Wheat preharvest herbicide application,whole‐grain flour properties,yeast activity and the degradation of glyphosate in bread

The aim of this study was to determine the effects of wheat preharvest application of a glyphosate‐based herbicide (Roundup WeatherMax^® with Transorb^® 2 Technology) on whole‐grain flour composition and properties, including yeast activity. The effect of dough fermentation on the degradation of herbicide residues was also estimated. Grain samples from two hard red spring wheat varieties exceeded the maximum residue limits (5 mg kg^?1) in Canada. Glyphosate had minor effects on wheat kernels composition and properties, including fructans content and yeast gassing power. No degradation of Roundup^® or pure glyphosate was seen after dough fermentation for up to 4 h and baking. These results call for more scientific studies on glyphosate residues in wheat.     

Spectrofluorimetric,spectrophotometric and chemometric analysis of wheat grains infested by Sitophilus granarius

Invisible infestation of wheat grains by Sitophilus granarius during postharvest handling is one of the main problems particularly for small enterprises and farm grain storage facilities due to the lack of cheap and fast methods for early detection of infestation, especially when only a small proportion of grain is infested by larvae. In order to determine whether the spectrofluorimetric, spectrophotometric or chemometric analysis of various extracts of wheat grains infested by S. granarius larvae could be used for detection of infested grain, four different types of extracts: 50 mmol dm⁻³ Tris–HCl pH 8.9, aqueous iso-propanol (φ = 0.55), methanol, and aqueous trichloroacetic acid (γ = 0.2 mg cm⁻³), of non-infested and infested wheat grains have been examined for fluorescence properties and UV/VIS spectral characteristics, while the chemometric analysis included determination of protein, reactive amino groups, polyphenols and soluble sugar content. Analysis of extracts revealed significant differences in UV/VIS spectral characteristics, level of reactive amino groups and polyphenol content between infested and non-infested grains. The results obtained indicate that instrumental analysis of spectral characteristics of grain extracts could be used as a method for determination of grain infestation.     

Comparative toxicity of nanostructured alumina and a commercial inert dust for Sitophilus oryzae (L.) and Rhyzopertha dominica (F.) at varying ambient humidity levels

The widespread concern for environmental and human health has raised the need for new reduced-risk control strategies and the search for new chemical classes of pesticides. Recently, a novel type of particulate material, nanostructured alumina (NSA) has been found to induce mortality in insects exposed to wheat treated with NSA dust. Preliminary studies have shown insecticidal activity of NSA particles on two insect species, Sitophilus oryzae (L.), and Rhyzopertha dominica, (F.), major pests of stored grain. We investigated the toxicity of NSA and Protect-It^® diatomaceous earth (DE) using dry dust applications at three different relative ambient humidity levels. Results showed that NSA was more effective in killing S. oryzae than Protect-It^® and was equally toxic to R. dominica. Treatment with both products also reduced progeny production. In addition, R. dominica was less susceptible to inert dusts than S. oryzae. Our results suggest that NSA might prove a good alternative or complement to DE based products, and encourage further testing with other insect pests and systems, plus experiments on delivery options to further enhance NSA products.     

The antioxidant activity and the composition of free and bound phenolic acids in dough of wheat flour enriched by Boletus edulis after mixing and thermal processing

The porcino is good source of phenolics and has been used to enrich wheat flour. The antioxidant activity and the content and composition of free and bound phenolic acids in the dough of wheat and porcino flour mixture (70:30 w/w) were investigated. The free form in the amount of 1305.76 μg g^?1 was the main part of the phenolic content in the flour mixture. By dough mixing, the content of free phenolics increased by approximately 70%. Further thermal processing decreased the content of both forms of phenolics compared to dough after mixing, but the content of free phenolics of 1764.24 μg g^?1 is still higher than in the flour mixture. The stability of the detected phenolic acids during mixing and thermal processing depended on whether they were in free or bound form. After thermal processing, the total content of detected phenolic acids was 683.31 μg g^?1, indicating that approximately 87% of the total content of phenolic acids detected in flour mixture was retained.     

