Distribution of phenolic compounds in the graded flours milled from whole buckwheat grains and their antioxidant capacities

Whole buckwheat grains were milled into 16 flour fractions using the gradual milling system and the phenolic compounds and the antioxidant capacity of each flour fraction were investigated. The phenolic and flavonoid contents of both free and bound phenolic extracts of buckwheat flour fractions significantly increased in the order from the fraction number 1 (phenolics less rich fraction) to the fraction number 16 (phenolics rich fraction). The phenolic compounds in buckwheat existed primarily in free form, whereas the flavonoids existed in grain in insoluble bound forms, bound to cell wall materials. The amounts of ferulic acid and rutin increased from 2.5 and 2.5 μg/g flour of the phenolics less rich fraction to 609.5 and 389.9 μg/g flour of the phenolics rich fraction of grain, respectively. The higher phenolic contents in the phenolics rich fractions exhibited the stronger antioxidant capacity than the phenolics less rich fractions. As a result, the flour milled from the outer layers of buckwheat grains with large amount of phenolic compounds and antioxidant capacity are considered to have significant health benefits.     

Characteristics of fractionated flours from whole buckwheat grain using a gradual milling system and their application for noodle making

BACKGROUND: Recently, the quality of buckwheat (Fagopyrum esculentum, Moench) flour was improved by using a gradual milling method in which whole buckwheat grains were milled into various fractions. In this study, 16 fractions milled from whole buckwheat grains from the outer to inner parts are characterised and used for noodle making. RESULTS: Protein and ash contents of flours increased in the order from the inner to the outer fractions. Each fraction contained nine main fatty acids in which the concentration of palmitic, stearic, linoleic and linolenic acids tended to decrease from the inner to outer parts of the grain, whereas the concentration of oleic acid in the middle parts of grain was higher than in the other parts. The peak viscosity was different among the fractions and the middle fractions had significantly higher peak viscosity than the other fractions. The optimum cooking time and whiteness of uncooked and cooked noodles substituted with 40% of the fractions decreased from the inner to outer fractions, whereas noodles made from the inner fractions were harder and less elastic than those from the outer fractions. CONCLUSION: The different buckwheat fractions contributed to different quality of soba noodles. However, the appropriate fractions could be used for noodle making to improve the quality of noodles depending on nutritional demands. Copyright © 2007 Society of Chemical Industry     

Antioxidant and free radical scavenging activities of whole wheat and milling fractions

The effects of milling on the phenolic content and antioxidant capacity of two wheat cultivars, namely CWAD (Canadian Western Amber Durum; Triticum turgidum L. var. durum) and CWRS (Canadian Western hard red spring; Triticum aestivum L.) were studied. The milling of wheat afforded several fractions, namely bran, flour, shorts and feed flour. In addition, semolina was the end-product of durum wheat milling. Among different milling fractions the bran had the highest phenolic content while the endosperm possessed the lowest amount and this was also reflected in free radical and reactive oxygen species (ROS) scavenging capacity, reducing power and iron (II) chelation capacity of different milling fractions in the two cultivars. This study demonstrated the importance of bran in the antioxidant activity of wheat, hence consumption of whole wheat grain may render beneficial health effects.     

Effects of germination on nutritional composition of waxy wheat

BACKGROUND: Germination is considered to improve the nutritive value, antioxidant capacity and functional properties of grains. In this study, changes in the chemical composition, nutritive value and antioxidant capacity of waxy wheat during germination were determined. RESULTS: Over a 48 h period of germination the protein and free lipid contents of germinated waxy wheat were not significantly different from those of the control, whereas the bound lipid content decreased significantly. An increase in levels of ash and dietary fibre was clearly observed for the 48 h‐germinated wheat. The total free amino acid content of the 48 h‐germinated wheat was 7881 mg kg^?1 flour (dry basis (d.b.)), significantly higher than that of the ungerminated wheat (2207 mg kg^?1 flour, d.b.). In particular, γ‐aminobutyric acid increased from 84 mg kg^?1 flour (d.b.) in the control to 155 mg kg^?1 flour (d.b.) in the 48 h‐germinated wheat. Germination did not significantly affect the fatty acid composition of both free and bound lipids of waxy wheat, whereas free phenolic compounds increased during germination, resulting in an increase in antioxidant capacity of germinated wheat. CONCLUSION: Germinated waxy wheat had a better nutritional composition, such as higher dietary fibre, free amino acid and total phenolic compound contents, than ungerminated waxy wheat. Therefore germinated waxy wheat should be used to improve the nutritional quality of cereal‐based products. Copyright © 2011 Society of Chemical Industry     

