Comparison of Swiss red wheat grain and fractions for their antioxidant properties

Swiss red wheat grain, bran, aleurone, and micronized aleurone were examined and compared for their free radical scavenging properties against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*), radical cation ABTS*+ and peroxide radical anion O(2)*-, oxygen radical absorbance capacity (ORAC), chelating capacity, total phenolic content (TPC), and phenolic acid composition. The results showed that micronized aleurone, aleurone, bran, and grain may significantly differ in their antioxidant properties, TPC, and phenolic acid composition. Micronized aleurone had the greatest antioxidant activities, TPC, and concentrations of all identified phenolic acids, suggesting the potential of postharvesting treatment on antioxidant activities and availability of TPC and phenolic acids. Ferulic acid was the predominant phenolic acid in Swiss red wheat and accounted for approximately 57-77% of total phenolic acids on a weight basis. Ferulic acid concentration was well correlated with scavenging activities against radical cation and superoxide anion, TPC, and other phenolic acid concentrations, suggesting the potential use of ferulic acid as a marker of wheat antioxidants. In addition, 50% acetone and ethanol were compared for their effects on wheat ORAC values. The ORAC value of 50% acetone extracts was 3-20-fold greater than that of the ethanol extracts, indicating that 50% acetone may be a better solvent system for monitoring antioxidant properties of wheat. These data suggest the possibility to improve the antioxidant release from wheat-based food ingredients through postharvesting treatment or processing.     

Carotenoid, tocopherol, phenolic acid, and antioxidant properties of Maryland-grown soft wheat

Consumers' desires to either reduce the risk of or manage a specific health condition through improved diet have stimulated the research of agricultural products for their potential health beneficial components such as tocopherols and natural antioxidants. Soft wheat is one of the major crops in Maryland, with little information available about its potentially beneficial components. This study examined eight selected Maryland-grown soft wheat varieties or experimental lines for their potential beneficial components including tocopherols, carotenoids, total phenolics and phenolic acids and their antioxidant properties, including Fe(2+) chelating capacity and free radical scavenging activities against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(*) ), radical cation ABTS(*)(+), and oxygen radical (ORAC). The results showed that all tested soft wheat grain samples contained alpha-tocopherol, with a range of 3.4-10.1 microg/g. Lutein was the primary carotenoid present in the grain samples at a level of 0.82-1.14 microg/g, along with significant amounts of zeaxanthin and beta-carotene. Vanillic, syringic, p-coumaric, and ferulic acids were found in soluble free, soluble conjugated, and insoluble bound forms in the grain extracts, with ferulic acid as the predominant phenolic acid. The eight soft wheat varieties differed in their antioxidant properties. The tested wheat grain samples exhibited ED(50) values against DPPH(*) of 23-27 mg of grain equiv/mL, ORAC of 32.9-48 micromol of Trolox equiv (TE)/g, and ABTS(*)(+) scavenging capacity of 14.3-17.6 micromol of TE/g. These data suggest the possibility of producing soft wheat varieties rich in selected health beneficial factors for optimum human nutrition though breeding programs.     

Analysis of Genotype,Environment, and Their Interaction Effects on the Phytochemicals and Antioxidant Capacities of Red Rice (Oryza sativa L.)

Fourteen red rice varieties were planted in two locations during summer (Hangzhou) and winter (Hainan) to study the effect of genotype and environment on the phytochemicals and antioxidant capacities of rice grain. B‐type proanthocyanidins in red rice were detected by LC‐MS/MS and quantified by using the vanillin assay. Analysis of variance showed that total phenolic content (TPC), total flavonoid content (TFC) and 2,2′‐azino‐bis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) radical scavenging capacity were mainly affected by environmental factors, which accounted for more than 60% of the total variance. However, total proanthocyanidin content (TPAC) and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging capacity were equally affected by both genotype and environment. The genotype × environment effects were significant for all traits. The pairwise correlations among TPC, TFC, TPAC, ABTS, and DPPH were also significant (r > 0.900, P < 0.001). Principal component analysis identified the genotypes that had higher contents of antioxidants and more stability across environments. This study showed that indirect selection of a simple trait (i.e., TPC) is an effective way to select rice high in antioxidant capacity in breeding programs. This study also suggests that rice should be produced specifically in a certain environment for the end user to minimize the variation in the functional properties and maximize their contents.     

