulations including of 0.5, 1, and 1.5% each gum addition and gum added samples were compared with the control meatballs. Physical and chemical analyses were carried out on raw and cooked samples separately. Moisture contents of raw samples decreased by addition of gums. There were significant decreases (p < 0.05) in moisture and fat contents of raw and cooked meatball samples formulated with gum when compared with control. Ash contents and texture values increased with gum addition to meatballs. Meatball redness decreased with more gum addition in raw and cooked meatball samples, which means that addition of gums resulted in a lighter-coloured product. According to sensory analysis results, locust bean gum added (1%) samples were much preferred by the panelists.