Physiochemical characterization and antioxidant activities of green tea extract microencapsulated by co-crystallization technique.

Green tea leaves is a non-fermented product which contains many phenolic compounds. Green tea polyphenols are natural compound with antioxidants and anti-carcinogenic potential. Polyphenols are sensitive to high temperature and alkaline pH. To improve the stability of polyphenols, green tea extract was microencapsulated by co-crystallization technique. Entrapment yield, loading capacity, antioxidant activity, characteristics of co-crystallized product such as moisture, water activity, bulk and tapped density, solubility and hygroscopicity, morphology as well as flowability properties of powder (carr index, hausner ratio and angle of repose) were characterized. It was revealed that the effect of concentration on total phenolic compounds of co-crystallized products was significant (p<0.05). Encapsulation efficiency was increased by increasing the extract concentration. The 10% concentration of microencapsulated extract showed the highest DPPH scavenging activity, ABTS and hydroxyl radicals inhibition activity, and reducing power (56.90, 69.37, 71.63% & 0.81, respectively). The difference in particle size of co-crystallized product was significantly (p˂0.05) influenced the flow properties. In general, the values of water activity, moisture content and hygroscopicity showed that co-crystallized product was stable and have good characteristics during storage. Therefore, microencapsulation by co-crystallization technique can be used as an efficient method for increasing the stability of green tea extract against the environmental conditions.