Cold atmospheric‐pressure plasma treatment of turmeric powder: microbial load, essential oil profile, bioactivity and microstructure analyses

Abstract

Summary Turmeric powder treated by cold atmospheric‐pressure plasma (CAPP) at 25 kV for various times of 3, 5 and 7 min was examined for microbial load, essential oil profile, colour parameters, total phenolic content, total flavonoid content, antioxidant activity and microstructure. CAPP treatment caused a reduction of approximately 1.5 log CFU g −1 in aerobic viable cell count of turmeric powder, which was most pronounced during the first 3 min of the treatment. The inactivation kinetic was fitted to the Weibull model with R 2 of 0.9913 and RMSE of 0.0641. Gas chromatography–mass spectrometry analysis of essential oils identified twelve different components for turmeric powder of which 1,8‐Cineole, α‐Terpinolene and trans‐Caryophyllene were lost and ar‐Turmerone and α‐Zingiberene experienced considerable increases after plasma treatment. The double‐edged effect of plasma treatment was also observed on bioactivity. Scanning electron microscopy showed formation of super‐agglomerates in plasma‐treated samples due probably to coalescence of the granules with plasma‐damaged walls.