岡山で生産される白色桃の果実サイズ別の果皮色と果汁成分

Skin color and juice constituents in large(L), medium(M), nad small(S) fruits of four peach cultivars, Hashiba-hakuho(early maturing), were analyzed to elucidate the effect of fruit size on the quality. The fruits containing higher soluble solids than 12°Brix were samled at a commercial packing-house located in southen Okayama. They were stored at 25℃ until fully ripened. The skin color on the cheeks (yellowish) was dark in S fruits of Hashiba-hakuto and Hakurei, respectively, compared to the fruits of other sizes. The sucrose + fructose content in juice, the major source of the sweetness, was higher in S and M fruits in Hakuho, Shimisu-hakuto, and Hakurei, while the malic+citric acid content, the major sour constituent, was lower in L fruits in those cultivars, although no significant difference was found in Hashiba-hakuho. Asparagine, the biggest amino acid fraction and thought to deteriorate the fruit taste at high levels, was higher in L fruits tahn in S fruits in Hashiba-hakuho and Hakuho. The content in Shimizu-hakuto and Hakurei fruits was generally low and not affected by fruit size. The content of γ-decalactone, the major peachy aromatic substance, was higher in L fruits in Hashiba-hakuto, in M fruits in Hakuho and Shimizu-hakuto, and in S fruits in Hakurei, than in those of other sizes. Sensory tests revealed that the L fruits of Hakuho and S fruits of Hakurei were poor in flavor. These results suggest that the larger fruits of Hakuho, Shimizu-kakuto, and Hakurei, the representative white peach fruits in Okayama, have rather falatter tastes than medium size fruits because of their lower sweetness and sourness and weaker aroma, as well as poorer texture.