Optimization of bromelain isolation from honi pineapple crown

Abstract

Bromelain is a proteolytic enzyme that can be found in all parts of pineapple plant varieties. Pineapple crown (PC) has higher bromelain activity than other pineapple wastes such as peels and leaves. This study isolated bromelain from one variety of PC, namely Honi, and determined the optimum drying temperature as well as concentration of ammonium sulphate to obtain the best bromelain characteristics such as protein content, unit activity and specific activity. Honi PC was dried at various drying temperatures (35, 40, 45, 50, and 55 °C), and then extracted and purified using ammonium sulphate in various concentrations (20, 40, 60, and 80%), in order, to get bromelain. Furthermore, the yield of isolated bromelain was calculated and the protein content, unit activity and specific activity of bromelain characterised. The highest yield of crude bromelain (CB) was achieved at 35 °C. However, the highest protein level, unit activity and specific activity of CB were achieved at 55 °C (p < 0.05). Purification of CB using concentrations of ammonium sulphate in the range 40 to 80% resulted in a higher protein level (p < 0.05). The highest unit activity and specific activity of bromelain were achieved at a 60% concentration of ammonium sulphate (p < 0.05). 55 °C and 60% were the optimum drying temperature and concentration of ammonium sulphate respectively to achieve the best characteristics (2.16% protein level, 1.61 U/mL unit activity and 0.75 U/mg specific activity) for bromelain isolated from Honi PC. Honi PC isolated bromelain was shown to inhibit the browning reaction on apple fruits. The agroindustry waste product, Honi PC, has potential as a future alternative bromelain source.