Protease activity and characterization of bromelain extract of pineapple (Ananas comusus (l.) merr) crown from Subang, Indonesia

Abstract

Pineapple (Ananas comusus (L.) Merr) has a high bromelain content with protease activity which hydrolyzes proteins. Bromelain is distributed to all parts of pineapple, including the pineapple crown, which is agricultural waste that has not been utilized properly. The purpose of this study was to determine the protease activity and the character of bromelain extract from the Indonesian pineapple crown. The pineapple crown was collected from Subang district, West Java, Indonesia. The bromelain extract was obtained through the precipitation process with ethanol, then a protein qualitative test was performed. Solubility test was conducted to determine the physicochemical property. UV spectrophotometer was used to determine protease activity by measuring the tyrosine concentration which produced from hydrolysis of casein as a substrate. The bromelain character was determined by protease activity in various pH, temperature, and substrate concentration. The bromelain extract was protein with specific solubility in various solvents and the protease activity was 7.72 ± 0.45 IU/mg. The optimal activity was reached at pH 5 and 55 °C, KM as 1.00 mg/mL, Vmax as 8.11 IU/mg.min, and Kcat as 0.03/sec for casein as substrate. Thermal inactivation of bromelain extract can be described by a first-order model and the calculated Ea value was 642.20 ± 10.60 kJ/mol. The bromelain extract of pineapple crown has protease activity with the specific character and first-order thermal inactivation.