Linda M. Pollak

Thermal Properties of Starch in Corn Variants Isolated after Chemical Mutagenesis of Inbred Line B73

ABSTRACT The starch from eight ethyl methanesulfonate (EMS) treated M4 families of the corn (Zea mays L.) inbred line B73 was analyzed using differential scanning calorimetry (DSC), a Rapid Visco Analyser (RVA), a texture analyzer (TA), and scanning electron microscopy (SEM) coupled with image analysis. The eight families were chosen from 144 families previously selected for having starch with unusual DSC parameters. Apparent amylose contents of the starch from the eight families generally were lower than that of the control. According to DSC, starches from mutagenized families tended to have lower onset temperature (T0) of gelatinization, enthalpy (ΔH) of gelatinization, and peak height index (PHI), but broader gelatinization range (R) than the B73 control. Their values for ΔH and percentage of retrograzdation (%R) were clustered around that of the control. Pasting properties from the RVA of the starches from the M4 families also were clustered around those of the control B73 starch, except for the setba...

The History and Success of the public–private project on germplasm enhancement of maize (GEM)

Publisher Summary This chapter introduces the Latin American Maize Project (LAMP) that was the first coordinated international project for evaluating a major world crop. A coordinated and cooperative effort, the germplasm enhancement of maize (GEM) project was organized among public and private sectors. The project provides the corn industry, early breeding lines by using germplasm enhancement to improve and adapt useful exotic germplasm. Throughout the world, approximately 50,000 accessions of corn exist in germplasm banks and, until recently, many had never been evaluated for useful traits. Evaluation is important in identifying potentially valuable traits in accessions, but most countries cite the lack of useful evaluation information as a major bottleneck to increasing germplasm utilization. US agricultural research includes three sectors: Federal programs, state programs in land-grant and other universities, and private industry. Both the state and federal programs are considered as the public sector. The private sector in 1994 employed 509.8 SYs, while the public sector employed 35.3 SYs. This represents a serious constraint in human resources and expertise preventing the public sector from carrying out a major maize enhancement effort without private involvement. The objective of GEM is to provide, to the maize industry, materials developed using germplasm enhancement of useful exotic germplasm, with the ultimate aim of improving and broadening the germplasm base of maize hybrids grown by American farmers. GEM provides the social returns to justify its public support, and the potential for private returns to justify private participation. One factor in its success seems to be its federal leadership that provides the funding certainty that would be difficult to achieve with university leadership and grant funding. Another factor in GEMs success is its collaboration between the public and private corn breeding sectors. Finally, GEM is careful to make sure that only the best germplasm is used.

Structure and function of starch from advanced generations of new corn lines

Objectives of this research were to evaluate functions and structures of starches from exotic X adapted inbred lines and exotic lines, to confirm that the functional traits continue into the next generation of inbreeding, and to establish relationships between the fine structure and functional properties of the starches. Several lines were characterized from the successive generations of exotic crosses and exotic inbreds containing kernels with unusual, and potentially useful, thermal properties as measured by differential scanning calorimetry (DSC, gelatinization onset temperature 14 degreesC). The frequency of these traits increased with succeeding generations, when selection of the plants was based on the desired trait. Strong correlations were found between DSC and Rapid ViscoAnalyser properties and the granular structure (granular size distribution and branch-chain-length distribution of amylopectin)

Fatty acid composition of oil from adapted, elite corn breeding materials

The fatty acid composition of corn oil can be altered to meet consumer demands for “healthful” fats (i.e., lower saturates and higher monounsaturates). To this end, a survey of 418 corn hybrids and 98 corn inbreds grown in Iowa was done to determine the fatty acid composition of readily-available, adapted, elite corn breeding materials. These materials are those used in commercial hybrid production. Eighty-seven hybrids grown in France (18 of which also were grown in lowa) were analyzed to determine environmental influence on fatty acid content. The parents of the hybrids and the inbreds were classified in one of four heterotic groups: Lancaster, Stiff Stalk, non-Lancaster/non-Stiff Stalk, and Other.t-Tests and correlation analyses were performed with statistical significance accepted at a level ofP≤0.05. The findings showed a wide range of fatty acid profiles present in adapted, elite corn breeding materials with ranges for each fatty acid as follows: palmitic acid, 6.7–16.5%; palmitoleic acid, 0.0–1.2%; stearic acid, 0.7–6.6%; oleic acid, 16.2–43.8%; linoleic acid, 39.5–69.5%; linolenic acid, 0.0–3.1%; and arachidic acid, 0.0–1.0%. Small amounts of myristic acid, margaric acid, and gadoleic acid also were found. Three lines had total saturates of 9.1% or less. Thirty-six of thet-tests involving hybrids showed significant differences among heterotic groups. There were small but significant correlations among protein, starch and oil content and the amounts of several fatty acids. Results from the corn grown in France vs. lowa demonstrated a large environmental effect that overwhelmed the genetic differences among lines. This study shows that for some attributes, a breeding program involving adapted corn breeding materials might produce the desired oil. Other types of oil (such as high-oleic) would have to be produced in a different manner, for example, by a breeding program with exotic breeding materials.

Comparison of laboratory and pilot-plant corn wet-milling procedures

ABSTRACT One waxy and three regular yellow dent corn hybrids were wet milled by using two scales of laboratory procedures (modified 100-g and 1-kg) and a pilot-plant procedure (10-kg). The modified 100-g and 1-kg laboratory procedures gave similar yields of wet-milling fractions. Starch yields and recoveries were significantly lower for the pilot-plant procedure, whereas gluten and fiber yields were greater because of their high contents of unrecovered starch. Protein contents of the starches obtained by all three procedures were within commercially acceptable limits (<0.50% db for normal dent corn and <0.30% for waxy corn). Rankings for starch yields and starch recoveries for the four hybrids, having very different physical and compositional properties, were the same for all three procedures. The harder the grain, the lower the yield and recovery of starch. Least significant differences (P < 0.05) for starch yield were 0.8% for the modified 100-g procedure, 1.2% for the 1-kg procedure, and 2.0% for the p...

