Protein Quality Of Wheat Research Articles

Lysine from Whole Wheat Bread Consumed by Healthy Adult Males Has High Metabolic Availability When Assessed Using the Indicator Amino Acid Oxidation Method

BackgroundThe protein quality of wheat is limited by its low content of the indispensable amino acid (AA) lysine and the metabolic availability (MA) of lysine in wheat bread for humans is unknown. ObjectivesThe study objective was to determine the MA of lysine in whole wheat bread. MethodsFive healthy young males (≤30 y, body mass index <25) were studied in a repeated-measures design using the indicator amino acid oxidation (IAAO) method, with L-[1-13C] phenylalanine as the indicator. Each received 7 levels of lysine intakes in random order; 4 levels of L-lysine; 5, 8, 12, and 15 mg/kg/d (reference diet), and 3 intakes of lysine from whole wheat bread (test diet). The MA of lysine in whole wheat bread was assessed by comparing the IAAO response to the test diet (whole wheat bread) with the IAAO response to the reference diet using the slope ratio method. ResultsThe MA of lysine from whole wheat bread was 90%. ConclusionsLysine has a high MA but it is still limiting in whole wheat bread due to its low concentration. A combination of wheat with a complementary protein source (that is, lentils which are sufficient in lysine) is recommended to meet the lysine requirement in a wheat-based diet for healthy young males.This trial was registered at clinicaltrials.gov as NCT03674736 and NCT03200652.

Enhancing wheat protein through low-water-fertility under climate change without yield penalty

Efforts to enhance wheat quality without compromising yield are imperative in the context of climate change. However, the quantification of management measures that simultaneously elevate wheat protein concentration, especially its components, while maintaining yield has been scarcely addressed due to its inherent complexity. In this study, we investigated the impact of various combinations of sowing dates, nitrogen fertilizer, and irrigation on improving the protein concentration of strong gluten winter wheat (Jimai 20) using a validated wheat grain protein component simulation model in Tai'an, Shandong. Our results indicate that climate change between 2031 and 2060 is anticipated to cause a significant decrease in wheat yield and an increase in wheat protein concentration compared to the period from 1981 to 2010. Albumin and globulin are projected to decrease, while gliadin and glutenin are expected to increase, respectively. The average glutenin-to-gliadin ratio in the baseline is 1.096, whereas in scenarios SSP2–4.5 and SSP5–8.5, it is 1.093 and 1.102, respectively. Adapted measures can effectively synergize to enhance both wheat protein quality and yield under climate change. Specifically, delaying sowing and reducing nitrogen application to 210–240 kg·ha−1 with 200–240 mm of irrigation contribute to maintaining yields at the current conventional treatment level. Furthermore, these practices result in a 3.89 % and 0.13 % increase in grain protein concentration, and a 1.19 % and 6.02 % enhancement in the glutenin-to-gliadin ratio under scenarios SSP2–4.5 and SSP5–8.5, respectively, compared to conventional treatments. This comprehensive analysis provides valuable insights into practical strategies for synergistically improving wheat yield and protein quality in the face of climate change.

Effect of Sitophilus zeamais (Coleoptera: Curculionidae) Infestation on the Protein Physicochemical and Structural Properties of Wheat Grain.

