Study Of Storage Stability Of Proanthocyanidins From Picea Koraiensis Nakat’s Cones Lamella

Redskins spruce (Picea koraiensis Nakai) is mainly distributed in Jilin and other regions of Xiaoxing’anling, which is used for pulp and construction industry. Picea koraiensis Nakai’s cones lamella contains considerable proanthocyanidins, but its storage stability has not been reported. Picea koraiensis Nakai’s cones lamella was used as raw materials in this experiment, content changes, degradation kinetics and color changes of proanthocyanidins were studied under different pH, different storage temperature and additive (malic acid and sucrose) in solutions of different concentrations; in addition, content changes, degradation kinetics and color changes of proanthocyanidins in the solid powder state were studied under different relative humidity(RH), different storage temperatures and additive (malic acid and sucrose). Results were listed below:The results of content changes, degradation kinetics and color changes of proanthocyanidins in solution showed that:proanthocyanidins was very stable under the condition of 4℃, pH 4.0 at the concentration of 3mg·mL-1; the degradation reaction of proanthocyandins in solution followed first-order kinetics and the activation energy Ea <42kJ·mol-1, so the reaction rate was larger; adding 1% sucrose at pH 4.0 and 0.2% malic acid at pH 5.0 at the concentrations of 2mg·mL-1and 3mg·mL-1 could delay reaction rate and increase the residual rate of proanthocyanidins, and the effect of sucrose is slightly better than malic acid; with the storage time going by, L value decreased, a value increased and little change in b value and color of solution changed from yellowish-brown to dark red.The results of content changes, degradation kinetics and color changes of proanthocyanidins in the solid powder state showed that:the degradation rate of proanthocyanidins in powder was relatively smaller and it was very stable under the condition of 4℃ when RH was 0%; the degradation reaction of proanthocyandins in powder followed first-order kinetics and the activation energy Ea>42kJ·mol-1, so the reaction rate was smaller; adding malic acid and sucrose at low temperature (≤25℃) and low relative humidity (RH≤ 43%) could delay reaction rate and increase the residual rate of proanthocyanidins; the color of proanthocyanidins solid was yellowish-brown, with the storage time going by, L value decreased, a value increased and b value decreased and color of solid finally changed from yellowish-brown to dark red.