David S. Jackson

Comparison of Amylose Determination Methods and the Development of a Dual Wavelength Iodine Binding Technique

ABSTRACT It has long been recognized that limitations exist in the analytical methodology for amylose determination. This study was conducted to evaluate various amylose determination methods. Purified amylose and amylopectin fractions were obtained from corn, rice, wheat, and potato and then mixed in proportion to make 10, 20, 30, 50, and 80% amylose content starch samples for each source. These samples, considered amylose standards, were analyzed using differential scanning calorimetry (DSC), high-performance size-exclusion chromatography (HPSEC), and iodine binding procedures to generate standard curves for each of the methods. A single DSC standard equation for cereal starches was developed. The standard curve of potato starch was significantly different. Amylose standard curves prepared using the iodine binding method were also similar for the cereal starches, but different for potato starch. An iodine binding procedure using wavelengths at 620 nm and 510 nm increased the precision of the method. Whe...

Chapter 5 Starch Gelatinization

Starch occurs as highly organized structures, known as starch granules. Starch has unique thermal properties and functionality that have permitted its wide use in food products and industrial applications. When heated in water, starch undergoes a transition process, during which the granules break down into a mixture of polymers-in-solution, known as gelatinization. The sequence of structural transformations that the starch granule undergoes during this order-to-disorder transition has been extensively researched. None of the published starch gelatinization theories can fully and adequately explain the exact mechanism of sequential structural changes that starch granules undergo during gelatinization. This chapter analyzes several published theories and summarizes our current understanding of the starch gelatinization process.

Asian Salted Noodle Quality: Impact of Amylose Content Adjustments Using Waxy Wheat Flour

ABSTRACT Fourteen flour blends of two natural wild-type wheat (Triticum aestivum L.) flours, ‘Nuplains’ and ‘Centura’, blended with one waxy flour sample were characterized and processed to Asian salted noodles. The flour amylose content range was <1–29%. Damaged starch contents were 10.4, 7.0, and 6.6% for the waxy wheat, Nuplains, and Centura, respectively. The waxy flour farinograph water absorption was as high as 79.5%, ≈20% higher than the wild-type flours. Because two types of starch granules (wild-type and waxy) existed in the flour blends, two peaks at 82°C (waxy) and 95°C (wild-type) were found in the RVA pasting curves. Reduced amylose content caused high flour swelling volume and power and low falling number. Significant effects of flour amylose content on noodle processing and textural (eating) qualities were found in the study. Noodle qualities, as reflected in covariate analysis, were not significantly affected by the flour blends protein content, SDS-sedimentation volume, mixograph dough d...

Thermal behavior of resistant starches RS 2, RS 3, and RS 4.

The thermal behaviors of 3 resistant starch types-RS 2, RS 3, and RS 4-were investigated. Samples were heated in excess water to specific temperatures, from 35 to 85 degrees C at 5 degrees C intervals, and freeze-dried. The treated samples were analyzed using SEM, DSC, XRD, and HPSEC to determine the structural changes at granular and molecular levels. Light microscopy was used to determine real-time thermal behavior of the starches. Although the resistant starches did not show significant morphological changes, as revealed by microscopy, they underwent internal structural changes at low temperatures before complete phase transitions occurred. The structural changes were less in RS 2 compared to the other 2 starches studied. The nongranular material of RS 3s crystallinity decreased gradually from 35 to 85 degrees C and showed microscopically visible changes at >80 degrees C. Cross-linking might have prevented RS 4 from becoming completely amorphous within the temperature range (35 to 85 degrees C) tested. The study indicated that the extent of structural changes depended on the treatment temperature and RS type.

Effects of Sorghum (Sorghum bicolor (L.) Moench) Tannins on α‑Amylase Activity and in Vitro Digestibility of Starch in Raw and Processed Flours

The purpose of this study was to investigate the effects of tannins on starch digestion in tannin-containing sorghum extracts and wholegrain flours from 12 sorghum varieties. Extracts reduced amylase activity in a tannin concentration-dependent manner when the extract was mixed with the enzyme before substrate (amylopectin) addition, with higher molecular weight tannins showing greater reduction. Conversely, when the extract and substrate were combined before enzyme addition an enhancement in amylase activity was experienced. In uncooked, cooked, and cooked and stored wholegrain sorghum flours, rapidly digestible, slowly digestible, and resistant starches were not correlated with tannin content or molecular weight distribution. Resistant starch increased from 6.5% to 22-26% when tannins were added to starch up to 50% (starch weight). Tannin extracts both reduced and enhanced amylase activity depending on conditions, and, while these trends were clear in extracts, the effects on starch digestion in wholegrain flours was more complex.

