Plant proteases from Carica papaya and Vasconcellea quercifolia with potential application for a cleaner processing in tanneries

Abstract

In the leather industry, proteases can be used as tools to achieve cleaner technology. In the present study, proteolytic preparations obtained from the latex of Carica papaya (Cp) and Vasconcellea quercifolia (Vq) were assayed as dehairing agents for leather processing. Both Cp and Vq showed activity against substrates representative of collagen, keratin, elastin, and epidermis in a range of moderate temperatures (25 to 55 °C). When comparing with a commercial dehairing enzyme, the activity of Cp and Vq on the substrates representative of epidermis and collagen was of around 70% and 100% of the commercial one, respectively, with that of Cp being more keratinolytic. Both Cp and Vq were able to dehair cowhides at 25 °C for 24 h without adding Ca(OH)2 or Na2S, two harmful pollutants used in conventional dehairing, Cp being more effective than Vq. Scanning electron microscopy microphotographs showed epidermis and hair-free hides with clean pores and without significant damage on the grain surface. Further, no damage was detected in collagen fibres and both Cp and Vq showed a slight opening of collagen fibres. We concluded that both Cp and Vq could be used as tools for a cleaner technology in tanneries, either for lime- and sulphide-free dehairing or for the treatment and valorisation of protein waste.