Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Food and Nutrition

First Advisor

Mark H. Love


Biochemical changes occurring in developing green peas were studied in order to understand the textural and flavor changes. The activity of pectinmethylesterase (PME), a pectin modifying enzyme, was measured by the continuous spectrophotometric assay. Specific activity of PME decreased over all varieties and all sieve sizes as the seeds matured. Chelate soluble pectin contents were decreased or remained constant in all varieties. Decreased PME activity and pectin content indicated that the crosslinking of pectin and calcium might not play an important role in the firmness of green peas. The moisture level decreased as maturity increased, which was inversely related to an increase in protein and nonpectin carbohydrate polymers;Sensory analyses showed that all cultivars except one of the round seeded samples exhibited increased firmness as they matured. The pastiness attribute significantly increased in all cultivars. The seed coat toughness and green pea flavor changed in a less consistent fashion. The sweetest scores for all cultivars decreased throughout the study;For all cultivars, the most abundant volatile compounds were hexanal, n-nonane, methyl heptanoate, n-undecane, and propyl benzoate. Each cultivar exhibited a different pattern of changes in major volatile compounds. There was no single volatile which could be used to indicate harvestable maturity.



Digital Repository @ Iowa State University,

Copyright Owner

Yu-Hee Kim



Proquest ID


File Format


File Size

113 pages