Antioxidant properties of commercial soft and hard winter wheats (Triticum aestivum L.) and their milling fractions

The total phenolic content (TPC), total antioxidant activity (TAA), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) scavenging capacity, inhibition of coupled oxidation in a β‐carotene–linoleate model system, iron(II) chelation activity and inhibition of copper‐induced oxidation of human low‐density lipoprotein (hLDL) cholesterol of 80% ethanolic extracts of soft and hard winter wheat samples and their milling fractions, namely flour, germ, bran and shorts, were investigated. Soft wheat extracts examined demonstrated higher TPC and TAA compared to those of hard wheat extracts. The germ fraction possessed the highest TPC, followed by bran, shorts, whole grain and flour for both wheat types examined. The TAA of both wheat types showed similar results except that shorts performed better than bran in this assay. Free radical scavenging properties of whole grain and milling fractions of both soft and hard wheat samples were examined against DPPH radical. The germ and flour fractions demonstrated the highest and lowest DPPH radical scavenging activity, respectively, among wheat fractions. Wheat extracts were also efficient in preventing bleaching of β‐carotene, which is also known to be free radical mediated. In the iron(II) chelation assay the flour extracts demonstrated excellent activity, while the germ extracts showed a weak activity. The trends were similar in both soft and hard wheat for the iron(II) chelation assay. Wheat extracts also inhibited copper‐induced oxidation of hLDL. In LDL oxidation assay, wheat extracts performed better than the reference antioxidant, ferulic acid. Thus wheat phenolics may serve as effective antioxidative components as measured by in vitro techniques. Copyright © 2005 Society of Chemical Industry     

Dough properties and breadmaking qualities of whole waxy wheat flour and effects of additional enzymes

BACKGROUND: Waxy wheat, a new kind of genetically back‐crossed wheat, was applied to make whole bread in this study. Dough properties and bread quality of the whole waxy wheat flour, which was milled from 100% whole grains containing bran and germ, were determined. RESULTS: Whole waxy wheat had lower protein and lipid contents but higher dietary fiber content than whole regular wheat flour. Pasting temperature and viscosity of the whole waxy wheat flour were significantly lower than those of the whole regular wheat. However, the white wheat flour milled from wheat grains with 48% recovery had significantly higher peak viscosity than the whole waxy wheat. Bread made from the whole waxy wheat flour was significantly softer than that from the whole regular wheat flour during storage. However, bread made from whole waxy wheat had significantly lower specific volume than that from the white waxy flour because of the high amount of dietary fiber. Addition of cellulase increased paste viscosity, lowered dough mixing properties and reduced the firmness of the bread. The addition of pentosanase also increased paste viscosity, lowered dough mixing properties, improved loaf volume of bread but increased the firmness of breadcrumbs, while the addition of α‐amylase only increased final viscosity of flour and did not affect dough properties and bread qualities of whole waxy wheat flour. CONCLUSION: As a result, waxy wheat shows superior properties for making whole breads. Additional enzymes are also necessary to improve bread quality and nutritive values of whole waxy bread. Copyright © 2007 Society of Chemical Industry     

Antioxidant activity of commercial buckwheat flours and their free and bound phenolic compositions

