Bromelain is a proteolytic enzyme, which is prominently found in all parts of a pineapple plant (Ananas comosus). It has found immense applications in the pharmaceutical industry as well as the food, cosmetic, and leather industries. However, bromelain from the pineapple fruit peels is a less explored source for making valuable products. Therefore, the objective of this study was to investigate the potential application of bromelain enzyme, extracted from pineapple juice processing waste peels, for gelatin hydrolysis from used X-ray film. Extraction of bromelain was performed with a 1:2 ratio (w/v) of extraction mix, pineapple fruit peel, and phosphate buffer (pH=7.0). The activity of a crude enzyme was found to be 7.2U/ml and it was active in a broad range of pH (2.5-12) and temperature (25-85oC) without losing its activity. The optimum temperature and pH of the enzyme were recorded at 70oC and pH 7.0 respectively. At optimum conditions (70oC and pH 7.0) complete hydrolysis of the gelatin layer from the film was observed at 30 and 34 seconds, respectively. The enzyme was used more than 50 times repeatedly without significant loss of its activity. Using a minimum concentration of bromelain (3ml=21.6U) along with buffer (37 ml) it is possible to remove gelatin within 210 seconds completely. The properties of the enzyme showed that it has promising potential industrial applications for repeated utilization of the enzyme in both silver recovery and recycling of the x-ray film base.

Keywords: Bromelain, Gelatin hydrolysis, Pineapple peel, Recovery of Silver, Used X-ray film