bluuebunny/crossref_metadata_2025 huggingface dataset:
Ice in Prefermented Frozen Bread Dough—An Investigation Based on Calorimetry and Microscopy
Authors: Baier‐Schenk A. , Handschin S. , Conde‐Petit B.
Published: June 2007

The amount, morphology, and distribution of ice in prefermented frozen bread dough were investigated by differential scanning calorimetry (DSC) and cryoscanning electron microscopy (cryo‐SEM). Bread dough was frozen after proofing, stored frozen at ‐22 ± 3°C and analyzed without previous thawing. At constant storage conditions, the ice fraction amounted to 53% of the total water and remained constant even over a period of 56 days. Unlike other frozen food foams, ice crystals were observed in the gas pores of the dough. Ice crystals were already present at 1 hr after freezing. Crystal growth and rounding off by recrystallization was observed after 1 day of frozen storage. After 149 days, crystal size reached several 100 μm. It is concluded that growth of ice crystals leads to a redistribution of water in the dough mix in the form of ice, which in turn affects the properties of polymeric compounds in dough and reduces the baking performance of prefermented frozen doughs.
Preparation and Properties of Starch Phosphates Using Waxy, Common, and High‐Amylose Corn Starches. I. Oven‐Heating Method
Authors: Landerito Nel Anterson , Wang Ya‐Jane
Published: June 2007

The structure and physicochemical properties of waxy, common, and high‐amylose corn starch phosphates prepared by oven heating were studied. Starch phosphates prepared by either slurry or dry‐mixing treatment before oven heating were also compared. The slurry treatment more efficiently incorporated phosphorus into starch relative to the dry‐mixing treatment under the reaction conditions studied. In general, the phosphorylated starch prepared by the slurry treatment exhibited a lower gelatinization temperature, a higher peak viscosity, a lesser degree of retrogradation, and improved freeze‐thaw stability compared with those prepared by the dry‐mixing treatment. Phosphorylation occurred probably in both amylose and amylopectin, and the amount and location of incorporated phosphate groups varied with starch types likely due to their different amylose and amylopectin contents. Waxy starch was more prone to phosphorylation, followed by common and high‐amylose starches, respectively.
Effect of Source and Proportion of Waxy Starches on Pasta Cooking Quality
Authors: Gianibelli M. C. , Sissons M. J. , Batey I. L.
Published: June 2007

Starches from the endosperm of three types of total‐waxy cereals (bread wheat, maize, and barley) were used in reconstitution studies of durum wheat semolinas to investigate the effect of waxy starch on pasta cooking quality. The chemical composition and the pasting and gelatinization properties of the starches used in this study were evaluated to define the functional properties of each waxy starch. The rheological properties of dough semolinas were evaluated by small‐scale mixograph. Spaghetti was prepared using a small‐scale pasta extruder and its cooking quality was assessed using a texture analyzer. Cooked pasta firmness, resilience, and stickiness were measured. The substitution of semolina starch with waxy starches from different sources changed the functional properties of dough and their pasta quality. A decrease in firmness was detected in all the semolinas reconstituted with waxy starches. An increase in stickiness was found when semolinas with waxy starch from wheat were evaluated. No improvement in pasta quality should be expected if the waxy character is introduced in durum wheat.
Sensory, Mechanical, and Microscopic Evaluation of Staling in Low‐Protein and Gluten‐Free Breads
Authors: Ahlborn Gene J. , Pike Oscar A. , Hendrix Suzanne B. , Hess William M. , Huber Clayton S.
Published: June 2007

Staling over a 120‐hr period was compared in a gluten‐free rice bread, a low‐protein starch bread, and two gluten‐containing breads (standard wheat and added‐protein wheat) using quantitative descriptive analysis (QDA), critical stress values obtained by mechanical compression testing, and scanning electron microscopy (SEM). The gluten‐free rice bread had the highest QDA scores for both moistness and overall freshness, whereas the low‐protein starch bread had the lowest scores for both attributes. Differences in critical stress values over the 120‐hr period demonstrated that the gluten‐free rice bread had the greatest resistance to mechanical collapse, indicating the least structural damage, whereas the low‐protein starch bread had the least resistance to mechanical collapse. Both wheat breads had QDA moistness and freshness scores, and critical stress values that ranged between the gluten‐free rice and low‐protein starch breads. SEM showed the formulation containing rice, egg and milk proteins, xanthan gum, and hydroxypropylmethylcellulose created a bicontinuous matrix with starch fragments, similar to gluten.
Fine Grinding and Air Classification of Field Pea
Authors: Wu Y. Victor , Nichols Nancy N.
Published: June 2007

Field pea has ≈23% protein, 48% starch, 8% sugars, 4% lipids, 7% crude fiber, and 3% ash. Pin milling at 1 × 14,000, 3 × 14,000, 9 × 14,000, and 12 × 14,000 rpm followed by air classification according to particle size resulted in fine fractions (<18 μm) with high protein content and coarser fractions (>18 μm) with high starch content. The yield of the high protein fraction increased with the intensity of grinding before air classification. The starch content of the high starch fraction increased with the intensity of grinding and subsequent air classification. Both whole pea and dehulled pea responded well to fine grinding and air classification, and the dehulled pea gave higher protein content and higher starch content than the corresponding fraction from whole pea. The protein fraction had high lysine content and met all the amino acid requirements of the World Health Organization for children older than two years and adults.
Effects of Drain and Harvest Dates on Rice Sensory and Physicochemical Properties
Authors: Champagne Elaine T. , Bett‐Garber Karen L. , Thompson James , Mutters Randall , Grimm Casey C. , McClung Anna M.
Published: June 2007

