Antioxidant Properties and Dominant Bacterial Community of Fermented Rohu (Labeo rohita) Sauce Produced by Enzymatic and Fermentation Method

Abstract

Sauce was produced from Rohu (Labeo rohita) by enzymatic and fermentatively under conditions optimized by response surface method. Salt (20% w/w) and commercial papain (3% w/w) were employed for enzymatic production; while, salt (25%, w/w), sugar (7.5%, w/w) and lactic culture (10%, w/v; Pediococcus pentosaceus FSBP4-40) were used in case of fermentative production. Total antioxidant activity (as ascorbic acid, µg/ml), 2,2`-diphenyl-1-picryl-hydrazyl (DPPH, %) and 2,2`- azinobis-3-ethylbenzothizoline-6 sulphonate (ABTS; %) scavenging activities of fermented sauce samples were higher at 3441±60, 49.57±1.7 and 99.0±0.3, respectively; as compared to enzyme treated samples which showed 803±13, 28.60±1.1 and 78.4±1.0, for the respective parameters, after 180 days storage at 37°C. Superoxide anion scavenging activity and reducing potential were found significantly higher (P<0.05) in both fermented as well as enzymatically prepared sauces in comparison to control. Fermented sauce exhibited excellent antibacterial property against Listeria monocytogenes ScottA. Bacterial counts such as total plate count and halophile count, after 180 days, were significantly lower (P<0.05) in the fermentatively produced sauce than enzymatically prepared sauce. Pediococcus, Micrococcus, Enterococcus and Staphylococcus were the dominant bacterial genera in fermented sauce. The study emphasizes the role of accelerating fermentation process, either enzymatically or fermentatively, to produce biofunctionally and bacteriologically superior rohu sauce.