Comparison of different rice flour- and wheat flour-based butter cookies for acrylamide formation

Acrylamide (AcA) contents of different rice flour- and wheat flour-based butter cookies baked at 130 °C for 20, 55, or 90 min were investigated. AcA contents of different flour-based cookies increased with baking time. Color parameters in terms of CIE L*, b*, C*, and ΔE values showed significant opposite correlation to the AcA formation in each of the raw flour cookie. The cookies based on white rice flour had the lowest AcA contents ranging from not detectable (ND) to 204 μg/kg, followed by cookies based on brown rice flour (ND to 450 μg/kg), white wheat flour (155 μg/kg to 661 μg/kg), and whole wheat flour (306 μg/kg to 982 μg/kg). Considerably lower AcA levels were found in the rice flour-based cookies than in the wheat flour-based cookies, as well as in the milled flour-based cookies than in the whole-grain cookies. Although the flour source was considered to play a primary role in determining the AcA content, AcA content was apparently not dependent on the quantities of reducing sugars and free asparagine in the starting raw flour and cookies during baking. In summary, given its reducing potential for AcA formation, rice flour could be used in the production of cookies safe from heat-induced contaminants.     

Over 40% of 450 registered wheat cultivars (Triticum aestivum) worldwide are composed of multiple biotypes

Many of 450 common wheat cultivars bred and registered during the twentieth century in 12 countries were proved, due to seed-by-seed analysis, to be composed of two or more biotypes differing in their alleles at the gliadin (Gli) loci. These multiple biotypes may be regarded as authentic progeny of the respective parent lines, as evidenced by the gliadin composition of the respective parents. Therefore, the official claim for each cultivar to be uniform is commonly not maintained in practice. The most frequent was a non-uniform cultivar composed of two biotypes differing at one Gli locus, but there were cultivars represented by a large set of related genotypes differing at several Gli loci. The proportion of the multi-biotype cultivars was never less than 15% for a country collection, exceeding 50% in other countries. This proportion differed significantly between neighbouring countries. In Australia, all multi-biotype cultivars were found in eastern states; in the state of Victoria, their frequency was statistically higher than in the rest of the country. The proportion of multi-biotype cultivars among newly-released cultivars decreased with time in Australia and the UK. Thus, the non-uniformity of registered cultivars represents a general and important phenomenon of common wheat as a crop.     

Evaluation of wheat and emmer varieties for artisanal baking,pasta making,and sensory quality

Identifying varieties best suited to local food systems requires a comprehensive understanding of varietal performance from field to fork. After conducting four years of field trials to test which varieties of ancient, heritage, and modern wheat grow best on organically managed land, we screened a subset of varieties for bread, pastry, pasta, and cooked grain quality. The varieties evaluated were three lines of emmer (T. turgidum L. ssp. dicoccum Schrank ex Schübl) and eleven lines of common wheat (Triticum aestivum L.), including two modern soft wheat varieties, four soft heritage wheat varieties, four hard modern wheat varieties, and one hard heritage wheat variety. A diverse group of bakers, chefs, researchers, and consumers compared varieties for qualities of interest to regional markets. Participants assessed differences in sensory profiles, pasta making ability, and baking quality for sourdough, matzah crackers, yeast bread, and shortbread cookies. In addition to detecting significant differences among varieties for pasta, sourdough, and pastry quality, participants documented variation in texture and flavor for the evaluated products. By demonstrating which varieties perform best in the field, in the bakery, and on our taste buds, these results can support recommendations that strengthen the revival of local grain economies.     

Effect of steam explosion on enzymatic hydrolysis and baking quality of wheat bran

In this study, the effect of steam explosion (SE) treatment on microstructure, enzymatic hydrolysis and baking quality of wheat bran was investigated. Coarse and fine bran were treated at different steam temperatures (120–160 °C) and residence times (5 or 10 min) and then hydrolysed with carbohydrase enzymes. The SE treatment increased water extractable arabinoxylan (WEAX) content from 0.75 to 2.06% and reducing sugars from 0.92 to 2.41% for fine bran. The effect was more pronounced with increased SE temperature and residence time. The highest carbohydrate solubilisation was observed in fine bran at SE treatment of 160 °C, 5 min. WEAX content increased to 3.13% when this bran was incubated without enzyme, while WEAX content increased to 9.14% with enzyme addition. Microscopic analysis indicated that cell wall structure of wheat bran was disrupted by severe SE conditions. Supplementation of SE treated (150 °C, 10 min) bran at 20% replacement level decreased the baking quality of bread. However SE followed by enzymatic hydrolysis increased specific volume and decreased crumb hardness (on the day of baking and after three days of storage). Phytic acid content of bread supplemented with SE treated bran was lower than the one supplemented with untreated bran.     

