2009 Protein and Co-Products
PCP 1: Protein Co-Products from Biofuel Productions
Chair(s): K. Liu, USDA ARS, USA; H. Wang, Iowa State University, USA; and J. Wanasundara, Agriculture & Agri-Food Canada, Canada
Corn Distillers Dried Grains with Solubles (DDGS): Opportunities and Challenges. Kurt A. Rosentrater, USDA, ARS, North Central Agricultural Research, Brookings, SD, USA
Corn-based ethanol in the U.S. has dramatically increased in recent years; so has the quantity of associated coproducts. Nonfermentable components are removed from the process as whole stillage, centrifuged to remove water - which is then evaporated to produce condensed distillers solubles (CDS), and then is recombined with the centrifuge solids and dried to produce distillers dried grains with solubles (DDGS). Each bushel of corn (56 lb) will result in nearly 2.9 gal of ethanol, 18 lb of CO2, and 18 lb of DDGS. DDGS are ~ 30% protein, 10% lipid, over 30% neutral detergent fiber, and up to 10% starch. Composition, however, can vary between plants and within a single plant over time. Distillers grains are primarily used as livestock feed, especially for beef and dairy, but also in swine and poultry as well. This helps to offset the use of corn for ethanol instead of feed or food. But there are many challenges associated with DDGS, including variability in nutrient content and quality; lack of an industry-wide quality grading system; inconsistent product identity and nomenclature; large quantities of energy required to remove water and the high cost of energy; moving DDGS to diverse and distant markets; potential mycotoxin contamination; and international marketing and export. Another challenge is poor flowability and material handling behavior.
Improving Co-products Composition by Dry Grind Ethanol Fermentation. Vivek Sharma1, Robert Moreau2, Vijay Singh1, 1Dept. of Agriculture and Biological Engineering, University of Illinois, Urbana, IL, USA, 2Crop Conversion Science and Engineering, ERRC, ARS, USDA, Wyndmoor, PA, USA
Hominy feed is a low value coproduct of the corn dry milling process that accounts for nearly 35% of the starting corn quantity. The average composition of hominy feed on a dry basis is 56.9% starch, 25.2% neutral detergent fiber, 11.1% protein, and 5.3% fat. Starch in hominy feed can be fermented to ethanol thus increasing its levels of protein and fat. The increase in protein and fat percentages may increase the market competitiveness and price of hominy feed. Hydrolysis and fermentation were performed on nine hominy feed samples collected from three corn dry milling plants in the US. The original hominy feed samples and post fermentation solids were analyzed for starch, protein, fat and fiber content. Compared to the original hominy feed, the percentage increase in protein, fat and fiber in post fermentation solids of nine samples ranged from 10.4 to 21.3, 6.78 to 10.6 and 12.6 to 28.7% (dry basis), respectively. Ethanol yields varied from 271.7 to 380.2 L/metric ton for the nine hominy feed samples. These results are indicative that the value of hominy feed as an ingredient in animal diets can be increased with fermentation.
Using a new Modified Wet, Biorefinery System in an Ethanol Plant to Produce Novel Food Products. T. Lohrmann, D. Hammes, T. Adler, Quality Technology International, Inc., Elgin, IL USA
A majority of the ethanol plants today, or those currently under construction, are designed such that the entire corn kernel is ground prior to fermentation. The non-fermentable fraction remaining after fermentation is commonly dried to make it more shelf stable and sold into the livestock markets as a lower value feed product termed dried distiller grains with solubles. Recently we converted a 40 million gallon ethanol plant from a traditional dry grind system into a next generation, modified-wet fractionation bio-refinery capable of making food products such as high TDF corn bran and high purity corn germ. Since the biorefinery is a food grade facility and the fiber and germ are removed prior to fermentation, they make an excellent substrate for new food products. In contrast to the traditional wet milling system, this new modified-wet fractionation system is novel because sulfur dioxide is not added during the initial soak process. Currently second generation, further-processed food products are in development which will bring even greater consumer benefits and value from this evolving industry.
