Multi-criteria assessment of pea protein quality in rats: a comparison between casein, gluten and pea protein alone or supplemented with methionine.

The objective of this study was to assess the nutritional quality of pea protein isolate in rats and to evaluate the impact of methionine (Met) supplementation. Several protein diets were studied: pea protein, casein, gluten, pea protein-gluten combination and pea protein supplemented with Met. Study 1: Young male Wistar rats (n 8/group) were fed the test diets ad libitum for 28 d. The protein efficiency ratio (PER) was measured. Study 2: Adult male Wistar rats (n 9/group) were fed the test diets for 10 d. A protein-free diet group was used to determine endogenous losses of N. The rats were placed in metabolism cages for 3 d to assess N balance, true faecal N digestibility and to calculate the Protein Digestible-Corrected Amino Acid Score (PDCAAS). They were then given a calibrated meal and euthanised 6 h later for collection of digestive contents. The true caecal amino acid (AA) digestibility was determined, and the Digestible Indispensable Amino Acid Score (DIAAS) was calculated. Met supplementation increased the PER of pea protein (2·52 v. 1·14, P < 0·001) up to the PER of casein (2·55). Mean true caecal AA digestibility was 94 % for pea protein. The DIAAS was 0·88 for pea protein and 1·10 with Met supplementation, 1·29 for casein and 0·25 for gluten. Pea protein was highly digestible in rats under our experimental conditions, and Met supplementation enabled generation of a mixture that had a protein quality that was not different from that of casein.

Comparative proteome analysis of glutenin synthesis and accumulation in developing grains between superior and poor quality bread wheat cultivars.

BACKGROUND: Wheat glutenins are the major determinants of wheat quality. In this study, grains at the development stage from three wheat cultivars (Jimai 20, Jin 411 and Zhoumai 16) with different bread-making quality were harvested based on thermal times from 150 °C(d) to 750 °C(d) , and were used to investigate glutenin accumulation patterns and their relationships with wheat quality. RESULTS: High and low molecular weight glutenin subunits (HMW-GSs and LMW-GSs) were synthesised concurrently. No obvious correlations between HMW/LMW glutenin ratios and dough property were observed. Accumulation levels of HMW-GSs and LMW-GSs as well as 1Bx13 + 1By16 and 1Dx4 + 1Dy12 subunits were higher in superior gluten quality cultivar Jimain 20 than in poor quality cultivar Jing 411 and Zhoumai 16. According to the results of two-dimensional gel electrophoresis, six types of accumulation patterns in LMW-GSs were identified and classified. The possible relationships between individual LMW-GSs and gluten quality were established. CONCLUSION: The high accumulation level of HMW-GSs and LMW-GSs as well as 1Bx13 + 1By16 and 1Dx4 + 1Dy12 subunits contributed to the superior gluten quality of Jimai 20. Two highly expressed and 16 specifically expressed LMW glutenin subunits in Jimain 20 had positive effects on dough quality, while 17 specifically expressed subunits in Zhoumai 16 and Jing 411 appeared to have negative effects on gluten quality.

Characterisation and comparison of selected wheat (Triticum aestivum L.) cultivars and their blends to develop a gluten reference material.

The reliability and comparability of gluten analytical results in gluten-free foods is hampered by the lack of reference materials (RM). This is partly caused by the yet incomplete knowledge of the effect of genetic and environmental variability of wheat proteins on immunochemical analyses, which affects the choice of gluten source to be applied for RM production. We investigated the genetic variability and the effect of harvest year on the protein composition of five previously selected wheat cultivars. We also compared the magnitude of these effects on ELISA results to get closer to the question of choosing individual cultivar or a mixture as an RM. Our results proved that the application of a blend for this purpose is advantageous. The candidates were also produced on pilot scale to investigate the feasibility of upscaling. The results of comparison studies showed that the pilot scale blended flour can also be suitable for RM.

Vegetable proteins: are they nutritionally equivalent to animal protein.

On the basis of the rate of animal growth, proteins have been traditionally classed as high quality, such as egg and milk protein, or low quality such as gluten. In general, vegetable proteins are of low quality but soy protein is an exception. The paper by Capristo et al. in this issue of the journal has shown that enteral formulations consisting of soy protein are as effective nutritionally as enteral formulations containing milk protein.

Improvement in the nutritional quality of bread.