Timing of field draining and harvesting of rice with meteorological conditions can allow growers to foster conditions for high head rice yield (HRY). The effects of timing of draining and harvesting on rice sensory and physicochemical properties are not well understood. The objective of this study was to determine the effects of varying drain and harvest dates on the sensory and physicochemical properties of M‐202 grown in California under controlled field conditions. Drain date had a significant (P < 0.05), but very small, effect on amylose and protein contents, with amylose being highest at the late drain date and protein being the lowest at the early drain date. Breakdown and setback were lowest for early and normal drain dates, respectively; however, no significant (P > 0.05) differences in texture were measured as a result of these parameters being low. Drain date did not affect the volatile composition or flavor of the rice. Harvest date had no effect (P > 0.05) on amylose content and a significant (P < 0.05), but very small, effect on protein content. Harvesting at the earliest date (9/30) resulted in rice with higher setback and lower breakdown than at the last date (10/16) and, subsequently, the early harvested rice, when cooked, was harder, more cohesive, and absorbed less saliva in the mouth. However, the differences in texture measured by the panelists were very small and would possibly not be noticed by untrained palates. The lowest levels of the lipid oxidation products 1‐pentanol, hexanal, and nonanal occurred in rice with the lowest harvest moisture content (HMC): rice harvested on 10/13 and 10/16. Differences in levels of lipid oxidation products and branched chain hydrocarbons did not lead to significant (P > 0.05) differences in flavor. In summary, M‐202 demonstrated stable composition, physicochemical properties, flavor, and texture across drain and harvest dates.
Chemical Composition and Starch Hydrolysis of Acacia colei and Acacia tumida Seeds
Authors: Falade Muyiwa S. , Owoyomi O. , Harwood C. E. , Adewusi Steve R. A.
Published: June 2007

Acacia seed is a promising famine food due to its ability to thrive in dry zones of the world. In this study, some chemical compounds of nutritional importance as well as starch hydrolysis in three cultivars of Acacia tumida and A. colei were determined. The crude protein was 20.6–23.0%, while extractable protein was 11.5–17.5%. Total dietary fiber (TDF) (28.5–32.7%) and soluble dietary fiber (SDF) (2.2–5.8%) were higher than values reported for most legumes. Reducing sugar range was 31.0–54.5 mg/g, while total sugar range was 137–161 mg/g. The starch content of the seed was 25.6–32.3%. The samples did not contain any alkaloid but did contain saponins. Phytate and trypsin inhibitor contents were low; oxalate was fairly high (2.2–2.6 g/100 g), but tannin was on the high side 66.0–86.7 mg/g) compared with legumes. In vitro starch digestibility was highest in A. tumida (III). Using a first‐order kinetic equation, A. colei showed the highest initial rate of starch hydrolysis (t1/2 = 411.56 and 1,893.4 min), followed by A. tumida (III) (539.25 and 1,738.1 min); the lowest vales were for A. tumida (II) (1,764.99 and 4,249.8 min) for both methods of starch digestion.
Relationship Between NIR Spectra and RVA Parameters During Wheat Germination
Authors: Juhász Réka , Gergely Szilveszter , Gelencsér Tímea , Salgó András
Published: June 2007

The process of germination in six different wheat cultivars was monitored using NIR spectroscopy and the Rapid Visco Analyser (RVA) method. Near‐infrared spectra provided insight into both chemical and physical changes that occur in the seed, in particular mobilization processes involving carbohydrates. RVA curves also contain physical and chemical information and can be interpreted as physicochemical spectra. The process of germination was followed sensitively through the RVA curves and some rheological parameters (peak viscosity, trough, breakdown, final viscosity, and setback) were highly correlated (R = 0.95–0.98) with predicted values calculated from NIR spectra. Viscosity data calculated from RVA curves collected at 200–480 sec showed the most characteristic changes during the early heat treatment stage of the pasting procedure. Strong intercorrelations were found between viscosity data and NIR spectra from the beginning of the swelling and gelatinization processes in germinating seed. The NIR and RVA methods were sensitive tools for the rapid investigation of the germination process, which is important both from a physiological and technological point of view.
Study on Different Emulsifiers to Retain Fatty Fraction During Extrusion of Fatty Flours
Authors: De Pilli Teresa , Giuliani Roma , Carbone Barbara F. , Derossi Antonio , Severini Carla
Published: June 2007

Doughs made from wheat and almond flours, water, and five types of emulsifiers commonly used in confectionary and bakery products (soy lecithin, sucrose esters, mono‐glycerides, mono‐ and di‐glycerides of fatty acids, and diacetyl tartaric acid esters of monoglycerides [DATEM]) were studied. To evaluate the additive ability to retain the fatty fraction during the extrusion process, electrical conductivity was measured and fat loss (%) that occurs during extrusion processing was determined. The electrical conductivity measurements showed that the lower and better concentration of soy lecithin and mixed mono‐ and di‐glycerides of fatty acids to obtain an oil‐water emulsion was 0.2 g/100 g of dough, while for sucrose esters and mono‐glycerides of fatty acids, it was 0.7 g/100 g of dough. No efficacy for DATEM was observed. The fat loss results showed that sucrose esters were the most suitable emulsifiers for retaining the fatty fraction during extrusion processing, even at a very low amounts (2 g/kg of dough).
Phosphorus and Mineral Concentrations in Whole Grain and Milled Low Phytic Acid (lpa) 1‐1 Rice
Authors: Bryant R. J. , Dorsch J. A. , Peterson K. L. , Rutger J. N. , Raboy V.
Published: June 2007