Transglutaminase and tyrosinase as potential cross-linking tools for the improvement of rheological properties of gluten-free amadumbe dough

Gluten-free bread remains of poor quality despite efforts to amend gluten-free flours with ingredients such as hydrocolloids and proteins. Enzymatic modification of the proteins in dough may result in polymers that mimic gluten. This research investigated the effects of transglutaminase and tyrosinase on the rheological properties of amadumbe dough. Tyrosinase oxidation resulted in a 7.7–39.4% decrease in dough-free amine, and a 16.8–46.3% decrease in the dough thiol content as activity was increased from 0 to 80 U g⁻¹ flour. Transglutaminase treatment decreased the dough-free amino groups by 10–38.1% as activity was increased from 0 to 2 U g⁻¹ flour. Evidence of tyrosinase and transglutaminase-mediated cross-linking was provided by relevant model reactions monitored by mass spectrometry. An increase in dough G′ and G″ showed that both transglutaminase and tyrosinase improved dough viscoelasticity. The increase in the viscoelasticity of the dough potentially improves carbon dioxide retention during proofing.     

Effects of cultivar and soil fertility on grain protein yield,grain protein content,flour yield and breadmaking quality of wheat

Grain protein content affects the flour yield and breadmaking characteristics of wheat (Triticum aestivum L). In this study, grain protein yield, grain protein content, flour yield and loaf volume were quantified for four wheat cultivars (Inia, Carina, Kariega and SST 86) grown under six different soil fertility regimes in a long-term fertilisation and irrigation experiment at the University of Pretoria. The experimental design was a randomised complete block replicated four times, with fertility as the main plots and cultivars as the subplot treatments. Grain protein yield, flour yield, loaf volume and mixograph dough peak mixing time varied among cultivars and soil fertility situations. Grain protein content differed among cultivars, but mixograph water absorption and dough characteristics did not differ. The highest grain protein yield was 873 kg ha⁻¹ for Carina and the lowest 527 kg ha⁻¹ for SST 86. Grain protein content averaged 131 g kg⁻¹ for Carina and 122 g kg⁻¹ for Kariega. Breadmaking performance showed that in a well-balanced soil fertility situation, Kariega produced 1025 cm³ of loaf volume while Inia averaged 950 cm³. Grain protein yield increased with increasing soil fertility, but grain protein content, flour yield, loaf volume, water absorption and mixograph peak mixing time varied with soil fertility. The interaction between cultivar and soil fertility was significant for grain protein yield, grain protein content, flour yield, loaf volume and water absorption but not dough peak mixing time. The results indicate cultivar differences in breadmaking quality characteristics and that soil fertility status affects grain protein yield, grain protein content, flour yield, loaf volume potential and water absorption but not mixograph peak mixing time and dough characteristics. © 1999 Society of Chemical Industry     

Extract of Salicornia europaea in fresh pasta to enhance phenolic compounds and antioxidant activity

Extract from Salicornia europaea was added to durum wheat fresh pasta. Sensory properties, cooking quality, microbiological stability, content in bioactive compounds and antioxidant activity, before and after pasta digestion were studied. The extract was obtained by ultrasound-assisted extraction. From the technological point of view the extract did not affect pasta dough and the cooking parameters and sensory properties of the enriched samples were found similar to the control pasta. No antimicrobial effect was exerted by the extract. From the chemical point of view interesting findings were recorded for pasta before and after digestion. Specifically, data of bioaccessible fraction of digested sample showed a significantly higher amount of total phenols and flavonoid content (11.52 mg gallic acid g⁻¹ and 0.55 mg quercetin g⁻¹ respectively) than digested control pasta (9.54 mg gallic acid g⁻¹ and 0.23 mg quercetin g⁻¹ respectively). The antioxidant activity of enriched sample also increased compared to the control pasta (6.20 vs. 2.50 μmoles FeSO₄ g⁻¹).     

