Whole wheat and white wheat flour— the mycobiota and potential mycotoxins

Mold growth has detrimental effects on the quality of flour and may result in mycotoxin contamination. The search for potential mycotoxins—almost 400 are known—is time-consuming and expensive. However, detailed knowledge about the mycobiota and especially the toxin producing fungi enables the effective search for these toxic fungal metabolites. Therefore, a whole wheat flour and a white wheat flour (type 405) were investigated for their total qualitative as well as quantitative mycobiota. Overall, 51 species belonging to 14 different genera could be isolated. Total fungal counts of the whole wheat flour amounted to 1833 molds while the white wheat flour contained 1730 cfu 2 g⁻¹. The mycobiota of both flours was dominated by Aspergillus spp. accounting for 84% and 77·3% of the isolations, respectively. Fungi of the genus Penicillium spp. occurred only to a minor degree: 8% of the isolations in whole wheat flour and 15% in white wheat flour. Aspergillus candidus was the most frequently encountered mold.Penicillium aurantiogriseum , Cladosporium cladosporioides, A. flavus, Eurotium herbariorum,P. griseofulvum , P. brevicompactum and P. viridicatum were isolated to a lesser degree. From the 3563 identified fungi 93·3% (32 species) belong to the group of toxigenic molds.     

Deoxynivalenol in wheat,maize, wheat flour and pasta: surveys in Hungary in 2008–2015

Among Fusarium mycotoxins, deoxynivalenol (DON) is the most common contaminant in case of cereals and cereal-based foods in Hungary. In this study, Hungarian wheat (n = 305), maize (n = 108), wheat flour (n = 179) and pasta (n = 226) samples were analysed (N = 818). The samples were collected during 2008–2015 in Hungary. Applied methods of analysis were enzyme-linked immunosorbent assay and liquid-chromatography coupled with a mass spectrometer. Results were compared and evaluated with Hungarian weather data. Among cereal samples, in 2011, wheat was contaminated with DON (overall average ± standard deviation was 2159 ± 2818 µg kg^?1), which was above the maximum limit (ML). In case of wheat flour and pasta, no average values above ML were found during 2008–2015, but higher DON contamination could be observed in 2011 as well (wheat flour: 537 ± 573 µg kg^?1; pasta: 511 ± 175 µg kg^?1).     

Small strain viscoelastic behaviour of wheat gluten – pentosan mixtures

Gluten and water-soluble pentosans were extracted from defatted flours of two different wheat cultivars, having different grain hardness and baking quality. The rheological behaviour of the hydrated gluten samples and the effect of arabinoxylan-rich fractions of water-soluble pentosans (WSP) on their viscoelastic properties were studied in shear by dynamic measurements. The hydrated gluten samples showed the typical viscoelastic behaviour of a transient network, approaching the plateau zone at low frequencies. The WSP had only a small impact on this behaviour, causing a reinforcement of the network, as shown by the increase of storage modulus (G), but also an increase in dissipative processes caused by a higher degree of structural rearrangements within the network, as shown by the higher frequency dependence of G and the higher value of the loss angle tangent. By interchanging the gluten and the WSP fractions of the two wheat varieties, it was shown that the observed effect was also dependent on the source from which the WSP originated. The glutens in the presence of WSP were also less sensitive to the thermal treatment than the glutens alone, as shown by the lower magnitude of variation of G with temperature.     

Dynamics of γ-aminobutyric acid in wheat flour bread making

The dynamics of the health-improving non-protein amino acid γ-aminobutyric acid (GABA) during bread making were studied. Wheat flour contains trace levels of GABA (<15 ppm) and ca. 160–175 ppm of its precursor, glutamic acid (GA). During dough mixing, the levels of both GA and GABA largely increased. While wheat flour endogenous glutamic acid decarboxylase (GAD) performs some minor conversion of GA into GABA, yeast is the main contributor to GABA formation. Comparison of amino acid levels of dough samples, without or with yeast, indicated that yeast favours both GA and GABA formation already during mixing. Fermentation decreased both GA and GABA contents, due to amino acid consumption by the yeast, which used more GA than GABA. Proofing and baking resulted in large GABA losses, the latter probably in Maillard browning reactions during baking. Thermal loss of GA was less pronounced than that of GABA. Breads contained only trace levels of GABA and ca. 90–130 ppm of its precursor. Exogenous supplementation of recombinantly produced GAD of Yersinia intermedia decreased GA levels in mixed and fermented dough and increased GABA levels. The highest GAD dosage used resulted in fermented doughs with ca. 300 ppm of GABA, i.e. three times higher than the level present in the reference sample (no GAD added). After baking, a significant GABA level was left in the bread samples (ca. 115 ppm) and GABA-enriched breads were obtained. Addition of sodium glutamate (100–380 ppm) to a bread recipe containing no added GAD clearly indicated that its precursor was not the limiting factor for GABA conversion during bread making since the resulting breads contained no GABA, or only trace levels (ca. 20 ppm).     

