Discrimination of Volatiles of Refined and Whole Wheat Bread Containing Red and White Wheat Bran Using an Electronic Nose

Abstract: The principal objective of this study was to evaluate the capability of electronic (E) nose technology to discriminate refined and whole wheat bread made with white or red wheat bran according to their headspace volatiles. Whole wheat flour was formulated with a common refined flour from hard red spring wheat, blended at the 15% replacement level with bran milled from representative samples of one hard red and 2 hard white wheats. A commercial formula was used for breadmaking. Results varied according to the nature of the sample, that is, crust, crumb, or whole slices. Bread crust and crumb were completely discriminated. Crumb of whole wheat bread made with red bran was distinct from other bread types. When misclassified, whole wheat bread crumb with white bran was almost invariably identified as refined flour bread crumb. Using crust as the basis for comparisons, the largest difference in volatiles was between refined flour bread and whole wheat bread as a group. When refined flour bread crust was misclassified, samples tended to be confused with whole white wheat crust. Samples prepared from whole bread slices were poorly discriminated in general. E‐nose results indicated that whole wheat bread formulated with white bran was more similar in volatile makeup to refined flour bread compared to whole wheat bread made with red bran. The E‐nose appears to be very capable to accommodate differentiation of bread volatiles whose composition varies due to differences in flour or bran type. Practical Application: Consumer preference of bread made using refined flour in contrast to whole wheat flour is partly due to the different aroma of whole wheat bread. This study used an electronic nose to analyze bread volatiles, and showed that whole wheat bread incorporating white bran was different from counterpart bread made using red bran, and was closer in volatile makeup to “white” bread made without bran. Commercial millers and bakers can take advantage of these results to formulate whole wheat flour with brans of preferred type in order to foster increased consumption of whole wheat products which confer many favorable health benefits.     

FLAVOR PROPERTIES OF PAN AND PITA BREADS MADE FROM RED AND WHITE HARD SPRING WHEATS

ABSTRACT

Red and white wheat comparisons have not always shown consistent flavor differences. The objective was to compare flavor properties of whole wheat pan and pita breads made from white and red Canadian hard spring wheats. Flavor attributes were defined by trained panelists who marked intensities using 15‐cm line scales. Pan bread made from BW275 and Kanata had significantly lower wheat and wheaty aftertaste intensity than AC Domain (red) and RL4863. Pita bread from Kanata had significantly higher sweet intensity than RL4858, Snowbird and AC Domain (red). Principal component analysis accounted for 74–75% of the variance in both bread types. Biplots showed that some of the white wheat breads tended to be sweeter with less wheaty and bitter with wheaty, bitter and sour aftertastes. Red wheat breads tended to be less sweet, more wheaty and bitter with wheaty, bitter and sour aftertastes. Higher wheaty flavor intensity was associated with visually darker breads.

PRACTICAL APPLICATIONS

The study revealed that there were distinct flavor differences in pan bread and pita bread made from red and white wheats. The sweeter and milder flavor observed for some white wheats could be a marketing advantage for these newly developed wheats. In pan and pita bread products targeted to consumers that dislike the often wheaty and bitter taste of whole wheat products made from red wheat, white wheat derived whole wheat products with their milder taste may be more acceptable.     

Arabinoxylan content and characterisation throughout the bread‐baking process

End‐use quality of wheat (Triticum aestivum L.) is influenced in a variety of ways by nonstarch polysaccharides, especially arabinoxylan (AX). The objective of this study was to track total and water‐extractable AX (TAX and WEAX, respectively) throughout the bread‐baking process, using wholemeal and refined flour. The TAX and WEAX content and the ratio of arabinose: xylose were assessed in flour, mixed dough, proofed dough and the bread loaf, which was separated into crumb, upper crust and bottom crust. Changes in TAX during the baking process differed between the refined flour and wholemeal samples, suggesting a change in the TAX availability which we ascribe to molecular interactions and heat treatment. WEAX content dramatically decreased during baking, suggesting that oxidative cross‐linkages rendered it unextractable. Higher levels of WEAX and lower levels of arabinose substitution were correlated with higher loaf volumes for refined flour among the hard wheat varieties. Having a better understanding of the importance of both WEAX content and arabinose substitution allows for directed breeding efforts towards improved hard wheat varieties for optimum bread baking.     

