Assessment of catalytic activity and stability of bromelain-polyphenol complex in pineapple juice

Abstract

The nutraceutical properties of pineapple (Ananas comosus) are attributed to bromelain, a mixture of cysteine proteases. To reduce or prevent denaturation and oxidation of bromelain in clarified pineapple juice, an ethanolic extract of dried cashew leaves, which contains significant amounts of polyphenols, was mixed with the juice. Analyses were made of free and complexed bromelain-polyphenol activities. Antioxidant activity was enhanced by about 15% after complexing 1.5 and 1.0% cashew extract with clarified pineapple juice and the increased antioxidant capacity was attributed to the polyphenol content of cashew leaf extract. The thermal stability of complexed bromelain was tested by heating the solution at 60°C for 150 min. Bromelain complexed with 1.0 or 1.5% cashew leaf extract was more stable than free bromelain and the addition of 1.0% cashew extract reduced denaturation 15-fold while 1.5% reduced it by 10-fold. Polyphenol from cashew leaf extract could protect bromelain from heat damage and oxidation. The results of the present study suggested that the complexion of polyphenol from cashew leaf with bromelain in pineapple juice would confer greater bromelain stability.