Changes in total phenolic content and color of bottle gourd (Lagenaria siceraria) juice upon conventional and ohmic blanching.

Abstract

Plant phenolics exist in a complex matrix and require a high separation capacity for analysis. Bottle gourd (BG) was blanched using conventional thermal and alternate thermal ohmic heating methods using different combinations of temperature (60-90°C) and time (1-5min), and the effect of these methods on total phenolic content (TPC) and color was examined. Complete characterization on the basis of the phenolic profile of unblanched, ohmically blanched, and conventionally blanched samples of BG was studied. Gas chromatography-mass spectrometry and Liquid chromatography-mass spectrometry were used to detect volatile and nonvolatile phenolic compounds, respectively. The color profiles of the unblanched and conventionally and ohmically blanched samples were studied via hunterLab colorimeter using L*, a*, and b* coordinates. The highest increase in TPC was observed at 80°C, 4 min and 90°C, 5min in the case of ohmic and conventional blanching, respectively. The conventionally and ohmically blanched samples both produced desirable green-color retention in comparison to the unblanched samples; however, highest retention was observed in the ohmically blanched samples. The ohmically blanched samples exhibited the maximum extraction of phenolic compounds and better color of BG juice in comparison to the other samples.