Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2002
Publication Date: 2/6/2003
Citation: JI, Y., SEETHARAMAN, K., DUVICK, S.A., POLLAK, L.M., JAY-LIN, J., WHITE, P.J. THERMAL AND STRUCTURAL PROPERTIES OF SEVERAL UNUSUAL STARCHES FROM DEVELOPMENTAL LINES. CARBOHYDRATE POLYMERS. 2003. v. 51. p. 439-450. Interpretive Summary: The cooking characteristics of native, unmodified corn starches are undesirable for many applications, thus starch is generally modified to overcome these problems by chemical means. We are exploiting natural genetic variation for starch characteristics in exotic x adapted germplasm lines utilizing plant breeding techniques of crossing and selection unusual properties. This approach is especially valuable to the food industry because of the opportunities for use in "all natural" foods. We found several corn germplasm lines that exhibited unusual and potentially useful characteristics, such as being able to cook and form a gel at lower temperatures. We developed these lines into usable inbred lines. These lines can be used by the seed industry to develop hybrids that have specialty starch characteristics, that can be used by starch processors for new and improved products, that will benefit the consumer.
Technical Abstract: Starches from exotic corn lines were screened for unusual thermal properties with Differential Scanning Calorimetry (DSC). Based on these screenings several lines with unusual thermal properties of potential use were identified and further characterized. Two independent gelatinization transitions, one corresponding to the melting of a peak at a lower temperature ~ 66 deg C and the other to a peak melting at a higher temperature ~ 69 deg C, located in different granules were found in some starches. All starches exhibited a typical A-type X-ray diffraction pattern. Starch granule size distribution profile of the selected starches were significantly different than that of normal starch (MO17). No significant differences were observed in the starch component profiles, as measured by gel permeation chromatography; however, starches with a lower peak onset gelatinization temperature (ToG) had lower relative intensities of chains at degree of polymerization (dp) 15-24 to Peak I and/or higher relative intensities of chains at dp 6-12 to peak I, and a lower proportion of chains with dp greater than 16 and a higher proportion of branch chains below dp 13 when compared to normal starch, as measured by high-performance anion-exchange chromatography (HPAEC). These studies will aid in understanding structure-thermal property relationships of starches, and in identifying corn lines of interest for commercial breeding.