Changes in fruit texture of crisp-flesh pear during fruit ripening

Abstract:【Objective】Fruit texture is a comprehensive character and also an important part of fruit quality. Traditional evaluation of fruit texture is mainly through taste, which depends on the tester's taste and touch. Therefore, the results of traditional evaluation are subjective and inconsistent. Texture analyzer can simulate human teeth chewing and generate texture parameters such as fracurability, hardness, chewiness,springiness, and so on. The results are more accurate and objective, and enable comparable quantitative evaluations. Many physical and chemical indicators such as sucrose, starch, organic acids, soluble sugars,fructose, soluble solids, vitamin C, chlorophylls, cell wall composition, enzyme activity, and peel metabolites vary during fruit maturation, and their changes provide references for judgment of fruit maturity. But there is no report about change in fruit texture during pear maturation. This study analyzed the differences and changes in fruit texture in different parts of pear fruit during fruit maturation.【Methods】Fruit texture of two crisp-flesh pear varieties,‘Huasu'and‘Wonhwang', was measured through texture profile analysis(TPA) and puncture test using a texture analyzer. Seven fruit texture parameters including fracurability, flesh hardness, adhensiveness, springiness, gumminess, chewiness and peel hardness were measured.Fruit samples were taken 3, 2 and 1 weeks before and at full maturity. The data of fruit texture were collected from three parts of the pear fruit including the calyx end, the middle part and the stem end. In TPA test, fruit were cut lengthwise into two halves. Cylindrical samples with a height of 0.85 cm and a diameterness, adhensiveness, springiness, gumminess and chewiness. Testing was conducted with a test speed of30 mm·min-1, a deformation of 60%, and a trigger force of 1.0 N. Ten fruit were tested for each variety,and the calyx end, the middle part and the stem end of each fruit were tested twice. In the puncture test,the probe with a diameter of 6.0 mm was used to test peel hardness. Tests were carried out with a test speed of 60 mm·min-1, a trigger force of 1.0 N, and test distance of 1.0 cm. Ten fruit were tested for each variety, and the calyx end, the middle part and the stem end of each fruit were tested twice.【Results】All the fruit texture parameters changed significantly during fruit maturation. Fracurability, flesh hardness,springiness, gumminess and chewiness gradually decreased with fruit maturation. But the change patterns of adhensiveness and peel hardness were not consistent between varieties. At the same maturity stage, fracurability, flesh hardness, springiness, gumminess and chewiness in‘Wonhwang'were higher than in‘Huasu'at the same fruit parts. Adhensiveness in‘Wonhwang'had no significant difference with that in‘Huasu'at the stage of 3 weeks before full maturity, but were higher from 2 weeks before full maturity in the same parts. Flesh hardness in the middle part of‘Wonhwang'was higher than that of‘Huasu', but in the other two parts, it had no significant difference between cultivars. Fruit texture at the calyx end, the middle part and the stem end of the fruit were different. The orders of fracurability, flesh hardness, gumminess and chewiness in different parts of pear fruits were calyx end > middle part > stem end. The distribution of adhensiveness in the whole fruit was relatively uniform and there were no significant differences in the three different parts. Springiness in the calyx end was higher than in the middle part and the stem end of the fruit, and it had no significant difference in the middle part and the stem end of the fruit. The distribution of peel hardness in pear fruit varied between varieties. The order of springiness was calyx end > middle part > stem end in‘Huasu', and was middle part > calyx end > stem end in‘Wonhwang'. Correlation analysis of the all the texture parameters showed that fracurability, flesh hardness,springiness, gumminess, chewiness and peel hardness had significant positive correlations, but the correlation between adhensiveness and the other parameters was poor.【Conclusion】Fruit texture is an important character related to pear fruit quality and also an important character for fruit maturity judgment. This work tested the changes in fruit texture in different parts of pear fruit during fruit maturation. The change patterns of different fruit texture parameters were shown, and fruit texture differences at different parts of pear fruit and different maturation stages were highlighted. The results can provide basis for determination of the optimum harvest period of crisp-flesh pears.