Effects of postharvest treatment and heat stress on availability of wheat antioxidants

This research evaluated the effects of postharvest treatment and heat stress on the availability of wheat antioxidants using Ankor and Trego wheat varieties. The grain, bran, and 40-mesh bran samples of both Ankor and Trego wheat were kept at 25, 60, and 100 degrees C for 9 days. Samples taken at day 0, 1, 2, 3, 5, and 9 were extracted with pure ethanol and examined for antioxidant properties including the scavenging activity against peroxyl (ORAC), cation ABTS, and 2,2-diphenyl-1-picryhydrazyl (DPPH.) radicals, as well as total phenolic content (TPC) and phenolic acid composition. Both heat stress and postharvest treatment significantly altered the antioxidant properties of wheat grain fractions. The ORAC values of Ankor bran and corresponding 40-mesh bran samples kept at 100 degrees C for 9 days reduced to 61 and 40% of that at day 0 on a per dry weight basis, respectively, while the ORAC values of the grain samples showed no significant change. The overall loss of DPPH. scavenging capacity was 38 and 100% for the bran and 40-mesh Ankor bran samples, respectively, and was 47 and 60% in the bran and 40-mesh Trego bran samples, respectively, whereas no reduction was detected in the grain samples under the same heat stress. Heat stress and postharvest treatment had similar effects on ABTS.+ scavenging capacities and TPC values of grain and fractions of both varieties. These data suggest that whole grain as opposed to its fractions is a preferred form of long-term storage for better preserving natural antioxidants and that the reduction of the particle size may accelerate the loss of natural antioxidants in wheat bran during storage and thermal processing but may enhance the releasable amount of wheat antioxidants from bran.     

Screening methods to measure antioxidant activity of sorghum (sorghum bicolor) and sorghum products

Specialty sorghums, their brans, and baked and extruded products were analyzed for antioxidant activity using three methods: oxygen radical absorbance capacity (ORAC), 2,2'-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS), and 2,2-diphenyl-1-picrylhydrazyl (DPPH). All sorghum samples were also analyzed for phenolic contents. Both ABTS and DPPH correlated highly with ORAC (R(2) = 0.99 and 0.97, respectively, n = 18). Phenol contents of the sorghums correlated highly with their antioxidant activity measured by the three methods (R(2) >or= 0.96). The ABTS and DPPH methods, which are more cost effective and simpler, were demonstrated to have similar predictive power as ORAC on sorghum antioxidant activity. There is a need to standardize these methods to allow for data comparisons across laboratories.     

Effects of solid-state yeast treatment on the antioxidant properties and protein and fiber compositions of common hard wheat bran

The bran fraction of wheat grain is known to contain significant quantities of bioactive components. This study evaluated the potential of solid-state yeast fermentation to improve the health beneficial properties of wheat bran, including extractable antioxidant properties, protein contents, and soluble and insoluble fiber compositions. Three commercial food grade yeast preparations were evaluated in the study along with the effects of yeast dose, treatment time, and their interaction with the beneficial components. Solid-state yeast treatments were able to significantly increase releasable antioxidant properties ranging from 28 to 65, from 0 to 20, from 13 to 19, from 0 to 25, from 50 to 100, and from 3 to 333% for scavenging capacities against peroxyl (ORAC), ABTS cation, DPPH and hydroxyl radicals, total phenolic contents (TPC), and phenolic acids, respectively. Yeast treatment increased protein content 11-12% but did not significantly alter the fiber composition of wheat bran. Effects of solid-state yeast treatment on both ORAC and TPC of wheat bran were altered by yeast dose, treatment time, and their interaction. Results suggest that solid-state yeast treatment may be a commercially viable postharvest procedure for improving the health beneficial properties of wheat bran and other wheat-based food ingredients.     