To assess whether the dipeptide N-epsilon-(gamma-L-glutamyl)-L-lysine (glutamyl-lysine) can serve as a nutritional source of lysine, we compared the growth of mice fed (a) an amino acid diet in which lysine was replaced by six dietary levels of glutamyl-lysine; (b) wheat gluten diets fortified with lysine; (c) a wheat bread-based diet (10% protein) supplemented before feeding with lysine or glutamyl-lysine (0, 0.75, 1.50, 2.25, and 3% lysine HCl-equivalent in the final diet), not co-baked and (d) bread diets co-baked with these levels of lysine or glutamyl-lysine. With the amino acid diet, the relative growth response to glutamyl-lysine was about half that of lysine. The effect of added lysine on the nutritional improvement of wheat gluten depended on both lysine and gluten concentrations in the diet. With 10 and 15% gluten, 0.37% lysine HCl produced a marked increase in weight gain. Further increase in lysine HCl to 0.75% proved detrimental to weight gain. Lysine HCl addition improved growth at 20 and 25% gluten in the diet and did not prove detrimental at 0.75%. For whole bread, glutamyl-lysine served nearly as well as lysine to improve weight gain. The nutritive value of bread crust fortified or not was markedly less than that of crumb or whole bread. Other data showed that lysine or glutamyl-lysine at the highest level of fortification, 0.3%, improved the protein quality (PER) of crumb over that of either crust or whole bread, indicating a possible greater availability of the second-limiting amino acid, threonine, in crumb. These data and additional metabolic studies with U-14-C glutamyl-lysine suggest that glutamyl-lysine, co-baked or not, is digested in the kidneys and utilized in vivo as a source of lysine; it and related peptides merit further study as a sources of lysine in low-lysine foods.

Determining the net energy value of wet and dry corn gluten feed in beef growing and finishing diets.

One growing and two finishing trials evaluated the feeding value of corn gluten feed for cattle. In the growth trial, calves were fed (DM basis) one of two control diets (44% dry-rolled corn [DRC], 50% alfalfa hay, 5% molasses, 1% supplement or 33% DRC, 33% alfalfa hay, 33% corn silage, 1% supplement), diets containing 49 or 65% wet corn gluten feed (WCGF) with alfalfa hay and supplement, or a diet containing 61% WCGF with cornstalks and supplement. Calves fed diets containing 49 or 65% WCGF with alfalfa hay gained faster (P < .10) and more efficiently (P < .10) than calves fed the two control diets. In finishing trial 1, yearling steers were fed 92.5% concentrate diets containing (DM basis) 79% DRC, a combination of DRC and 35 or 70% WCGF, a combination of DRC and 70% dry corn gluten feed (DCGF) with or without added water, or a combination of high-moisture corn (HMC) and 70% WCGF. Steers fed 35 or 70% WCGF in combination with either DRC or HMC had gains and efficiencies similar (P > .10) to those of steers fed DRC. Inclusion of water in the 70% DCGF diet reduced DMI (P < .10) and daily gain (P < .10) but did not affect (P > .10) feed efficiency. In Trial 2, WCGF replaced either 20, 40, 60, 80, or 100% of the DRC and molasses (DM basis). Feed efficiency was not different (P > .10) among diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of wet distillers composite for finishing ruminants.

Two trials evaluated the effect of a composite of feed ingredients formulated to be similar in nutrient composition to wet distillers byproducts on finishing performance of sheep and cattle. Trial 1 used 60 crossbred lambs (31 kg) assigned to one of four treatments: dry-rolled corn (DRC) control, dried distillers grains plus solubles, wet corn gluten feed (WCGF), and wet distillers grains composite (COMP1). The COMP1 consisted (DM basis) of 47.5 WCGF, 11.9% condensed distillers solubles, 30.5% corn gluten meal, 9.7% tallow, and .4% dicalcium phosphate and was fed at 40% of the diet DM. Lambs fed the COMP1 diet were 27% more efficient (P < .10) than lambs fed WCGF and 12% more efficient (P > .10) than lambs fed DRC. In Trial 2, 60 yearling crossbred steers (272 kg) were assigned to one of five treatments: DRC control, WCGF, wet distillers grains composite (COMP2), COMP2 minus tallow (-FAT), or COMP2 minus corn gluten meal (-CGM). the COMP2 consisted (DM basis) of 65.7% WCGF, 26.3% corn gluten meal, and 8.0% tallow and was fed at 40% of the diet DM. Steers fed COMP2 were more efficient (P < .10) than steers fed DRC or WCGF, and the steers fed -FAT and -CGM were intermediate to these three dietary treatments. A composite diet of WCGF, condensed distillers solubles, corn gluten meal, and tallow, formulated to be similar in nutrient composition to wet distillers byproducts, may improve feed efficiency compared with WCGF or DRC.

Effects of feed intake and dietary level of wet corn gluten feed on feedlot performance, digestibility of nutrients, and carcass characteristics of growing-finishing beef heifers.

