Smart cleaning-in-place process through crude keratinase: an eco-friendly cleaning techniques towards dairy industries

Abstract

Abstract Crude keratinolytic protease produced from Bacillus tequilensis hsTKB2 was screened for its ability to clean milk foul generated upon the stainless steel panels as deposit in dairy plants. Enzyme yield was maximized by optimizing the culture conditions of a low-cost culture medium under solid culture condition with a try bed reactor. The highest keratinolytic protease activity of (1770.6 U g−1) was obtained by maintaining fermentation conditions of keratinase production at 45 °C, chicken feathers moisture ratio of 1:1 and an initial pH of 10 of the media. The crude keratinase was active in broad range of pH (8–11) with keratin as a substrate. However, it exhibited highest activities at pH 10.5. The crude keratinase which was strongly inactivated by Phenylmethylsulfonyl fluoride (PMSF) indicated that it was a serine type protease. The crude enzyme showed remarkable stability with Triton X-100 making it suitable for CIP process. The surface immobilized enzyme alginate beads prepared by 3% glutaraldehide fixation with beads improved significant cleaning activity rendering it suitable for commercial exploitation. The proteases produced were assessed on a lab-scale in terms of their potential suitability for cleaning-in-place (CIP) in the dairy industry. Cleaning performance was assessed by determining the ability of the enzymes to remove an industrial-like milk fouling deposit from stainless steel. Satisfactory cleaning, judged by quantification of residual organic matter and protein on the stainless steel surface after cleaning, was achieved using the developed CIP procedure at 70 °C. In addition this CIP procedure based on biodegradable enzymes working at high temperature is more environmentally favorable than conventional CIP methods using caustic based cleaning solutions. Potential environmental benefits of the developed enzymatic CIP procedure include decreased chemical usage of the resultant waste prior to release. This cleaning not only produces alkaline and acidic waste water with detergents but also takes significant time and reduction of odorous compounds.