Total phenolics, phenolic acids, isoflavones, and anthocyanins and antioxidant properties of yellow and black soybeans as affected by thermal processing

The effects of boiling and steaming processes on the phenolic components and antioxidant activities of whole yellow (with yellow seed coat and yellow cotyledon) and black (with black seed coat and green cotyledon) soybeans were investigated. As compared to the raw soybeans, all processing methods caused significant (p < 0.05) decreases in total phenolic content (TPC), total flavonoid content (TFC), condensed tannin content (CTC), monomeric anthocyanin content (MAC), DPPH free radical scavenging activity (DPPH), ferric reducing antioxidant power (FRAP), and oxygen radical absorbing capacity (ORAC) in black soybeans. Pressure steaming caused significant (p < 0.05) increases in TPC, CTC, DPPH, FRAP, and ORAC in yellow soybeans. The steaming resulted in a greater retention of TPC, DPPH, FRAP, and ORAC values in both yellow and black soybeans as compared to the boiling treatments. To further investigate the effect of processing on phenolic compounds and elucidate the contribution of these compounds to changes of antioxidant activities, phenolic acids, isoflavones, and anthocyanins were quantitatively determined by HPLC. The pressure steaming treatments caused significant (p < 0.05) increases in gallic acid and 2,3,4-trihydroxybenzoic acid, whereas all treatments caused significant (p < 0.05) decreases in two predominant phenolic acids (chlorogenic acid and trans-cinnamic acid), and total phenolic acids for both yellow and black soybeans. All thermal processing caused significant (p < 0.05) increases in aglucones and beta-glucosides of isoflavones, but caused significant (p < 0.05) decreases in malonylglucosides of isoflavones for both yellow and black soybeans. All thermal processing caused significant (p < 0.05) decreases of cyanidin-3-glucoside and peonidin-3-glucoside in black soybeans. Significant correlations existed between selected phenolic compositions, isoflavone and anthocyanin contents, and antioxidant properties of cooked soybeans.     

Free radical scavenging properties of wheat extracts

Three hard winter wheat varieties (Akron, Trego, and Platte) were examined and compared for their free radical scavenging properties and total phenolic contents (TPC). Free radical scavenging properties of wheat grain extracts were evaluated by spectrophotometric and electron spin resonance (ESR) spectrometry methods against stable 2,2-diphenyl-1-picryhydrazyl radical (DPPH*) and radical cation ABTS*+ (2,2'-azino-di[3-ethylbenzthiazoline sulfonate]). The results showed that the three wheat extracts differed in their capacities to quench or inhibit DPPH* and ABTS*+. Akron showed the greatest activity to quench DPPH radicals, while Platte had the highest capacity against ABTS*+. The ED50 values of wheat extracts against DPPH radicals were 0.60 mg/mL for Akron, 7.1 mg/mL for Trego, and 0.95 mg/mL for Platte under the experimental conditions. The trolox equivalents against ABTS*+ were 1.31 +/- 0.44, 1.08 +/- 0.05, and 1.91 +/- 0.06 micromol/g of grain for Akron, Trego, and Platte wheat, respectively. ESR results confirmed that wheat extracts directly reacted with and quenched free radicals. The TPC were 487.9 +/- 927.8 microg gallic acid equivalents/g of grain. No correlation was observed between TPC and radical scavenging capacities for DPPH* and ABTS*+ (p = 0.15 and p > 0.5, respectively).     

Diversity in Antioxidant Capacity,Phenolic Contents,and Flavonoid Contents of 42 Edible Beans from China

Edible beans are among the most important grain legumes consumed by humans. To provide new information on the antioxidant phenolics of edible beans, the antioxidant capacity, total phenolic content (TPC), and total flavonoid content (TFC) in both soluble and bound fractions of 42 edible beans from China were systematically evaluated, with main phenolic compounds identified and quantified in 10 beans possessing the highest TPC. Edible beans contained a wide range of total antioxidant capacity and TPC generally comparable with common grains, fruits, and vegetables, and their bound fractions had significant antioxidant capacity, TPC, and TFC. Red sword bean was found for the first time to show extremely high total antioxidant capacity (ferrous[II] at 235 ± 13.2 μmol/g and Trolox at 164 ± 10.5 μmol/g) and TPC (1767 ± 58.3 mg of GAE/100 g). Phenolic compounds such as catechin, ferulic acid, gallic acid, p‐coumaric acid, and protocatechuic acid were widely detected in selected beans. A positive correlation was found between antioxidant capacity (ferric‐reducing antioxidant power [FRAP] and Trolox equivalent antioxidant capacity [TEAC] values) and TPC, with correlation coefficient r = 0.974 (FRAP value versus TPC) and r = 0.914 (TEAC value versus TPC). Therefore, beans with high antioxidant capacity and phenolic content can be valuable sources of dietary natural antioxidants for the prevention of oxidative stress‐related chronic diseases.     

