Corn Protein Research Articles

Corn proteins solubility changes during extrusion and traditional nixtamalization for tortilla processing: A study using size exclusion chromatography

Changes in the solubility of corn proteins occurring during traditional nixtamalization and extrusion processes used to produce tortillas were studied using size exclusion chromatography, SDS-PAGE and the Dumas method to measure 50% propanol-insoluble protein. Size exclusion chromatography (HPL-SEC) studies furthered the understanding of protein solubility changes during both processes. Extrusion caused more protein aggregation in tortilla intermediate and final products than traditional nixtamalization. Mixing during extrusion and in the intermediate step of masa production in the traditional nixtamalization process was critical in reducing protein solubility. Baking tortillas also considerably reduced the protein solubility for the traditional nixtamalization process. Baking produced aggregation that could not be disrupted with a reducing agent.

Near-infrared spectroscopy combined with equidistant combination partial least squares applied to multi-index analysis of corn

Development of small, dedicated, reagentless, and low-cost spectrometer has broad application prospects in large-scale agriculture. An appropriate wavelength selection method is a key, albeit difficult, technical aspect. A novel wavelength selection method, named equidistant combination partial least squares (EC-PLS), was applied for wavenumber selection for near-infrared analysis of crude protein, moisture, and crude fat in corn. Based on the EC-PLS, a model set that includes various models equivalent to the optimal model was proposed to select independent and joint-analyses models. The independent analysis models for crude protein, moisture, and crude fat contained only 16, 12, and 22 wavenumbers, whereas the joint-analyses model for the three indicators contained only 27 wavenumbers.Random validation samples excluded from the modeling process were used to validate the four selected models. For the independent analysis models, the validation root mean square errors (V_SEP), validation correlation coefficients (V_RP), and relative validation root mean square errors (V_RSEP) of prediction were 0.271%, 0.946, and 2.8% for crude protein, 0.275%, 0.936, and 2.6% for moisture, and 0.183%, 0.924, and 4.5% for crude fat, respectively. For the joint-analyses model, the V_SEP, V_RP, and V_RSEP were 0.302%, 0.934, and 3.2% for crude protein, 0.280%, 0.935, and 2.7% for moisture, and 0.228%, 0.910, and 5.6% for crude fat, respectively. The results indicated good validation effects and low complexity. Thus, the established models were simple and efficient.The proposed wavenumber selection method provided also valuable reference for designing small dedicated spectrometer for corn. Moreover, the methodological framework and optimization algorithm are universal, such that they can be applied to other fields.

Digestibility of feed ingredients in Florida pompano,Trachinotus carolinusadapted to either sea water or low salinity

Seven potential feed ingredients were evaluated for digestibility with Florida pompano Trachinotus carolinus using extruded diets. Ingredients included Special Select™ menhaden meal, fishery processing by-product (Montlake meal), NuPro® yeast extract, canola protein concentrate, corn protein concentrate, barley protein concentrate and Spirulina. Digestibility values were determined when fish were held at 3 and 28 g L−1 salinity to determine the effect of salinity on digestibility. With the exception of the canola protein concentrate, the coefficients were numerically higher in pompano held at 28 g L−1. No significant differences were detected for apparent crude protein or apparent energy digestibility between the two salinities. Amino acids were highly available from the two marine-based ingredients and the barley and canola concentrates. The availability of alanine, leucine, isoleucine and phenylalanine was significantly higher (P < 0.05) from the barley protein concentrate at 28 g L−1 than 3 g L−1 salinity. Methionine and phenylalanine were highly available from all the ingredients except the yeast protein. Conversely, glycine was not well utilised from any of the ingredients. The apparent digestibility coefficients provided here allow for more precise formulation of diets for Florida pompano reared in both seawater and low-salinity environments.