Functionality Behavior of Raw and Extruded Corn Starch Mixtures

ABSTRACT Relationships between the structural properties of raw and extruded corn starches and their functionalities were investigated using mixtures of these starch types. Extruded starch had higher water absorption and water solubility indices, and produced lower RVA viscosity profiles when compared with raw starch. It also had no differential scanning calorimetry (DSC) endotherm. Gel cohesiveness and adhesiveness of both starch types were similar, while extruded starch gels were softer. Extruded starch produced lower Rapid Visco Analyser (RVA) viscosity profiles than raw starch due to starch degradation during extrusion. The raw and extruded starch components had negative interaction coefficients, thus RVA viscosity parameters were lowered as the fraction of extruded starch in the mixture increased. Starch degradation in the extruded starch was a likely significant factor associated with low viscosity profiles. Mixtures of raw and extruded starches could be commercially prepared to obtain finished star...

Alkaline processing (nixtamalization) of white Mexican corn hybrids for tortilla production : Significance of corn physicochemical characteristics and process conditions

ABSTRACT Five white corn hybrids were processed (nixtamalized) using 10 different processing conditions; tortillas were prepared to establish relationships between corn composition, physical characteristics, and nixtamalization process or product properties. Corn hybrids were characterized by proximate analysis and by measuring Stenvert hardness, Wisconsin breakage, percent floaters, TADD overs, thousand-kernel weight, and test weight. Corn characteristics were correlated with process and product variables (effluent dry matter loss and pH; nixtamal moisture and color; masa moisture, color, and texture; and tortilla moisture, color, and rollability). Process and product variables such as corn solid loss, nixtamal moisture, masa texture, and tortilla color were influenced not only by processing parameters (cook temperature, cook time, and steep time) but also depended on corn characteristics. Significant regression equations were developed for nixtamalization dry matter loss (P < 0.05, r2 = 0.79), nixtamal ...

The Impact of Thermal Events on Amylose‐Fatty Acid Complexes

The molecular behavior of amylose-lipid complexes was studied using differential scanning calorimetry. rapid viscoanalysis and texture analysis methods. Three amyloses were fractionated, one each from regular, 50% amylose and 70% amylose corn starches. High performance size exclusion chromatography, coupled with multiple angle laser light scattering, was used to determine amylose molecular weight profiles; fractions differed statistically (P<0.05) in their z-average molecular weights (M z ). Each amylose fraction was complexed with five different fatty acids. After 12 days of storage, amylose-lipid complexes had recrystallization percentages ranging from 42.7 to 98.2%. Cohesiveness (r = -0.84) and adhesiveness (r = -0.75) decreased with increasing M z of amyloses (P<0.05). An inverse relationship was obtained between fatty acid chain length and percent recrystallization (r = -0.84, P<0.05). Percent recrystallization decreased when fatty acid chain length increased from C16:0 to C18:0. All complex samples, when adjusted to an equal total starch basis, had decreased viscosities when pasted compared to their native starch or amylose counterparts. Shear thinning of complexes increased with increasing molecular weight (M z ) of amyloses (r = 0.71, P<0.05). Lower recrystallization rates and decreased viscosity properties could be accomplished complexing by amylose and fatty acids.