Boring pests such as Sitophilus zeamais (S. zeamais) are major threats in grain storage. However, how these pests affect the proteins of stored grains remains largely unknown. Here we aimed to investigate the effect of S. zeamais infestation on wheat protein during postharvest storage. In this study, wheat grain infested by S. zeamais was sampled at egg (4 d), larval (20 d), pupal (35 d), and adult stages (45 d), respectively. The protein's physicochemical and structural properties and the edible quality of whole wheat noodle were analyzed. The results showed that S. zeamais infestation significantly decreased the quality of wheat protein by altering its constitution and structure properties. Especially, compared with the control, the content of wet and dry gluten, gluten index, sodium dodecyl sulfate sedimentation volume, sulfhydryl groups, and disulfide bonds in insect-infested wheat decreased by 19.40, 5.42, 18.40, 8.12, 29.13, and 14.30%, respectively, during the storage period of one life cycle of S. zeamais. Additionally, the proportions of wheat protein fractions (albumin [1.16-fold], globulin [0.96-fold], gliadin [1.16-fold], and glutenin [0.95-fold]) and secondary structures (α-helix [0.91-fold], β-fold [0.96-fold], β-turn [1.06-fold], and random coil [1.05-fold]) of protein changed significantly, and the gluten network structure was broken in S. zeamais-infested wheat. Furthermore, the color of whole wheat noodle became darker, cooking loss rate increased, and textural properties (hardness, adhesiveness, springiness, cohesiveness, chewiness, and resilience) decreased as well. The results in the present study provided new insights for analyzing the quality deterioration mechanism and further quality improvement of boring pests-infested wheat grain.

Effects of Post-Anthesis Temperature and Radiation on Grain Filling and Protein Quality of Wheat (Triticum aestivum L.)

Due to climate change, global warming, and reduced radiation, there is an urgent need for research to explore the effects on wheat grain filling and protein-related quality. In this study, two spring and two semi-winter varieties were analyzed. Six sowing dates were set in the experiment, at 10-day intervals from the beginning of the local sowing window. The seedling population of the first sowing date (S1) was 300 × 104 plants ha−1, which was observed to have increased by about 10% by the subsequent sowing date. During the experiment, due to the different dates of sowing, the treatments were in different growth stages; so, all the treatments were grown under different day and night temperatures and radiation to study the effects on post-anthesis grain filling and protein quality. The results showed that the sowing date decreased the effective accumulated temperature (EAT) and the cumulative radiation after anthesis and increased the daily average, maximum, and minimum temperatures. The decrease in the EAT of 94.99 °C d and the increase in the daily average temperature of 1.59 °C after antrum resulted in a decrease in the wheat grain weight of 4.5 g and an increase in the grain filling rate of 0.029 mg d−1. This may be due to the shortening of the wheat filling time with the increase in the day/night temperatures. Compared with the normal sowing date, the later sowing date caused a decrease in the EAT and an increase in the Tmean, which led to an increase in the wheat protein content, wet gluten content, and sedimentation value. There was a positive correlation between the grain filling rate and the protein content in the wheat. Compared with radiation, temperature significantly regulates wheat grain filling and protein formation. These results can be used to guide the sowing date to obtain a higher quality of wheat protein in the future climate change.

Effects of Low Temperature on the Amino Acid Composition of Wheat Grains

Global warming can have detrimental effects on crop production formation, but the effect of low-temperature stress on crop quality should not be ignored. Wheat is one of the main grain crops in the world, and the quality of wheat is directly related to human health. The nutritional importance of wheat in the human diet necessitates pursuing a study to collect detailed and accurate knowledge of the amino acid composition of wheat proteins under low-temperature conditions. To better understand the effect of low temperature on the composition of amino acids in mature wheat, we conducted a two-year low-temperature-controlled wheat pot experiment in artificial climate chambers with two different wheat cultivars at four low-temperature intensities during the jointing, booting, and both jointing and booting stages. Our results suggest that the contents of total amino acids, essential amino acids, and nonessential amino acids for the cold-sensitive wheat cultivar (Yangmai16) increased under the low-temperature treatments, while the contents of the cold-tolerant cultivar (Xumai30) decreased when low-temperature was applied during the jointing and double (both jointing and booting) stages. Through the amino acid score (AAS), we found that the first limiting amino acid was Lys, while the second limiting amino acid varied among Ile, Met + Cys, and Val after the low-temperature treatments. Comparing the amino acid ratio coefficients (RCs), we found that Leu and Thr in wheat grains were close to the standard protein after the low-temperature treatments, while Phe and Tyr were in a surplus, and the other essential amino acids did not meet the standard. Thus, to improve the protein quality of wheat, protective measures should be taken when low temperatures occur.