Commercial buckwheat flours were investigated for their antioxidant activities, free, and bound phenolic compositions using spectrophotometer, LC–ESI-IT-MS, and LC–ESI-Q-TOF-MS. Farinetta flour contained the highest free and bound phenolic contents, followed by Supreme, whole buckwheat, and Fancy flour, respectively. The 50% ethanol extraction achieved significantly higher free phenolic content compared with water and absolute alcohol. The absolute ethanol extraction contained considerable more bound phenolic and flavonoid compounds. A high extraction temperature increased the phenolic contents. The optimal solvent to solids ratio was 50:1, and the optimal extraction time was 5 h for flavonoids. The spectral method was reproducible for analysing the total flavonoid contents. The LC–ESI-Q-TOF-MS studies on whole buckwheat flour showed that p-coumaric and gallic acids were found in the bound phenolics along with isoquercitrin but were not present in the free phenolic compounds. The free flavonol-glycosides were found in whole buckwheat flour but not in any other buckwheat flours.     

Distribution of deoxynivalenol and nivalenol in milling fractions from fusarium-infected Japanese wheat cultivars

The fate of the Fusarium mycotoxins deoxynivalenol and nivalenol during the milling of Japanese wheat cultivars artificially infected with Fusarium was investigated. Grain samples with different mycotoxin concentrations were milled using a laboratory-scale test mill to produce eight fractions: three breaking flours (1B, 2B, and 3B), three reduction flours (1M, 2M, and 3M), wheat bran, and wheat shorts. Patent flour for human consumption was made from the 1B, 2B, 1M, and 2M flours, and low-grade flour was made from 3B and 3M flours. The four resulting samples (patent flour, low-grade flour, bran, and shorts) were analyzed for deoxynivalenol and/or nivalenol with an in-house validated analytical method using high-performance liquid chromatography with UV absorbance detection. In samples with different mycotoxin concentrations, the distribution of those toxins differed among the milling fractions. Grains with a lower level of contamination produced bran and shorts samples with a high relative concentration of nivalenol. A high percentage of nivalenol was found in patent flour, followed by bran. Contrary to the less-contaminated sample, the concentration of nivalenol in moderately contaminated grain was high only in the shorts sample. The highest percentage of deoxynivalenol and nivalenol was observed in the patent flour. The results of this study indicate that the distribution of deoxynivalenol and nivalenol in milled Japanese wheat could be influenced by the contamination level of the original grain, and the milling process is not always effective for removal of toxins from wheat grains.     

Functional Characteristics of Sprout-Damaged Soft White Wheat Flours

Soft white wheat was sprouted in the laboratory for 1, 2 and 4 days, respectively, before milling the wheat into flours. The flours were used to bake cakes and cookies and to determine thickening powers. The flours milled from wheat which had been sprouted for 2 or 4 days were slightly higher in ash and protein and darker in color than the flour from the sound wheat. Sprouting of the grain for longer than 1 day resulted in flours of poor cake baking quality. The cakes were low in volume, had a dip in the center, a coarse grain and a firm texture. Cookie spreads increased and cookie top grain score improved with longer times of sprouting of the grain, but the crust color of the cookies darkened. The flavor was not affected by sprouting. The thickening power of the sprout-damaged soft wheat flours decreased with time of sprouting of the soft wheat before milling into a flour. Generally, laboratory sprouting of soft white wheat had an adverse effect on the functionality of flours in soft wheat applications. Effects of field sprouting on soft wheat flour performance are expected to be similar to those observed with laboratory sprouted soft wheat.     

Preparation of β-glucan and antioxidant-rich fractions by stone milling of hull-less barley

Stone milling of hull-less barley in combination with size-based separation of the milled fractions was used for preparation of flours with different compositions of macronutrients and bioactive compounds. According to similar compositions, specific milled fractions were combined to define three flours. The flour with the largest mass fraction (~70%) comprised particle sizes < 124 μm, which showed lower fibre, residual ash and antioxidant contents than the unfractionated flour. The flour with particles from 124 to 250 μm (~20% mass fraction) had >twofold greater β-glucan content, and the flour with particles > 250 μm (~10% mass fraction) had >threefold greater content of antioxidants than unfractionated flour. Each of these three flour fractions represents valuable material that can be incorporated into bakery products to enhance functional and health-related properties. Large enrichment factors of bioactive compounds in barley flours can be obtained using small-scale and widely available milling equipment.     