Preparation of antioxidative corn protein hydrolysates, purification and evaluation of three novel corn antioxidant peptides

Corn gluten meal is a major co-product of corn wet milling. Corn gluten meal was hydrolyzed with Alcalase, Flavourzyme, Alcalase+Flavourzyme and Flavourzyme+Alcalase. At the substrate concentration of 10%, corn protein hydrolysate catalyzed by Alcalase had a degree of hydrolysis of 17.83%, which was higher than that by Flavourzyme (3.65%). The hydrolysate catalyzed by Alcalase+Flavourzyme exhibited better antioxidant activities and was further purified. Three novel antioxidant peptides were purified by a series of chromatographic techniques. Sequences of the three peptides were identified as Cys-Ser-Gln-Ala-Pro-Leu-Ala, Tyr-Pro-Lys-Leu-Ala-Pro-Asn-Glu and Tyr-Pro-Gln-Leu-Leu-Pro-Asn-Glu, respectively. Among the three peptides, Cys-Ser-Gln-Ala-Pro-Leu-Ala exhibited good reducing power and excellent scavenging capacities for DPPH radical and superoxide anion radical, with IC50 values of 0.116 and 0.39mg/ml, respectively. The results from our study indicate antioxidant potency of corn protein hydrolysates and peptides separated from corn gluten meal and can provide basic understanding for the application of corn protein hydrolysates as natural antioxidants.

Replacing soybean meal with gelatin extracted from cow skin and corn protein concentrate as a protein source in broiler diets

Two experiments were conducted to investigate the effects of replacing soybean meal with gelatin extracted from cow skin and corn protein concentrate as a protein source in broiler diets. Experiments were carried out as a completely randomized design where each experiment involved 4 treatments of 6 replicates and 10 chicks in each pen. Soybean meal proteins in a corn-soy control diet were replaced with 15, 30, and 45% of cow skin gelatin (CSG) or corn protein concentrate (CPC), respectively, in experiments 1 and 2. BW and cumulative feed intake were measured at 7, 21, and 42 d of age. Blood characteristics, relative organs weight and length, ileal digesta viscosity, ileal morphology, and cecal coliform and Salmonella population were measured at 42 d of age. Apparent total tract digestibility of protein was determined during 35 to 42 d of age. Replacement of soybean meal with CSG severely inhibited BW gain, decreased feed intake, and increased FCR in broilers during the experimental period (P ≤ 0.01). The inclusion of CPC reduced BW and increased FCR significantly (P ≤ 0.05) at 21 and 42 d of age without any consequence in feed intake. Protein digestibility was reduced and ileal digesta viscosity was increased linearly by increasing the amount of CSG and CPC in the control diet (P ≤ 0.01). Replacement of soybean meal with CSG and CPC did not significantly alter blood cell profile and plasma phosphorus, creatinine, blood urea nitrogen, Aspartate transaminase, and HDL and LDL cholesterol concentration. The inclusion of CSG linearly (P ≤ 0.05) increased plasma uric acid concentration and alkaline phosphatase activity. Triglyceride and cholesterol levels were decreased significantly (P ≤ 0.05) when the amount of CSG replacement was 15%. The results of this experiment showed that using CSG and CPC negatively affects broiler performance and therefore is not a suitable alternative to soybean meal in commercial diets.

Simultaneous transfer of noble metals and three-dimensional micro- and nanopatterns onto zein for fabrication of nanophotonic platforms

In this paper, we report a method to manufacture green nanophotonic sensors made of corn protein zein. The method is direct transfer of three-dimensional metallic (gold and silver) nanostructures onto biodegradable zein films. We have transferred both micro-scale and nano-scale structures with several geometries. Inverted and positive pyramid structures, with 2 μm by 2 μm square base, nanopores, and nanopillars with an approximately 250 nm diameter were successfully transferred onto zein along with 200- and 80-nm-thick gold layers onto pyramids and nanopillars/pores, respectively. Rhodamine 6G was used as a model molecule for surface-enhanced Raman spectroscopy (SERS) measurements, and it was found that the inverted pyramid gold zein sensors had the highest enhancement factor, compared to the other zein sensors. The novel zein sensor platform we developed has the potential to serve as a biodegradable SERS platform for applications in agricultural, medical, and food analysis purposes.