Proteome and transcriptome analyses of wheat near isogenic lines identifies key proteins and genes of wheat bread quality

The regulation of wheat protein quality is a highly complex biological process involving multiple metabolic pathways. To reveal new insights into the regulatory pathways of wheat glutenin synthesis, we used the grain-filling period wheat grains of the near-isogenic lines NIL-723 and NIL-1010, which have large differences in quality, to perform a combined transcriptome and proteome analysis. Compared with NIL-1010, NIL-723 had 1287 transcripts and 355 proteins with significantly different abundances. Certain key significantly enriched pathway were identified, and wheat quality was associated with alanine, aspartate and glutamate metabolism, nitrogen metabolism and alpha-linolenic acid metabolism. Differentially expressed proteins (DEPs) or Differentially expressed genes (DEGs) in amino acid synthesis pathways were upregulated primarily in the glycine (Gly), methionine (Met), threonine (Thr), glutamic acid (Glu), proline (proC), cysteine (Cys), and arginine (Arg) synthesis and downregulated in the tryptophan (trpE), leucine (leuC), citrulline (argE), and ornithine (argE) synthesis. Furthermore, to elucidate changes in glutenin in the grain synthesis pathway, we plotted a regulatory pathway map and found that DEGs and DEPs in ribosomes (RPL5) and the ER (HSPA5, HYOU1, PDIA3, PDIA1, Sec24, and Sec31) may play key roles in regulating glutenin synthesis. The transcriptional validation of some of the differentially expressed proteins through real-time quantitative PCR analysis further validated the transcriptome and proteomic results.

Effect of Processing Conditions on the Quality of Wheat Protein

Wheat protein determines the biochemical and rheological properties of most wheat products. The final product depends critically upon the balance between different ratios of proteins that interact with each other through various processing methodologies. Protein is the most substantial component of our intake. As we belongs to Asia, wheat is enriched source of protein for us. Excessive amount of protein is found in wheat grain as compared to wheat flour. Wheat grains is transformed into variety of food products by enduring various food processing techniques. Nutritional quality is been correlatively effected by milling. Cell wall lysing in this process inflate the nutrients whereas it result in polysaccharide by stripping off wheat nutritional layers. Solubility of wheat protein rises through mixing which is further essential in dough kneading. Structural and functional properties of proteins is affected upon heating. Proteins became denature through heating and shearing during extrusion.

Degradation of gluten proteins by Fusarium species and their impact on the grain quality of bread wheat

The protein quality of wheat, the most important crop worldwide, is affected by the presence of fungi, mainly those belonging to the Fusarium genus. The aim of this study is to analyze the effects of Fusarium spp. on ground wheat grains quality by measuring gluten strength and quantifying the gliadin/glutenin content. A total of 23 Fusarium spp. isolates and two bread wheat (Triticum aestivum L.) genotypes with contrasting baking quality were used in the investigation. The results of SDS sedimentation test (SDSS) revealed that the presence of Fusarium species significantly affected the gluten strength negatively; while F. pseudograminearum and F. graminearum are the species that predominantly affected the SDSS values. Principal component analysis of gluten composition showed that the effect of Fusarium species on gluten composition depended on the wheat genotypes analyzed. Cluster analysis revealed that all the Fusarium species used as inoculum produced severe effects on grain quality and gluten composition on both the genotypes. In summary, our results showed that the presence of Fusarium spp. impaired storage proteins affecting the wheat dough properties. Therefore, constant monitoring is necessary to reduce the presence of Fusarium in the food chain for reducing the negative potential impact on bread quality.

