EFFECTS OF SURFACTANTS TWEEN 80 AND RHAMNOLIPID ON FERMENTATION OF PROTEIN RICH ANIMAL WASTESAYAN SAMADDAR AND ANILAVA KAVIRAJ
Experiments were made to evaluate if non-ionic chemo-surfactant Tween80 and anionic biosurfactant rhamnolipid could stimulate lactic acid bacteria (LAB) to expedite fermentation of a mixture of fish offal waste (FOW) and slaughter house blood (SHB) and produce microbiologically hygienic product with minimum loss of nutrients. Whey was used as the fermentation inoculum and fermentation medium was either free of surfactant (control) or contained any one of the following concentrations of surfactants (treatments): 0.05 (T1), 0.1 (T2) and 0.15 (T3) % Tween80 and 0.005 (R1), 0.01 (R2) and 0.015 (R3) % rhamnolipid. The mixtures were incubated at 35°C. The results showed that growth and metabolic activity of LAB in T2 and T3 treatments sharply increased over control, T1 and R1 treatments and fermentation was completed 1 day earlier than the later groups. After an initial growth, LAB population started declining in R2 and R3 and the fermentation mixture was dominated by yeast population. Clostridium population declined to negligible level at the end of fermentation in T2 and T3. As compared to pre-fermented mixture crude protein level reduced in all treatments, but crude lipid level remained unchanged except significant reduction in R2 and R3. Protease activity and free amino acid (FAA) content increased in T2 and T3 mixtures. It is concluded from the present study that Tween80 can be used to stimulate growth of LAB and to expedite fermentation of mixture of OW and SHB. But precautions are necessary to use proper dose of Tween80 to check proteolysis and minimize loss of crude protein.
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