Application of Light Reflectance Properties of Satsuma Oranges to Automatic Grading in the Packinghouse Line (I)
Relationship between Grading Index and Spectral Reflectance
1978 Volume 40 Issue 3 Pages 389-395
Details
1978 Volume 40 Issue 3 Pages 389-395
In order to establish the automatic grading in the packinghouse line of Satsuma oranges, spectral reflectance method by using single wavelength was applied for grading index.
1. Spectral reflectance intensity of Satsuma oranges increased at the diminishing rate with the area of sample port. The sample port of 50mm in diameter was considered to be upper limit.
2. Spectral reflectance intensity was not affected by the size of sample when the sample was spotilluminated in the sample port. From this, the color measurement by single wavelength became possible.
3. The chlorophyll content and the attenuance, i. e. log (1/R), at the wavelength of 680nm had high correlation coefficient of 0.84 at the part of blossom end, and of 0.88 at the stem end. Also, the correlation coefficient between the chlorophyll content at the blossom end and the attenuance at the stem end was 0.80, and that in the replaced relation between the blossom end and the stem end was 0.81. All correlations was significant at the 0.1% level.
4. The color index at the part of stem end, evaluated by the manual sorting, had high rank correlations with the attenuance at the stem end and the blossom end. Its value was 0.95 and 0.90 respectively in the first trial, and 0.94 and 0.78 respectively in the second. Also, the color difference between the stem end and the blossom end of peel was not negligible. Measuring the difference of the attenuance at the both parts of a fruit will be useful for the color sorting of Satsuma oranges.
5. The chlorophyll content had correlations with sugar content and acidity, but the correlation values were not higher as compared with those of the attenuance and the color index to the chlorophyll content.
6. Spectral reflectance of Satsuma oranges decreased with the lapse of time after picking. Therefore, the fruits should be handled as fast as possible on the same day after picking.
