Enzymatic Activity and Microstructural Changes of Hot Water Treated Banana during Ripening

Berangan banana were treated with hot water at 50 ºC for 0 (control), 10, and 20 min and then kept at room temperature (25±2 ºC), 75-80% RH to observe the ripening progress. Firmness and activity of cell wall degradation enzymes such as polygalacturonase (PG), pectin methylesterase (PME), and pectate lyase (PL) were determined for treated and untreated banana. The microstructure of banana peel cell wall was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Treated fruit was firmer than the control fruit during ripening process. PG, PME, and PL activities were reduced in the treated bananas when compared with the control treatment. Hot water treatment disturbed cell wall degrading enzymes activity and delayed the disassembling of pectin fraction of Berangan banana. The micrographs of SEM and TEM exhibited lower changes in cell compartment and less loosening of cell wall fibril fractions in treated fruits. The electrolyte leakage in Berangan banana decreased with the increase of exposure time. The results of this study indicated that hot water treatment at 50 ºC slowed down the ripening process and extended shelf lifeof banana.