Studies On Stability And Antioxidant Activity Of Anthocyanins From Blueberry

Blueberry is one of the fruits riched with nutrient contents, as known "the king of thefruits". Studies have shown that anthocyanins, which are found in the tissue of many kinds of plants, are a group of flavonoid combining with six kinds of anthocyanins composed with monosaccharide or disaccharide. Anthocyanins have many biological effects, such as anti-oxidation, anticancer, free radical scavenger.1. Blanching for2min can better maintain anthocyanins and polyphenolics and inactivate PPO. The blueberry juice yeied was66.7%. It can improve blueberry juice quality, compared with the effect of PPO inhibitor Vc and microwave. The addction of Vc and microwave had a lower level of anthocyanins and polyphenolics.2. Blueberry anthocyanins stability results showed that as pH value increased, the maximum absorption wavelength first increased then decreased, with the color from red to blue. Anthocyanin maintained its red color only in acidic circumstance, but it was not stable in alkaline circumstance. Blueberry juice anthocyanin faded faster in natural light than in dark condition.3. Blueberry juice anthocyanin has a higher stability under the temperature of60℃.After heated for4hours, residual rate of anthocyanin stays above80%. Na+on the stability of anthocyanins no adverse effects; Cu+, Mg+, Cu2+, Fe3+on the stability of anthocyanins have adverse effects. Zn2+, K+, Ca2+, Al3+had positive effects. Malic acid, tannic acid, oxalic acid and malonic acid can enhance the stability of anthocyanins because they can add pH value.The addition of H2O2significantly undermined the stability of anthocyanins. When at a low level, the addition of sodium sulfite and Ascorbic acid can slightly enhance the stability of anthocyanins. But a high level can led to the decrease of anthocyanins. D-fructose was better than maltose and Sucrose on the stability of anthocyanin enhancement, glucose less stable.4. Based on the single factors experiment, the optimum copiment parameters of Al3+, malic acid, D-fructose were0.07mol/L,0.03mol/L,0.1mol/L5. Blueberry anthocyanins antioxidant activity was investigated. The results show that blueberry anthocyanins have antioxidant activity. The ability of scavenging DPPH free radical was also nearly the same as Vc. Blueberry anthocyanins can clear hydroxyl free radical and have the ability of superoxide free radical, stronger than Vc; The blueberry anthocyanins also have reduction power, less stronger than Vc. After the addition of copigment, blueberry anthocyanins anti-oxidation has greatly been improved.