Effect of Corn Breaking Method on Oil Distribution in the Thin Stillage of Dry-Grind Corn Ethanol Production. Hui Wang, Tong Wang, Lawrence Johnson, Iowa State University, Ames, Iowa, USA
One strategy to increase oil recovery from dry-grind corn ethanol production is through increasing oil distribution from solid fraction (wet distillerâ€™s grains) to the liquid fraction (thin stillage) by physical treatment of the corn before fermentation. Several physical corn breaking methods were investigated in this study, including grinding, flaking, extrusion, and combination of them. A laboratory fermentation process and a bench-scale decanting procedure were successfully developed to stimulate the industry fermentation and decanting operation. It was found that oil distribution into thin stillage was positively correlated with the dry matter content of the thin stillage. The extractability of the oil in the slurry was also investigated. Flaking then high-shear-extrusion treatment released the highest amount of free oil. However, this treatment also produced the highest amount of fine particles, which led to the highest dry matter content in thin stillage. The combinations of low-shear-extrusion with grinding/flaking were also tested. All results indicate that it is difficult to increase oil distribution into liquid fraction without producing extensive fine particles.
Factors Affecting Fat Analysis of DDGS as Compared with Ground Corn. Keshun Liu, U.S. Dept. of Agriculture, Agricultural Research Services, Aberdeen, Idaho, USA
There are a few official methods for measuring oil/fat content in grains and feed. Yet guidelines on which method to be used for dried distiller grains with solubles (DDGS) are yet to be fully developed. In this study, a rapid determination of oil/fat utilizing high temperature solvent extraction (AOCS Approved Procedure Am 5-04) was used for measuring oil in ground corn and resulting DDGS. Factors, including sample type (ground corn and DDGS), sample variety (from ethanol plant 1, 2 and 3), sample particle size (original matrix, <25, and <35 U.S. standard mesh), solvent type (petroleum ether and hexane), extraction time (30 and 60 min), and drying time after extraction (30 and 60 min), were investigated by a complete factorial design. When measuring corn, only sample variety and extraction time had significant effect (p < 0.05) on oil values measured, but for DDGS, besides the two factors, sample particle size, solvent type and drying time also had significant effects. Among them, particle size affected most. On average, the measured oil content in DDGS ranged from 11.11% (original matrix), to 12.12% (< 25 mesh) and to 12.55% (< 35 mesh). In measuring oil in DDGS, particle size reduction, 60 min extraction and 60 min drying are recommended. Although petroleum ether gave a significantly higher value than hexane, the difference was relatively small.
Causes of Physical and Chemical Variability in Corn Distillers Dried Grains with Solubles (DDGS). Klein E. Ileleji, A.R.P. Kingsly, C.C. Clementson, K. Probst, Purdue University, West Lafayette, IN, USA
Variability in corn distillers dried grains with solubles (DDGS) is said to be one of the major reasons hindering the adoption of DDGS as a feed in livestock diets. Current production of DDGS in the U.S. is about 14 million tons from about 125 operating plants using corn with a total capacity of about 6.0 million gallons of ethanol. DDGS produced by a majority of the corn ethanol plants have high feed value due to its nutritive contents. However, the variability of DDGS product makes feed formulation by nutritionist difficult, especially when compared with its corn substitute. Past studies have shown that physical and chemical variability of DDGS is not just among plants but can vary between batch to batch from the same plant. Recent bench-scale and plant-scale research at Purdue University have identified the production process causes of DDGS variability and its effect on the chemical and physical properties of the product. This presentation and paper will bring the cumulative results of both the bench-scale and plant scale studies and discuss what can be done to minimize variability.
Co-Products of Biodiesel Manufacturing. M. Reaney, J. Shen, K. Ratanapariyanuch, C. Schock, R. Sani, University of Saskatchewan, Saskatoon, SK, Canada
A typical biodiesel plant using transesterification catalysis will produce at two products - biodiesel and glycerin. Both of these molecules are relatively low value commodities. However, it is possible to produce a wide range of value added products as diverse as health foods and industrial lubricants. Strategies for increasing the value of biodiesel production facilities by recovering high value co-product streams including lithium grease, lubricity concentrates, phytosterols and conjugated linoleic acid will be discussed.