Advancing the science of wheat quality evaluation using nuclear magnetic resonance (NMR) and ultrasound‐based techniques

Background and objectivesThe need for cost‐effective, fast, and reliable techniques to evaluate wheat protein content and quality has led to the modification of available methods as well as the development of new methods. This review provides information on two emerging methods, that is, low‐field nuclear magnetic resonance (LF‐NMR) and low‐intensity ultrasound, with potential for evaluating wheat protein content and quality.FindingsNew techniques with additional capabilities have been developed over the years to provide wheat researchers with information that could not be acquired by the use of conventional methods. LF‐NMR and low‐intensity ultrasound are two emerging techniques in the world of cereal science whose speed, ease of operation, and reliability could promote their applications to wheat screening research studies. This review of these two potential wheat protein quality evaluation methods highlights the necessity of developing such cutting‐edge tools which are advantageous over the conventional tools.ConclusionsEasy‐to‐use LF‐NMR and low‐intensity ultrasound seem to have the potential to provide nondestructive, fast evaluation methods that are superior to the currently used techniques in terms of accuracy and cost, respectively. However, further investigations to achieve complete development of such methods are still required.Significance and noveltyThe potential of LF‐NMR and low‐intensity ultrasound as fast, accurate, and cost‐effective wheat screening tools was confirmed through critical discussions and comparisons of a variety of most widely used wheat quality evaluation techniques.

Effect of ozone gas processing on physical and chemical properties of wheat proteins

Purpose: To investigate the effects of ozone treatment on chemical and physical properties of wheat ( Triticum aestivum L.) gluten, glutenin and gliadin. Methods: Wheat proteins isolated from wheat flour were treated with ozone gas. The physical and chemical properties of gluten proteins were investigated after treatment with ozone gas, with 5 g/h produced as a function of time (0, 30, and 60 min) in the study. To check whether the process of ozonation promoted changes in the quality of gluten proteins, sulfhydryl groups (SH), differential scanning calorimetry (DSC), secondary structure, SDS-PAGE, and rheology analyses were performed. Results: Sulfhydryl group contents of wheat proteins ranged from 1.1 to 7.12 μmol/g. Sulfhydryl group content for all ozonated proteins was significantly lower than that of the control samples. Gluten proteins showed reduced SDS-PAGE band intensities of both high (HMW) gluten and glutenin subunits with increasing ozone gas treatment. The denaturation temperatures (Td) of ozonated gluten proteins were higher (99.80–106.79 °C) and the enthalpies of the ozonated gluten proteins were lower than those of the control samples. The storage moduli (G') and loss moduli (G”) of gluten and glutenin tended to increase from 7.84 to 10.20 KPa and 43.19 to 48.28 KPa, and from 3.33 to 4.06 KPa and 20.74 to 22.56 KPa, respectively, as ozone exposure increased from 0 to 30 min. Conclusion: Ozone gas can oxidize wheat proteins. Exposing wheat proteins to ozone gas for an extended time (60 min) deteriorated wheat protein quality. Keywords: Ozone treatment, Gluten proteins, Chemical changes, Rheological studies, CD spectroscopy, Thermal properties

Utilization of processedVigna mungoL. flour in cookies

Purpose– The purpose of this paper is a study designed to utilizeVigna mungoL. (black gram) flour to improve the protein quality of wheat through supplementation. Wheat is utilized as a cereal crop all over the world, but its protein quality is inferior owing to the deficiency of amino acids like lysine.Design/methodology/approach– Black gram seeds were roasted and germinated and then incorporated at 10, 15 and 20 per cent level in wheat flour. The composite flour was evaluated for its chemical composition, physiochemical properties and rheological characteristics, and cookies were developed from the composite flour.Findings– Chemical composition of composite flour revealed significant results (p&lt; 0.05). The level of crude protein increased from 9.69 to 11.79 per cent, while ash and crude fat content enhanced from 0.33 to 1.80 per cent and 1.13 to 2.40 per cent, respectively. There was a significant effect (p&lt; 0.05) on the sedimentation value by the addition of black gram in wheat flour. Water absorption of composite flour was higher than control (52.21 per cent), as maximum value was observed in flour having 15 per cent germinated black gram flour (69.45 per cent). Dough development time also increased from 2.90 min to 4.80 min. The pasting properties revealed significant results for all the parameters. Cookies were developed from composite flour, and sensory evaluation has shown that addition of pulse flour at 15 per cent yields cookies with better hedonic response.Originality/value– The black gram is a locally grown legume crop, but there is a lack of systematic approach for its chemical composition and product development. Scientists are in urge to explore such economical and assessable food ingredients to cope with the nutritional deficiencies prevailing in the developing societies. In this regard, black gram has been recognized as a rich source of nutrients, so it can be exploited to improve wheat protein quality.