The objective was to compare the relative energy value of wet corn gluten feed (WCGF) to that of corn in a feedlot situation when diets were initially offered ad libitum (AL) or at restricted feed intake (RFI; 80% of AL). In a completely randomized block (pen location) design experiment, 144 beef heifers (204.1 +/- 18.2 kg) were used (six treatments; three pens of eight heifers/treatment). Treatments were levels of WCGF (on DM basis) in corn silage-based diets (AL; 25 or 50% WCGF) or high-moisture corn-based diets (RFI; 0, 25, 50, or 75% WCGF) during the growing phase (127 d). During finishing (84 d), all diets were offered AL and contained 5% corn silage by replacing corn silage with high-moisture corn in diets that were offered AL. Heifers that were initially at AL had similar (P > .1) feedlot performance (during growing and during the whole trial), digestibility of nutrients (OM, NDF, CP, and GE), and carcass characteristics. During finishing, however, these heifers had better (P = .06) ADG and gain:feed when 25% WCGF was fed. Heifers that were initially at RFI showed a linear decrease (P < .01) in ADG and gain:feed during growing with increasing dietary level of WCGF. However, increasing dietary level of WCGF resulted in a quadratic (P = .02) response in ADG and gain:feed during finishing and also in a quadratic (P = .07) response in ADG and a linear (P = .005) decrease in gain:feed during the whole trial. These quadratic responses indicated that the best performance was achieved at the 25 and 50% levels of WCGF. The decrease in cumulative gain:feed was only 3.5% at the 25 and 50% levels of WCGF but it was 11.4% at the 75% level. Increasing the level of WCGF in diets of heifers that were initially at restricted feed intake did not affect (P > .1) digestibility of nutrients but it improved some carcass characteristics linearly, decreasing fat thickness (P = .04), liver abscess (P = .02), and yield grade (P = .13). Results suggest that WCGF can substitute up to 25 or 50% of dietary DM without negative effects on feedlot performance, digestibility of nutrients, or carcass characteristics. In addition, restricting feeding during growing may be strategy that improves the utilization of WCGF at these levels.

Effect of protein supplementation on forage intake and nitrogen balance of lambs fed freshly harvested wheat forage.

Wether lambs (mean BW = 32 kg) fed wheat forage freshly harvested daily (Exp. 1, n = 28; Exp. 2, n = 25) were used to evaluate the effects of supplemental energy and protein on forage intake, diet digestibility, and N retention. Experiment 1 was conducted in the winter of 1988 and the four treatments were 1) CONTROL, no supplement; 2) ENERGY, low-protein corn-based supplement; 3) CSM, 22% CP supplement with cottonseed meal; and 4) CGM, 22% CP supplement with corn gluten meal. Experiment 2 was conducted in the spring of 1989, and the five treatments were 1) CONTROL; 2) ENERGY; 3) CSM, 23% CP with cottonseed meal; 4) FTM, 25% CP supplement with feather meal and corn gluten meal; and 5) BM, 25% CP supplement with blood meal and corn gluten meal. All supplements were isoenergetic and composed 22 and 24% of total DMI in Exp. 1 and 2, respectively. In Exp. 1, forage intake was not affected but total and digestible DMI were increased (P < .01) by energy and protein supplementation. Protein supplements did not (P > .10) increase total and digestible DMI compared to ENERGY supplementation but tended (P < .10) to increase N retention (g/d). In Exp. 2, digestible DMI and N retention did not differ among the five treatments. Results suggest that lambs consuming wheat forage in the vegetative stage (Exp. 1) will have greater digestible DMI if supplemental energy or protein is provided. When more mature wheat forage was fed (Exp. 2), energy seemed to limit animal performance.

Alfalfa and escape protein supplements for grazed corn residues.

Two calf corn-residue grazing trials were conducted to evaluate the effect of supplementing with two alfalfa hays (Medicago sativa), varying in their amount of CP and ADF, with and without escape protein (EP). In Trial 1, heifers (204 kg) grazed (1.36 heifers/ha) non-irrigated fields for 92 d. No difference (P > .05) in ADG was found when medium-protein (16.3% CP) and high-protein (18.0% CP) alfalfa hays were provided at 2.7 kg of DM.heifer-1.d-1. In Trial 2, 60 steers (257 kg) were supplemented individually with medium-protein (17.6% CP) alfalfa hay, 1.86 (MPL) and 2.27 kg DM (MPH), and one level of high-protein (18.7% CP) alfalfa hay, 1.86 kg DM (HPL). In a 2 x 3 factorial arrangement of treatments, steers were fed with or without EP (113 g.steer-1.d-1 from blood meal and corn gluten meal). Steers grazed a non-irrigated corn residue field (2.58 steers/ha) for 57 d and were watered and individually supplemented overnight. Diet quality and composition was estimated by collecting extrusa samples twice each week using four esophageally fistulated steers. No effects of alfalfa protein content or level (P > .05) were reflected in gain: 357, 309, and 326 g.steer-1.d-1 for steers receiving MPL, MPH, or HPL alfalfa treatments, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Accuracy of ELISA detection methods for gluten and reference materials: a realistic assessment.

