Refining Bromelain Extraction: Procedures and Precipitant Effects on Enzyme Activity Recovered from Pineapple Peel

Introduction

Pineapple (Ananas comosus Merr.) is extensively used in various food products due to its widespread popularity. The residue from pineapple, which contains valuable bioactive compounds like bromelain, offers an eco-friendly approach to waste management. Bromelain, a protease prevalent in pineapples, can be extracted from waste parts, using methods such as solvent precipitation and ultrafiltration. An increasingly popular and environmentally friendly method for protein concentration and purification is polyelectrolyte precipitation, which preserves protein integrity while aiding separation.

This study utilized polyelectrolytic precipitation with carrageenan (Carr) to assess an efficient and sustainable method for extracting bromelain from pineapple stems.

Methods

An optimal purification methodology was assessed considering various steps, including centrifugation, pellet washing, and different Carr stock concentrations. The extracts were analysed for bromelain and proteolytic specific activities using LPNE and Azocasein substrates and the BCA assay.

Results

Bromelain-specific activity was shown in all samples, with no significant differences among peel extractions. The highest activity was observed in pellets from Process A and E, the lowest and highest Carr concentrations, respectively.

Specific proteolytic activity, assessed at pH 9, showed that all samples had this activity. Standard commercial bromelain served as a reference (≥3 U/mg protein). Peel extraction samples generally showed higher activity than the reference bromelain (≥4 U/mg protein), except Process C (~2 U/mg protein). Process A exhibited the highest specific activity among all processes.

Conclusion

In conclusion, changes to the extraction process did not significantly affect the bromelain-specific activity of peel samples. Specific proteolytic activity was higher for Process A, likely due to higher free total protein post-precipitation and other interacting components.

Extracting bromelain from pineapple waste offers a sustainable solution for waste reduction and supports health-focused products, promoting a zero-waste approach in pineapple production.