Low dose irradiation of plum peel anthocyanins: Impact on stability and antioxidant activity

Abstract

Consumer demand for both natural food colorants and non-thermal methods of preservation has increased overwhelmingly during the last few decades. Preventing loss of appeal and color through non-thermal methods without compromising on quality will provide an alternative to conventional thermal methods. In the present study, irradiation of plum peel anthocyanins after extraction and purification was done in a range of 0.1-1.0 kGy. Results revealed that degradation was significantly (p ≤ 0.05) dependent on both time and dose of irradiation. The percentage degradation observed in the first 3 h of treatment was 9.0-21.0±1.2%. The maximum anthocyanin degradation recorded during 8 h of irradiation was 45.3%. Anthocyanin degradation was apparently less at 0.1-0.5 kGy compared to 0.6-1.0 kGy. The retention of anthocyanins was up to the extent of 88.8-62.3% in samples irradiated at 0.1-0.5 kGy. Comparison of the individual anthocyanin indicated that diglucoside anthocyanins were stable towards irradiation than monoglucoside anthocyanins. For monoglucoside anthocyanins, a 50% decrease was observed as the irradiation treatment exceeded 0.6 kGy. A close comparison of the data revealed that at irradiation dose of 1.0 kGy, the decrease in L* and a* values was almost four and three times higher than that observed in samples irradiated at 0.5 kGy and below; while an increase in b* value was almost double. In spite of marginal degradation in color, low dose irradiation (up to 0.5 kGy) significantly (p≤0.05) increased the antioxidant activity of the plum peel anthocyanins.

Dye stability of black cherry plum anthocyanins in the interaction with co‐pigments and sucrose sweetener

“…Koulani et al. (2016) have also concluded that the furfural content in anthocyanin samples containing sucrose is higher than the samples without sucrose.…”