Evaluation of Edible Quality of Commercail Satsuma mandarin (Citrus unshiu MARC.)

II. Relationship of Palatability with Refractive Index and pH of Commercial Satsuma mandarin

Abstract

This research was conducted to determine the relationship between refractive index (Bx) pH value and sensory ratings for sweetness and palatability of commercial Satsuma mandarin (Citrus unshiu MARC.), and to examine whether Bx and pH value suited for the indices of edible quality of the fruits.
1. When sensory evaluation using the fruits classified into nine sections by Bx and pH values was carried out, sensory ratings of panels for the sections varied largely with the two parameters and were high significant and independent of each other.
2. Within a Bx level, the palatability depended on pH values exhibiting a maximum at 3.7-3.8 which was seemed to a point of inflection in the palatability curve.
3. There were least significant differences among the sensory ratings of palatability where the differences among the sections were at least 1.4-1.8 in Bx, or 0.3-0.4 in pH; as the differences in the two parameters increased more over, the differences of the ratings increased further.
4. Distribution ranges of Bx and pH values were 8-14 and 3.0-4.0 respectively. The numbers of the ranges diveded by Bx 2.0 and pH 0.35, which were values arising high significant difference in sensory ratings, were both about three. Therefore, it was considered that three grades were reliable for grading of edible quality.
5. when sensory ratings of palatability were showed by means of height on the plane consisting of Bx and pH axis intersecting at right angles, a shape of mountain, having a peak at about Bx 11-13, pH 3.7, was considered. It was suggested that some contour lines of the mountain were able to show the edible quality of commercial Satsuma mandarin.