Pectin extraction from food industry wastes by microwave: Determination of optimum conditions, structural and technological characterisation

In this study, the microwave extractions of pectin from apple, carrot and black carrot pomaces, which are fruit juice factory wastes, were investigated and yield, degree of esterification and galacturonic acid contents of pectins were determined. Conventional extraction was also performed as a control. In addition, color and texture analysis were performed in model gels produced from the extracted pectins. The yield values of apple, carrot and black carrot pomace pectins produced by microwave extraction were in the ranges of 2.28-9.9%, 4.84-20.54% and 4.13-20.38%, respectively. Degree of esterification values were found in the ranges of 25.8-67.7%. Galacturonic acid contents of apple pomace pectins varied from 22.25 to 50.38 g 100g-1. These values were determined in the ranges of 44.50-74.63 g 100g-1 and 25.50-56.13 g 100g-1 for carrot and black carrot pomace pectins, respectively. Optimum conditions for microwave extraction of apple, carrot and black carrot pomace pectins were determined as pH 1.5, 600 Watt, 14.3 min; pH 1.5, 600 Watt, 15 min and pH 1.5, 600 Watt, 5 min, respectively. According to FT-IR results, the extracted samples were found similar to commercial pectin and the data reported in the literature. Texture parameters of model gels at pH 3.2 were determined higher than those at pH 2.8. The highest firmness and consistency values were observed in commercial pectin and black carrot pomace pectin. Different pH values do not have significant effects on lightness of gels. According to these results; carrot and black carrot pomaces are considered to be suitable as pectin sources and microwave extraction has advantageous.