Enzyme-based integrated solution to cleaning of coconut milk foulants

Abstract

This work studied enzymatic cleaning of coconut milk foulants to find more efficient and more environmental friendly cleaning method than the current method using sodium hydroxide (NaOH). Swelling studies of the foulants in cellulase (Celluclast®) (1–4wt%, 55°C, pH 5.5, 2h) were conducted using a gravimetric method. Continuous reduction of foulants mass was observed but the foulants remained at the end of 2h. Larger mass reduction was observed when protease (Alcalase) was mixed with cellulase. Nevertheless, when lab-scale tests for cleaning in place (CIP) were conducted, the highest mass removal achieved was only 64.7%. This was significantly lower than 88.1% removal obtained with 1wt% NaOH (70°C, pH 13.7). Removal percentages of enzymatic cleaning also varied with foulants formed at different positions in a heat exchanger. Surfactants (LAS24 and LAS95) were then used to assist enzymatic cleaning. Although addition of surfactants improved cleaning efficiencies of enzymes, the cleaning efficiencies were lower than when using surfactants alone. Hence, cleaning in 2 steps was studied. Based on 1-stage CIP results, only cellulase and LAS24 were used in 2-stage CIP studies. Cleaning time of each step was varied but total cleaning time was 2h. Using LAS24 first showed more removal and lower concentration of enzyme could also be used. Moreover, there was no variation in removal of the foulants at different positions. Using LAS24 (0.1wt%, 1h) followed by cellulase (0.012wt%, 1h) could remove the foulants to similar extent to using NaOH.