Effect of wheat bran dietary fibre on the rheological properties of dough during fermentation and Chinese steamed bread quality

The effects of wheat bran dietary fibre (WBDF) on the rheological properties of dough during fermentation and quality of Chinese steamed bun (CSB) were investigated. The study revealed that with the increase of the content of WBDF, the dough extensibility and time at which gas starts to escape from the dough significantly decreased but the dough firmness significantly increased (P < 0.05). The elastic modulus and viscous modulus showed an upward trend, probably due to the increased molecular weight of the viscoelastic body resulting from the presence of WBDF. Additionally, by changing the quality of the gluten network, the specific volume and L^* value significantly decreased from 2.52 to 1.31 mL g⁻¹, and from 87 to 51, respectively, these adverse effects on CSBs could be moderated by the fermentation process.     

Effects of japonica rice flour on the mesoscopic and microscopic properties of wheat dough protein

The aim of this study was to study the effects of twelve varieties of japonica rice flour on the gluten protein composition and structure of wheat dough. Experimental results indicated that the addition of japonica rice flour significantly decreased the α-helix structure in the gluten protein sample, but increased the random coil content, indicating that the protein secondary structure became more disordered. The ratio of α-helix/β-sheet structures in the dough supplemented with different varieties of japonica rice flour was decreased, contributing to improved dough stability. Increasing the proportion of japonica rice flour from 10% to 40% significantly decreased the sulfhydryl content of the mixed flour dough. However, the total sulfhydryl content was only positively correlated with the amount of Longdao 19 japonica rice flour, reaching a maximum of 25.34 mol g⁻¹ at 40% japonica rice flour. The gluten structure of mixed flour dough typically forms a porous three-dimensional network, with the Longdao 19, 20, 23 and 25, Longjing 31 and Mudanjiang 31 japonica rice flours leading to improved gluten protein networks. In summary, the supplementation of standard wheat flour with japonica rice flour can alter dough properties and gluten structure.     

A comparison of the ability of several small and large deformation rheological measurements of wheat dough to predict baking behaviour

The rheological characteristics of twenty wheat flour samples obtained from four organic flour blends and a non-organic control were compared in relation to their ability to predict subsequent loaf volume in the baked bread. The flour samples considered had protein contents that varied between 11–14 g/100 g. Four different rheological methods were employed. Oscillatory stress rheometry on the protein gel extracted from the wheat flour, oscillatory stress rheometry and creep measurement on undeveloped dough samples and biaxial extensional measurements on simple flour–water doughs. None of the fundamental rheological parameters correlated with loaf volume. There was a correlation between the storage modulus of the gel protein and storage modulus for the undeveloped dough (r = 0.85). There was a weak negative correlation between protein content and biaxial extensional viscosity (r = −0.62). Stepwise multiple regression related loaf volume to dough stability time (measured on the Farinograph) and tan (phase angle) for the undeveloped dough samples (overall model r² = 0.54). The results indicate that the four rheological tests considered could not be used as predictors of subsequent loaf volume when the bread is baked.     

Rheological and baking properties of cowpea and wheat flour blends

Effect of blending 50 to 250 g kg⁻¹ cowpea flour in wheat flour on rheological, baking and sensory characteristics of bread, chapati, cookies and muffins was studied. Farinograph water absorption, dough development time, mixing tolerance index and dough stability increased significantly with increased amount of cowpea flour. Incorporation of cowpea flour lowered gelatinisation time and peak viscosity. Loaf volume and overall acceptability scores of bread were reduced significantly beyond 150 g kg⁻¹ incorporation of cowpea flour. There were significant changes in specific volume and overall acceptability scores of muffins, registering an initial improvement up to 50 g kg⁻¹ and a significant decline thereafter. © 1999 Society of Chemical Industry     

Efficacy of diatomaceous earths and their low-dose combinations with spinosad or deltamethrin against three beetle pests of stored-maize

