Utilization of tannery fleshings: Optimization of conditions for fermenting delimed tannery fleshings using Enterococcus faecium HAB01 by response surface methodology

Conditions for fermentation of delimed tannery fleshings – to obtain higher degree of protein hydrolysis and reasonably better antioxidant activity – using Enterococcus faecium HAB01 (GenBank #FJ418568) were optimized. Three independent variables – viz., inoculum level (X1), glucose level (X2) and fermentation time (X3) – were optimized using response surface method considering degree of hydrolysis (DH; %) and total titrable acidity (TTA) as response variables. The optimized conditions were found to be 12.5% (v/w) inoculum, 17.5% (w/w) glucose and 96 h of fermentation at 37 ± 1 °C to obtain a maximum DH%. The usefulness of the predicted model was further validated by considering random combinations of the independent factors. The chemical score of the hydrolysate revealed an excess amount of essential amino acids, viz., arginine and leucine compared to reference protein. The liquor portion had relatively high antioxidant activities, indicating its potential for use as a high value feed ingredient.