Properties of Arabinoxylans in Frozen Dough Enriched with Wheat Fiber

The global market for frozen bread dough is rising; however, its quality could deteriorate during extended storage. Our previous study indicated that undesirable changes caused by freezing could be reduced by adding arabinoxylan‐rich fiber sources. The present study investigated the changes in arabinoxylan properties of yeasted dough during frozen storage. Dough samples made from refined, whole, and fiber‐enriched (15% either wheat aleurone or bran) flours were stored at –18°C for nine weeks, and structural properties of arabinoxylan were probed during storage. Water‐extractable arabinoxylan (WEAX) content in dough samples increased by about 19–33% during the first three weeks of storage. Prolonged storage of dough (weeks 6 and 9), however, correlated with a decline in WEAX content. Average molecular weight and intrinsic viscosity of WEAX decreased during storage for all frozen dough samples. Arabinose‐to‐xylose ratios also decreased by 11 and 6% for control and composite dough samples, respectively. There was a significant positive correlation (r = 0.89, P < 0.0001) between WEAX content of dough and bread quality throughout the storage period. The results demonstrated that changes in dough quality during frozen storage were related to changes in the content and structure of WEAX that took place during frozen storage.     

Distribution of Total,Water‐Unextractable,and Water‐Extractable Arabinoxylans in Wheat Flour Mill Streams

Arabinoxylans are a minor but important constituent in wheat that affects bread quality, foam stability, batter viscosity, and sugar snap cookie diameter. Therefore, it is important to determine the distribution of arabinoxylans in flour mill streams to better formulate flour blends. Thirty‐one genetically pure grain lots representing six wheat classifications common to the western U.S. were milled on a Miag Multomat pilot mill, and 10 flour mill streams were collected from each. A two‐way ANOVA indicated that mill streams were a greater source of variation compared to grain lots for total arabinoxylans (TAX), water‐unextractable arabinoxylans (WUAX), and water‐extractable arabinoxylans (WEAX). TAX and WUAX were highly correlated with ash at r = 0.94 and r = 0.94, respectively; while the correlation for WEAX and ash decreased in magnitude at r = 0.60. However, the 5th middlings mill streams exhibited disparity between TAX and ash content as well as between WUAX and ash content. This may indicate that TAX and WUAX in mill streams are not always the result of bran contamination. Cumulative extraction curves for TAX, WUAX and WEAX revealed increasing gradients of arabinoxylans parallel to extraction rate. Therefore, arabinoxylans may be an indicator of flour refinement.     

Frozen and Unfrozen Water Contents of Wheat Flours and Their Components

The properties of frozen and unfrozen water in two different wheat flours (hard and soft), and in their main components (gluten, starch, damaged starch, water‐soluble and water‐insoluble pentosans), were described using modulated differential scanning calorimetry (DSC). As a reference, enthalpy values of crystallization (298 J/g) and melting (335 J/g) of pure water were determined from the total heat flow curves. The separation of thermal events between the reversing and nonreversing heat flows with modulated DSC was not effective due to disturbances in the modulated temperature scan. For wheat flours and their components, linear regressions described well the changes in frozen water content calculated from enthalpies of freezing (R² = 0.970–0.982) or melting (R² = 0.783–0.996). The unfrozen water content (UFWC) calculated for the hard wheat flour (29–31%, db) was close to that calculated for the soft wheat flour (30–32%). The UFWC of wheat gluten (38–47%), starch (38–42%), damaged starch (37–40%), water‐soluble pentosans (51%), and water‐insoluble pentosans (40–44%) were higher than the corresponding values for the flours. The simple summation of the contributions of each component cannot be used to estimate the overall behavior of flours.     

