Variations in firmness and sugar content in ‘Huanghua’ pear (Pyrus pyrifolia ‘Nakai’)

Abstract

SummaryKnowledge of the firmness and sugar content of fruit flesh and intact fruit is required for grading and processing. Little detailed information is available on anisotropic differences in firmness and sugar content, and their relationship within fruit. The objectives of this study were to determine any spatial or orientational differences in firmness and/or sugar content in ‘Huanghua’ pear, and to analyse the relationship between firmness and sugar content. Significant differences in firmness and sugar content existed between unripe and ripe pears. Our analyses showed that firmness and sugar content did not differ significantly in the radial (longitudinal) axis, but along the stem-to-calyx (latitudinal) axis (i.e., the proximal to distal end of the fruit) there were significant differences between the two parameters. Firmness and sugar content were greatest in the top or proximal, stem-end of the fruit, and lowest in the distal or calyx end. Thus, it is necessary to consider axis orientation and spatial or positional effects when the quality of pear is being evaluated by measuring firmness and/or sugar content.The “equatorial” area (i.e., the middle of the stem-to-calyx axis) of pear was the best part to evaluate firmness and sugar content. The relationship between firmness and sugar content within pear, and for different harvest periods could be expressed using quadratic models.