Effect of different milling methods on chemical composition of whole wheat flour

In order to assess the effect of different types of milling methods on protein and lipid composition of whole wheat flour, two types of wheat varieties belonging to strong and weak wheat type were selected and milled in different mills such as plate, hammer, stone and roller mills. The temperatures generated during grinding of wheat in stone, plate, hammer and roller mills were 90, 85, 55 and 35 °C respectively. The studies on SDS-PAGE indicated degradation in proteins of whole wheat flour obtained from stone and plate mills, especially in the high molecular glutenin regions. Greater loss of total amino acids was also observed in the above milled flours when compared with that of hammer and roller milled samples. Free lipid content was lower in flours milled in stone and plate mills when compared with that of flours milled in other mills. Unsaturated fatty acid content, particularly linolenic acid, was lower in stone milled flour (1.3%) followed by plate mill (2.2%), hammer mill (2.8%) and roller flour mill (3.8%). The trends in the above values as influenced by different milling methods remained similar both in the weak and strong wheat types.     

Effects of fiber addition on antioxidant capacity and nutritional quality of wheat bread

Wholegrain and high fiber foods are recognized as nutritious and healthful products due to their content of dietary fiber, antioxidants and bioactive compounds. In this study, wheat, rye, barley, oat wholegrain flours and two fibers namely cellulose (insoluble fiber) and xanthan gum (soluble fiber) were used to replace a portion of wheat flour in pan bread to study effects of fibers on phenolic compounds, antioxidant capacity, dietary fiber fractions, and starch digestibility in vitro. Incorporation of wholegrain flours increased free and bound phenolics and antioxidant capacity of all the breads examined to various extent depending on the source of fiber. Additionally, soluble, insoluble and total dietary fiber fractions and total minerals increased with the addition of wholegrain flours or fibers. Rapidly and slowly digestible and resistant starches were not significantly influenced by adding wholegrain flours or fibers to breads. The study demonstrates the importance of enriching wheat bread with wholegrain flours to boost antioxidants and dietary fibers. On the other hand, more research is required to better understand impact of wholegrain flours or fiber on starch digestibility in vitro and glycemic response.     

Enrichment of Antioxidant Capacity and Vitamin E in Pita Made from Barley

This study aimed to enhance total antioxidant and vitamin E content of pita bread, by replacing 50% of the standard baker's flour with flours milled from covered (WI2585 and Harrington) or hulless (Finniss) barley genotypes, previously shown to have high antioxidant and vitamin E levels at harvest. Pita breads were made from either 100% baker's flour (control) or 50% malt flour, whole‐grain flour, or flour from barley grains pearled at 10%, 15%, and 20% grain weight. Antioxidant capacity and vitamin E content of flours and pitas were determined by their ability to scavenge 2,2‐diphenyl‐1‐picrylhydrazyl radicals and high performance liquid chromatography, respectively. The physical and sensory properties of the pitas were also assessed. All pitas made from either whole grain or pearled barley flour had a higher antioxidant capacity and most also had higher vitamin E content than standard pita. The antioxidant and vitamin E levels were reduced in pearled compared to whole grains, however the extent of that reduction varied among genotypes. The greatest antioxidant and vitamin E levels were found in pita made from malt flour or Finniss whole grain flour. Furthermore, sensory analysis suggested these pitas were acceptable to consumers and retained similar physical and sensory properties to those in the control pita.     