Crop Rotation and Soil Amendment Alters Sorghum Grain Quality

Soybean [Glycine max (L.) Merr.] rotation enhances grain sorghum [Sorghum bicolor (L.) Moench] yield, but infl uence on grain quality has not been measured. The objective was to determine the effect of cropping sequence (CS) and soil amendment (SA) on grain yield and quality. Sorghum grain yield and quality, soil NO3–N and water were measured in a rotation study in 2003 and 2004 on a Sharpsburg silty clay loam (fi ne, smectitic, mesic Typic Argiudoll). Cropping sequences were continuous sorghum, and sorghum rotated with non-nodulating and nodulating soybean. Soil amendments consisted of no amendment, manure (17–26 Mg dry matter ha−1 yr−1), and N (84 kg ha−1 yr−1). CS × SA interaction effects were found for most parameters. Rotation with non-nodulating soybean without SA increased yield by 2.6 to 2.8 Mg ha−1 over continuous sorghum without SA. Rotation without SA with nodulating soybean further increased yield by 1.7 to 1.8 Mg ha−1 over rotation with non-nodulating soybean. Grain N increased by 0.5 to 1.0, 2.5 to 5.0, and 3.3 to 4.9 g kg−1 for N application to continuous sorghum and sorghum rotated with non-nodulating and nodulating soybean, respectively. Tangential abrasive dehulling device (TADD) removal indicated that continuous sorghum without SA produced the softest grain with 43 to 44% TADD removal, and sorghum rotated with nodulating soybean with manure produced the hardest grain with 22 to 27% TADD removal. As food end-use opportunities for sorghum grain evolve, use of crop rotation and SA application will be important to produce grain with desirable quality attributes. Crop Rotation and Soil Amendment Alters Sorghum Grain Quality Nanga Mady Kaye, Stephen C. Mason,* David S. Jackson, and Tom D. Galusha Dep. of Agronomy and Horticulture, and Food Science and Technology, Univ. of Nebraska, Lincoln, NE 68583-0915. Paper No. 14668 of the Journal Series of the Nebraska Agric. Res. Div. Research supported by USAID Grant No. DAN 1254-G-0021 through INTSORMIL, the International Sorghum and Millet Collaborative Research Program. Received 25 May 2006. *Corresponding author (smason1@unl.edu). Abbreviations: CS, cropping sequence; SA, soil amendment; TADD, tangential abrasive dehulling device. Grain sorghum is an important grain crop in the Central Great Plains due to its drought tolerance (Sander and Frank, 1980), high nutrient use effi ciency (Maranville et al., 1980), and use for livestock feed. During the past 50 yr, sorghum grain yields have increased by 139% largely due to improved hybrids and soil water management (Unger and Baumhardt, 1999). Due to interest in using sorghum grain for human food (Shayo et al., 2001; Johnson, 2005) and industrial products (Buff o et al., 1998, Johnson, 2005) research eff orts are presently underway to develop sorghum hybrids with improved kernel characteristics (Maunder, 2005). Rotating soybean with sorghum has been shown to increase grain yield (Gakale and Clegg, 1987; Roder et al., 1989a, Peterson and Varvel, 1989), alter soil stored water (Roder et al., 1989a), increase soil N (Bagayoko et al., 1992), improve soil physical properties (Gakale and Clegg, 1987), and reduce yield variability (Varvel, 2000). None of these studies addressed crop rotation or N supply infl uences on grain quality. One tool to help separate biologically fi xed N from other rotation eff ects is the inclusion of nodulating and non-nodulating soybean isolines into a crop rotation as previously done by Maloney et al. (1999), Gentry et al. (2001), and Bergerou et al. (2004). Manure as a soil amendment in sorghum studies has improved soil physical properties (Eghball, 2000), increased water and Published in Crop Sci 47:722–729 (2007). doi: 10.2135/cropsci2006.05.0346

Dry Matter Loss During Nixtamalization of a White Corn Hybrid: Impact of Processing Parameters

ABSTRACT Nixtamalization is the primary step in the production of products such as corn chips, tortilla chips, tacos, and corn tortillas. The process involves cooking and steeping of corn in lime and excess water to produce nixtamal. Commercial nixtamalization results in 5–14% corn solids loss in the liquid generated during cooking-steeping and washing. Loss of corn solids not only causes economic loss to corn processors but also creates costly waste and wastewater disposal problems. Empirical results show that, besides corn kernel characteristics, processing parameters are critical variables influencing corn solids loss and effluent pH during nixtamalization. This work was designed to systematically study the impact of processing parameters on corn dry matter loss and effluent pH generated during nixtamalization by using response surface methodology. Corn cooking temperature and lime concentration were more critical factors influencing corn solid loss than were cooking and steeping time. In the ranges st...