Benefits of β-xylanase for wheat biomass conversion to bioethanol

BACKGROUND: The efficiency of bioethanol production from wheat biomass is related to the quality of end products as well as to safety criteria of co‐products such as distiller's dried grains with solubles (DDGS). The inclusion of a new biocatalyst for non‐starch polysaccharide degradation in fermentation processes could be one of the solutions. The objective of this study was to evaluate the influence of β‐xylanases in combination with traditional amylolytic enzymes on the efficiency of bioethanol production and DON detoxification during fermentation of Fusarium‐contaminated wheat biomass with high concentration of deoxynivalenol (DON; 3.95 mg kg^?1). RESULTS: The results showed that the negative effect of Fusarium spp. on yield and quality of bioethanol could be eliminated by the application of Trichoderma reesei xylanase in combination with amylolytic enzymes. This technological solution allowed to increase the concentration of ethanol in the fermented wort by 35.3% and to improve the quality of bioethanol by decreasing the concentrations of methanol, methyl acetate, isoamyl and isobutyl alcohols. Mass balance calculations showed that DDGS was the main source of DON contamination, comprising 74% of toxin found in wheat biomass. By using new enzyme combination for wheat biomass saccharification, a higher level of detoxification (41%) of DON was achieved during the fermentation process. CONCLUSION: The addition of Trichoderma reesei xylanase played a positive role in bioethanol production from Fusarium‐contaminated wheat biomass, indicating that the yeast‐growing medium was enriched during the enzymatic treatment. Copyright © 2011 Society of Chemical Industry     

Mycotoxins’ evaluation in wheat flours used in Brazilian bakeries

Food Science and Biotechnology - The aim of this study was to evaluate the mycotoxicological quality of wheat flours used by bakeries from the North Region in Rio Grande do Sul state, Brazil,...     

A survey of β-glucan and arabinoxylan content in wheat

BACKGROUND: Dietary fibre lowers the risk of coronary heart disease and colorectal cancer. This survey quantifies mixed link β‐glucan (MBG) and arabinoxylan (AX) in wheat and investigates relationships between the grain carbohydrates. MBG and AX contents were measured in 500 and 200 wheat accessions respectively, including diploid, tetraploid and hexaploid genotypes comprising primitive, synthetic and elite lines. RESULTS: Overall, MBG contents ranged between 1.8 and 18.0 g kg^?1 grain dry weight. In wheat–barley addition lines and triticale hexaploids the levels were 9.0–11.3 and 3.5–9.6 g kg^?1 respectively. The amounts in synthetic wheats were nearer their tetraploid parents than their diploid parents. AX and total non‐starch polysaccharide (NSP) contents ranged from 23.7 to 107.5 g kg^?1 and from 31.7 to 136.7 g kg^?1 respectively. Linear regressions showed that the relationships of starch and grain weight with NSP glucose were stronger than those with AX. CONCLUSION: The results indicated insufficient genetic diversity in the germplasm surveyed to initiate a breeding programme to increase the amount of MBG in wheat grain to 20 g kg^?1, a level considered high enough to confer a 10–15% reduction in blood cholesterol. Copyright © 2011 Society of Chemical Industry     

Investigation of α-glucosidase inhibitory activity of wheat bran and germ

Postprandial hyperglycaemia is a primary risk factor in the development of Type 2 diabetes. α-Glucosidase inhibitors that reduce postprandial hyperglycaemia have a key role in the treatment of Type 2 pre-diabetic states and also have the potential to reduce the progression to complications of diabetes. Epidemiological studies showed that risk for Type 2 diabetes mellitus was decreased with consumption of whole grains. The bran and germ of whole wheat are major components of whole grain consumption and are widely accepted as important ingredients in many low glycaemic index (GI) foods. In this study, the α-glucosidase inhibitory activity of wheat bran and germ was investigated. The active compounds were screened using an in vitro enzyme-inhibitory assay guided fractionation. Potent α-glucosidase inhibitory compounds from wheat germ were identified as phosphatidic acids, 1,2-dilinoleoylglycero-3-phosphate and 1-palmitoyl-2-linoleoyl-glycero-3-phosphate. The low GI property of whole grain wheat could be attributed to these α-glucosidase inhibitory phosphatidic acids, which have the potential to prevent or treat Type 2 diabetes.     

