| Summary: | 碩士 === 國立臺灣大學 === 園藝學研究所 === 95 === Papaya (Carica papaya L.) fruits have values for abundant of lycopene, β-carotene, and β-cryptocanthin. They are potent natural antioxidants. To improve the healthy nutrients will benefit papaya breeding. Genetic manupulating fruit carotenoid content requires genetic variability and a rapid and accurate method of carotenoid quantitication. High-performance liquid chromatography (HPLC) is often used to quantify pigment contents; however, it is laborious. It requires skilled labor, and use highly toxic solvents. Fruit carotenoids estimation measured by colorimeter has been proposed as an alternative rapid method. Regrssion of the main carotenoids contents of papaya on the color readings has not been reported yet. The L*, a*, b* values and the main carotenoids content of ‘Tainung No.2’ and one virus tolerant papaya line were used to quantify papaya pigments and chromaticity values at fruit maturity stages. The lycopene, β-carotene, and β-cryptocanthin content, measured by HPLC, were highly significantly correlated with the color readings. Regression of three main carotenoids content of ‘Tainung No.2’ papaya on a* value yielded the equations β-cryptoxanthin+ β-carotene +lycopene, μg．g-1 as followed: -0.0006 a* 4 + 0.0161 a* 3 - 0.0386 a* 2 + 0.2484 a* + 2.3905. The regression that color reading a* of the viral tolerant breeding papaya line to β-cryptoxanthin+ β-carotene +lycopene, ug．g-1 was as followed: 4.2309 (b*) - 42.239. The coefficient of determination of these 2 regression line were 90.3% and 92.4%, respectively. Estimation of the lycopene, β-carotene, and β-cryptocanthin contents of papaya can be achieved rapidly and reliably across wide range of papaya lines by using a portable colorimeter measurement. It will benefit the selection efficiency in the field work to quantify papaya color pigments.
‘Tainung No.2’ papaya is the most important variety with high yield potentiality, and rich of pigments. It supply the market demand throughout the year. ''Tainung No.2'' is a hybrid; however, ‘Tainung No.2’ papaya fruit has various shapes, size, flesh color in the market. It possibly is due to parental genetic make-up, cultivation practices, and local conditions. We collected the different sources which have a common name of ‘Tainung No.2’ variety planted design by RCBD with two repetitions in the net-house under the same management. Significant difference of fruit weight, the total soluble solids, fruit pulp color, pigment contents, hue, lycopene content, vitamin A content were found among collections of diffeent locations. Oxygen radical absorbance capacity assay (ORAC) was also to quantify papaya fruit total antioxidant activity. Each gram papaya fruit pulp was 2.3~4.9 folds equal to 1 μmol Trolox.. The colormeter value of a* value measured by colorimeter and the total soluble solids of different ‘Tainung No.2’ was linear correlated. Regressing total soluble solids content of ‘Tainung No.2’ papaya on a* value yielded the regression equations as Brixo = 0.2604 (a*) + 2.7107 (R2= 0.514). Variety so-called ‘Tainung No.2’ under the same cultivation management practices has different genetic make-up, it also permitted to provide useful genetic variability to improve pigment contents in the future.
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