Extraction and identification of endopeptidases in convection dried papaya and pineapple residues: A methodological approach for application to higher scale

Abstract

The use of agro-industrial waste for application in the obtention of products with high added value has become a trend in recent years, especially in tropical countries whose main economic sector is agricultural exports. In the present study, an applicable method to food industry of extracting proteolytic enzymes from dryed papaya and pineapple residues by convection was developed. Different to other scientific reports the heat treatment at 40 °C of waste residues, to reach 20% moisture, allowed an increase in total soluble protein content and did not alter the proteolytic activity of the extracts when phosphate buffer pH 7.0 was used as solvent. In the residues evaluated as candidates for the extraction of endopeptidases, we observed that green dried papaya peel and dried pineapple core, had higher activity values (914.34 ± 25.47 U/mg and 2152.36 ± 75.99 U/mg, respectively). These results, combined with one-dimensional electrophoresis and protein identification methods by MALDI TOF-TOF, showed the presence of signal peptides characteristic of papain, bromelain and other endopeptidases previously reported in extracts of fresh papaya and pineapple residues. These findings show that the drying of the residues by convection does not alter neither the activity nor the structure of the proteolytic enzymes. Finally, it is confirmed that the use of 20% ammonium sulfate as a precipitating agent allows to reach an efficiency of 74% in different work scales the use of purification and identification protocols in a more adaptable way, making them the most promising waste in Colombia, due to its potential for the production of bromelain on a larger scale.

Keywords: Agro industrial waste; Bromelain; Convection drying; Papain; Proteolytic activity.