Carbohydrate Digestibility and Resistant Starch of Steamed Bread

Sixteen Australian hard and soft wheats and two U.S. hard wheats were milled into flours (break and reduction) for preparation of steamed breads. Chemical composition and rheological properties of the flour were determined. Steamed breads were analyzed for carbohydrate digestibility and resistant starch. There was no relationship between flour type, protein content and specific volume of steamed breads. Carbohydrate digestibility of steamed breads from soft wheat flour was higher than that of breads from hard wheat flour. Reduction flours produced steamed breads with higher carbohydrate digestibility than break flours. Resistant starch was higher in steamed breads from soft wheat flours than in those from hard wheat flours. Reduction flour produced higher resistant starch levels than break flours. Commercial white bread had resistant starch levels similar to those of steamed breads from soft wheat flour and hard wheat reduction flour.     

QUALITY ATTRIBUTES OF CANADIAN HARD WHITE SPRING WHEAT

Quality characteristics of five pilot‐scale milled Canadian hard white spring wheats were compared to a No.1 grade commercial composite Canada Western Red Spring (1CWRS) wheat. One metric ton of samples was milled on the Canadian International Grains Institute pilot Buhler mill (Buhler AG, Uzwil, Switzerland) into straight‐grade (SG), 85% and whole wheat flours. At the SG extraction level, the white wheats with their lighter colored seed coats had improved milling yields (up to 2.6%) and lower ash (0.01–0.09%) than the 1CWRS control wheat. Majority of white wheat flours had higher protein contents than the 1CWRS control flours for all flour extractions. Based on dough rheological properties of the flours, three of the white wheats (Kanata, Snowbird and BW 275 ) were equal to or better than the red 1CWRS control for nearly all farinograph and mixograph parameters at all flour extractions other than farinograph absorption. Two of the white wheat lines (RL 4863 and RL 4858 ) had excessively weak and overly strong dough properties, respectively. Evaluation of pan bread, bagels and tortillas showed that white wheats generally produced end‐products that were comparable or superior to 1CWRS and that their most significantly positive quality compared to 1CWRS was their substantially lighter colored end‐products.     

STEAMED BREADS MADE FROM COLORADO GROWN WHITE WHEATS

Seven Colorado grown white wheats and a commercial all-purpose flour were used to prepare Chinese steamed bread. Steamed bread doughs were made from 41.8% flour (200g per batch), 0.7% instant active dry yeast, and 57.5% water. Steamed breads were evaluated for specific volume (cm³/g), color of crumb and crust, texture using a texture analyzer, and by a subjective sensory evaluation.
Specific volume of steamed bread ranged from 3.3 to 3.6 cm³/g. There was no statistical significant difference in crust and crumb color among breads from all flour samples. Low peak force and area texture measurements which indicate softness, were correlated with high specific volume. Overall, the flours from Colorado grown white wheats were desirable for making steamed bread with one exception. The all-purpose commercial flour was found to be desirable for making steamed bread.     

Effects of Processing on Wheat Tortilla Quality: Benefits of Hard White Wheat

Hard white wheat was established as a new wheat class by Grain Inspection, Packers and Stockyards Administra- tion in 1990. Originally supplying a domestic niche market, several states, Kansas in particular, have steadily increased production and investme…     

The application of dextran compared to other hydrocolloids as a novel food ingredient to compensate for low protein in biscuit and wholemeal wheat flour

Wheat is primarily used for bread-making. However, fungal diseases, grain moisture at harvest and low-protein contents strongly influence the quality of the wheat flour, thus creating challenges for traders, millers and commercial bakers who struggle to produce consistently high-quality products. This paper address the replacement of low-protein/wholemeal flour functionality for bread-making purposes. Three hydrocolloids, xanthan gum, dextran and hydroxypropyl methylcellulose, were incorporated into bread recipes based on high-protein flours, low-protein flours and coarse wholemeal flour. Hydrocolloid levels of 0–5 % (flour basis) were used in bread recipes to test the water absorption. The quality parameters of dough (farinograph, extensograph, rheofermentometre) and bread (specific volume, crumb structure and staling profile) were determined. Results showed that xanthan had negative impact on the dough and bread quality characteristics. HPMC and dextran generally improved dough and bread quality and showed dosage dependence. Volume of low-protein flour breads were significantly improved by incorporation of 0.5 % of the latter two hydrocolloids. However, dextran outperformed HPMC regarding initial bread hardness and staling shelf life regardless the flour applied in the formulation.     

