Study On Effective Methods To Improve The Stability Of Natural Red Kermel Color

Red kermel color is an important natural edible pigment and it has been recently reported as a good source of anthocyanins, which were shown to have the characteristics of edibleness, innocuousness, free of side effects and high nutritional value. At the same time, a large number of researches have shown that red kermel color had a lot of biological activities such as antioxidant, lowering blood pressure, liver protection, anticancer, etc, and it exhibits broad application prospects in the food, pharmaceutical, cosmetics and other fields. In this paper, the main composition of red kermel color was identified. The copigmentation effect of auxiliary agent type, concentration on red kermel color was investigated. The red kermel color microcapsule process was optimized and the stability of microcapsule products were evaluated.Firstly, red kermel color anthocyanin which is the main functional ingredient had been quantitied by HPLC-MS at the wavelength of 517nm. The main anthocyanin cyanidin-3-glucoside was identified.Secondly, the copigmentation effect of auxiliary agent to improve the stability of red kermel color was investigated. Results showed that:oxalic acid, malonic acid, tartaric acid and malic acid showed well copigmentation effect and enhanced the absorbance values obviously (P<0.05); However, succinic acid of red kermel color copigmentation effect was not significant, and ascorbic acid, tea polyphenols showed copigmentation effect of subtractive color. Choosing the best concentration of auxiliary agent according to the color values L*, a*, b*, △E and the transmittance value, the absorbance values of a number of factors, and the best concentration of oxalic acid, malonic acid, tartaric acid was 0.08mol/L, malic acid was 0.06mol/L. The thermal stability of red kermel color was significantly improved through the copigmentation effect of oxalic acid, malonic acid, tartaric acid and malic acid. The anthocyanin degradation followed first-order reaction kinetics and copigmentation effect of auxiliary agent to improve the stability of red kermel color by increasing the half-life and activation energy. In addition, no anthocyanins derivatives were formed during the copigmentation. In the process of application, malic acid can improve the stability of the heat and light and sucrose, NaCl had no influence on copigmentation effect, glucose had some influence on copigmentation effect.Finally, Choosing maltodextrin as wall material, the optimum microencapsulation process conditions were determined through single factor and orthogonal experiments: maltodextrin concentration 30%, temperature 25℃,the ratio of wall-material to core-material (w/w) 1:1, microencapsulation time 0.5h. Under these conditions, red kermel color microcapsule efficiency was (93.53±1.17)% and microcapsule efficiency after copigmentation was (94.00±1.89)%. The effective pariticle size of red kermel color became smaller, the thermal and light stability of red kermel color were all significantly improved after microencapsulation. In addition, the copigmentation effect of auxiliary agent could make further improvement on the thermal and light stability of microencapsulation products.