Fatty Acid Composition of Oil from Exotic Corn Breeding Materials

The fatty acid composition of corn oil can be altered to meet consumer demand for “healthful” fats. The first step in altering the oils is to survey existing corn breeding materials for fatty acid composition. The Latin American Maize Project (LAMP), an international program designed to evaluate the agronomic characteristics of maize accessions in Latin American and U.S. germplasm banks for future use, provides useful starting materials. LAMP was based on the cooperative efforts of 12 countries. In a two-stage evaluation, the project identified the highest-yielding open-pollinated top 20% of populations, then approximately the top 5% of those 20%. Twenty of the populations from four countries with temperate climates were randomly selected for fatty acid analysis. The populations were from United States, Chile, Argentina, and Uruguay. Fifty S1 lines from each population were randomly chosen for analysis for a total of 1,000 genotypes sampled. Statistical differences in fatty acid composition were computed among the 20 populations and among the four countries. The findings showed a wide range of fatty acid profiles present in unadapted, elite corn breeding materials with ranges for each fatty acid as follows: palmitic acid, 6.3–18.2%; stearic acid, 0.9–4.5%; oleic acid, 18.5–46.1%; linoleic acid, 36.6–66.8%; linolenic acid, 0.0–2.0%; and arachidic acid, 0.0–1.4%. Several populations were significantly different from the others. Some lines had unusual fatty acid compositions, including one with 8.3% total saturates and another with 20.2% total saturates. This study shows that existing corn breeding materials could be used to produce high- and low-saturate oils, but other methods would probably be required to produce a high-oleic corn oil.

Thermal Properties of Corn Starch Extracted with Different Blending Methods: Microblender and Homogenizer

Thermal properties of starch can be evaluated by using differential scanning calorimetry (DSC). DSC generates data of the thermal parameters of starch, such as onset temperature (To), peak temperature (Tp), and enthalpy of gelatinization (∆H). These parameters may help determine the functionality of specific starches and, therefore, their utility in the food industry. Thermal properties of corn starch can also be used as criteria for selection of desirable lines for breeding purposes to obtain starch with specific properties useful in industry (Meuser et al 1989). Disciplines Food Biotechnology | Food Processing | Food Science | Human and Clinical Nutrition Comments This article is from Cereal Chemistry, September 1997, 74(5); 553-555. Doi: 10.1094/ CCHEM.1997.74.5.553. Rights Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/fshn_ag_pubs/143

Compositional, Physical, and Wet-Milling Properties of Accessions Used in Germplasm Enhancement of Maize Project

ABSTRACT Forty-nine accessions used in the Germplasm Enhancement of Maize (GEM) project, two commercial hybrids (Pioneer Brand Hybrids 3394 and 3489), and two Corn Belt inbreds (B73 and Mo17) were evaluated for compositional, physical, and wet-milling properties. GEM accessions had lower starch contents (65.9–69.1% vs. a mean of 72.2% for the commercial hybrids) and greater protein contents (12.0–14.4% vs. a mean of 8.2% for the commercial hybrids) than did the improved Corn Belt material. Absolute densities were consistently higher for the GEM accessions compared with the commercial hybrids (1.320 vs. 1.265 g/cm3, respectively). The wet-milling characteristics of the GEM accessions were not nearly as good as for the commercial hybrids. Mean starch yields were only 54.3% for the GEM accessions versus 64.8% for the commercial hybrids. Residual protein levels in the starches recovered from the GEM accessions were much greater (0.45–2.03%) than for commercial corn hybrids (<0.3%).

Thermal starch properties in corn belt and exotic corn inbred lines and their crosses

ABSTRACT More knowledge is needed about variability of starch functional traits in adapted and exotic germplasm and possible genetic effects of these traits before conducting rigorous inheritance studies and breeding programs for starch quality. We studied and compared the range of variability for starch functional traits in a set of Corn Belt inbred lines with a set of exotic inbred lines from Argentina, Uruguay, and South Africa. Reciprocal hybrids of some of the lines within each set were compared with their parents. Functional traits were examined by using differential scanning calorimetry on starch extracted from single kernels of genotypes. The set of Corn Belt lines had a wider range of values for most traits than did the set of exotic lines. For both sets of lines, the maximum value for peak height index was as high as that previously reported for the waxy endosperm mutant. Although the Corn Belt lines exhibited a wider range of values for range of retrogradation than the exotic lines, the exotic ...

Gelatinization Properties of Starches from Three Successive Generations of Six Exotic Corn Lines Grown in Two Locations

ABSTRACT The objectives of this research were to evaluate the intra- and interpopulation variability in gelatinization properties of starches from exotic corn lines and their derivatives when grown 1) during two successive years in the same location; and 2) in both temperate and tropical environments. Six novel exotic corn lines (two 100% exotic and four 25% exotic derived from a breeding cross developed by crossing an exotic hybrid with Corn Belt lines) were selected for this research because their starches have significantly different (and potentially useful) thermal properties from those found in starch from normal Corn Belt corn. The Sn (n = 3 for 25% exotic lines and n = 1 for 100% exotic lines) generations of the six exotic lines were self-pollinated and grown in the winter nursery in Puerto Rico. Two successive generations (Sn+1 and Sn+2) of lines selected for low onset of gelatinization temperature were self-pollinated and grown in the same environment near Ames, IA. To evaluate the effect of envi...