Partitioning of bromelain from pineapple peel (Nang Lae cultv.) by aqueous two phase system

Pineapple peel is a potential source for the extraction of beneficial bioactive compounds due to the large amount of waste after processing. The extraction of bromelain from pineapple peel by using aqueous two-phase system (ATPs) and its application in muscle models were investigated. Bromelain predominantly partitions to the polyethylene glycol (PEG) rich top phase. The highest enzyme activity and recovery were presented in the top phase of 15% PEG-3000-20%MgSO4. Protein pattern and activity staining showed the molecular weight (MW) of bromelain was 29 kDa. The extracted bromelain showed the highest activity when incubated with buffer pH 9.0. Its activity decreased by 50% after 5 min incubation at 90°C and dropped drastically after 10 min incubation. Its activity also decreased continuously with increasing of NaCl concentration. Crude bromelain extract was applied to the muscles of beef, giant catfish and squid at the levels 0.05-1.0 grams per two grams of muscle. Higher muscle protein breakdown was observed to occur more in the beef and the giant catfish muscles than that of the squid sample. The myosin heavy chain (MHC) of beef and giant catfish muscles was extensively degraded into degradation proteins with lower MW.