Separation of Protein and Corn Oil from Dry Milling Ethanol Plants. M. Dasari1,2, M. Abdullah1,2, 1FEC Solutions, Des Moines, IA, USA, 2Feed Energy Company, Des Moines, IA, USA
Byproducts from dry-mill ethanol production, conventionally sold as bulk livestock feed, are increasing at a significant rate and the supply may soon exceed the feed demand from the livestock industries. Specifically, high value corn fractions containing oil, limit the ability of livestock industries to increase the amounts of byproduct included in feed rations. With the lack of cost effective processes to extract value components from byproduct, an opportunity exists to develop technology to fill this emerging gap.The overall goal of this project is to demonstrate the feasibility of producing value-added co-products from the fermentation byproducts of dry-milling ethanol plants.
Pilot Process for Decolorizing/Deodorizing Commercial Corn Zein Products. D.J. Sessa, National Center for Agricultural Utilization Research, USDA, ARS, Peoria, Illinois, USA
Corn zein is the major protein component of ground corn, and co-products of the corn ethanol industry which includes distiller's dried grains and corn gluten meal. Zein products generated from those materials all possess some degree of yellow color and off-odor that deters their usage in food systems as well as in the medical, pharmaceutical and cosmetic industries. A pilot-scale process(patent pending) was developed to purify those products based on the protein and contaminants adsorption characteristics onto activated carbons (ACs) and zeolites (Zs), clay-based particles acting as molecular sieves. Statistical analyses of the binding characteristics of protein and contaminants for a series of ACs and Zs demonstrated that ACs from coconut hulls and Zs with a 5 Angstrom pore size proved ideal for adsorbing the least amount of protein relative to the adsorption of contaminants.These findings were used to select the media for packing the four columns of our pilot scale apparatus. The operating principles involve selective sequestration of the low molecular weight contaminants by continuous recycling of the column eluates. Sequential filtration proved to be an alternative to methodologies involving ultrafiltration/diafiltration on a tangential flow system that provided good recoveries of a purified zein product.
Tracking Lipid Levels during Ethanol Fermentation. C. Weller, E. Newgard, C. Leguizamon, Department of Biological Systems Engineering, University of Nebraska, USA
Producers using a dry-grind process to produce ethanol from corn and grain sorghum are actively searching for modifications that can be made to their process so as to extend their line of end products. Such modifications may result in valuable fiber, protein and lipid fractions. If such fractions become reality, a baseline level for each component in the various process unit operations and associated changes in the levels across the whole process need to be known for optimization. Observed lipid levels in unit operations of a bench-scale dry-grind ethanol production process using corn and grain sorghum will be presented. The observed lipids will be those reported to have health benefits when consumed. Speculation as to the reasons for changes in levels within or between unit operations will be described.
New Corn Degerming Processes and the Germ Quality. Hui Wang, Tong Wang, Lawrence Johnson, Iowa State University, Ames, IA, USA
A new degerming process was developed in this study. The germ yield, oil content in the germ, and the oil quality were investigated. It was found that this process effectively recovered the germ fraction from the corn and produced co-products with good purity.
PCP 2: Effect of Processing on Protein Functionality
Chair(s): S. Jung, Iowa State University, USA; and C. Onwulata, USDA, ERRC, USA
Effect of High Pressure Processing on Functional Properties of Food Proteins. M. de Lamballerie, H. Simonin, ENITIAA, BP 82225 44322 Nantes cedex 3 France
High pressure processing (200-800 MPa) is an alternative to traditional thermal food preservation methods, becoming current at the industrial scale, mostly for meat, seafood, fruit and vegetables. High pressure processing has limited effects on covalent bonds resulting in few protein modifications; however effects of high pressure treatment on weak bonds induce protein modifications. As food protein functional properties are linked with protein conformation, every property including water binding, emulsifying, foaming and gelling ability (consequently texture and rheology behaviour), enzymatic characteristics, colouring features and digestibility, may be modified by high pressure processing.This presentation will review main effects of high pressure processing on functional properties of food proteins, and will focus on our own results about:- several substrates: fish, meat, hen egg yolk, soy, and lupin proteins- high pressure at ambient temperature, and pressure shift freezing- texture, ultra structure, proteolytic activity (cathepsin and calpain), colour, emulsifying and gelling properties, and digestibility (related to allergenic properties).Finally the aim of this work is to improve the knowledge of effect of high pressure on proteins, to intend to favourably use main protein modifications under high pressure treatment.
