ABSTRACT
Four enzyme-containing fractions were separated by ammonium sulfate fractionation of 2-day, postbreaker tomato (Lycopersicon esculentum L. cv. Manhattan). The pH optima and substrate specificities are reported. The enzymes were identified as a nonspecific beta-glucosidase, an exo-beta-1,4-glucanase, and two endocellulases. Both endocellulase fractions were able to catalyze the hydrolysis of various insoluble cellulose materials.Together, the enzymes studies are capable of completely degrading insoluble cellulose to short chain cellodextrins and glucose. Ripening tomato fruit apears to contain a complex of cellulases similar to that of cellulolytic bacteria and fungi.
Subject(s)
Glucose/analysis , Glucosidases/antagonists & inhibitors , Glucose Oxidase , Lactones , Methods , Peroxidases , SpectrophotometryABSTRACT
A low-cost, automatic firmness measuring instrument was developed using commercially available components such as: dial gage, dashpot lowering mechanism, weight sets and probe tips. The details of the assembly and the names of parts manufacturers are given. The instrument is an automated modification of the original P-L Meter developed by Parker and Levin at Michigan State University. The application of the instrument to firmness measurements on cherries and tomatoes is summarized and illustrated with typical results. Tomato studies covered the relationship between firmness and variables such as: fruit size, cultivar type, changes in protopectin content, polygalactu-ronase and cellulase activity. The readings compared favorably with those obtained with the Instron Universal Testing machine.