Novel electrospun poly(glycerol sebacate)–zein fiber mats as candidate materials for cardiac tissue engineering

The application of a cardiac patch made of biodegradable polymer is a novel approach in regenerative therapies for infarcted cardiac tissue and aims to deliver healthy and functional cells on a mechanically supporting matrix to the damaged area of the myocardium. In this study a novel type of tissue engineered cardiac construct based on poly(glycerol sebacate) (PGS) blended with the corn protein zein was developed. Bead free electrospun PGS–zein fibers were fabricated using acetic acid as a benign solvent. In vitro degradation studies in PBS revealed a physicochemically stable system over a 28day period showing only a slight drop in pH after 28days. The results indicate that the novel PGS–zein fibrous structures are attractive biomaterials which can be valuable for cardiac patch applications thus warranting their further investigation in vitro and in vivo.

Evaluation of green solvents for a sustainable zein extraction from ethanol industry DDGS

Corn-ethanol industry in US alone generates about 35 Tg of Dried Distillers Grains with Solubles (DDGS) per year as co-product. DDGS is enriched with zein, a well-known corn protein. Vast potential of zein application in industries ranging from pharmaceuticals to bio-plastics resulted in a serious quest to develop process technologies for its extraction. A broad spectrum of primary, binary, ternary and tertiary solvents is available which can extract zein from DDGS. But most organic solvents are hazardous which limits their sustainable industrial-scale use. Our study evaluated green solvents: isopropanol, n-butanol, isobutanol, 2,3-butanediol (2,3-BDO), 1,4-butanediol, isoamyl alcohol, 1,3-dioxolane, 1,4-dioxane, tetrahydrofuran, acetic acid, lactic acid and ionic liquids [emim]Ac and [emim]Br for zein extraction. Isopropanol, 1,4-dioxane and 2,3-BDO showed promising results, with 75, 41 and 38% extraction efficiency, respectively. Operational parameters for efficient extraction such as temperature, pH and solvent-to-water ratio were subsequently optimized using response surface methodology for selected solvents. A combination of solvent to water volume ratio of 66:34, temperature of 77 °C and pH of 4.4 was found to be optimal for isopropanol, whereas 2,3-BDO worked best at solvent to water volume ratio of 73: 27, temperature of 85 °C and pH of 3.8. These results are encouraging and could lead to the development of green technology for efficient zein extraction.

Effects of various dietary levels of copper hydroxychloride on growth performance and tissue response in Pacific white shrimpLitopenaeus vannameifed practical diets

Two trials were conducted to evaluate the performance of Pacific white shrimp Litopenaeus vannamei offered diets containing various copper (Cu) levels from Cu hydroxychloride (Cu2(OH)3Cl) containing 58.81% copper in the clear water recirculating system. In both trials, the basal diet (360 g kg−1 protein, 80 g kg−1 lipid) containing approximately 10 mg Cu kg−1 was primarily comprised of fishmeal, soybean meal, corn protein concentrate and whole wheat. In trial 1, test diets were produced supplementing the basal diet with 5, 10, 20, 40 and 60 mg Cu kg−1 from Cu hydroxychloride. Four replicate groups of 15 shrimp per tank (initial weight 0.28 g) were offered diets in slight excess over 8 weeks. In trial 2, the basal diet was supplemented with 30, 90, 150, 210 and 270 mg Cu kg−1 from Cu hydroxychloride. Seven replicate groups of 15 shrimp per tank (initial weight 0.22 g) were offered feed in slight excess over 7 weeks. At the end of the two growth trials, no significant differences were observed in final biomass, final mean weight, percentage weight gain, feed conversion ratio (FCR) and survival. In trial 1, the Cu concentrations of the carapace, hepatopancreas and whole shrimp linearly increased with increasing dietary Cu supplements. In trial 2, polynomial regression of Cu concentrations of the carapace, hepatopancreas and whole shrimp against analysed dietary Cu content indicated that a plateau was reached at 215 mg analysed Cu kg−1. Results of this study indicate that there was no negative effect of high levels of Cu supplement with regard to growth and survival. Tissue levels generally increased up to around 200 mg Cu kg−1 diet and then decreased, possibly indicating a shift in physiology.

