RELATIONSHIP BETWEEN THE TEXTURE AND PECTIN CONSTITUENTS OF JAPANESE PEAR

Abstract

The relationship between texture and pectin constituents and some related compounds of the Japanese pear (Pyrus serotina Render var. culta ‘Housui') during fruit enlargement and ripening was studied. The modulus of elasticity, deformation ratio, and relaxation value from the flat plate compression test, and all the properties from the puncture test were affected by the pectin constituents, alcohol insoluble solids, and soluble solids. The hardness and deformation of the fruit obtained from the plate compression test might depend on the combination of the alcohol insoluble solids in fresh weight and weight of the fruit. The oxalate soluble pectin both in alcohol insoluble solids and in fresh weight affected the fruit texture more than the water soluble pectin. The solubitization of nonsoluble pectin to water soluble pectin appeared to influence the textural properties more than that of the nonsoluble pectin to oxalate soluble pectin. The puncture test was superior in analyzing the textural properties of the Japanese pear fruits with regard to changes in the pectin constituents.