Genetic Variation for Starch Thermal and Functional Properties Among Nonmutant Maize Inbreds\u27

Differential scanning calorimetry (DSC) has been used in previous \u3c 0.01) inbred by year interaction was present for all DSC parameters studies to detect differences in thermal properties among starches of non- with the exception of AH. Differences were observed in starch viscosities mutant maize (Zea mays L.) genotypes. This study was conducted to and gel strengths for six inbreds selected for highest and lowest Tp, AH, determine the magnitude of genetic and genotype by environmental effects and range (R,). Several significant (P \u3c 0.05) correlations occurred on starch properties among a set of exotic and domestic inbred lines. between DSC parameters and starch paste viscosities and gel strengths. Functional properties of starches from selected lines exhibiting extreme These data suggest that evaluation of starches from nonmutant genotypes DSC values also were investigated. Highly significant (P\u3c 0.01) differences by DSC can be used to predict some functional properties. A practical for DSC starch thermal properties were seen among the lines. Starches application of DSC in breeding programs may include screening maize from exotic lines generally had lower gelatinization onset temperature germplasm for extreme DSC values or population improvement through (TO), peak temperature (Tp), and enthalpy (AH). A highly significant (P recurrent selection. The maize wet-milling industry produces a number of starch- based products important in the food industry. Genetic variability in starch structure and functional properties has led to the use of specialty starches from waxy and high-amylose genotypes (Shannon and Garwood 1984). More recently, the introduction of starches containing double mutant combinations with proper- ties similar to chemically modified starches has resulted in several patents (Katz 1991). The application of differential scanning calorimetry (DSC) to the study of starch was first described by Stevens and Elton (1971). This technique offers a thermodynamic approach to the study of starch gelatinization by monitoring changes in the physical and chemical properties of starches (Donovon et al 1983). Use of DSC in investigating the thermal behavior of starches has become increasingly more popular because it requires only a small sample size and is easy to operate (Sanders et al 1990). Addi- tionally, DSC is relatively rapid compared with more traditional methods of studying starch gelatinization, making it suitable for breeding programs. Extensive variations in DSC parameters have been observed among starches of single- and double-mutant genotypes of maize indicating differences in starch structure and function (Brockett et al 1988, Sanders et al 1990, Wang et al 1992). More recent studies have revealed variations in DSC parameters among non- mutant sources of maize starch. Krueger et al (1987), for example, found differences in DSC parameters among two maize inbred lines and suggested that AH and peak height index (PHI) could be used as a means of identifying maize genotypes. White et al (1990) reported variability in thermal properties by DSC in genetically variable maize populations. The largest differences were observed for gelatinization onset (T.), range (Rn), and total enthalpy (AH). In addition, Li et al (1994) found large variations in DSC values among several exotic populations of maize, sug- gesting that selection among these on the basis of DSC values would identify genotypes having desired starch properties