Development of a biodegradable sensor platform from gold coated zein nanophotonic films to detect peanut allergen, Ara h1, using surface enhanced raman spectroscopy

Peanuts are among the most common food allergies, which may result in life-threatening reactions in certain people. For this reason, it is very important to monitor the presence of peanuts in the food system. Biosensors are an emerging way of detecting allergen proteins. In this research, we present a surface enhanced Raman spectroscopy (SERS) technique to detect the main allergen protein, Ara h1. The sensors were biodegradable and made out of a corn protein, zein. Nanophotonic structures on zein films consisted of gold coated pyramid structures. It was found that both detection and quantification was possible by using a statistical clustering technique principal component analysis (PCA). An optimization in data processing yielded the result that baseline correction and shorter data collection times were needed in order to successfully cluster data. The limit of detection was found to be 0.14mg/ml. Furthermore, specificity of the sensor was provided by functionalizing the surface with monoclonal antibodies of Ara h1. Antibody functionalization, and Ara h1 capturing was tested and identified by also utilizing PCA analysis. As a proof-of-concept, this study showed that a biodegradable platform can be used in detection of a peanut allergen protein, Ara h1, using surface enhanced Raman spectroscopy.

Impact of Dry-milled Germ Processing on Aqueous Protein and Oil Extraction

Reduced petroleum cost and public objection to using corn for bioenergy rather than food have challenged grain ethanol producers to come up with new bioprocess and coproducts that can add value but maintain ethanol cost competitiveness. Novel dry and wet milling fractionation processes of corn that could generate higher value coproducts and improve coproduct economics, long-term outlook, and economic stability of corn processing plants have been being recently proposed. Germ Wet Milling™ is such novel aqueous processing method designed to increase germ protein and oil concentration by water soaking and wet fractionation of dry-milled corn germ. The goal of this study was to investigate the sequential oil and protein extraction after Germ Wet Milling and to develop economically viable processes for producing protein concentrates. Corn protein concentrates were prepared after aqueous processing of dry-milled germ using membrane filtration or isoelectric precipitation. The amount of protein recovered was a function of the protein dispersibility index of the starting material, which depended on soak temperature and time. Extracts prepared after Germ Wet Milling™ contained 59.1 to 64.7 % protein (db), while concentrates had 64.9 to 82.4 % protein. The technique used for protein recovery also influenced the mass and protein yield and composition. For all treatments, membrane filtration was a more effective method than isoelectric precipitation for recovering protein from extract. Aqueous enzymatic oil extraction (AEOE) was used to evaluate the oil recovery potential after Germ Wet Milling. The effect of enzyme dosages and/or elimination of the acidic protease on oil extraction from high protein, high protein dispersibility index (PDI) corn germ and high protein, low PDI corn germ were evaluated. AEOE using a combination of cellulases and xylanase (Optimash XL®), an acidic protease (Fermgen®), and a basic protease (Optimase®) resulted in oil recoveries as high as 71.9 % of the initial oil content. A twofold reduction in enzyme dosages was possible with little or no effect on oil recoveries for both types of germ.

Plant protein sources in the diets of the sciaenids red drum (Sciaenops ocellatus) and shortfin corvina (Cynoscion parvipinnis): A comparative study