Wheat Arabinoxylan Structure Provides Insight into Function

Recent attention to dietary fiber in wheat (Triticum aestivum L.) has invigorated research in the nonstarch carbohydrate arabinoxylan (AX). AX molecules are composed of a linear xylose backbone with arabinose substitutions along the backbone. These arabinose substituents can also carry a ferulic acid moiety. AX molecules can be fractionated into two categories based on extraction properties that have a structural and conformational basis: water‐extractable (WEAX) and water‐unextractable (WUAX) molecules. The ferulic acid moieties also allow for oxidative cross‐linking between AX molecules or the tyrosine residues of proteins. The contents of total AX and WEAX molecules are primarily influenced by genetic differences; however, there is also evidence of environmental influence on content. There are several useful methods for quantifying AX molecules, providing varying levels of structural information as well as accuracy and precision. The high water‐absorption capacity of AX molecules results in a strong influence of AX on end‐use quality. Whereas WEAX molecules, in particular, tend to be detrimental for the quality of soft wheat products such as cookies, WEAX molecules are beneficial to the quality of hard wheat products such as bread. The role of WUAX molecules among the range of soft wheat products is as yet unclear; however, WUAX molecules tend to have a detrimental influence on bread. Because of the variable influence of AX structure on end‐use product functionality, closer examination of structure–function relationships may provide key insights into how to direct breeding efforts to maximize these relationships between AX molecules and other ingredients. Further investigation is necessary to obtain a more complete understanding of how the arabinose substitution levels and patterns affect end‐use quality and how the genetic basis of these traits can be resolved and manipulated for optimum end‐use quality.     

Antioxidant properties of bran extracts from "Akron" wheat grown at different locations

Bran extracts of Akron wheat grown at four nonirrigated and one irrigated testing locations were examined and compared for their free radical scavenging properties against the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(*)) and the radical cation ABTS(*)(+), chelating capacities, and total phenolic content (TPC) to determine the potential effects of environmental factors on the antioxidant properties of hard winter wheat. The environmental factors included total solar radiation, average daily solar radiation, and number of hours exceeding 32 degrees C. The results showed that bran samples from different growing locations may significantly differ in their radical scavenging activities against both DPPH(*) and ABTS(*)(+), chelating capacities, and TPC. A significant negative correlation was detected between the chelating activities of the bran samples from the four nonirrigated locations and total solar or daily average solar radiation (r = -0.999 and P = 0.001). These data suggest potential influences of growing conditions on the antioxidant properties of hard winter wheat and the possibility of producing wheat that is strong in a selected antioxidant property by optimizing the growing conditions of a selected wheat variety. More research is required to further investigate the relationship among antioxidant properties and environmental factors using different wheat varieties and larger sample sizes.     

Water‐Extractable Nonstarch Polysaccharide Distribution in Pilot Milling Analysis of Soft Winter Wheat

Commercial wheat (Triticum aestivum em. Thell) flour milling produces flour streams that differ in water absorption levels because of variability in protein concentration, starch damaged by milling, and nonstarch polysaccharides. This study characterized the distribution of water‐extractable (WE) nonstarch polysaccharides (NSP) in long‐flow pilot‐milling streams of soft wheat to model flour quality and genetic differences among cultivars. Existing reports of millstream analysis focus on hard wheat, which breaks and reduces differently from soft wheat. Seven soft winter wheat genotypes were milled on a pilot‐scale mill that yields three break flour streams, five reduction streams, and two resifted streams. Protein concentration increased linearly through the break streams. WENSP concentration was low and similar in the first two break streams, which are the largest break streams. Flour recovery decreased exponentially through the reduction streams; flour ash and water‐extractable glucose and galactose polymers increased exponentially through the reduction streams. Protein concentration and WE xylan concentration increased linearly through the reduction streams. The ratio of arabinose to xylose in WE arabinoxylan (WEAX) decreased through the reduction streams, and response varied among the genotypes. Flour ash was not predictive of stream composition among genotypes, although within genotypes, ash and other flour components were correlated when measured across streams. The second reduction flour stream was the largest contributor to straight‐grade flour WEAX because of both the size of the stream and the concentration of WEAX in the stream.     

Hardness Measurement of Bulk Wheat by Single‐Kernel Visible and Near‐Infrared Reflectance Spectroscopy

