Preliminary study on green tea juice extracted by ultrahigh pressure process

To study the feasibility of ultrahigh pressure process (UHPP) applied on green tea juice manufacturing, green tea juice was extracted from green tea (the ratio of green tea to water was 1︰15 and 1︰50, respectively) by three methods, which were cold water extraction, hot water extraction and ultrahigh pressure processing with 100, 300 and 500 MPa, respectively. The results of analyzing the chemical composition showed that the contents of free amino acids in green tea juice extracted by UHPP in the same ratio of green tea to solvent were higher than those by cold water extraction and hot water extraction, but the contents of water-soluble saccharide were lower than those by cold water extraction and hot water extraction. The yield of tea polyphenols by ultrahigh pressure was higher than that by cold extraction. The analysis of chromatic aberration showed that the degree of yellow-green of the juice extracted by ultrahigh pressure was deeper than that by cold water extraction and hot water extraction. The ultrahigh pressure had a passive effect on activities of polyphenol oxidase and peroxidase.