Takashi Tomana

Use of refractometer to determine soluble solids of astringent fruits of Japanese persimmon (Diospyros kaki L.)

SummaryA method was developed to determine soluble solids refractometrically in astringent Japanese persimmon fruits with a high soluble tannin content. Adding 5% PEG # 6000 to the fruit juice in equal amount followed by centrifugation or filtration removed interfering tannins effectively from the mixture by forming precipitates. The refractometer readings were taken with the resultant solution and 2.5% PEG # 6000 and then the refractometer sugar value of the original juice was calculated by multiplying by two the difference of the two readings. The calculated value approximated closely to the total sugar content of juice.

Distinguishing between Japanese persimmon cultivars (Diospyros kaki L.) by means of pollen isozymes

Abstract Pollen isozyme systems of 19 cultivars of Diospyros kaki L., and 1 and 2 clones of D. lotus L. and D. virginiana L., respectively, were studied by starch gel electrophoresis in an attempt to discriminate between cultivars and species. Eight enzymes gave 4–20 different banding patterns, of which glucose phosphate isomerase (GPI) and phosphoglucomutase (PGM), both having a variety of well-resolved banding patterns, were thought to be the most useful enzymes for discriminating between the cultivars studied. Thirteen out of 19 cultivars were distinguished by either GPI or PGM. By using the two isozyme systems together, all cultivars were uniquely discriminated. D. lotus and D. virginiana showed unique banding patterns not observed with D. kaki . Based on similarity index values calculated from 9 isozyme systems, some conclusions could be drawn on the possible relationships among the cultivars and species examined.