Pectin is a heterogeneous branched polysaccharide with complex structure. Microwave-assisted
extraction (MAE) is more efficient in extracting pectin compared to conventional method. The objective of this study was to compare the efficiency of microwave-assisted pectin extraction against conventional extraction method. This study was also to investigate the effect of power level on yield and quality of extracted pectin from jackfruit rinds. Water-based extraction method was performed with the extraction duration for conventional extraction and MAE were 1 h and 10 min, respectively. The temperature of conventional extraction was set at 90°C and the power levels of MAE were 450 W, 600 W and 800 W. High yield of pectin was obtained from conventional extraction (14.59%) and MAE (16.72-17.63%). All quality characteristics determined were found to be insignificant different for pectin extracted from both conventional extraction and MAE except moisture and ash content. Increase in microwave power did not affect yield and quality characteristics of pectin from jackfruit rinds significantly. In conclusion, MAE requires shorter time than conventional extraction in extracting comparable amount and quality of pectin from jackfruit rinds. Microwave-assisted extraction at 450 W was the most effective and economic extraction condition among the different power levels tested.
The objective of the present work was to investigate the effects of alginate coating combined with repetitive pulsed light (RPL) treatment on the enzymatic activity of fresh-cut cantaloupes during chilled storage. Fresh-cut cantaloupes were coated with alginate (1.86%, w/v) followed by RPL treatment (0.9 J/cm2 at every 48 h up to 26 d) during storage. Untreated samples and samples with alginate or RPL alone were used as controls. Enzymatic activities [polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), peroxidase (POD), pectinesterase (PE), polygalacturonase (PG), pectate lyase (PEL), β-galactosidase (β-Gal), α-arabinofuranosidase (α-AF) and cellulase] of fresh-cut cantaloupes were evaluated every 4 d during storage. Neither alginate coating nor RPL treatment has any effect on the activities of PE and PEL of freshcut cantaloupes during storage. The individual treatment or in combination did not increase the PAL, PPO, PG and cellulase activities of fresh-cut cantaloupes throughout the storage. Alginate coating with or without RPL was effective in maintaining low POD activity of freshcut cantaloupes. In addition, treatments using alginate coating or alginate coating+RPL were effective in reducing the β-Gal and α-AF activities of fresh-cut cantaloupes during storage. Overall, alginate without or with RPL was effective in reducing changes of enzymatic activities in fresh-cut cantaloupes during storage.