Reflectance spectra (400 to 1700 nm) of single wheat kernels collected using the Single Kernel Characterization System (SKCS) 4170 were analyzed for wheat grain hardness using partial least squares (PLS) regression. The wavelengths (650 to 700, 1100, 1200, 1380, 1450, and 1670 nm) that contributed most to the ability of the model to predict hardness were related to protein, starch, and color differences. Slightly better prediction results were observed when the 550–1690 nm region was used compared with 950–1690 nm region across all sample sizes. For the 30‐kernel mass‐averaged model, the hardness prediction for 550–1690 nm spectra resulted in a coefficient of determination (R²) = 0.91, standard error of cross validation (SECV) = 7.70, and relative predictive determinant (RPD) = 3.3, while the 950–1690 nm had R² = 0.88, SECV = 8.67, and RPD = 2.9. Average hardness of hard and soft wheat validation samples based on mass‐averaged spectra of 30 kernels was predicted and compared with the SKCS 4100 reference method (R² = 0.88). Compared with the reference SKCS hardness classification, the 30‐kernel (550–1690 nm) prediction model correctly differentiated (97%) between hard and soft wheat. Monte Carlo simulation technique coupled with the SKCS 4100 hardness classification logic was used for classifying mixed wheat samples. Compared with the reference, the prediction model correctly classified mixed samples with 72–100% accuracy. Results confirmed the potential of using visible and near‐infrared reflectance spectroscopy of whole single kernels of wheat as a rapid and nondestructive measurement of bulk wheat grain hardness.     

Characterization of phenolic substances and antioxidant properties of food soybeans grown in the North Dakota-Minnesota region

Phenolic profiles and antioxidant properties of a total of 30 soybean samples, including 27 grown in the North Dakota-Minnesota region and three soybeans from the other regions, were investigated. The total phenolic content (TPC), total flavonoids content (TFC), phenolic acids, flavonols, anthocyanins, and isoflavones were quantified. Antioxidant properties of soybean extracts were assessed using 2-diphenyl-1-picryhydrazyl free radical scavenging activity (DPPH), ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC) methods. Results showed that black soybean cultivars possessed significantly higher TPC, TFC, DPPH, FRAP, and ORAC values than all yellow soybean cultivars. However, black soybean cultivars did not exhibit significantly higher individual phenolic contents (except for anthocyanins), such as phenolic acids and isoflavones, than the yellow soybean cultivars. The isoflavone profiles of North Dakota soybean cultivars were similar to those of South Dakota, but average values of total isoflavone (TI) contents were higher than soybeans grown in the other states and Korea and Japan according to the U.S. Department of Agriculture-Iowa State University Database on the isoflavone contents of foods. Correlation assays showed that TPC, TI, total phenolic acids, daidzin, genistin, malonyldaidzin, daidzein, genistein, and trans-cinnamic acid significantly ( r = 0.73, 0.62, 0.49, 0.68, 0.59, 0.59, 0.56, 0.47, and 0.76, respectively, p < 0.0001) correlated with ORAC values of yellow soybeans. Both isoflavones and phenolic acids contributed to the ORAC values of yellow soybeans. These data suggest that some selected soybean cultivars may be used as high-quality food-grade soybeans for providing high phenolic phytochemicals and antioxidant activities.     

High-amylose corn exhibits better antioxidant activity than typical and waxy genotypes

The consumption of fruits, vegetables, and whole grains rich in antioxidative phytochemicals is associated with a reduced risk of chronic diseases such as cancer, coronary heart disease, diabetes, Alzheimer's disease, cataract, and aged-related functional decline. For example, phenolic acids are among the main antioxidative phytochemicals in grains that have been shown to be beneficial to human health. Corn (Zea mays L.) is a major staple food in several parts of the world; thus, the antioxidant activity of several corn types was evaluated. The 2,2-Diphenyl-1-picryhydrazyl free radical (DPPH*) scavenging activity, total phenolic content (TPC), antioxidant capacity of lipid-soluble substances (ACL), oxygen radical absorbance capacity (ORAC), and phenolic acid compositions of typical and mutant genotypes (typical-1, waxy, typical-2, and high-amylose) were investigated. The DPPH* scavenging activity at 60 min was 34.39-44.51% in methanol extracts and 60.41-67.26% in HCl/methanol (1/99, v/v) extracts of corn. The DPPH* scavenging activity of alkaline hydrolysates of corn ranged from 48.63 to 64.85%. The TPC ranged from 0.67 to 1.02 g and from 0.91 to 2.15 g of ferulic acid equiv/kg of corn in methanol and HCl/methanol extracts, respectively. The TPC of alkaline hydrolysates ranged from 2.74 to 6.27 g of ferulic acid equiv/kg of corn. The ACL values were 0.41-0.80 and 0.84-1.59 g of Trolox equiv/kg of corn in methanol and HCl/methanol extracts, respectively. The ORAC values were 10.57-12.47 and 18.76-24.92 g of Trolox equiv/kg of corn in methanol and HCl/methanol extracts, respectively. ORAC values of alkaline hydrolysates ranged from 42.85 to 68.31 g of Trolox equiv/kg of corn. The composition of phenolic acids in alkaline hydrolysates of corn was p-hydroxybenzoic acid (5.08-10.6 mg/kg), vanillic acid (3.25-14.71 mg/kg), caffeic acid (2.32-25.73 mg/kg), syringic acid (12.37-24.48 mg/kg), p-coumaric acid (97.87-211.03 mg/kg), ferulic acid (1552.48-2969.10 mg/kg), and o-coumaric acid (126.53-575.87 mg/kg). Levels of DPPH* scavenging activity, TPC, ACL, and ORAC in HCl/methanol extracts were obviously higher than those present in methanol extracts. There was no significant loss of antioxidant capacity when corn was dried at relatively high temperatures (65 and 93 degrees C) postharvest as compared to drying at ambient temperatures (27 degrees C). Alkaline hydrolysates showed very high TPC, ACL, and ORAC values when compared to methanol and HCl/methanol extracts. High-amylose corn had a better antioxidant capacity than did typical (nonmutant) corn genotypes.     

