bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

ABSTRACTColor 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

ABSTRACTThe 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

ABSTRACTOne 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

ABSTRACTNutrim 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

ABSTRACTInstrumental 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

ABSTRACTFourteen 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

ABSTRACTMillstream 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

ABSTRACTThe 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

ABSTRACTThe 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

ABSTRACTAccumulating 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

ABSTRACTStructural 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

ABSTRACTDifferences 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.
Creep Deformation Modeling of Glutinous Rice Cakes (Mochi)
Authors: Chuang George Chao‐Chi , Yeh An‐I 
Published: June 2007

ABSTRACTThe viscoelastic properties of glutinous rice cakes (mochi) made by extrusion at different conditions (water contents of 45–55% and barrel temperatures of 75–95°C) and commercial rice cakes were studied by a creep test. The maximum compliances of extruded mochi were 0.15–4.23 1/kPa. Among the extruded samples, the mochi extruded at 75°C with a water content of 55% was the one that yielded the largest maximum compliance. At the same barrel temperature, the creep compliance increased with the water content. Four models with different numbers of elements (spring and dashpot) were employed to fit the experimental data. The model coefficients were able to provide the corresponding elastic and viscous behavior of the sample. The 3‐element model (a spring in series with a Kelvin‐Voigt model) did not exhibit steady‐state compliance as observed in the experimental data. The 4‐element (Burger's model), modified 4‐element (an approximation of Burger's model), and 6‐element model (adding one more Kelvin model to the Burger's model) yielded R2 > 0.99. Results showed that the 4‐element model was adequate to describe the creep behavior of mochi.
In Vitro Starch Digestibility of Tortillas Elaborated by Different Masa Preparation Procedures
Authors: Bello‐Pérez Luis A. , Rendón‐Villalobos J. Rodolfo , Agama‐Acevedo Edith , Islas‐Hernández José Juan 
Published: June 2007

ABSTRACTStarch digestibility was evaluated in freshly prepared tortillas elaborated from masa obtained from different procedures (laboratory‐made masa, commercial masa, and nixtamalized corn flour) and from laboratory‐made masa with added commercial hydrocolloid, and stored for 24, 48, and 74 hr. Tortillas prepared with commercial masa had the highest available starch (AS) content and the commercial tortillas had the lowest, showing a decrease in AS content when storage time increased. Tortilla of commercial masa showed the lowest resistant starch (RS) content that agrees with the AS measured. However, tortilla of laboratory‐made masa presented the highest AS and RS contents. RS increased with storage time, a pattern that is related to the starch retrogradation phenomenon observed when retrograded resistant starch (RRS) was quantified. Commercial tortillas showed predicted glycemic index (pGI) values of 62–75% using a chewing/dialysis procedure (semi in vitro method). Index values were lower than those determined in vitro. The pGI of tortillas decreased, and the values were different depending on the method used to prepare the masa and tortilla. Commercial tortilla and tortilla of NCF had the lowest pGI. Therefore, the procedure to obtain masa and thereafter obtain tortillas influenced the starch digestibility of the product.