Stability enhancement of beetroot betalains through copigmentation

Background Like other natural pigments, betalains also face stability problem. Copigmentation can be explored to address this issue. In this study, black carrot anthocyanins were first time used as copigment with betalains so that copigmented betalains with enhanced stability could be developed that can withstand the deteriorative processing and storage conditions. Results Increase in hyperchromic and bathochromic shift with subsequent increase in black carrot anthocyanins extract (0.250 g L-1) addition from 0.2 to 1.0 ml L-1 was observed in native betalains pigments from 0.28 to 1.90 and 538 nm to 564 nm, respectively. For maximum recorded bathochromic shift, 0.8 ml L-1 addition of copigment was optimized. Copigmented betalains pigment showed better stability in comparison with native pigment, when exposed to light, temperature more than 60oC, and ≥1.0 g L-1 NaCl. At constant incubation time (3h), copigmented betalains degraded up to 20.79-41.43% whereas the non-copigmented counterpart degraded up to 83.49-86.86% at 60, 75 and 90°C, respectively. Lower rate constant (k) and enhanced activation energy (Ea) showed higher thermostability of copigmented betalains. With constant light exposure, the half-life value of betalains was 145.2h which increased approximately by two-fold (274.08h) after copigmentation. The t1/2of betalains pigment at 10, 15 and 18% salt addition was 81.12, 75.36 and 83.52h which increased to 186.96, 226.56 and 152.88h after copigmentation. Conclusion These findings support that black carrot anthocyanin, is a potential and compatible copigment for water soluble betalains pigment which enhances stability of betalains under extreme processing conditions