Effect of gamma radiation processing on turmeric: Antioxidant activity and curcumin content

Highlights: • We evaluated the effects of gamma radiation on turmeric in doses up to 20 kGy. • 15 and 20 kGy decreased total phenolic compounds. • 5 and 15 kGy decreased AAI, but not the ability to scavenge free radicals. • Curcumin quantification was lower in samples irradiated by 15 kGy. • Doses up to 10 kGy should be applied. - Abstract: The aim of this study was to evaluate the effectiveness of gamma radiation from ⁶⁰Co at doses 0, 5, 10, 15 and 20 kGy on turmeric (Curcuma longa Linn.). The quantification of phenolic compounds was performed by Folin-Ciocalteu method and assessing the potential of antioxidant activity by the free radical [2,2 difenil-1-pricril-hidrazil (DPPH• )] scavenging and by Rancimat® method. The curcumin quantification was performed by High Performance Liquid Chromatography. Compared to control, there were significant losses (p < 0,05) of total phenolic compounds in the samples irradiated with 15 kGy (p = 0001) and 20 kGy (p = 0001). Regardless the irradiation, there was no decrease in the ability to scavenge free radicals. The Antioxidant Activity Index (Rancimat® method) was significantly lower (p < 0,05) in 5 kGy (p < 0001) and 15 kGy (p = 0003) irradiated extracts and the curcumin quantification was significantly lower (p < 0,05) in 15 kGy irradiated extract (p < 0001). It is concluded that gamma radiation processing technology on turmeric can be viable. To maintain safety of antioxidant activity it should be applied doses up 10 kGy.