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This thesis investigates the concentration of total phenolics and total flavonoids in pulp extracts of pawpaw harvested in 2008, 2009, and 2010, and the concentration of (+)-catechin and quercetin flavonoids in 2010 pawpaw pulp extracts using high performance liquid chromatography (HPLC). Next, influence of frozen storage and air or vacuum packaging of pawpaw pulp on the concentration of (+)-catechin and quercetin flavonoids was examined. In addition, properties of pawpaw pulp such as moisture content, lipid content, percent sugar, color, and pH were measured. Total phenolics were determined using the Folin-Ciocalteu assay and reported as µmol gallic acid equivalent (GAE)/ g wet tissue. The concentration was observed in the order of 2009 sample (3.91 ± 1.61) < 2008 sample (11.19 ± 0.57) < 2010 sample (14.11 ± 1.90). Total flavonoids were determined spectrophotometrically using flavonoid rutin as a standard and reported as µmol rutin/ g wet tissue. The order of concentration was 2009 (0.46 ± 0.24) = 2010 (0.76 ± 0.40) < 2008 (2.01 ± 0.44). By using HPLC, the concentration of (+)-catechin and quercetin was determined as 0.43 ± 0.79 mg/ 100 g wet pulp and 0.46 ± 0.79 mg/ 100 g wet pulp, respectively. In both air and vacuum packaging under frozen condition, the concentration of (+)-catechin and quercetin increased during the first 4 months and decreased until the twelve-month period. In the meantime, an unknown compound was detected after quercetin was eluted. Pawpaw pulp has 75.24 % moisture, 0.45 % lipid, and 24.1 % percent sugar and color was close to white, magenta, and yellow. The pH of pawpaw pulp was 4.85 which indicates slightly acidic. In conclusion, pawpaw pulp has considerable concentration of phenolic compounds which include flavonoids, and (+)-catechin and quercetin were major phenolic flavonoids in the pulp which increase their concentration during frozen storage before extraction. These results suggest that the two important flavonoids from pawpaw pulp can be essential sources for value-added functional food ingredients by optimization of storage condition of the pulp. |