Phenolics from walnut (Juglans regia L.) kernels: Antioxidant activity and interactions with proteins

Walnut (Juglans regia L.) kernels have important amounts of phenolic compounds. The objectives of the work were twofold: (a) to extract the phenolic fraction from hulls and walnut flour, and to examine its antioxidant capacity and (b) to evaluate the effect of hull removal on solubility of protein fractions from walnut flour. In accordance with their higher total phenolic content, hull extracts had stronger antioxidant activity than had flour extracts. The presence of phenolic compounds decreased protein solubility in walnut flour obtained from whole kernels. Dehulling of kernels significantly improved protein recovery but this result was strongly affected by the solvent system employed. Proteins from whole kernels, especially those extracted with water and NaCl solution, had a reduced solubility, indicating that phenolics bind to proteins when they are dispersed in aqueous media at neutral pH. The results are discussed in the light of the different complex-forming mechanisms that bind phenolics to proteins.     

Studies on distribution of protein and allergen in graded flours prepared from whole buckwheat grains

Buckwheat (Fagopyrum esculentum Moench) is one of the traditional crops and has become a renewed target of interest or a popular crop as a healthy foodstuff, because it is a good source of cereal protein which is rich with essential amino acids. However, what is critical to our health is that buckwheat contains proteins which cause a hypersensitive reaction (allergy). In this study, to decrease the allergenic activity of buckwheat products, some graded flours were prepared from various portions of buckwheat grain, and its protein distribution and characteristics of each graded flour fractions were determined. The protein and ash contents of all buckwheat fractions increased in the order from the inner fraction to the outer fraction. From SDS–PAGE patterns, the concentrations of 15, 22, 35, 39 and 50 kDa proteins of the inner fractions were lower, and there were clear differences in the protein compositions between the inner and outer buckwheat flour fractions. Detection of allergenic proteins by IgE-immunoblotting showed that sera pooled from 9 patients reacted with proteins of 15 and 22 kDa bands, named Fag e 2 and Fag e 1, respectively. IgE binding activities of proteins, Fag e 1 or Fag e 2 of the inner fractions were weaker than those of the outer fractions. Therefore, the inner fractions without major allergic proteins could be separated from whole buckwheat grains, and also expected to be applied to manufacturing processed foods with low allergen. Furthermore, the graded-milling procedure could be used to provide less-allergenic buckwheat flours.     

Effects of toasting on the carbohydrate profile and antioxidant properties of chickpea (Cicer arietinum L.) flour added to durum wheat pasta

The effects of the toasting process on the carbohydrate profile and antioxidant properties of chickpea flour were studied, along with the cooking behaviour, and antioxidant and nutritional properties of pasta enriched with the chickpea flour. The toasting process increased the resistant starch, insoluble dietary fibre and antioxidant properties of the flour. Addition of chickpea flour (raw and toasted) to durum wheat semolina changed the carbohydrate profile in the uncooked and cooked enriched pasta, especially with the toasted chickpea, and worsened the overall quality of the pasta. The increase in total phenolic content and total free phenolic acid content in the uncooked pasta was due to positive effects of addition of the chickpea flours, while the increase in the bound phenolics fraction in the cooked pasta was from the durum wheat, which was crucial for its high concentrations of ferulic acid. The increase in the free fraction of the Trolox equivalent antioxidant capacity in cooked pasta was consistent with the addition of chickpea.     

Can the sprouting process applied to wheat improve the contents of vitamins and phenolic compounds and antioxidant capacity of the flour?

The content of tocopherols, B vitamins, as well as free soluble, soluble conjugated and insoluble bound phenolic compounds was determined in untreated, steeped and sprouted wheat grains. Antioxidant capacity of whole wheat grains and their phenolic fractions was also evaluated. Sprouting significantly increased the levels of tocopherols, niacin, riboflavin, as well as free and bound phenolic compounds improving nutritional value and antioxidant capacity of wheat grains/flour. After sprouting for 5 days, the content of total phenolics, flavonoids and ferulic acid calculated as the sum of its fractions was increased by 9.9, 30.7 and 21.6%, respectively. The content of α‐, β+γ‐ and δ‐tocopherols was increased for 3.59‐fold, 2.33‐fold and 2.61‐fold respectively, while the content of niacin, as predominant B vitamin, was increased for 1.19‐fold after sprouting. The total antioxidant capacity of untreated, steeped and sprouted whole wheat grains was 19.44, 20.37 and 22.70 mmol Trolox Eq/kg, respectively. Sprouted wheat, as a rich source of bioavailable phytochemicals, should be used to improve the nutritional quality of food.     