Improvement of spring wheat protein quality and quantity by mutation breeding

Improvement of spring wheat protein quality and quantity by mutation breeding

Improving the nutritional quality and health benefits of wheat

Wheat is an important source of calories (derived from starch), protein, dietary fibre, minerals, vitamins and health-promoting phytochemicals to the human diet. However, many of the beneficial components are concentrated in the outer layers of the grain (bran) and embryo (germ). Consequently, whereas the consumption of whole grain products has health benefits in reducing the risk of a number of medical conditions including the metabolic syndrome, the consumption of highly refined products derived from the starchy endosperm (white flour) may be associated with increased risk. This work will therefore discuss the composition of the wheat grain, focusing on components which positively or negatively affect health outcomes and their distributions in grain tissues and fractions. It will also discuss strategies for developing new types of wheat with improved health benefits, focusing on the three major components in the grain: protein, starch and dietary fibre. Classical plant breeding can be used to increase the content and improve the composition of dietary fibre in flour and wholemeal, exploiting the existence of wide variation in composition and high genetic heritability (Ward et al. 2008; Shewry et al. 2010), and using molecular markers for selection. In particular, increasing the content of soluble fibre content leads to increased intestinal viscosity and reduced glycaemic index (with reduced risk of type-2 diabetes). The glycaemic index of wheat products can also be reduced by increasing the amylose content of starch, and increases from 25% to 40% amylose can be achieved by combining naturally occurring or induced mutations in genes controlling the synthesis of amylopectin (Sestili et al. 2010). The nutritional quality of wheat protein is limited by the low contents of essential amino acids, notably lysine, in the gluten protein fraction. Although high lysine mutations have been studied widely in maize and barley, they have achieved little commercial success and this approach has not been adopted in hexaploid bread wheat. However, lessons learned from studies in these cereals should allow the use of genetic engineering to improve the protein quality of wheat. The combination of these traditional and novel approaches will allow the development of new types of wheat with enhanced nutritional quality and health benefits for wholegrain and white products.

Identification and analysis of genes encoding a novel ER-localised Cyclophilin B in wheat potentially involved in storage protein folding

The storage protein deposition processes in cereal endosperm follow a strict script involving protein folding and refolding, assortment and protein body deposition by two distinct pathways. The endoplasmic reticulum-localised enzymes called peptidyl prolyl cis– trans isomerases (PPIases) are expected to play crucial ‘foldase’ and chaperone roles in the deposition of wheat prolamins due to their proline-rich nature. The storage protein quality of wheat is important for nutritional and food technological purposes; however, little information exists on genetic control of protein sorting and deposition processes. In this study, CypB genes encoding an ER-localised cyclophilin (a PPIase) have been characterised from common wheat ( Triticum aestivum L. AABBDD) and its progenitors for the first time. The full-length genes contain seven exons and six introns, the exons being significantly more conserved. The putative CypB protein contains all PPIase signature sites including the putative active site and cyclosporin-binding residues, but an atypical ER localisation signal. Using the sequence variations, the common wheat genes were localized to chromosomes 7AL, 7BL and 7DL. The promoters of wheat genes were identified by inverse-PCR and show a number of potential tissue specific regulatory elements. The wheat genes are similar in structure to rice CypB and the putative proteins are 83% identical. Further, certain QTLs related to protein quality occur at the rice and wheat CypB loci. The results support this enzyme being a strong candidate for regulating storage protein quality in wheat.