Phytic acid (myo‐inositol‐1,2,3,4,5,6‐hexakisphosphate) is the most abundant form of phosphorus (P) in cereal grains and is important to grain nutritional quality. In mature rice (Oryza sativa L.) grains, the bulk of phytic acid P is found in the germ and aleurone layer, deposited primarily as a mixed K/Mg salt. Phosphorus components and minerals were measured in whole grain produced by either the rice (Oryza sativa L.) cv. Kaybonnet (the nonmutant control) or the low phytic acid 1‐1 (lpa1‐1) mutant, and in these grains when milled to different degrees (10, 12, 17, 20, 22, and 25%, w/w). Phytic acid P is reduced by 42–45% in lpa1‐1 whole grain as compared with Kaybonnet, but these whole grains had similar levels of total P, Ca, Fe, K, Mg, Mn, and Zn. In both genotypes, the concentration of phytic acid P, total P, Ca, Fe, K, Mg, and Mn in the milled products was reduced by 60–90%, as compared with whole grain. However, a trend was observed for higher (25–40%) total P, K, and Mg concentrations in lpa1‐1 milled products as compared with Kaybonnet milled products. The reduction in whole grain phytic acid P in rice lpa1‐1 is accompanied by a 5‐ to 10‐fold increase in grain inorganic P, and this increase was observed in both whole grain and milled products. Phytic acid P was also reduced by 45% in bran obtained from lpa1‐1 grain, and this was accompanied by a 10‐fold increase in inorganic P. Milling had no apparent effect on Zn concentration. Therefore, while the block in the accumulation of phytic acid in lpa1‐1 seed has little effect on whole grain total P and mineral concentration, it greatly alters the chemistry of these seed constituents, and to a lesser but detectable extent, alters their distribution between germ, central endosperm, and aleurone. These studies suggest that development of a low phytate rice might improve the nutritional quality of whole grain, milled rice and the bran produced during milling.
Separation of Fiber from Distillers Dried Grains with Solubles (DDGS) Using Sieving and Elutriation
Authors: Srinivasan Radhakrishnan , Moreau Robert A. , Rausch Kent D. , Belyea Ronald L. , Tumbleson M. E. , Singh Vijay
Published: June 2007

A process was developed to separate fiber from distillers dried grains with solubles (DDGS) in a dry‐grind corn process. Separation of fiber from DDGS would provide two valuable coproducts: 1) DDGS with reduced fiber, increased fat, and increased protein contents; and 2) fiber. The process, called elusieve process, used two separation methods, sieving and elutriation, to separate the fiber. Material carried by air to the top of the elutriation column was called the lighter fraction and material that settled to the bottom of the column was called the heavier fraction. We evaluated the compositions of fractions produced from sieving and elutriation. Two commercial samples of DDGS were obtained from two dry‐grind corn plants. Sieving over four screens (869, 582, 447, and 234 μm openings) created five size categories. The two smallest size categories contained >40% (w/w) of the original DDGS and had reduced fiber and increased protein and fat contents relative to the original DDGS. Elutriation of the remaining three size categories increased protein and fat contents and reduced fiber contents in the heavier fractions. Elutriation at air velocities of 1.59–5.24 m/sec increased the protein content of the heavier fraction by 13–41% and increased the fat content of the heavier fraction by 4–127% compared with the bulk fractions of each size category. This process was effective in separating fiber from both DDGS samples evaluated. Elusieve process does not require changes in the existing dry‐grind process and can be implemented at the end of the dry‐grind process.
Sorghum (Sorghum bicolor L. Moench) Flour Pasting Properties Influenced by Free Fatty Acids and Protein
Authors: Zhang Genyi , Hamaker Bruce R.
Published: June 2007

A second unusually high viscosity peak appeared at the cooling stage (50°C) of a Rapid Visco‐Analyser (RVA) profile of short‐term stored (two months at room temperature) whole grain sorghum flour, while freshly ground flour had a typical pasting curve with one viscosity peak at the 95°C holding period. The formation of the second viscosity peak was caused by liberation of free fatty acids (FFA), mainly palmitic (15.6%), oleic (41.9%), and linoleic (37.9%) acids from stored flour. After the flour samples were pretreated with pepsin or the protease thermolysin, the second peak disappeared in the presence of FFA while the high viscosity was partially retained, indicating that flour protein was another essential component to the production of the actual peak. Effects of dithiothreitol (DTT), pH, and NaCl on RVA profiles of stored flour suggested that disulfide‐linked protein and electrostatic interaction are required for the peak production. In the presence of sufficient FFA, similar cooling stage viscosity peaks appeared in the RVA profiles of flour samples from maize, rice, millet, and wheat; thus, the effect was not unique to sorghum flour. Coinciding with previously reported findings from our laboratory of a three‐component interaction and discernable complex in a model system, a similar three‐component (starch, protein, and FFA) interaction was revealed in natural flour systems resulting in formation of an unusual and notably high cooling stage viscosity peak. Practical applications and an interaction mechanism are discussed.
Identification of QTL Controlling Thermal Properties of Maize Starch
Authors: Scott M. P. , Duvick S. A.
Published: June 2007

