Effects of four different cooking methods on anthocyanins, total phenolics and antioxidant activity of black rice.

Jeonghee Surh, Eunmi Koh

Index: J. Sci. Food Agric. 94(15) , 3296-3304, (2014)

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Abstract

Two cultivars of black rice were investigated for the effects of different cooking methods on anthocyanins, total phenolic compounds and antioxidant activities.There was a significant loss of anthocyanins during cooking: roasting resulted in the greatest decrease (94%), followed by steaming (88%), pan-frying (86%) and boiling (77%). Contents of phenolic compounds decreased drastically after cooking, with significantly lower retention in the black rice cultivar that had higher amylose content. DPPH radical-scavenging activity of black rice decreased after cooking. In contrast, metal-chelating activity increased significantly after cooking. Anthocyanins showed a high positive correlation with total phenolic compounds (r2 = 0.936) but a significant negative correlation with metal-chelating activity (r2 = 0.6107).The results indicate that cooking degraded anthocyanins and other phenolic compounds, but with a concomitant increase in phenolics from possible degradation of anthocyanins, which resulted in the enhancement of metal-chelating activity.