The Firmness of Tomato Fruit in Relation to Polygalacturonase Activity

Abstract

Firmness measurements made on tomato fruit at various degrees of ripeness by means of a machine recently described have been compared with those produced by an established instrument. Highly significant correlations were obtained between results from the two types of apparatus. Because of its greater ease of operation the newer instrument was used to compare the firmness of six varieties of tomato fruit, all judged to be in a uniform condition known as the “ commercial picking stage ”. The polygalacturonase activity in the same tomato samples was also measured, and a highly significant positive correlation established between the activities of the enzyme and the compression of the different varieties of fruit under a standard load. These results strongly suggest that pectolytic enzyme activity is one of the predominant factors governing the firmness of different varieties of tomato fruit.