Starch has many uses and some of these uses would be facilitated by altering its thermal properties. Genetic manipulation of starch thermal properties will be facilitated by a better understanding of the genetic control of starch gelatinization. We used differential scanning calorimetry to characterize the gelatinization parameters of maize (Zea mays L.) kernel starch prepared from two populations of recombinant inbred lines, an intermated B73xMo17 population (IBM) and an F6:7 Mo17xH99 population. The traits examined were the onset and peak temperatures of gelatinization and the enthalpy of gelatinization. These traits were measured for both native starch and for gelatinized starch allowed to recrystallize, a process called retrogradation. Substantial variation in these traits was found in spite of the narrow genetic base of the populations. We identified several quantitative trait loci (QTL) controlling traits of interest in each population. In the IBM population, a significant QTL for the peak temperature of gelatinization of retrograded starch co‐localized to a molecular marker in the Wx1 gene, which encodes a granule bound starch synthase. The major QTL identified in this study explain, on average, ≈15% of the variation for a given trait, underscoring the complexity of the genetic control of starch functional properties.
New Insights Into the Role of Gluten on Durum Pasta Quality Using Reconstitution Method
Authors: Sissons M. J. , Egan N. E. , Gianibelli M. C.
Published: June 2007

The effects of varying the gluten composition at constant protein, protein content at constant composition, and glutenin‐to‐gliadin (glu/gli) ratio on durum semolina rheological properties and the quality of the spaghetti derived from these doughs was investigated using the reconstitution method. Reconstituted flours were built up from a common durum starch and water‐soluble fraction but with varying gluten types from a range of wheats at both 12 and 9% total protein. A 10‐g mixograph and microextensigraph properties were affected by the source of the gluten, which was related to glutenin composition and polymeric molecular weight distribution. Cooked pasta firmness was highly correlated to mixograph development time (MDDT). Furthermore, varying the protein content (9–20%) showed an increase in mixograph peak resistance (PR) with no effect on extensigraph Rmax. Pasta firmness increased and stickiness decreased with increasing protein content. In another experiment, the glutenin and gliadin fractions isolated from durum wheat were added to the respective base semolina to investigate the effect of varying the glu/gli ratio by 1.3–1.6 fold. Increasing the ratio increased MDDT but had no effect on PR and resistance breakdown. Variable effects were obtained for spaghetti firmness. The information obtained should prove useful to durum breeders by providing further evidence for the importance of protein to pasta quality.
Effects of a Novel Barley, Himalaya 292, on Rheological and Breadmaking Properties of Wheat and Barley Doughs
Authors: Mann G. , Leyne E. , Li Z. , Morell M. K.
Published: June 2007

A barley mutant with high‐amylose starch, Himalaya 292, combines the potential cholesterol reducing effects of barley with the gastrointestinal benefits of high‐amylose resistant starches. Himalaya 292 has alterations in the content and composition of a range of grain constituents, thus conditions for successful addition to foods need to be defined. In this study, the rheological and breadmaking properties of doughs prepared by combining wheat flours (with various gluten protein compositions) with various barley genotypes (Himalaya 292 and the control cultivars Himalaya and Torrens) have been determined. The effects of barley addition on the rheological properties of the admixtures differed. While addition of Himalaya 292 increased the strength and reduced the extensibility of admixture doughs, addition of the Himalaya and Torrens barley flours to the wheat flours reduced both strength and extensibility. The addition of Himalaya and Torrens barley flour reduced water absorption levels. However, addition of Himalaya 292 whole grain flour increased the water absorption of the admixtures significantly (P < 0.01). The baking data showed that selection of an appropriate wheat flour with a combination of strength and extensibility allows higher levels of incorporation of barley, facilitating an increased delivery per serving of constituents with positive health attributes in β‐glucan and resistant starch.
Starch Retrogradation and Firming of Bread Containing Hydroxypropylated, Acetylated, and Phosphorylated Cross‐Linked Tapioca Starches for Wheat Flour
Authors: Miyazaki M. , Maeda T. , Morita N.
Published: June 2007

The present investigation aims at understanding the role of chemically modified starch on the firmness of fresh or stale bread. Bread was prepared from wheat flour or substituted wheat flour that contained 18% chemically modified tapioca starch and 2% vital gluten. Hydroxypropylated tapioca starch (HTS), acetylated tapioca starch (ATS), phosphorylated cross‐linked tapioca starch (PTS), and native tapioca starch (NTS) were tested. Bread prepared from the substituted flour with PTS showed a firmer texture on the day of baking compared with bread prepared from NTS, HTS, and ATS. PTS retained its granular structure in the gluten network after baking and seemed to play the role of filler particles in the gluten matrix, thereby increasing firmness of fresh bread crumb. Bread prepared from the substituted flour with HTS or ATS firmed at a lower rate and showed a lower endothermic melting enthalpy of amylopectin after three days of storage compared with NTS or PTS. These findings suggest that the staling of bread containing chemically modified tapioca starch involves recrystallization of amylopectin.
Food Amylose Content Affects Postprandial Glucose and Insulin Responses
Authors: Behall Kay M. , Scholfield Daniel J.
Published: June 2007