Investigation of product quality, sensory profile and ultrastructure of breads made from a range of commercial gluten-free flours compared to their wheat counterparts

Bread is a major staple food consumed daily in all parts of the world. A significant part of the human population cannot tolerate gluten, a storage protein found in wheat, rye and barley, and therefore, products made from alternative cereals are required. During this study, the bread-making potential of seven gluten-free flours, wheat and wholemeal wheat flour was compared. Fermentation potential of the different flours was determined, showing that dough development height of gluten-free and wholemeal wheat samples was lower than for wheat and oat flour. Apart from standard bread quality parameters such as loaf-specific volume and physical crumb texture, also water activity and shelf life have been determined. The shelf life of gluten-free breads was reduced compared to wheat bread. Aroma profiles were evaluated by a trained panel. Wheat, oat and wholemeal wheat breads were liked moderately, while the remaining samples had lower liking scores. Crumb grain characteristics were investigated using image analysis, and microstructure was observed by scanning electron microscopy. Overall, only breads produced from oat flour were of similar quality to wheat bread, and the utilization of buckwheat, rice, maize, quinoa, sorghum and teff flours resulted in breads of inferior quality.     

Wheat bran particle size effects on bread baking performance and quality

Commercial hard red spring, hard red winter, soft white and durum wheat brans were used to evaluate the particle size effect of wheat bran on bread baking performance and bread sensory quality. Three different particle size bran samples were obtained from each bran by grinding, not by sifting, the bran samples. The bran samples were similar in chemical composition, but different in particle sizes. Results of baking experiments showed that breads containing fine bran had lower specific loaf volume and darker crumb colour than breads containing coarse or medium size bran. Sensory test panellists found that fine bran contributed smoother crust appearance and less gritty mouthfeel than the coarse bran. The sensory panel also indicated that breads containing soft white wheat bran had significantly better flavour and mouthfeel than breads containing hard red spring wheat bran. © 1999 Society of Chemical Industry     

Hard Winter Wheat and Flour Properties in Relation to Breadmaking Quality of Straight-dough Bread： Flour Particle Size and Bread Crumb Grain

Samples of 12 hard winter wheats and their flours that produced breads varying in crumb grain scores were studied for 38 quality parameters including： wheat physical and chemical characteristics; flour ash and protein contents, starch damage, swelling power, pasting characteristics, and flour particle size distribution; dough properties determined by a mixograph; and breadmaking properties for pup loaves （100g flour）. Only two parameters, the protein content of wheat and the granulation of flour, showed significant correlations with bread crumb grain scores. Protein content of wheat ranging 12.9%- 14.5% determined by an NIR method showed a weak inverse relationship （r =-0.61, p〈0.05） with bread crumb grain score. Flour particle size distribution measured by both Alpine Air Jet Sieve and NIR methods revealed that the weight wt % of particles less than 38 μ m in size and representing 9.6% - 19.3 % of the flour weights was correlated positively （r =0.78, p 〈 0.01） with crumb grain score, whereas wt % of flour particles larger than 125μm had an inverse relationship （r =-0.60, p〈0.05） with crumb grain score.     

Effect of preharvest applied herbicides on breadmaking quality of hard red spring wheat

Certain herbicides can be applied prior to harvest for weed control in wheat. Research was conducted to determine the effect of preharvest applications of glyphosate, paraquat and metsulfuron + 2, 4‐D on grain, flour and the breadmaking quality of hard red spring wheat. Herbicides were applied at soft dough (SD), ～500 g kg^?1 kernel moisture and hard dough (HD), ～350 g kg^?1 kernel moisture stages of ‘Parshall’ hard red spring wheat. Test weight was reduced 1.3 and 2.3 kg hl^?1, 1000 kernel weight was reduced 3.5 and 4.5 g, and large kernel content was reduced 230 and 280 g kg^?1 by glyphosate and paraquat respectively when applied at SD. Metsulfuron + 2, 4‐D did not affect physical grain quality. Glyphosate and paraquat applied at SD and HD increased gluten index two to eight units. Metsulfuron + 2, 4‐D reduced the gluten index four units when applied at SD. Dough mixing stability was increased 1.7 min by glyphosate applied at SD or HD, and by paraquat applied at SD. Dough mixing time during bread making was 0.5 min longer with flour from wheat treated with glyphosate and was 0.4 min shorter with flour from wheat treated with Metsulfuron + 2, 4‐D at SD. Loaf volume, symmetry and crumb score were not affected by herbicide treatments. Copyright © 2004 Society of Chemical Industry     

