PREPARATION OF STARTER CULTURE FROM DIFFERENT SOURCES OF GUNDRUK & GUNDRUK FERMENTATION FROM WASTE LEAVES OF CABBAGE
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Date
2023
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Gundruk is an ethnic fermented food produce by fermenting leafy vegetables primarily valued for its uniquely appetizing taste and flavor. From nutritional standpoint, Gundruk can be considered as a concentrated source of minerals, vitamins, therapeutically active compounds and probiotics. During this present investigation, effort towards finding the possibility of improving the production technology of fermenting Gundruk from waste leaves of cabbage has been made. 3 different samples of Gundruk were collected from 3 different districts of Assam (Jorhat, Biswanath and Sonitpur), from which 6 different bacterial strains were isolated (coded as JR1, JR2, BN1, BN2, SP1 and SP2) characterized and screened for Gundruk fermentation as starting culture. Along with these starting cultures, a mixture of microbial isolates directly isolated from the collected Gundruk samples by soaking them with sterilized distilled water and keeping in shaking incubator overnight at room temperature and 200rpm (coded as JR3, BN3 and SP3). These mixture cultures were also used directly for Gundruk fermentation as stating cultures, separately. Proximate analysis of all the final Gundruk products produced after 14 days of fermentation and sun drying was carried along with the raw waste cabbage leaves (used as substrate). The results obtained after the proximate analysis showed that the crude fiber and moisture contents of all the Gundruk samples decreased considerably over the non-fermented leaves to a level of 8.61 percent and 8.13 percent from 12.67 percent & 82.3 percent, respectively. But, all the other minerals (Potassium, Phosphorus, Iron, Calcium, Magnesium, Sodium and Zinc) as well as the ash contents found to be increased considerably in fermented products over the non-fermented one. Gundruk product fermented using bacterial isolates showed increased level of mineral profile than the Gundruk fermented naturally. The highest level of K (257.29mg/100g), P (43.59mg/100g), Mg (33.79mg/100g) and Ca (63.79mg/100g) were found in product treated with the bacterial isolate BN1 (isolated from Biswanath-Gundruk). This increase in the minerals content of the Gundruk product might be associated with the presence of more numbers of lactic acid bacteria in the added starting cultures which facilitate the process of fermentation leading to the release of more minerals. Microbial load was evaluated in each final product and it was found that the product inoculated with bacterial mixture SP3 (prepared from Sonitpur-Gundruk) used as starter culture showed the highest microbial growth (7.17 log cfu/g)) over all the treated and absolute controlled-products.
Sensory evaluation of all the final fermented products was carried out by 20 evaluators using 9-point hedonic rating scale. The highest scoring in terms of flavor, taste and overall appearance goes with the product treated with bacterial isolate JR2 (isolated from Jorhat-Gundruk) as starting culture as. However, there were no considerable difference found among the different products in terms of color and appearance. From the present investigation it can be concluded that it is possible to prepare Gundruk with acceptable quality characteristics using readily available seasonal leafy vegetables, specifically unused leaves of cabbage as well as known bacterial isolates, isolated from naturally fermented Gundruk product under controlled conditions. However, to make it commercialized product it needs more investigation in details like standardization of starter culture, evaluation of more leafy vegetables, standardization of procedures for storage as well as packaging and estimation profitability etc