Beneficial reduction in glycemic response has been observed after consumption of some high‐amylose foods. This study examined the effect of varying the moisture content and the particle size of the starch in a test food. Twelve men and 12 women consumed corn chips or corn muffins made with starch or starch plus cornmeal from standard corn (30% amylose, 70% amylopectin) or high amylose (70%) corn. Half of the subjects were hyperinsulinemic based on a prestudy glucose challenge. No gender differences were observed. The hyperinsulinemic subjects had significantly higher insulin and glucose responses and area under the curve as compared with the normal responders. Average glucose, insulin and glucagon were usually lower after muffins compared with chips or foods containing cornmeal. Insulin and glucose responses, but not glucagon, were significantly lower after the consumption of foods made with high‐amylose compared with standard corn starch and in control versus hyperinsulinemic subjects. Average plasma glucose and insulin area under the curves after high‐amylose foods were approximately half those after standard corn starch. The presence of cornmeal (increasing the particle size of the starch) had less effect on the response of glucose, insulin or glucagon than the type of starch or food consumed.
Genotypic and Environmental Effects on Color and Discoloration Potential of Barley in Food Products
Authors: Quinde‐Axtell Z. , Ullrich S. E. , Baik B.‐K.
Published: June 2007

Twelve genotypes of barley, including hulled and hulless proanthocyanidin‐containing and hulled proanthocyanidin‐free types, were grown in five environments (location‐year combination) to determine the relative contribution of genotype and environment on quality traits associated with discoloration potential of barley. Barley grains were abraded and milled into flour. Protein, ash, total polyphenol content, and polyphenol oxidase (PPO) activity were determined. Brightness (L*) of abraded kernels, cooked kernels, gels, and dough sheets were determined and used as indicators of discoloration potential. Genetic factors were more important in determining total polyphenol content, PPO activity, and brightness of dough sheets and as important as environmental factors for protein and ash content. Across environments, L* of dough sheets was consistently higher in proanthocyanidin‐free barley (73–76) than in proanthocyanidin‐containing barley (59–70). Total polyphenol content of abraded grains was highest in barley grown in a dry area at 0.18%, lower in high rainfall areas at 0.13%, and lowest in irrigated areas at 0.12%. Genotype (G) by environment (E) interactions were significant for all traits, except for brightness of cooked kernels. However, the effects of the G × E interactions were generally small compared with either the genetic or the environmental effect alone and primarily due to changes in magnitude rather than in rank. Stability analyses confirmed the nature of the G × E interactions.
Comparison of Enzymatic (E‐Mill) and Conventional Dry‐Grind Corn Processes Using a Granular Starch Hydrolyzing Enzyme
Authors: Wang Ping , Singh Vijay , Xu Li , Johnston David B. , Rausch Kent D. , Tumbleson M. E.
Published: June 2007

A new low temperature liquefaction and saccharification enzyme STARGEN 001 (Genencor International, Palo Alto, CA) with high granular starch hydrolyzing activity was used in enzymatic dry‐grind corn process to improve recovery of germ and pericarp fiber before fermentation. Enzymatic dry‐grind corn process was compared with conventional dry‐grind corn process using STARGEN 001 with same process parameters of dry solid content, pH, temperature, enzyme and yeast usage, and time. Sugar, ethanol, glycerol and organic acid profiles, fermentation rate, ethanol and coproducts yields were investigated. Final ethanol concentration of enzymatic dry‐grind corn process was 15.5 ± 0.2% (v/v), which was 9.2% higher than conventional process. Fermentation rate was also higher for enzymatic dry‐grind corn process. Ethanol yields of enzymatic and conventional dry‐grind corn processes were 0.395 ± 0.006 and 0.417 ± 0.002 L/kg (2.65 ± 0.04 and 2.80 ± 0.01 gal/bu), respectively. Three additional coproducts, germ 8.0 ± 0.4% (db), pericarp fiber 7.7 ± 0.4% (db), and endosperm fiber 5.2 ± 0.6% (db) were produced in addition to DDGS with enzymatic dry‐grind corn process. DDGS generated from enzymatic dry‐grind corn process was 66% less than conventional process.
Polyphenol Oxidase in Wheat Grain: Whole Kernel and Bran Assays for Total and Soluble Activity
Authors: Fuerst E. Patrick , Anderson James V. , Morris Craig F.
Published: June 2007

Color is a key quality trait of wheat products, and polyphenol oxidase (PPO) is implicated as playing a significant role in darkening and discoloration. In this study, total and soluble PPO activities were characterized in whole kernel assays and bran extracts. In whole kernel assays similar to AACC Approved Method 22–85, four wheat cultivars were ranked the same for both total and soluble (leached) PPO activity with L‐DOPA (diphenol) as the substrate. Total kernel PPO activity was much greater than soluble PPO activity in three hexaploid wheat cultivars, indicating that insoluble PPO was the major contributor to kernel PPO measurements. Tyrosine (monophenol) was an excellent PPO substrate in kernel assays as expected but had no activity as a substrate for soluble PPO. However, soluble PPO activity with tyrosine was activated by the addition of the diphenols chlorogenic acid and caffeic acid. When PPO was assayed in homogenized bran, 89–95% of total PPO activity remained insoluble, associated with the bran particles. The kernel assay detected <2% of PPO measured in an equivalent amount of homogenized bran. However, total PPO activity was 2‐fold higher in Klasic than in ID377s, both when measured in the kernel assay and in homogenized bran, indicating that the kernel assay was an accurate predictor of relative total extracted PPO activity in these two cultivars. Adding detergents (0.1% SDS plus 0.2% NP‐40) to the bran extraction buffer increased both soluble and insoluble PPO activity. Results indicate that relative PPO activities among wheat cultivars are similar in whole kernel and kernel leachate assays, and that the predominant insoluble fraction of PPO, which is relatively uncharacterized, may be largely responsible for wheat product discoloration.
Effect of Decorticating Sorghum on Ethanol Production and Composition of DDGS
Authors: Corredor D. Y. , Bean S. R. , Schober T. , Wang D.
Published: June 2007