Nutritional and quality aspects of wheat sourdough bread using L. luteus and L. angustifolius flours fermented by Pedioccocus acidilactici

Lupine has the potential to be a new domestic source of vegetable protein due to its comparable quality to the commonly used soy proteins. However, the bioprocessing that take place in the production of wheat bread with non‐conventional flours could play an important role. The wholemeal Lupinus angustifolius and Lupinus luteus flours were fermented by bacteriocin‐producing strain of Pediococcus acidilactici. The effect of lupine flour supplementation on wheat bread quality, sensory and safety criteria was studied. The lupine additives significantly decreased the quality of bread. The fermented L. luteus flour (10% of flour basis) had a slightly higher positive effect on the specific volume and crumb porosity (5.4%) and lowering of crumb hardness (9.5%) than those of L. angustifolius. In contrary, consumers rated higher for bread with L. angustifolius sourdough, which contributed to a stronger taste score. The levels of tyramine, histamine and putrescine (32.6–215.8, 20.8–96.7 and 33.7–195.2 mg kg^?1, respectively) do not present a health risk for consumers due to their relatively low levels in lupine fermented products. Bioprocessing used for wheat bread production with lupine flour additives could improve the nutritional profile of bread without increasing the risk of biogenic amine formation.     

Refrigerated dough quality: effect of environment and genotypes of hard red spring wheat

Refrigerated dough products use wheat flour as their primary ingredient, so the quality and chemical composition of the flour determine the quality of the final product. Six varieties of hard red spring wheat, grown in 3 locations in Minnesota, U.S.A., were evaluated for use in refrigerated dough products. Total arabinoxylan percentages in the flours ranged from 0.97 to 1.54. Xylanase activity of the flour was measured and ranged from 0.20 to 0.84 mU/g. An important factor in the suitability for refrigerated dough is the syruping during storage. A large amount of variability in dough syruping was observed among the varieties and locations when the extent of dough syruping was measured over a period of 10 d. The mean dough syruping on day 10 ranged from 2.05% to 14.83%. Despite the significant interaction effect of genotype and environment, 2 varieties, Glenn and Oklee, had lower dough syrup formation with greater stability across growing locations and storage days than other varieties. Practical Application: Refrigerated dough production is one of the fastest growing segments of the ready-to-use food industry. Well-formulated and processed refrigerated doughs are practical to consume and should stay fresh during extended periods of storage; thus, maintenance of dough quality during refrigeration is critical. This study was designed to perform the research on genotypic and environmental effects on variations in dough syruping during refrigeration storage of doughs from hard red spring wheats.     

Fate of ochratoxin A in the processing of whole wheat grains during milling and bread production.

Batches of whole wheat contaminated with ochratoxin A were produced by inoculation with Penicillium verrucosum under controlled conditions in the laboratory. The fate of ochratoxin was followed through initial cleaning, abrasive scouring of the outer grain coat, milling into wholemeal wheat or into 10 milled fractions. Bread was baked from both wholemeal flour and straight-run white flour. Concentrations of ochratoxin A in the cleanings, scourings, and the bran and offal fractions were increased, but reduced in the white flour. Scouring removed up to 44% of the ochratoxin A present, but only a small further loss occurred in the bread-making process. An overall reduction of about 75% could be achieved in white bread using a combination of cleaning scouring and removal of the bran and offal fractions. Maximum overall reduction in producing wholemeal bread was about 40%. The reduction in ochratoxin A that can be achieved must be considered in relation to economic constraints concerning the disposal of wasted grain. Appropriate strategies for the use or disposal of potentially highly contaminated cleanings, scourings, bran or offal must be established.     