A key element in postharvest IPM is the reduction of chemical residues in food through the use of reduced dosages of less toxic grain protectants. Two laboratory experiments were conducted: Experiment I determined the efficacies of straight diatomaceous earths (DEs) – “Chemutsi” (African raw DE), MN51 (new formulation) and Protect-It^® (enhanced DE), and two new food grade DE-based formulations (A2 and A3) against adult Prostephanus truncatus (Horn), Sitophilus zeamais (Motschulsky) and Tribolium castaneum (Herbst) admixed with shelled maize. In Experiment II, Chemutsi and Protect-It^® were further tested in varying combinations with low-dose deltamethrin and spinosad. At 21 days post-exposure, MN51 800 ppm and 1000 ppm, Chemutsi 1000 ppm, Protect-It^® 600 ppm and food grade A3 150 ppm caused S. zeamais mortalities that were not significantly different from the positive control (Protect-It^® 1000 ppm). However, after the same exposure period, all the straight DEs (applied at ≤ 1000 ppm) and the DE-based food grade formulations were not effective on P. truncatus and T. castaneum. In low dose combinations, 7 day mortalities showed high S. zeamais susceptibility to both DE-spinosad and DE-deltamethrin while P. truncatus was more susceptible only to DE-spinosad and T. castaneum to Protect-It^®-deltamethrin only. At 21 days, all DE-spinosad and DE-deltamethrin treatments were effective and not significantly different from the commercial grain protectant (fenitrothion 1.0% w/w (10000 ppm) + deltamethrin 0.13% w/w (130 ppm)) on all test species. DE-spinosad and DE-deltamethrin combinations significantly suppressed (P < 0.001) F₁ progeny for the three test species whereas straight DEs and DE-based food grade formulations did not. Our results showed that at half the label rates or lower, DE-spinosad and DE-deltamethrin combinations were effective alternative grain protectants that are safer and possibly cheaper. We also give the first report on the effectiveness of Chemutsi in combination with spinosad or deltamethrin on maize grain.     

Bread fortified with dietary fibre extracted from culinary banana bract: its quality attributes and in vitro starch digestibility

The effect of fortification of dietary fibre (DF) on dough rheology, quality characteristics and in vitro starch digestibility of bread was studied. Bread was prepared incorporating DF (2–4 g per 100 g of flour mixture). Rheological study of dough showed an increase in dough stiffness and elasticity with higher incorporation of the DF. The results of chemical composition revealed that addition of DF increased total DF (19.65 g per 100 g) content of bread. However, incorporation of 2 g per 100 g DF of flour mixture with 66 g per 100 g moisture showed higher water retention and specific volume of 86.76% and 5.83 cm³ g⁻¹, respectively, which was close to control bread. Improved textural property with acceptable sensory attributes was observed for bread fortified with 2 g per 100 g DF of flour mixture and 66 g per 100 g moisture content. Incorporation of DF (2–4 g per 100 g of flour mixture) showed a decrease in rapidly digestible starch (RDS) and an increase in slowly digestible starch (SDS) content with lower predicted glycaemic index (pGI) than control bread.     

Improved physicochemical and fermentation properties of frozen dough with bacterial cellulose

Effects of a novel category of hydrocolloid (Bacterial cellulose, BC) on physicochemical and fermentation properties of frozen dough were studied to address the reduction in baking performance due to refrigeration. The addition of BC reduced free thiol content and inhibited the de-polymerisation degree of glutenin macropolymers, resulting in enhanced emulsifying activities of frozen dough, when the amount was added up to 0.1 g 100 g⁻¹of wheat flour (dry basis). Further supplement hurt these attributes due to competition for water molecules. However, increasing the addition of BC significantly enhanced its protective effect on yeast activity, which in turn improved the fermentation properties of frozen dough. After 8 weeks of storage at −18 °C, 31% of yeast survived in with the protection of BC. When BC was added at a ratio of 0.1 g 100 g⁻¹ of wheat flour, the improved frozen dough showed maximum volume of gas which was 2.7 times higher than that of the control after 3 h of fermentation. Baking performances confirmed the effect of BC as bread crumbs containing intermediate addition of BC rose optimally during proofing and baking, which contributed to the higher specific volume, less firm and more tender crumb texture of bread. These results suggested that BC might act as an effective additive to improve the shelf-life stability of frozen food during long periods of frozen storage.     

