Theses and Dissertations Collection

In this program, we studied a critical issue in wheat from starch aspects and improved a reducing sugar assay that could be potentially utilized in the potato industry for quality control. Both wheat and potato are important to the US agricultural economy, especially in the Pacific Northwest Region. In recent years, wheat growers have faced huge economic loss due to low falling number (FN) wheat. Wheat with low FN is considered having a high α-amylase activity, which is associated with poor end-use quality. The research of low FN wheat has mainly focused on α-amylase; however, its substrate, starch, did not receive much attention. We hypothesized that starch in the low FN wheat might have structural changes that could decrease flour paste property and influence FN measurement. Starch from three soft white wheat lines with normal and low FNs were examined. Starch in the low FN wheat was found having altered granule size distribution and structure. The changes led to a reduction in paste viscosity and influence the interaction between α-amylase and starch that could further decrease FN.

Quantifying reducing sugar is a common practice in carbohydrate research as well as in the food industry. Multiple colorimetric methods are available to measure the reducing sugar content. One of the assays developed by Somogyi and Nelson can accurately measure reducing sugars in a board range of concentrations. The drawback of this method is that it is time-consuming when analyzing a large number of samples. Therefore, we aimed to improve this method so it can be used to quantify reducing sugars with ease and high efficiency. The traditional Somogyi-Nelson assay, which is conducted in test tubes, was adopted into a 96-well microplate. This modification greatly improved the analytic capacity and efficacy and maintained the advantages of the traditional assay at the same time.