Study On The Extraction, Purification And Properties Of The Anthocyanins From Purple Corn And Pilot Production

Anthocyanin is a water-soluble natural pigment, being used in foods, cosmetics and medicine for its nutritional and the pharmacological functions. The purple corn and its byproduct have high anthocyanin contents. Consequently, they have the potential capacity to provide high quality and quantity anthocyanins for food industry as a natural pigment or a nutritional ingreadent.The extraction, purification, characterization, and functionlity of the anthocyanins from"Zhouzi 1"purple corn and its byproduct were studied for their future application as the natural food additives. Finally, powder and tablets of purple corn anthocyanins are produced in pilot-scale.The conclusions of the study are summarized as followed.The traditional solvent extraction was optimized for the production of"Zhouzi 1"purple corn anthocyanin. The order of the influence of anthocyanins content was the ratio of solid/liquid, temperature, ethanol concentration, and time. The optimal parameters of the solvent extraction were 70% ethanol (including 0.4% citric acid), temperature 60℃, 120 min, solid-liquid ratio 1:20, for 2 times. The purity of the final purple corn anthocyanin was 3 %. Furthermore, complex hydrolase-assisted extraction were evaluated for the production of the purple corn anthocyanins. The optimum conditions of complex hydrolase-assisted extraction were: complex hydrolase concentration 1%, temperature 55℃, pH3.2, 30 min. The complex hydrolase-assisted extraction has higher extraction efficiency and less extraction time, comparing with that of the traditional solvent extraction. The yelid of anthocyanins was improved by 6.6% and the time was reduced 60 min.The characterization and distribution of the purple corn anthocyanins were studied. The main anthocyanins were accumulated from premilk stage, milk stage and dough stage in the growth of"Zhouzi 1"purple corn. The anthocyanin content in purple corn byproducts was higher than that in grains.The purification of the purple corn anthocyanin was studied by XAD7HP macroporous resin adsorption. The optimum elution conditions of XAD7HP adsorption for the purple corn anthocyanin was eluted by 70% ethanol at the speed of 1.0 mL/min. The purity of purple corn anthocyanin was improved from 6.3% to 17.87% by XAD7HP macroporous resin adsorption, when the recovery of the anthocyanin reached89.74%. Moreover, the purple corn anthocyanin before and after the resin purification showed no significant differences by comparing the HPLC profiles.The stability testing of purple corn anthocyanins indicated that anthocyanin was stable under acid condition and unstable under alkaline condition. Moreover, anthocyanin was stable under 60℃, and was decomposed when the temperature exceeded 80℃. The light also influenced the stability of anthocyanins greatly. H2O2, a strong oxidant, showed the strong degradablity to the purple corn anthocyanins. Furthermore, ascorbic acid also influenced the stability of anthocyanins.The effects of metallic ion on the stability and color of anthocyanins were studied. Cu2+, Al3+, Zn2+, and Fe3+ increased the stability and color of the purple corn anthocyanin when Na+ and Ca2+ did not. Moreover, NaCl, saccharose, glucose, fructose-glucose syrup, and preservative had no influence on the stability of anthocyanins.The individual compositions of the purple corn anthocyanins were evaluated by HPLC-DAD/ESI-MS analysis. Eleven compounds were found and nine of them were identified. The results showed that the principal component was the cyanidin derivatives that was 73.96% of the total anthocyanins. The peonidin derivatives and the pelargonidin derivatives were 15.13% and 5.08% of the total anthocyanins, respectively.The antimicrobial activities and antiproliferative capacity of the anthocyanin of purple corn were evaluated in vitro. The purple corn anthocyanin showed antimicrobial activity against Salmonella enteritidis, Staphylococcus aureus, and Candida albicans in dose dependent manner, and showed no antimicrobial activity against Escherichia coli. Furthermore, purple corn anthocyanin showed the antiproliferative capacity against the colon-cancer-cell HT-29 in a dose dependent manner with IC50 of 0.525μg/mL of the anthocyanin content. The antimicrobial activity and antiproliferative capacity of EZPC were related to both its high anthocyanin content and anthocyanin composition (cyanidin derivatives especially).In pilot-scale production, the purple corn byproducts (bracts and cobs, 157 Kg) were used as raw material for anthocyanin production by traditional solvent method, followed by the concentration and spray drying, etc. Then, 22 Kg anthocyanin powder was obtained with the purity of 6.3%. Finally, the enterprise standard for purple corn anthocyanins tablets was formed, including the regulations of Sensory Evaluation, Hygienic Evaluation, and Stability Evaluation, etc.