Influence of water and barley β-glucan addition on wheat dough viscoelasticity

The effects of the addition of two barley β-glucan isolates (0.2–1.0% of wheat flour), differing in molecular weight, and water (53–63% in a poor breadmaking wheat flour, cv. Dion, and 58–68% in a good breadmaking wheat flour, cv. Yekora) on the viscoelastic properties of wheat flour doughs were investigated. A response surface model (CCF) was used to evaluate the effects observed on the dynamic and creep-recovery parameters of the dough. The evaluation was done separately for each combination of β-glucan isolate (BG1 of ～10⁵ Da and BG2 of ～2 × 10⁵ Da) and flour type. Besides the contents of β-glucan and water, the molecular size of the polysaccharide and the flour quality were important determinants of the dough’s viscoelastic behavior. Compared to BG1, the higher molecular weight β-glucan (BG2) brought about major changes on all the rheological responses of the fortified doughs. The addition of appropriate levels of β-glucans and water in the poor breadmaking cultivar (Dion) doughs could yield similar viscoelastic responses to those observed by a non-fortified good breadmaking quality flour dough (Yekora).     

Evaluation of rheological properties,microstructure and water mobility in buns dough enriched in aleurone flour modified by enzyme combinations

This study aimed to explore the differences between single enzyme and combined enzymes in improving buns dough quality characterised by changes in rheological properties, microstructure and water mobility. The results indicated that xylanase (60 μg g⁻¹)–glucose oxidase (GOX) (40 μg g⁻¹) and xylanase (60 μg g⁻¹)–glucose oxidase (40 μg g⁻¹)–cellulase (30 μg g⁻¹)-modified dough can improve the negative effects of the single enzyme on the dough in terms of extensibility, tenacity and stability, leading to the formation of a softer gluten matrix. This may be due to xylanase (60 μg g⁻¹)–GOX (40 μg g⁻¹) and xylanase (60 μg g⁻¹)–GOX (40 μg g⁻¹)–cellulase (30 μg g⁻¹)-modified dough reduced the free sulfhydryl and significantly increased water-extractable arabinoxylan content (P < 0.05) and enhanced more less-tightly bound water availability. The microstructure observation showed that xylanase (60 μg g⁻¹)–GOX (40 μg g⁻¹) and xylanase (60 μg g⁻¹)–GOX (40 μg g⁻¹)–cellulase (30 μg g⁻¹) modified dough exhibited a more compact and continuous gluten matrix.     

From wheat sourdough to gluten‐free sourdough: a non‐conventional process for producing gluten‐free bread

Gluten‐free (GF) sourdough was prepared from wheat sourdough and analysed both in fresh (GFS) and dried forms (DGFS). The gluten content in each GF sourdough sample was <20 mg kg^?1. The dough leavening capacity and the properties of the bread samples were investigated and compared to those of bread prepared using bakery yeast (Saccharomyces cerevisiae). Two commercial rice‐based mixtures (different for the presence/absence of buckwheat flour) were used to prepare bread samples. In GFS, lactic acid bacteria (LAB) and yeasts were found in amounts corresponding to 10⁸ and 10⁷ CFU g^?1, respectively, whereas both LAB and yeasts were detected in lower amounts (about 10⁶ CFU g^?1) in DGFS. When used in bread‐making, both GFS types produced significant dough acidification and exhibited good dough development during proofing, resulting in loaves with specific volume values between 3.00 and 4.12 mL g^?1, values similar to those obtained for reference bread (3.05÷4.15 mL g^?1). The use of GFS was effective in lowering the bread staling rate during storage for up to 7 days.     