Acrylamide–asparagine relationship in baked/toasted wheat and rye breads

Acrylamide in baked and toasted wheat and rye bread was studied in relation to levels of asparagine in flour, dough, bread and toasts. Asparagine was consumed during bread preparation resulting in reduced acrylamide content in the products. In wheat bread, 12% of the asparagine initially present in the flour (0.14 g kg^?1) remained after yeast fermentation and baking; for rye bread, 82% of asparagine remained after sourdough fermentation and baking. Asparagine present in untoasted wheat bread had totally reacted after hard toasting. Toasted wheat and rye bread slices contained 11–161 and 27–205 µg kg^?1 acrylamide, respectively, compared to untoasted wheat and rye bread with <5 and 7–23 µg kg^?1 acrylamide, respectively. The dietary intake of acrylamide from bread (untoasted) of 2 µg day^?1 is relatively low; however, acrylamide exposure from bread increases several fold for people eating toasted bread.     

Cereal fructosans: Part 2—Characterization and structure of wheat fructosans

Wheat fructosans were prepared from two different flours and separated according to degree of polymerization by gel permeation chromatography.The different fractions were quantified and characterized with regard to monomer carbohydrate composition. The tri-, tetra- and pentasaccharides made up about 50% of the total fructosan content.The structures of the trisaccharides were identified by gas chromatography/mass spectrometry. Two fructosan trisaccharides were found, neokestose and 6-kestose, along with raffinose.     

Occurrence of ochratoxin A in Canadian wheat shipments, 2010–12

Randomly selected domestic and export shipments (n = 1907) of Canadian durum and other wheat that occurred between 1 January 2010 and 31 December 2012 were analysed for ochratoxin A (OTA). The majority of samples did not contain OTA above the LOQ of 1 μg kg^–1. Only 37% of samples analysed contained quantifiable OTA; the median OTA of the positive results was 2.10 μg kg^–1. Canada Western Amber Durum shipments contained OTA more frequently, and at slightly higher concentrations, than Canada Western Red Spring wheat. For both wheat classes the frequency of OTA occurrence and mean concentrations appeared to increase in the lower grades, but these increases were not statistically significant. A periodic trend of a late summer increase of mean monthly OTA concentrations in shipments appears tied to the cycle of producer deliveries of wheat to primary grain elevators.     

Occurrence of deoxynivalenol and its 3-β-D-glucoside in wheat and maize

Deoxynivalenol-3-β-D-glucoside (D3G), a phase II plant metabolite of the mycotoxin deoxynivalenol (DON), occurs in naturally Fusarium-contaminated cereals. In order to investigate the frequency of occurrence as well as the relative and absolute concentrations of D3G in naturally infected cereals, 23 wheat samples originating from fields in Austria, Germany and Slovakia as well as 54 maize samples from Austrian fields were analysed for DON and D3G by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Both analytes were detected in all the 77 field samples. DON was found at levels from 42 to 4130 ng g^?1 (977 ± 1000 ng g^?1 on average). The D3G concentrations in all cereal samples were in the range 10–1070 ng g^?1 (216 ± 253 ng g^?1 on average), corresponding to about 5–46 mol% of their DON concentrations (15 ± 8 mol% on average).     

Morphological characterization of wheat powders, how to characterize the shape of particles?

A quantitative method was developed to evaluate the shape of wheat powder particles. The method relies on a dispersion system designed to scatter particles on a transparent glass slide. A digital image acquisition system based on specialized software was then used to analyze the acquired images. Particles (1000) were analyzed with respect to four shape factors (circularity, elongation, convexity, and compactness). Dispersion of experimental values characterizes the large heterogeneity in wheat flour particles’ shapes. The results demonstrate that small particles of wheat powders have more regular shape than big ones, due to possible erosion mechanisms occurred during milling.     