Two parallel feeding trials were conducted to determine the responses of red drum (Sciaenops ocellatus, initially weighing 4.7±0.3g) and shortfin corvina (Cynoscion parvipinnis, initially weighing 8.6±1.0g) to increasing dietary percentages of non-genetically modified soybean meal (SBM-3010), soybean protein concentrate (Soy-PC) and corn protein concentrate (Corn-PC) as replacements for menhaden fishmeal. A basal diet contained (dry-matter basis) 40% crude protein from menhaden fishmeal and 10% crude fat primarily from menhaden fish oil. Then, nine diets were formulated by replacing 25%, 50% and 75% of protein in the basal diet with SBM-3010, Soy-PC and Corn-PC, while adding crystalline supplements of lysine, methionine, taurine, and glycine. After 7weeks of culture for red drum and 8weeks for shortfin corvina, treatment mean final weights ranged from 28.8 to 40.7g and from 35.2 to 51.6g, respectively. Significant (P<0.05) differences were detected across all growth performance and feed utilization parameters for both red drum and shortfin corvina. When supplemented with amino acids, SBM-3010 and Soy-PC can replace up to 75% of menhaden fishmeal protein, and that Corn-PC can successfully replace up to 50% of fishmeal protein without compromising the performance of red drum. Likewise, for juvenile shortfin corvina, Soy-PC and Corn-PC can replace up to 75% of fishmeal protein in the diet, while SBM-3010 successfully replaced up to 50% of fishmeal protein without compromising fish performance. The whole-body proximate composition was significantly influenced by the dietary treatments in shortfin corvina, but not in red drum. Statement of relevanceThe present manuscript provided an excellent opportunity to conduct comparative nutrition research and advance the development of more sustainable diets for the aquaculture of sciaenid species. For red drum, Sciaenops ocellatus, it was observed that Soybean meal (SBM) and soybean protein concentrate (Soy-PC) can replace up to 75% of fishmeal protein in the diet; while corn protein concentrate (Corn-PC) can successfully replace up to 50% of fishmeal protein, without compromising fish growth performance. For shortfin corvina, Cynoscion parvipinnis, Soy-PC and Corn-PC can replace up to 75% of fishmeal protein in the diet, while SBM successfully replaced up to 50% of fishmeal protein.

Evaluation of various cottonseed products on the growth and digestibility performance in Florida pompano Trachinotus carolinus

Two 10-week growth trials and digestibility trials were conducted to assess the efficacy of various cottonseed products in practical diets for the Florida pompano Trachinotus carolinus. In trial 1, a basal diet containing 150g/kg of fishmeal (FM150) was modified by the iso-nitrogenous replacement of fishmeal (FM) with cold pressed cottonseed flour (CSF) resulting in diets containing 100g/kg (FM100), 50g/kg (FM50) and 0g/kg (FM0) of fishmeal. To determine if lysine was limiting in the FM0 diet, two additional diets were developed using a high lysine corn protein concentrate (FM0-LCPC) or a crystalline source of lysine (FM0-CL). In trial 2, the basal diet was formulated to contain 457.0g/kg of soybean meal (SBM) and 150g/kg of poultry by-product meal (PBM), the other three diets were made by replacing SBM on an iso-nitrogenous and iso-lipidic basis with varying cottonseed flours (CSF) which included cottonseed flour (CSF), gossypol-extracted cottonseed flour (ECSF), and glandless cottonseed flour (GCSF). In trial 1, results showed that the use of up to 196g/kg of CSF with a lysine supplement does not inhibit growth performance of the fish. In trial 2, no significant differences were observed in growth performance of the fish maintained on the various diets. Although gossypol was detected in the livers of fish offered diets with gossypol, no differences were observed in the cells of the liver samples or organization of the liver cells amongst any of the treatments. After each growth trial, apparent digestibility coefficients for dry matter (ADMD), energy (AED), and protein (APD) were determined for primary ingredients. In the first digestibility trial, no significant differences were observed with regard to digestibility coefficients for FM, CSF, and corn protein concentrate (CPC). In the second digestibility trial, no significant differences were observed on ADMD and AED for the ingredients GCSF, CSF, and ECSF. However, the APD values for ECSF were found to be significantly lower than those values of GCSF and CSF. Results of this study provide support that cottonseed products are acceptable for use in practical diets for Florida pompano. Statement of relevanceIn this study, we assessed the efficacy of various cottonseed products in practical diets for the Florida pompano. These findings will be useful because the feed producers need the growth and digestibility data of the cottonseed products as an alternative ingredient to use in the diet formulation. The conclusions in this manuscript provide valuable information which researchers and feed producers need to use the cottonseed products in diets of this species.

Controlled Release from Zein Matrices: Interplay of Drug Hydrophobicity and pH.

