A study of kernel composition affecting the quality ofshrunken2 sweet corn

The research in this thesis is made up of three related experiments each concerned with the various chemical components that contribute to eating quality in shrunken2 (sh2) sweet corn (Zea mays L.) kernels. In each experiment, the primary focus was on the levels of dimethyl sulfide (DMS), the compound responsible for the characteristic "corny" aroma, and sugars (i.e. fructose, glucose, sucrose and total sugar), which are the principal kernel flavor constituents in sweet corn. Other kernel chemical components evaluated in this research included S-methylmethionine (MMS), methionine (MET), and moisture.In the first experiment, significant effects from both genotype and harvest maturity affected the concentrations of DMS, moisture, and sugars in kernel samples for the 31 hybrids evaluated. Using a subset of six sh2 hybrids that displayed wide variation in kernel DMS concentration, the levels of MMS and MET in the kernels were measured and found to differ substantially between hybrids and harvest maturities. Based on a mole to mole ratio and averaged over the six sh2 hybrids, the conversion of MMS could account for approximately 77% of the total DMS generated in the kernels, compared with only 45% from the conversion of MET in the same sample.The results from the second experiment demonstrated that there were significant effects due to N-S fertilization, hybrid and harvest maturity on the various kernel chemical components. Although the study was conducted at two very different locations, there were similar trends for the effects of N and S fertilizer application on kernel DMS and sugar production at both Illinois River Valley Sand Field (IRVSF) and Urbana. In three of the six hybrids tested at IRVSF, there was a positive response in kernel DMS concentration to increase rates of either N or both N and S fertilizer treatments. At Urbana, kernel DMS content in two of the three hybrids increased as N fertilization rate increased. Kernel fructose and glucose levels tended to decrease as N rate increased, while kernel sucrose and total sugar concentrations remained relatively constant.In the third experiment, hybrid significantly affected the three most important predictors of sweet corn quality (i.e. sweetness, texture and aroma). To some degree, fertilizer treatment may have an influence on the sweetness of the kernel. In addition, hybrids with high levels of kernel DMS and sucrose had more intense sweet corn aroma and sweetness, respectively, with a corresponding increase in sweet corn flavor. Although overall liking did not display significant differences between hybrids and was not correlated with any of the chemical components of flavor, it exhibited positive association with aroma, flavor, sweetness and texture, and was negatively related to grassy aroma and starchy flavor in the kernels.U of I OnlyETDs are only available to UIUC Users without author permissio