Preparation and evaluation of chili powder-enriched layered noodles

Chili powder-enriched dough was sandwiched between two dough layers prepared from (a) wheat flour, (b) wheat flour plus resistant starch flour and (c) wheat flour plus soy protein isolate (SPI) and microbial transglutaminase (MTGase), and these were used for preparing wheat flour control (LN-C), wheat flour-resistant starch (LN-F) and wheat flour-SPI-MTGase (LN-S) noodles, respectively. All cooked noodles were assessed for physical properties, starch digestibility and capsaicin-retaining abilities. Compared to other noodles, the LN-S noodles exhibited the highest tensile strength and elasticity, and the highest capsaicin retaining ability at pH 7.4. However, at pH 1.2 the capsaicin-retaining ability of all noodles was similar. The predicted glycemic indices (pGIs) of LN-F and LN-S noodles were similar (P > 0.05), and were significantly (P < 0.05) lower than that of LN-C noodles. In conclusion, the resistant starch flour helped to lower pGI of the layered noodles, but it was not effective at retaining capsaicin. The occurrence of additional cross-linking between protein matrices of LN-S noodles could be a factor that had impaired structural integrity and retarded the diffusion of capsaicin from the capsaicin-enriched dough.     

Effects of wheat sourdough process on the quality of mixed oat-wheat bread

The aim of this work was to study the effects of sourdough fermentation of wheat flour with Lactobacillus plantarum, on the quality attributes of mixed oat-wheat bread (51 g whole grain oat flour and 49 g/100 g white wheat flour). Emphasis was laid both on β-glucan stability as well as bread structure and sensory quality. The variables of the sourdough process were: dough yield (DY), fermentation time, fermentation temperature, and amount of sourdough added to the bread dough. The sourdough process was shown to be a feasible method for mixed oat-wheat bread, and, when optimized, provided bread quality equal to straight dough baking. A small amount (10g/100 g dough) of slack sourdough fermented at high temperature for a long time resulted in the most optimal sourdough bread with the highest specific volume (3.5 cm³/g), the lowest firmness after 3 days storage (0.31 kg), and low sensory sourness with high intensity of the crumb flavour. Wheat sourdough parameters did not affect the content of oat β-glucan in the bread. Additionally, both straight dough and sourdough bread contained 1.4-1.6 g β-glucan/100 g fresh bread. The average molecular weight of β-glucan was 5.5 × 10⁵ in both types of bread, while that of oat flour was 10 × 10⁵. This indicates that a slight degradation of β-glucan occurred during proofing and baking, and it was not affected by variation in the acidity of the bread between pH 4.9-5.8.     

Evaluation of viscoelastic properties and air-bubble structure of bread containing gelatinized rice

The impact of addition of gelatinized rice porridge to bread has been investigated on loaf volume, viscoelastic properties and air-bubble structure. We prepared four variety of bread: bread containing rice porridge (rice porridge bread), bread containing gelatinized rice flour (gelatinized rice flour bread), and wheat flour and rice flour breads for references. Instrumental analyses the bread samples were carried out by volume measurement of loaf samples, creep test and digital image analysis of crumb samples. Rice porridge bread showed the maximum specific volume of 4.51 cm³/g, and even gelatinized rice flour bread showed 4.30 cm³/g, which was larger than the reference bread samples (wheat and rice flour breads). The values of viscoelastic moduli of gelatinized rice flour bread and rice porridge bread were significantly smaller (p < 0.05) than those of wheat flour and rice flour breads, which indicates addition of gelatinized rice flour or rice porridge to bread dough encouraged breads softer. Bubble parameters such as mean air- bubble area, number of air-bubble, air-bubble area ratio (ratio of bubble area to whole area) were not significantly different among the bread crumb samples. Therefore, the bubble structures of the bread samples seemed to similar, which implied that difference of viscoelasticity was attributed to air-bubble wall (solid phase of bread crumb) rather than air-bubble. This study showed that addition of gelatinized rice to bread dough makes the bread with larger loaf volume and soft texture without additional agents such as gluten.