Biscuit making properties of flours from hard and soft milling single variety wheats

Bench scale baking tests for two types of biscuits,¹ a hard sweet (HS) and a short sweet (SS), have been used to examine the biscuit making properties of a large number of flour samples from wheats grown in four consecutive years (1980–1983). Multiple regression models for prediction of biscuit properties using a range of standard cereal laboratory tests as independent variables on results from 1980–1981 harvest wheats confirmed earlier observations that such tests are of limited commercial value for biscuit flour specification. However the results of baking tests, with both types of biscuit, from single wheat varieties grown during 1981–1983 showed that flours from soft milling wheats (SMW) required less water to give biscuit doughs of standard consistency (measured instrumentally) than did flours from hard milling wheats (HMW). In addition biscuit doughs made with SMW flours gave greater oven spring, i.e. biscuits of lower bulk density, than doughs made from HMW flours. In each season the difference in the mean values of both parameters for flours milled from SMW and HMW was highly significant (P<0.001). With one exception the variability of the measured parameters within seasons was not significantly different between SMW and HMW. However within both SMW and HMW varieties highly significant differences (P<0.001) were observed between seasons for the mean values of both measured biscuit parameters. The effect of flour particle size on the biscuits was studied by regrinding a number of flours. With flours from both SMW and HMW reduction in particle size resulted in HS biscuits of higher density but SS biscuits of lower density.     

Selenium concentration and speciation in biofortified flour and bread: Retention of selenium during grain biofortification,processing and production of Se-enriched food

The retention and speciation of selenium in flour and bread was determined following experimental applications of selenium fertilisers to a high-yielding UK wheat crop. Flour and bread were produced using standard commercial practices. Total selenium was measured using inductively coupled plasma-mass spectrometry (ICP-MS) and the profile of selenium species in the flour and bread were determined using high performance liquid chromatography (HPLC) ICP-MS. The selenium concentration of flour ranged from 30 ng/g in white flour and 35 ng/g in wholemeal flour from untreated plots up to >1800 ng/g in white and >2200 ng/g in wholemeal flour processed from grain treated with selenium (as selenate) at the highest application rate of 100 g/ha. The relationship between the amount of selenium applied to the crop and the amount of selenium in flour and bread was approximately linear, indicating minimal loss of Se during grain processing and bread production. On average, application of selenium at 10 g/ha increased total selenium in white and wholemeal bread by 155 and 185 ng/g, respectively, equivalent to 6.4 and 7.1 μg selenium per average slice of white and wholemeal bread, respectively. Selenomethionine accounted for 65–87% of total extractable selenium species in Se-enriched flour and bread; selenocysteine, Se-methylselenocysteine selenite and selenate were also detected. Controlled agronomic biofortification of wheat crops for flour and bread production could provide an appropriate strategy to increase the intake of bioavailable selenium.     

Comparative study of colorectal health related compounds in different types of bread: Analysis of bread samples pre and post digestion in a batch fermentation model of the human intestine

Seven different types of wheat and rye bread were analysed for colorectal health related compounds, pre and post digestion, in batch fermentation model of the human intestine. Pre digestion, higher amounts of colorectal health-related dietary fibre compounds (soluble/insoluble/total dietary fibre, arabinoxylans, β-glucans) and phytochemicals (mono-/di-phenolic acids, phytic acid, hydroxymethylfurfural) were detected in wholemeal than in refined flour types of bread, as well as in rye flour types than in wheat flour types of bread. Post digestion, faecal bacterial metabolites of colorectal health promoting (acetate/propionate/butyrate, lactate, free mono-/di-phenolic acids) and impairing (amino metabolites, bile acid metabolites) activities were found in fermentation supernatants of bread samples. All types of bread positively affected faecal bacterial metabolism; among the different types of bread, the highest stimulation of organic acid production (acetate/propionate/butyrate, lactate) and the lowest detrimental bacterial enzyme activities (β-glucuronidase, urease) were detected for wheat flour bread, whereas the strongest retardation of bacterial bile acid degradation and the strongest stimulation of phenolic acid metabolite release (phenylpropionic/phenylpropenoic acid derivatives) were induced by wholemeal rye bread. This study for the first time presents a qualitative and quantitative overview over the broad spectrum of colorectal health related compounds in high- and low-fibre types of bread, pre and post in vitro digestion, and highlights the significance of bread for the preventive nutritional intervention of colorectal cancer.     

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