The use of a renewable biomass that contains considerable amounts of starch and cellulose could provide a sugar platform for the production of numerous bioproducts. Pretreatment technologies have been developed to increase the bioconversion rate for both starch and cellulosic‐based biomass. This study investigated the effect of decortication as a pretreatment method on ethanol production from sorghum, as well as investigating its impact on quality of distillers' dry grains with solubles (DDGS). Eight sorghum hybrids with 0, 10, and 20% of their outer layers removed were used as raw materials for ethanol production. The decorticated samples were fermented to ethanol using Saccharomyces cerevisiae. Removal of germ and fiber before fermentation allowed for greater starch loading for ethanol fermentation and resulted in increased ethanol production. Ethanol yields increased as the percentage of decortication increased. The decortication process resulted in DDGS with higher protein content and lower fiber content, which may improve the feed quality.
Network Formation in Gluten‐Free Bread with Application of Transglutaminase
Authors: Moore Michelle M. , Heinbockel Meike , Dockery Peter , Ulmer H. M. , Arendt Elke K.
Published: June 2007

One of the main problems associated with gluten‐free bread is obtaining a good structure. Transglutaminase (TGase), an enzyme that catalyzes acyl‐transfer reactions through which proteins can be cross‐linked could be a way to improve the structure of gluten‐free breads. The objective of this study was to evaluate the impact of TGase at different levels (0, 0.1, 1, and 10 U of TGase/g of protein) on the quality of gluten‐free bread. The recipe consisted of white rice flour (relative amount: 35), potato starch (30), corn flour (22.5), xanthan gum (1), and various protein sources (skim milk powder [SMP] [12.5], soya flour, and egg powder). The influence of the various proteins in combination with the different addition levels of TGase on bread quality (% bake loss, specific volume, color, texture, image characteristics, and total moisture) was determined. Confocal laser‐scanning microscopy (CLSM) was used to evaluate the influence of TGase on the microstructure of the bread. Baking tests showed that TGase had an effect on the specific volume of the bread. For instance, the SMP bread with 10 U of enzyme contained the most compact structure, which was reflected in the crumb texture profile analysis results (highest values) (P < 0.05), digital image analysis (highest level of cells/cm2) (P < 0.05), and CLSM micrographs (network formation). Finally, it can be concluded that it is possible to form a protein network in gluten‐free bread with the addition of TGase. However the efficiency of the enzyme is dependent on both the protein source and the level of enzyme concentration.
Multiple‐Particle Tracking Study of Microheterogeneity of Nutrim‐10 Suspensions
Authors: Xu Jingyuan , Chang Tungsun , Inglett George E. , Carriere Craig J. , Tseng Yiider
Published: June 2007

Nutrim is a newly developed food product containing dietary soluble fiber β‐glucan. The microstructural heterogeneities of Nutrim‐10 suspensions were investigated by monitoring the thermally driven displacements of well‐dispersed microspheres through video fluorescence microscopy. By comparing the distribution of the time‐dependent mean‐square displacement (MSD) of polystyrene microspheres embedded in three concentrations of Nutrim‐10 suspensions, we found that the degree of heterogeneity of suspensions increased dramatically within a narrow range of Nutrim‐10 concentrations. The ensemble‐averaged MSD of 5.5% Nutrim‐10 suspension exhibited a power‐law behavior scaling linearly with time, which was similar to the behavior for a homogeneous aqueous glycerol solution. But the MSD distribution was wider and more asymmetric than for glycerol. Increasing Nutrim‐10 concentration rendered the MSD distribution much more asymmetric and skewed. This study provided a quantitative method to characterize the organization of Nutrim‐10 in suspension.
Instrumental Measurement of Physical Properties of Cooked Asian Wheat Flour Noodles
Authors: Ross Andrew S.
Published: June 2007