Determination of endosperm protein secondary structure in hard wheat breeding lines using synchrotron infrared microspectroscopy

One molecular aspect of mature hard wheat protein quality for breadmaking is the relative amount of endosperm protein in the α-helix form compared with that in other secondary structure forms including β-sheet. Modeling of α-helix and β-sheet absorption bands that contribute to the amide I band at 1650 cm −1 was applied to more than 1500 spectra in this study. The microscopic view of wheat endosperm is dominated by many large starch granules with protein in between. The spectrum produced from in situ microspectroscopy of this mixture is dominated by carbohydrate bands from the large starch granules that fill up the field. The high spatial resolution achievable with synchrotron infrared microspectroscopy enables revealing good in situ spectra of the protein located interstitially. Synchrotron infrared microspectroscopic mapping of 4 μm thick frozen sections of endosperm in the subaleurone region provides spectra from a large number of pixels. Pixels with protein-dominated spectra are sorted out from among adjacent pixels to minimize the starch absorption and scattering contributions. Subsequent data treatment to extract information from the amide I band requires a high signal to noise ratio. Although spectral interference of the carbohydrate band on the amide band is not a problem, the scattering produced by the large starch granules diminishes the signal to noise ratio throughout the spectrum. High density mapping was done on beamlines U2B and U10B at the National Synchrotron Light Source at Brookhaven National Laboratory, Upton, NY. Mapping with a single masked spot size of 5.5 μm diameter or confocal 5 μm × 5 μm spot size, respectively, on the two beamlines used produced spectra for new breeding lines under current consideration. Appropriate data treatment allows calculation of a numerical estimate of the α-helix population relative to other secondary protein structures from the position and shape of the amide I absorption band. Current breeding lines show a substantial variance in this feature and its determination allows the prediction of relative quality for breadmaking to be taken into consideration for subsequent steps in the wheat breeding process. Data treatments include deconvolution, modeling of the individual resulting bands that contribute to the amide I band to enable measurement of the relative amounts of both forms. Results with specimens representing multiple crop years of hard winter wheat breeding are reported. It is evident that a range is available for the breeder to choose from, that allows including this protein molecular structural attribute in the selection process.

Wheat protein quality in relation to baking performance evaluated by the Chorleywood bread process and a hearth bread baking test

Abstract The relationships between wheat protein quality and baking properties of 20 flour samples were studied for two breadmaking processes; a hearth bread test and the Chorleywood Bread Process (CBP). The strain hardening index obtained from dough inflation measurements, the proportion of unextractable polymeric protein, and mixing properties were among the variables found to be good indicators of protein quality and suitable for predicting potential baking quality of wheat flours. By partial least squares regression, flour and dough test variables were able to account for 71–93% of the variation in crumb texture, form ratio and volume of hearth loaves made using optimal mixing and fixed proving times. These protein quality variables were, however, not related to the volume of loaves produced by the CBP using mixing to constant work input and proving to constant height. On the other hand, variation in crumb texture of CBP loaves (54–55%) could be explained by protein quality. The results underline that the choice of baking procedure and loaf characteristics is vital in assessing the protein quality of flours.

Wheat Intercultivar Differences in Susceptibility of Glutenin Protein to Effects of Bug (Eurygaster integriceps) Protease

ABSTRACTPreharvest bug damage to wheat can cause significant losses in bread‐making quality. One of the most prevalent forms of bug damage which frequently occurs in most countries of the Middle East, Eastern Europe and North Africa can be attributed to Heteropterous insects, particularly Eurygaster spp. Intercultivar differences in the susceptibility of glutenin to proteolytic degradation by the bug Eurygaster integriceps were investigated using six breadwheat cultivars of Turkish origin. Crude enzyme extract was prepared with distilled water from bug‐damaged wheat. The freeze‐dried extract was blended with sound samples of ground wheat, and the mixture was incubated in distilled water for 30 and 60 min at 37°C and subsequently freeze‐dried. The proteolytic effects of bug damage were determined on large polymeric glutenin. The latter was measured as 50% 1‐propanol insoluble (50PI) glutenin extractable with 50% 1‐propanol in reductant dithiothreitol. The decreases in the amount of 50PI glutenin and the high and low molecular weight subunits were quantified using reversed‐phase HPLC. There was a substantial and progressive decrease in the quantity of 50PI glutenin and its subunits with increasing incubation time. Intercultivar differences were observed that were unrelated to intrinsic levels of proteolytic activity. After 60 min of incubation, the relative decrease in 50PI glutenin compared with control samples ranged from 43% (cv. Ankara) to 65 % (cv. Kirkpinar). Some cultivars (Lancer, Ankara and Gün) with similar levels of intrinsic proteolytic activity showed significantly different responses to bug protease. One cultivar (cv. Kirkpinar) with the lowest proteolytic activity was the most susceptible. High quality breadwheats (cvs. Bezostaya, Lancer, Kiraç and Gün) were generally more resistant to the bug protease, although Ankara, with both intermediate protease activity and breadmaking quality, was the most resistant cultivar. While the 50PI glutenin test was very effective in quantifying the damaging effects of bug protease on wheat protein quality, the nature of the intercultivar differences was unclear.

