The effect of microwave heating on the optical characteristics of berry extracts

Abstract

The paper presents the optical characteristics of extracts obtained from marc berries of the heather family - lingonberries, cranberries, blueberries and blueberries. To obtain extracts, the berries were pressed by electromechanical method. From the obtained marc berries, water extracts were obtained in a microwave oven with a power of 800 W and a generation frequency of 2450 MHz for different exposure modes from 288 W to 800 W. Hydraulic module 1:10. The duration of the microwave heating 60 seconds. Controls were extracts obtained using hot water and infusion for 10 minutes. The optical characteristics of the juices and extracts from the marc berries were measured spectrophotometrically in the wavelength range of 410-630 nm. The maximum values of the optical spectra were recorded at D520, regardless of the berries used. An increase in the power of the microwave effect led to an increase in the optical values of the spectra of the extracts: bilberry > blueberry> lingonberry> cranberry. The optical characteristics of microwave extracts reached control values when exposed to 464 W for bilberries and blueberries, 648 W for lingonberries and 800 W for cranberries, which affected the color intensity and color coordinates, but did not significantly affect the shade, with the exception of bilberries. The color coordinates of bilberry extracts were closest to the color coordinates of the juices, the hue was more intense than in the juices, but was within the limits characteristic of the formation of color under the influence of anthocyanins. Bilberry extracts had a higher color intensity than blueberry extracts, but smaller shade values. Optical characteristics of berry extracts can be used to optimize the hydronic module and extraction modes.