Instrumental texture tests on cooked noodles are valuable research tools and are well suited for monitoring noodle texture after changes in formulations, raw materials, and processing. Uniaxial tests are most common, and a variety of test types, strains, strain rates, and probe dimensions are used. Consequently, standardization is a challenge. Compressive tests (cutting and blunt probe compression) are more frequently reported than tensile tests. Combining results of tensile and compressive tests shows potential to uncover aspects of noodle texture not detectable using one method alone. Tensile and blunt‐probe compression tests can be both adapted for stress relaxation experiments and may be used to derive fundamental rheological information. Dynamic oscillating rheometry shows promise as a tool for investigating composition/structure/function relationships in cooked noodles. However, unlike large deformation “texture” tests, dynamic oscillating rheometry struggles to match sensory perceptions of noodle texture. This may result from the scale of the deformations applied, which are commonly much smaller than the deformations required for rupture. Limitations of small deformations become more evident when considering fracture properties of noodles and how these are affected by changes in flour composition and inhomogenieties in noodle structure at the macro‐, meso‐, and micro‐scales. Combining information from small and large deformations has been used to investigate changes in noodle texture occurring after changes in amylose and protein composition. This combined approach may prove to be useful in resolving differences and similarities in noodle texture wrought by changes in the constituent polymers of wheat flour.
Distribution of Glutathione in Millstreams and Relationships to Chemical and Baking Properties of Flour
Authors: Every D. , Morrison S. C. , Simmons L. D. , Ross M. P.
Published: June 2007

Fourteen millstream flours, a straight‐run flour, bran, pollard, and germ were prepared separately from two Australian and two New Zealand wheat cultivars using a 650 kg/hr pilot roller mill. Glutathione (GSH) and oxidized glutathione (GSSG) were measured in all samples. The Australian cultivars had higher levels of GSH and GSSG than the New Zealand cultivars, and in all cultivars the levels in pollard and germ were considerably higher than in flour samples. Generally, the early break flours and early reduction flours had lower GSSH/GSSG levels than the tail‐end break and reduction flours. There was a strong correlation between GSH/GSSG and ash content in millstream flours, which indicated that much of the GSH/GSSG in the flour was likely to have derived from contamination by bran, aleurone (pollard), and germ. There were also moderate to strong correlations between GSH/GSSG and the cysteine content of all proteins in flour. GSH/GSSG correlated strongly with the albumin and globulin content of flour but not with gliadin and glutenin. The volume and crumb texture properties of bread made with millstream flours in the absence of ascorbic acid (AA) were negatively correlated with GSH/GSSG. The change in bread volume and texture properties when AA was added to dough (baking improver effect of AA), however, were poorly correlated with GSH/GSSG.
Distribution of Redox Enzymes in Millstreams and Relationships to Chemical and Baking Properties of Flour
Authors: Every D. , Simmons L. D. , Ross M. P.
Published: June 2007

Millstream flours, bran, pollard, and germ fractions were prepared from two Australian and two New Zealand wheat cultivars using a pilot‐scale roller mill. The distribution of six redox enzymes in milling fractions and the relationship of the enzymes to baking parameters were investigated. Lipoxygenase (LOX), dehydroascorbate reductase (DAR), and protein disulfide isomerase (PDI) tended to be higher in the tail‐end fractions of break and reduction flour streams, but the highest levels were in the bran, pollard, and germ fractions. These enzymes had moderate to strong correlations with ash content of flour. These results indicated that a considerable amount of these enzymes in the tail‐end flour streams were likely to be derived from contamination with bran, aleurone, or germ components of grain. Peroxidase (POX) tended to be higher in the break flours, but polyphenol oxidase (PPO) and ascorbate oxidase (AOX) tended to be evenly distributed in the millstream flours. These three enzymes generally had poor correlations with ash and baking parameters. LOX and DAR had a negative correlation with the baking quality of bread made in the absence of ascorbic acid (AA) but a poor correlation with improvement of bread quality made with AA. The negative correlation probably reflects the high content of ash (hence trichomes), glutathione, and protein thiols in those fractions that have high LOX and DAR, and these high‐reducing‐power components and trichomes in flour may be the actual cause of poor quality bread. PDI generally had a poor correlation with bread quality in the absence of AA but a significant positive correlation with improvement in the quality of bread made with AA. It thus seems that the endogenous levels of these six enzymes were not a limiting factor in the breadmaking process, except for PDI, the levels of which may have positively influenced breadmaking in the presence of AA.
Effect of Processing Conditions on Color Change of Brown and Milled Parboiled Rice
Authors: Lamberts L. , De Bie E. , Derycke V. , Veraverbeke W. S. , De Man W. , Delcour J. A.
Published: June 2007

The effects of the soaking and steaming steps in rice parboiling on color changes and the levels of reducing sugars in rice were studied. Brown rice was soaked to different moisture contents (MC, 15, 20, 25, and 30%). The L*, a*, b* color parameters of the Commission Internationale de L'Eclairage (CIE 1976) indicated that during soaking, red and yellow bran pigments diffused from the bran into the endosperm. The increase in brightness brought about by soaking rice was attributed to migration of rice compounds (e.g., lipids) from the inner to the outer bran layers (rice surface). The levels of reducing sugars in brown and milled soaked rice samples increased with increasing brown rice MC after soaking. The total color difference (ΔE) between parboiled and nonparboiled rice increased with increasing MC after soaking and depended on the intensity of the steaming conditions as reflected in the degree of starch gelatinization. Parboiling affected yellowness more than redness in mildly steamed brown rice and most in intermediately steamed brown rice. Severe steaming of brown rice affected redness more than yellowness. All three parboiling conditions equally affected the yellow color more than the red color in milled rice. Linear regression analyses indicated that parboiling had a larger effect on ΔE of milled parboiled rice than of brown parboiled rice. Furthermore, the linear relationship between the level of gelatinized starch and ΔE of the milled parboiled rice samples showed that both parameters are indicators for the degree of parboiling. Reducing sugars were formed and lost during steaming, suggesting Maillard reactions during steaming.
Evaluation of the Single Kernel Characterization System (SKCS) for Measurement of Sorghum Grain Attributes
Authors: Bean S. R. , Chung O. K. , Tuinstra M. R. , Pedersen J. F. , Erpelding J.
Published: June 2007