The determination of prolamins by ELISA and subsequent conversion of the resulting concentration to gluten content in food appears to be a comparatively simple and straightforward process with which many laboratories have years-long experience. At the end of the process, a value of gluten, expressed in mg/kg or ppm, is obtained. This value often is the basis for the decision if a product can be labeled gluten-free or not. On the basis of currently available scientific information, the accuracy of the obtained values with commonly used commercial ELISA kits has to be questioned. Although recently several multilaboratory studies have been conducted in an attempt to emphasize and ensure the accuracy of the results, data suggest that it was the precision of these assays, not the accuracy, that was confirmed because some of the underlying assumptions for calculating the gluten content lack scientific data support as well as appropriate reference materials for comparison. This paper discusses the issues of gluten determination and quantification with respect to antibody specificity, extraction procedures, reference materials, and their commutability.

[Meteorological conditions affecting the quality of strong gluten- and medium gluten- wheat and climate division in Shandong Province].

With stepwise and one-factor non-linear regression analyses, and based on the meteorological data during the period from anthesis to maturity at 31 experimental sites in Shandong Province, this paper studied the relationships of the kernel quality of 4 strong gluten- and 12 medium gluten wheat cultivars with main meteorological factors in 1999-2003. The results showed that for strong gluten- and medium gluten wheat cultivars, the optimum mean temperature for dough stability time was 20.0 degrees C and 20.5 degrees C, the optimum mean difference of diurnal temperature for protein content was 12.7 degrees C and 11.7 degrees C, the optimum precipitation for sedimentation volume and dough stability time was 48.6 mm and 52.1 mm, and 53.5 mm and 53.9 mm, and the optimum total sunshine for sedimentation volume and dough stability time was 297 h and 299 h, and 295 h and 298 h, respectively. The effects of single meteorological factor on the protein content, sedimentation volume, and dough stability time of wheat cultivars were not identical. Based on the comprehensive evaluation of weather condition, Shandong Province was divided into three production zones for the production of wheat, i.e., central and east Shandong adaptable for strong gluten- and medium gluten- wheat cultivars, northwest and southwest Shandong sub-adaptable for strong gluten- and medium gluten- wheat cultivars, south Shandong sub-adaptable for strong gluten wheat cultivars and adaptable for medium gluten wheat cultivars.

Striking differences in the incidence of childhood celiac disease between Denmark and Sweden: a plausible explanation.

Among 771 children (381 Swedish and 390 Danish) investigated between 1972 and 1989 because of suspected celiac disease (CD), 179 proved to have the disease. Surprisingly only 24 CD patients were found among the Danish children, compared with 155 in the Swedish group, despite the close ethnic, geographical, and cultural background of the two populations. The Swedish CD children were diagnosed at an earlier age than the Danish children (mean, 1.5 vs. 5.5 years). The symptoms of the Swedish patients were dominated by failure to thrive (93 vs. 71%), whereas a higher proportion of the Danish CD patients suffered from stomach pain (21 vs. 5%). Breast-feeding habits were comparable. The estimated content of gliadin in the officially recommended diets of the two countries in 1987 differed substantially, the Swedish diet containing more than 40 times more gliadin than the Danish (4,400 vs. 100 mg) at the age of 8 months, and 4 times more (3,600 vs. 900 mg) at the age of 12 months. The Danish infant diet differed significantly from the Swedish in containing a larger amount of the lower gluten-containing rye flour. The earlier introduction of food items with a high gluten content in the Swedish compared with the Danish diet seems to be an obvious explanation for the great difference in incidence and symptomatology of CD between the two populations.

Nutritive value of globin-amino acid and complementary globin-cereal mixtures.

Protein efficiency ratios (PER) were determined using male weanling rats fed diets containing bovine globin alone and with wheat and corn gluten. Simultaneous equations and graphical methods were devised for selecting combinations of globin and cereal proteins to provide optimal and suboptimal profiles of limiting amino acids. Supplementation of the globin with amino acids established isoleucine and methionine as limiting amino acids. Addition of globin, whose amino acid pattern is complementary to that of the cereal proteins, markedly improved the PER values of the proteins. However, growth rates of rats fed various combinations of proteins were not identical, even though PER values differed only slightly. The PER of combined proteins were not predictable from amino acid composition or from correlations between PER and chemical score based on National Research Council (NRC) requirements for essential amino acids. The inability of the optimal mixtures to meet expected nutritional performance clearly indicated that other factors affecting availability of amino acids are implicated. Nevertheless, mutual improvement of two incomplete proteins such as globin and wheat or corn gluten was demonstrated. Addition of globin to widely used diets consisting mainly of corn or wheat can be nutritionally beneficial.