Amino acid content and composition of winter wheat affected by Nitrogen Fertilization

The protein quality of wheat is closely correlated with its amino composition. Consequently, when conducting a N fertilization experiment, it is important to know how the ratio of essential amino acids determining the nutritional quality, especially that of the most important limiting amino acids of wheat within the increased protein content, works out. The effect of nitrogen fertilizer applied at different times and/or doses (0–200 kg/ha) was investigated on grain protein and amino acid contents and yields of a Hungarian bread wheat variety on a soil type of medium ? status (eutric cambisol) in Western Hungary for three years. 160 kg N/ha was necessary to reach the highest possible crude protein content and the split application of this dose proved to be the most beneficial to the crude protein yield on the three years’ average. Though most of the treatments seemed to be disadvantageous from the point of view of amino acid composition considering the nutritional quality, the amount of essential amino acids, especially that of lysine harvested per hectare showed a considerable increase (up to 28.4%).

SDS‐Protein Gel Test for Prediction of Bread Loaf Volume

ABSTRACTFlour dispersed in aqueous solutions of sodium dodecyl sulfate (SDS) forms a proteinaceous gel when centrifuged at high speed. The conventional methodology for SDS gel testing was modified to develop a small‐scale (&lt;1 g of flour or wheat meal) screening test for evaluation of the protein quality of wheat for breadmaking. The principal modification involved centrifugation with a swinging‐bucket rotor to facilitate direct measurement of gel height, which is the primary test parameter. The effects of suspension temperature and time, centrifugation speed, sample size, and sieving of ground wheat or flour on the efficacy of the test were examined. Gel height, wet weight, and protein content were assessed as test parameters. In the standard test procedure that was developed, 0.67 g of flour or ground whole wheat was dispersed in 13.5 mL of 1.5% SDS solution for 15 min at 20°C, followed by centrifugation at 80,000 × g for 30 min. The test was evaluated using seven Canadian commercial wheat flours with diverse breadmaking quality. For the samples, gel height was strongly related to loaf volume (R2 = 0.89 and 0.95 for flour and ground wheat, respectively). Sieving flour through a 75‐μm sieve slightly increased the predictive power of the test (R2 = 0.94). SDS gel height gave better discrimination of samples for prediction of loaf volume than did the traditional SDS sedimentation test. The performance of the sedimentation test improved when sieved ground wheat was used. The relationship between gel height or protein content and flour protein content was comparatively poor (R2 = 0.25). The SDS gel test appears to primarily measure the effects of flour protein quality.

Biological evaluation of protein quality of wheat as affected by insect infestation

Protein quality of wheat grains having 25%, 50% and 75% infestation caused by mixed populations of Trogoderma granarium Everts and Rhizopertha dominica Fabricius was biologically evaluated by rat growth and nitrogen balance studies. Feeding of a diet containing insect-infested wheat grain (50% and 75%) resulted in marked decreases of food intake, body weight gain, food efficiency ratio, protein efficiency ratio, nitrogen absorption, biological value, net protein utilization and dry matter digestibility. These parameters showed negative association with infestation levels. However, a 25% level of grain infestation did not affect the parameters significantly.