Studies on combined technologies of pulsed electric field and microwave assisted process for extraction of pectin from Jack fruit rind and core

Abstract

Value addition of inedible parts of Jackfruit such as rind and core using efficient and environment friendly methods would reduce wastage, and its disposal problem and also fetch additional profit to farmers. Pectin, a secondary food ingredient used as gelling, stabilizing and emulsifying agent in food products is such a valuable by-product having nutritional as well as health benefits. Conventional extraction method includes direct boiling using acidified water, which is time consuming and degrades quality pectin. Application of combined novel technologies might help in conquering the inadequacies of conventional methods. In this study, a pulsed electric field and microwave assisted extraction system for extracting pectin from Jackfruit rind and core was developed. To evaluate the developed system towards pectin extraction, the effect of process parameters influencing pectin yield and energy consumption such as PEF strength (5, 10 and 15 kV/cm); PEF treatment time (2, 4 and 6 min); microwave power density (450, 550 and 650 W/g) and time of exposure (5, 10 and 15 min) were studied. The physicochemical and quality parameters of extracted pectin such as moisture content, ash content, protein content, viscosity, solubility, colour, equivalent weight, methoxyl percentage, galacturonic acid and degree of esterification of the pectin were analyzed and compared with that obtained through conventional extraction. A PEF strength of 11.98 kV/cm, PEF treatment time of 5.46 min, microwave power density of 647.55 W/g and time of exposure of 5 min were found to be the optimized process variables of the combined treatment. High methoxyl pectin of good quality was obtained through the combined process. The moisture content, viscosity, ash content, protein content, equivalent weight, methoxyl percentage, galacturonic acid and degree of esterification of the combined PEF and microwave treated samples were 8.95 %, 39.78 cP, 6.78 %, 3.283 %, 557.473 g/mol, 8.37 %, 69.44 % and 68.43 % respectively with light brown colour whereas that of conventional extracted pectin were respectively 10.04 %, 38.14 cP, 7.27 %, 9.98 %466.905 g/mol, 9.376 %, 67.85 % and 78.45 % with dark drown colour pectin. Scanning Electron Micrographs of jackfruit rind and core powder samples before and after combined treatment and conventional extraction revealed an increase in rupture and severing of parenchymal cells of the combined treated samples indicating better extraction efficiency. It was concluded that combined pulsed electric field and microwave treatment resulted in increased extraction of high quality pectin from Jackfruit rind and core.