The single kernel characterization system (SKCS) has been widely used in the wheat industry, and SKCS parameters have been linked to end‐use quality in wheat. The SKCS has promise as a tool for evaluating sorghum grain quality. However, the SKCS was designed to analyze wheat, which has a different kernel structure from sorghum. To gain a better understanding of the meaning of SKCS predictions for grain sorghum, individual sorghum grains were measured for length, width, thickness (diameter), and weight by laboratory methods and by the SKCS. SKCS predictions for kernel weight and thickness were highly correlated to laboratory measurements. However, SKCS predictions for kernel thickness were underestimated by ≈20%. The SKCS moisture prediction for sorghum was evaluated by tempering seven samples with varying hardness values to four moisture levels. The moisture contents predicted by SKCS were compared with a standard oven method and, while correlated, SKCS moisture predictions were less than moisture measured by air oven, especially at low moisture content. Finally, SKCS hardness values were compared with hardness measured by abrasive decortication. A moderate (r = 0.67, P < 0.001) correlation was observed between the hardness measurements. The SKCS predictions of kernel weight and diameter were highly correlated with laboratory measurement. Moisture prediction, however, was substantially lower by the SKCS than as measured by an air oven method. The SKCS should be suitable for measuring sorghum grain attributes. Further research is needed to determine how SKCS hardness predictions are correlated to milling properties of sorghum grain.
Disulfide Proteome Analysis of Buckwheat Seeds to Screen Putative Allergens
Authors: Yano Hiroyuki , Kusada Osamu , Kuroda Shigeru , Kato‐Emori Sumie
Published: June 2007

Accumulating evidence suggests a correlation between disulfide bonding and the allergenicity of proteins. Also, a significant characteristic of most food allergens is that they are stable to proteases. We sought to identify putative allergens of buckwheat seed comprehensively by combining a disulfide proteome technique with an in vitro digestibility test. First, a dilute acetic acid fraction of buckwheat seed was found to be rich in disulfide proteins. Internal amino acid sequence analyses of these proteins showed that most of them were known allergens or putative allergens sharing high amino acid sequence similarities to known allergens. Next, the fraction was subjected to in vitro protease digestion, which revealed relatively large fragments that were resistant to prolonged enzymatic digestion. These protease‐resistant fragments contained disulfide bonds that should have protected the potential enzyme cleavage sites by forming compact structures. These results confirm and extend our knowledge of the correlations among the disulfide bonding of proteins, their protease stability, and their allergenicity. Also, these observations suggest a new strategy to identify putative allergens by proteomic approaches as well as to mitigate them.
Structural and Retrogradation Properties of Rice Endosperm Starch Affect Enzyme Digestibility of Steamed Milled‐Rice Grains Used in Sake Production
Authors: Okuda Masaki , Aramaki Isao , Koseki Takuya , Inouchi Naoyoshi , Hashizume Katsumi
Published: June 2007

Structural and physicochemical characteristics of endosperm starch from milled rice grains of seven Japanese cultivars used in sake production were examined. Amylose content was 15.2–20.2%, number‐average degree of polymerization (DPn) of amylose was 900–1,400, and the ratio of short‐to‐long chain amylopectin was 2.7–3.5, respectively. The degree of retrogradation of purified starch stored for seven days at 4°C after gelatinization was 20–31%. The degree of retrogradation correlated negatively with the ratio of short‐to‐long chain amylopectin. The effect of holding time after steaming on enzyme digestibility and starch retrogradation of steamed rice grains was investigated. The longer the holding time after steaming, the greater the extent of retrogradation, and the less the degree of enzymatic digestibility. The decreased rate of enzyme digestibility correlated with amylopectin chain length distribution. Samples with short‐chain amylopectin exhibited a slow decrease in enzyme digestibility. It was determined that the structure and retrogradation properties of endosperm starch in Japanese rice cultivars affect the decreasing rate of enzyme digestibility of the steamed, milled rice grains.
Restriction of Starch Granule Swelling by Iodine During Heating
Authors: Patel B. K. , Saibene D. , Seetharaman K.
Published: June 2007

Differences in the degree of starch granule swelling and granule morphology are shown as a function of iodine concentration during heating. The observations reveal a restriction and delay in wheat and corn starch swelling in presence of iodine (0.02%) and a lack of swelling at higher iodine concentration (0.2%). The presence of iodine during heating did not influence waxy corn starch granule swelling, even at the higher concentration. A delay in the increase in paste viscosity during heating was observed, and gel formation was precluded after cooling at the higher iodine concentration. Waxy corn starch pastes formed a weak gel even at the higher iodine concentration. Spectrophotometric analyses showed that polymers leach into the solution when heated in the presence of 0.02% iodine, while no leaching was observed at 0.2% iodine concentration. Furthermore, the length and the amount of polymers leaching from normal corn were different from that observed for wheat starch. Thermal analyses reveal a shift in the onset of gelatinization temperature and an increase in the enthalpy in the amylose‐lipid region of the endotherm. While the iodine‐polymer complex did not appear to exhibit an endotherm during heating, the granules exhibited a diffused polarized cross, suggesting the presence of an ordered complex.