Effects of particle size in wasted bread flour properties

Bread is wasted at different stages in the food value chain, mainly in industry and retail markets. Wasted bread can be milled into flour to be used in the elaboration of other food products. Milling can generate flours with different particle sizes that influence their properties. This study analysed the effect of particle size (200, 500 and 1000 μm) on the hydration, pasting and gel properties of flours elaborated with four different stale breads. Bread flours show a higher cold water absorption capacity and a lower oil absorption capacity than wheat flour. No differences in water absorption properties after heating were observed. The viscosity curves of bread flours presented lower values than wheat flour curves, and the gels obtained were weaker. Bread flour properties were not influenced by different particle sizes. Therefore, a less aggressive milling, with a lower energy cost, can generates flours with properties similar to finer flours.     

Evaluation of the performance of flours from cross- and self-pollinating Canadian common buckwheat (Fagopyrum esculentum Moench) cultivars in soba noodles

Two Canadian cross-pollinating common buckwheat (Fagopyrum esculentum Moench) varieties, Koban and Koto, and two self-pollinating lines, BR01 and BR06, were dehulled and roller milled on a pilot mill to produce three distinct milled products, white flour, dark flour and whole groat flour. The white flours contained mostly starch (79.2–87.2%), whereas the dark flours were rich in proteins (37.1–38.7%), dietary fibre (15.2–22.0%), ash (5.49–5.99%), and fagopyritols (1420–2220 mg/100 g). The buckwheat flours were blended with wheat flour (Canada Western Red Spring straight grade flour) at 60:40 ratios and evaluated for soba noodle properties. Significant differences in milling properties, and in raw noodle colour and texture were detected among cultivars, although the impact of flour type on noodle properties was far greater. The self-pollinating lines exhibited comparable milling and soba noodle properties to Koban. Koto exhibited slightly higher white flour yield and generally firmer noodle texture compared to the other lines. White flours produced the brightest noodles, followed by whole groat and dark flours. Dark flours yielded the thickest cooked noodles with the largest maximum cutting stress and greatest resistance to compression. Noodles prepared with white flour offered the best chewiness, springiness and recovery parameters. Soba noodles prepared with dark flours contained considerably higher amounts of minerals, proteins, dietary fibre, and fagopyritols than noodles prepared with white flour.     

藜麦粉营养成分及抗氧化活性研究

以不同藜麦品种的原粮粉与脱皮粉为实验材料,对其主要营养成分、总酚、总黄酮含量及抗氧化活性进行测定。结果表明,不同藜麦品种的营养成分存在一定差异。3种原粮粉的粗蛋白、总淀粉含量显著低于脱皮粉,灰分含量显著高于脱皮粉(P0.05);原粮粉与脱皮粉的之间粗脂肪、粗纤维含量没有明显差异。原粮粉中总酚、总黄酮及皂甙含量均高于脱皮粉,格尔木原粮粉的总酚(1.70 mg GRE/g)、总黄酮(2.08 mg RE/g)及皂甙(10.38 mg OAE/g)含量最高,海藜脱皮粉的总酚(1.13 mg GRE/g)、总黄酮(0.76 mg RE/g)及皂甙(6.55 mg OAE/g)含量最低。不同品种间脱皮粉及原粮粉的抗氧化活性存在显著差异(P0.05),藜麦原粮粉提取物的总抗氧化能力、DPPH·清除能力、ABTS~+·清除能力、铁离子还原力(FRAP)均显著高于脱皮粉(P0.05)。