PurposeIn earlier studies, the corn protein zein is found to be suitable as a sustained release agent, yet the range of drugs for which zein has been studied remains small. Here, zein is used as a sole excipient for drugs differing in hydrophobicity and isoelectric point: indomethacin, paracetamol and ranitidine.MethodsCaplets were prepared by hot-melt extrusion (HME) and injection moulding (IM). Each of the three model drugs were tested on two drug loadings in various dissolution media. The physical state of the drug, microstructure and hydration behaviour were investigated to build up understanding for the release behaviour from a zein based matrix for drug delivery.ResultsDrug crystallinity of the caplets increases with drug hydrophobicity. For ranitidine and indomethacin, swelling rates, swelling capacity and release rates were pH dependent as a consequence of the presence of charged groups on the drug molecules. Both hydration rates and release rates could be approached by existing models.ConclusionThe drug state and pH dependant electrostatic interactions are hypothesised to influence release kinetics. Both factors can potentially be used to influence release kinetics release, thereby broadening the horizon for zein as a tuneable release agent.Electronic supplementary materialThe online version of this article (doi:10.1007/s11095-015-1818-8) contains supplementary material, which is available to authorized users.

Process integration for recovery of recombinant collagen type I α1 from corn seed.

Because of safety concerns and product consistency issues with the use of animal-derived collagen, several recombinant protein expression hosts have been considered for recombinant collagen corn seed. Full length, triple-helical, recombinant collagen (rCIα1) is expressed as a fusion with a foldon domain, which must later be removed. Here we have examined integration of purification and foldon removal by comparing advantages of removal before or after purification, using salt precipitation as the main purification step. Because expression levels in available maize lines are low, Pichia-produced recombinant collagens, both with and without foldon, were added to corn seed germ at the extraction step. Salt precipitation of an acidic corn seed extract yielded 100% of the collagen without foldon at >70% purity without the pepsin pretreatment. With pepsin pretreatment, yield was 94.0% with purity of 76.5%. Analysis of the protein molecular weight distribution of the pre- and post-treatment extracts showed that the corn proteins are largely resistant to pepsin proteolysis, explaining why little benefit was obtained by pepsin treatment. In the absence of pepsin treatment, the recovery of rCIα1 with foldon was still above 90% but the purity was only 44%. This still represented at about 13-fold purification with a 2.7-fold volume reduction which would reduce the pepsin requirement for post-recovery foldon cleavage.

Inhibition of Hepatocyte Apoptosis: An Important Mechanism of Corn Peptides Attenuating Liver Injury Induced by Ethanol.

In this study, the effects of mixed corn peptides and synthetic pentapeptide (QLLPF) on hepatocyte apoptosis induced by ethanol were investigated in vivo. QLLPF, was previously characterized from corn protein hydrolysis, which had been shown to exert good facilitating alcohol metabolism activity. Mice were pre-treated with the mixed corn peptides and the pentapeptide for 1 week and then treated with ethanol. After treatment of three weeks, the biochemical indices and the key ethanol metabolizing enzymes, the serum TNF-α, liver TGF-β1 concentrations and the protein expressions related to apoptosis were determined. We found that the Bcl-2, Bax and cytochrome c expressions in the intrinsic pathway and the Fas, FasL and NF-κB expressions in the extrinsic pathway together with higher TNF-α and TGF-β1 concentrations were reversed compared with the model group by both the mixed corn peptides and the pentapeptide. The activation of caspase3 was also suppressed. Additionally, apoptosis was further confirmed with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and the TUNEL assay demonstrated peptides suppressed hepatocyte apoptosis. Our results suggest that apoptosis induced by ethanol is alleviated in response to the treatment of corn peptides, potentially due to reversing the related protein expression.

Utilization of Different Corn Fractions by Broilers

This study was conducted to evaluate the nutritional values of fractions of damaged corn. One hundred and eighty 22-d-old Cobb 500 male broilers were distributed in batteries according to a completely randomized design with six treatments of six replicates each. The treatments consisted of diets containing five corn fractions, classified as sound, fermented, insect-damaged, mold-damaged, or reference corn. The test diets consisted of 60% of reference diet + 40% of each corn fraction. Only the reference corn fraction included all the fractions at different proportions (0.8% fermented, 0.05% insect-damaged, 3.3% mold-damaged, and 95.85% sound grains). The method of total excreta collection was used to determine AMEn values and metabolizability coefficients of dry matter (MDM), crude protein (MCP), ether extract (MEE), and gross energy (MGE) of the reference corn and its fractions. The density values of the corn fractions were used to calculate the correlations among the evaluated parameters. The evaluated corn fractions presented different compositions values. The insect-damaged and mold-damaged grains presented higher CP level, lower density, and MDM and MCP coefficients compared with the other fractions. However, calculated AMEn values were not significantly different (p>0.05) among corn fractions. A low correlation between density and AMEn content (r 0.8) were calculated. Although the evaluated corn fractions presented different nutritional values, there were no marked differences in their utilization by broilers.