The Prevention and Elimination of Insects in Storage of wheat Grains by Gamma Irradiation

This article deals with radiation sensitivity and lethal dose on the main cereal insects such as:Oryzaephilus Surinamensis Linnaeus(OSL),Sitophilus Oryzae Linnaeus(SOL),Rhizopertha Dominica Fabricius(RDF)and Tribolium Castaneum Herbst(TCH)in China.The experiments showed that there was a difference in radiation sensitivity.Among four insects species,OSL had the least tolerance;the second was RDF;the next was SOL and TCH had the biggest tolerance.After radiation with 0,15KGY-0.3KGY all OSL were dead in 2 weeks,all SOL and RDF dead in 3 weeks and all TCH dead in 4 weeks.All eggs could not be incubated with 0.1KGY radiation dose and adults insects had no bearing ability with 0.1 KGY radiation.There was no negative effect on germination potential and germination percentage of wheat with less than 1.0 KGY radiation.The article deals with bioeffect and lethal dose on OSL,SOL,RDF and TCH by ^60Co gamma ray radiation and with wheat germination potential and germination percentage.The economical and reasonable conditions are found for the development of science and technology and to provide the basis for the commercial operation.     

Creating hypo-/nonallergenic wheat products using processing methods: Fact or fiction?

Wheat allergy is a potentiallylife-threatening disease that affects millions of people around the world. Food processing has been shown to influence the allergenicity of wheat and other major foods. However, a comprehensive review evaluating whether or not food processing can be used to develop hypo-/nonallergenic wheat products is unavailable. There were three objectives for this study: (1) to critically evaluate the evidence on the effect of fermentation, thermal processing, and enzyme or acid hydrolysis on wheat allergenicity so as to identify the potential for and challenges of using these methods to produce hypo-/nonallergenic wheat products; (2) to identify the molecular effects of food processing needed to create such products; and (3) to map the concept questions for future research and development to produce hypo-/nonallergenic wheat products. We performed literature research using PubMed and Google Scholar databases with various combinations of keywords to generate the data to accomplish these objectives. We found that: (1) food processing significantly modulates wheat allergenicity; while some methods can reduce or even abolish the allergenicity, others can create mega allergens; and (2) fermentation and enzymatic hydrolysis hold the most potential to create novel hypo-/nonallergenic wheat products; however, preclinical validation and human clinical trials are currently lacking. We also identify five specific research concepts to advance the research to enable the creation of hypo-/nonallergenic wheat products for application in food, medical, and cosmetic industries.     

Cookie making behavior of wheat–barley flour blends and effects on antioxidant properties

Refined wheat flour was replaced with whole barley flour at varying levels and the blends were evaluated for their cookie making behavior. The spread factor of cookies decreased as the proportion of barley flour increased while snap force and water activity increased significantly upto 114.7 N and 0.397 in only barley flour cookies. Increasing levels of barley flour lead to a significant decrease in L^∗ and b^∗ values of cookie dough. Peak viscosity (PV) and final viscosity (FV) increased significantly as the levels of barley flour increased. A significant increase in antioxidant activity (AOA), total phenolic content (TPC), metal chelating activity (MCA), reducing power (RP) and total flavonoid content (TFC) was observed as the proportion of barley flour increased. Baking lead to a significant decrease in TPC and TFC whereas AOA, MCA and RP increased. Baking lead to a significant increase in the non-enzymatic browning index of cookies.     

Effects of two barley β-glucan isolates on wheat flour dough and bread properties

The effects of wheat flour fortification with two different molecular weight barley β-glucan isolates (1.00 × 10⁵, BG-100 and 2.03 × 10⁵, BG-200) on the rheological properties of dough and bread characteristics, using flours from two wheat cultivars that differ in their breadmaking quality, have been examined. The farinograph water absorption of doughs and the moisture content and water activity of the breads increased with increasing β-glucan content; the β-glucan isolate with the higher molecular weight (BG-200) exerted a greater effect than did BG-100. The addition of β-glucans to the dough formula increased the development time, the stability, the resistance to deformation and the extensibility of the poor breadmaking quality doughs, as well as the specific volumes of the respective breads, exceeding even that of the good breadmaking cultivar. Furthermore, the colour of the bread crumbs got darker and their structure became coarser, whereas the bread crumb firmness decreased with increasing level of β-glucan addition. Generally, the BG-200 was more effective in increasing the specific bread volume and reducing the crumb firmness, especially when used to fortify the poor breadmaking quality flour. The results further indicate a requirement for optimisation of the fortified doughs (level and molecular size of the β-glucan) to maximise bread quality attributes (loaf volume, texture, and staling events).