Responses of glutamine synthetase activity and gene expression to nitrogen levels in winter wheat cultivars with different grain protein content

Glutamine synthetase (GS) plays a central role in plant nitrogen (N) metabolism, which improves crops grain protein content. A pot experiment in field condition was carried out to evaluate GS expression and activity, and grain protein content in high (Wanmai16) and low grain protein (Loumai24) wheat cultivars under two N levels (0.05 and 0.15 g N kg⁻¹ soil). High nitrogen (HN) resulted in significant increases in GS1 and GS2 expression at 10 days after anthesis (DAA), and higher GS activity during the entire grain filling stage. HN also significantly increased yield, grain protein content and protein fraction (except for glutenin of Luomai24) in two wheat cultivars, which indicated that it increased grain yield and protein content by improving nitrogen metabolism. Wanmai16 showed higher grain protein content, gliadin and glutenin content, and had higher expression level of GS2 both in flag leaves and grains at early grain filling stage. However, Luomai24 had greater yield and higher expression level of GS1. The difference expression of GS2 and GS1 genes indicates they had various contributions to the accumulation of protein and starch in wheat grains, respectively. The results suggest that GS2 would be serving as a potential breeding target for improving wheat quality.     

Prediction of baking results from farinograph measurements by using stepwise linear regression and artificial neuronal networks

In an effort to extract additional data from farinograph experiments a model was developed to simulate the measurements and correlate the parameters of the model with results from baking tests. This additional information can be used in bakeries to predict the baking properties of the flours and adjust the recipes to maintain a constant product quality. For this eight different flours were characterized with a farinograph and 13 different results from baking experiments. An approach with five nonlinear differential equations was able to model the farinograph measurements very well (average R² = 0.995 ± 0.005). While a stepwise multilinear regression only showed weak correlations in cross validation between a single parameter of the model and the baking volume (R² = 0.745) and the volume yield (R² = 0.796) respectively, the artificial neuronal network was more successful. For the baking weight (R² = 0.926), the dough yield gross (R² = 0.909) and net (R² = 0.913) strong correlations were found. A good correlation for the baking volume (R² = 0.853) was also determined, while the volume yield showed comparable results to the linear regression (R² = 0.792).     

Soil sterilization effects on root growth and formation of rhizosheaths in wheat seedlings

Sterilized soils are frequently used in experiments related to soil biology. Soil sterilization is known to alter physicochemical characteristics of soil, plant growth and community structure of the newly developed bacterial population. However, little information exists regarding soil sterilization effects on belowground processes mediated through root–microbe–soil interactions, e.g., development of rhizosheaths which significantly promote the plant growth under stress environments. The present study was conducted to elucidate effects of soil sterilization on wheat root growth and formation of rhizosheaths in relation to chemical changes caused by soil sterilization and the proportion of expolysaccharide (EPS)-producers in bacterial population recolonizing the sterilized soils. Wheat plants were grown for two weeks under greenhouse conditions either in the unsterilized soil or in soils sterilized by autoclaving (121 °C, 1 h) or by gamma (γ)-irradiation (50 kGy). While soil sterilization had no effect on the release of macronutrients, both sterilization procedures significantly increased the electrical conductivity, water-soluble carbon and DTPA-extractable Mn. Seedlings grown in sterilized soils produced higher root biomass and the rhizosheath soil (RS) mass as compared to those grown in the unsterilized soil. Soil sterilization also increased the root length, surface area, volume and number of tips. In bulk soil, RS and on roots, the proportion of EPS-producers in the total bacterial population was higher in sterilized treatments than in the unsterilized. Amending the unsterilized soil with glucose-C increased the root biomass, whereas adding Mn II increased the RS mass. The results showed that soil sterilization by autoclaving or γ-irradiation increases the root growth and RS mass of wheat seedlings. The water-soluble C and DTPA-extractable Mn released upon sterilization, and the increased proportion of EPS-producers in the bacterial population recolonizing the sterilized soils were involved in the observed effects. The results may have implications in studies using autoclaved or γ-irradiated soils to investigate soil–plant–microbe interactions and signify the need to account for intrinsic stimulatory effects of soil sterilization.     