Antioxidative Activities and Peptide Compositions of Corn Protein Hydrolysates Pretreated by Different Ultrasonic Methods

Three different ultrasonic methods were compared based on the production of antioxidative peptides from corn protein. The corn protein was sonicated with probe ultrasound (PU), flat plate ultrasound with sweeping frequency , and flat plate ultrasound with fixed frequency before hydrolysis by acalase. Degree of hydrolysis (DH), antioxidative activities and peptide compositions were determined. The hydrolysates derived from PU pretreatment yielded the highest DH. However, lower Fe2+-chelating activity, 1,1-diphenyl-2-picrylhydrazyl radical and hydroxyl radical scavenging activities were observed for the corn protein hydrolysates (CPH) under PU pretreatment. The percentage of peptides with molecular weight of 500–180 Da increased with the increasing of DH. While the order of percentage of MW 2000–500 Da relative to ultrasonic method was in accord with Fe2+-chelating activity and OH radical scavenging activity. Amino acid analysis indicated that CPH under FPUSF and FPUFF pretreatments, with higher hydrophobic amino acid contents, had stronger antioxidative activities.

Effect of fertigation on amount of protein, yield and yield components of corn

To study effect of furrow fertigation on amount of protein, yield and yield components of corn, a field experiment was conducted in Seed and Plant Improvement Institute of Karaj, Iran in the summer of 2012. The study design was a factorial design based on randomized complete block with 4 replication. First factor (N) includes three fertilizer levels of 60%, 80% and 100% recommended fertilizer value and the second factor (T) includes two split application fertilizer levels (four and three split application). The nitrogen required for the plant is provided by urea fertilizer and used along with water irrigation. Finally, these 6 treatments were compared with traditional fertilizer application method (Control). The results showed that treatment of 80% and 100% recommended fertilizer has not a significant difference with amount of protein. Therefore, 80% recommended fertilizer in four split application is recommended for increase of protein. The results in terms of yield of corn showed that 60% fertilizer in four split application has the most yield. In addition, the results showed that fertigation comparing method of surface fertilizer distribution increases yield and yield components. Therefore, fertigation is recommended as fertilizer management choice comparing traditional method of fertilizer distribution.

Effects of dietary taurine supplementation on growth, feed efficiency, and nutrient composition of juvenile sablefish (Anoplopoma fimbria) fed plant based feeds

Abstract Juvenile sablefish were fed a low taurine, basal feed with seven graded levels of supplemental taurine to determine taurine requirements for growth and feed efficiency. The basal feed was plant based, formulated primarily with soy and corn proteins with a minimal (9%) amount of fishmeal. The unsupplemented, basal feed contained 0.14% taurine. Experimental feeds were supplemented with 0, 0.25, 0.50, 1.0, 1.5, 3.0, and 6.0% taurine. Using the five parameter, saturated kinetic model (5 SKM), peak weight gain was predicted at 1.5% dietary taurine. Optimum weight gain, as defined as the region of the 5 SKM curve corresponding to at least 95% of peak, was predicted between 0.4% and 5.8% dietary taurine. Peak feed efficiency was predicted at 1.1% dietary taurine with optimum weight gain predicted between 0.4% and 4.2%. Whole body and muscle tissue protein and lipid content were not affected by taurine supplementation. Tissue taurine content increased asymptotically with increasing dietary taurine supplementation. Whole body tissue became saturated at 0.25 ± 0.02% taurine, expressed on a wet weight basis. Muscle tissue became saturated at 0.34 ± 0.02% taurine. Results from this study should increase the performance of alternative, plant based feeds formulated for sablefish and enable regulatory agencies better estimate the potential human exposure to taurine from the consumption of sablefish receiving these feeds.