Effects of genotype and environment on the antioxidant properties of hard winter wheat bran

Recent consumer interest in controlling and preventing chronic diseases through improved diet has promoted research on the bioactive components of agricultural products. Wheat is an important agricultural and dietary commodity worldwide with known antioxidant properties concentrated mostly in the bran fraction. The objective of this study was to determine the relative contributions of genotype (G) and growing environment (E) to hard winter wheat bran antioxidant properties, as well as correlations of these properties to growing conditions. Bran samples of 20 hard winter wheat varieties grown in two locations were examined for their free radical scavenging capacities against DPPH, ABTS cation, peroxyl (ORAC), and superoxide anion radicals and chelating properties, as well as their total phenolics and phenolic acid compositions. Results showed significant differences for all antioxidant properties tested and multiple significant correlations between these properties. A factorial designed analysis of variance for these data and pooled previously published data showed similar results for four of the six antioxidant properties, indicating that G effects were considerably larger than E effects for chelating capacity and DPPH radical scavenging properties, whereas E was much stronger than G for ABTS cation radical scavenging capacity and total phenolics, although small interaction effects (GxE) were significant for all antioxidant properties analyzed. Results also showed significant correlations between temperature stress or solar radiation and some antioxidant properties. These results indicate that each antioxidant property of hard winter wheat bran is influenced differently by genotype and growing conditions.     

Phenolic Content and Antioxidant Activity of Pearled Wheat and Roller‐Milled Fractions

Wheat contains phenolic compounds concentrated mainly in bran tissues. This study examined the distribution of phenolics and antioxidant activities in wheat fractions derived from pearling and roller milling. Debranning (pearling) of wheat before milling is becoming increasingly accepted by the milling industry as a means of improving wheat rollermilling performance, making it of interest to determine the concentration of ferulic acid at various degrees of pearling. Eight cultivar samples were used, including five genotypes representing four commercial Canadian wheat classes with different intrinsic qualities. Wheat was pearled incrementally to obtain five fractions, each representing an amount of product equivalent to 5% of initial sample weight. Wheat was also roller milled without debranning. Total phenolic content of fractions was determined using the modified Folin‐Ciocalteau method for all pearling fractions, and for bran, shorts, bran flour, and first middlings flour from roller milling. Antioxidant activity was determined on phenolic extracts by a method involving the use of the free radical 2,2‐diphenyl‐l‐picrylhydrazyl (DPPH). Total phenolics were concentrated in fractions from the first and second pearlings (>4,000 mg/kg). Wheat fractions from the third and fourth pearlings still contained high phenolic content (>3,000 mg/kg). A similar trend was observed in antioxidant activity of the milled fractions with ≈4,000 mg/kg in bran and shorts, ≈3,000 mg/kg in bran flour, and <1,000 mg/kg in first middlings flour. Total phenolic content and antioxidant activity were highly correlated (R² = 0.94). There were no significant differences between red and white wheat samples. A strong influence of environment (growing location) was indicated. Pearling represents an effective technique to obtain wheat bran fractions enriched in phenolics and antioxidants, thereby maximizing health benefits associated with wheat‐based products.