Economics of foliar fungicides for hard red winter wheat in the USA southern Great Plains

Grain yields of winter wheat (Triticum aestivum L.) in the southern Great Plains are often reduced by the presence of foliar diseases. This study was conducted to determine whether the application of foliar fungicides is an economically optimal management strategy. The effects of fungicide treatment on commercially available hard red winter wheat varieties with differing levels of genetic resistance (i.e., resistant, intermediate, and susceptible) to foliar diseases were investigated at two locations, Apache and Lahoma, OK, USA, for the harvest years 2005–2012. Two fungicides were rotated between the two locations and applied at approximately Feekes growth stage 9–10.5. When averaged across years, plots to which fungicide was applied generated greater average net returns than plots that did not receive fungicide for susceptible varieties at Apache, and for resistant, intermediate, and susceptible varieties at Lahoma. However, foliar fungicide application was not economical in every year at either location suggesting fungicide use should be reassessed each year given that profitability depends on year specific yield potential, prices, and foliar disease conditions. At both locations high disease incidence occurred in all but one site-year when the average March through May relative humidity exceeded 65%. Additional research would be required to determine the relationship between weather, including relative humidity, and disease incidence, and to develop an economic threshold for treatment decision aid.     

Relative abundance and damage of some insect pests of wheat under different tillage practices in rice–wheat cropping in India

Tillage changes the physical and chemical properties of soil and can also inhibit or enhance useful and harmful fauna. In agriculture, different tillage technologies are being tried to enhance crop productivity, but little concrete information seems to exist on their effects on pest abundance and damage. To address this lack of information, sowing of wheat was investigated under different tillage systems. In order to monitor pest abundance and damage in altered tillage systems, the present studies on the relative abundance and damage due to insect pests viz. pink stem borer (PSB, Sesamia inferens Walker), termites (Microtermes obesi Holmgren and Odontotermes obesus Rambur) and root aphid (Rhopalosiphum rufiabdominalis Sasaki) were undertaken in a rice–wheat cropping system during 2010–11 and 2011–12. Pest abundance and damage was monitored in four tillage systems i.e. conventional tillage (CT), zero tillage (ZT), ZT + mulch and rotary tillage (RT) under insecticide protected and unprotected conditions. The application of insecticide did not affect root aphid incidence or termite damage. However, significant differences in PSB damage in insecticide protected (0.9%) and unprotected (1.2%) conditions were observed. The investigations demonstrated that in CT, damage by PSB (0.6%) was minimum; however termite damage (2.2%) was maximum as compared to all other tillage conditions. In ZT, PSB damage (1.4%) was maximum and root aphid incidence (3.1 aphids/tiller) was minimum in comparison to other tillage conditions. ZT + mulch resulted in inter-mediate insect pest incidence/damage; however, RT was the least effective practice which showed relatively high incidence/damage of these three insects (1.2% PSB damage, 1.9% termite damage and 5.1 aphids/tiller). The insecticide × tillage interaction indicated that insecticide application is needed only in ZT and RT for PSB management.     

Diazotroph community structure and abundance in wheat–fallow and wheat–pea crop rotations

Biological input of nitrogen (N) from the atmosphere by free-living diazotrophs can help alleviate fertilizer use in agricultural systems. In this study, we investigated the effect of N fertilizer and winter pea (Pisum sativum L.) crop on the community structure and abundance of free-living diazotrophs in a two year study of dryland winter wheat (Triticum aestivum L.) no-till production system in Eastern Oregon, USA. Based on quantification of the nifH gene, diazotroph abundance was strongly influenced by plant species and the crop year in which the soil samples were collected. A greater amount of nifH copies was recovered in 2012 compared to 2011 either as copies per gram soil or normalized to the abundance of bacterial 16S rRNA genes. The quantity of genes was greater under pea than wheat in 2012 although no difference was observed in the preceding year. The nifH gene abundance was positively correlated to ammonium concentration in 2011 and bacterial abundance in 2012. Nitrogen application did not influence diazotroph abundance in the top 0–5 cm; however the abundance was reduced by application at the lower 5–10 cm depth under wheat crop. The diazotroph community structure appeared to be influenced more by N fertilization rather than plant species with the exception of wheat in 2012. Changes in the community structure over the two years were greater for fertilized than unfertilized soil. Collectively, these data suggest that year-to-year variability had a greater influence on diazotroph communities rather than specific parameters of plant species, fertilization, total N, total organic C, or soil pH. Multi-year studies are necessary to define the specific drivers of diazotroph abundance, community structure and function.