Value Added Uses of Bitter Melon (Momordica charantia) Seed Protein (Emulsifying Property Enhancement). N. Hettiarachchy, R. Horax, P Chen, University of Arkansas, Fayetteville, AR, USA
Bitter melon is mainly used in Asia for food and medicinal purposes. The ripe seed is rich in protein. However, no information is available on its use as a functional protein.The objectives were to prepare bitter melon seed protein isolate (BMSPI), and investigate the functional properties before and after modification by glycosylation. BMSPI was prepared under optimum conditions (1.3M NaCl, pH 9.0). Glycosylation was conducted at varying relative humidities and temperatures using central composite design. Degree of glycosylation (DG), thermal and emulsifying properties were determined by fluorescamine assay, differential scanning calorimetry, and turbidimetry, respectively. The protein content of BMSPI was 90.2%. DG ranged from 39.3-52.5%, 61.7-70.9%, and 81.2-94.8% for treatments at 40, 50, and 60oC, respectively (p-values <0.0001). No significant differences in the denaturation temperature were observed between unmodified BMSPI (113.2oC) and glycosylated BMSPI (113.2-114.6oC) with the exception of glycosylation at 60oC (111.6-111.9oC). Emulsifying activity increased from 0.35 to 0.80 for 80% DG or above, while emulsifying stability increased from 63 min to 72 min for above 70% DG. This glycosylated BMSPI with improved emulsifying properties can be used as an ingredient in foods where such properties are required.
A Mechanistic Study of Pea Protein Isolate - Gum Arabic Complex Formation. S. Liu, N. Low, M. Nickerson, Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK, Canada
Turbidity measurements were used to study the formation of soluble and insoluble complexes between pea protein isolate (PPI)-gum Arabic (GA) mixtures as a function of pH (6.0-1.5), salt concentration (NaCl, 0-50 mM) and protein-polysaccharide weight mixing ratio (1:4 to 50:1 w/w). For mixtures in the absence of salt and at a 1:1 mixing ratio, two structure-forming transitions were observed as a function of pH. The first event occurred at a pH of 4.2, with the second at 3.7, indicating the formation of soluble and insoluble complexes, respectively. Sodium chloride (≤7.5 mM) was found to have no effect on biopolymer interactions, but interfered with interactions at higher levels (>7.5 mM) due to substantial PPI aggregation. The pH at which maximum PPI-GA interactions occurred was 3.5, and was independent of NaCl concentrations. As PPI-GA ratios increased, structure-forming transitions shifted to higher pH. Complexation was greatest at a protein-polysaccharide weight-mixing ratio of 2:1. The nature of interactions involved during complex formation was subsequently studied in the presence of high levels of salt, urea, and as a function of temperature (6-60°C) to reveal mechanisms dominated by electrostatic forces, with secondary stabilization by hydrogen bonding and hydrophobic interactions.
Extraction and Characterization of Corn Germ Proteins. M.P. Hojilla-Evangelista, USDA ,ARS, NCAUR, Peoria, IL USA
Our study was conducted to develop methods to extract corn germ protein economically and characterize and identify potential applications of the recovered protein. Protein was extracted from both wet germ and finished (dried) germ using 0.1M NaCl as solvent. The method involved homogenization, stirring, centrifugation, dialysis and freeze-drying. Factors evaluated were temperature (45, 55, or 65°C) and presence of reducing or denaturing agents. The recovered protein was analyzed for proximate composition and functional properties. Extraction was done at 45°C because no benefit was obtained by using higher temperatures. Addition of 2% SDS and 1% β-mercaptoethanol to the solvent nearly doubled protein yield; however, SDS-PAGE indicated protein denaturation. The recovered freeze-dried protein was least soluble (20%) at pH 2.0-4.0, but solubility increased gradually at higher pH. Wet germ protein extract was more soluble than finished germ protein at all pH values; however, the finished germ protein showed much better foaming and emulsifying properties.
Characterization of Protein Compositional Profiles and Structural Changes in Extruded WPI. P. Qi, C. Onwulata, USDA, ARS, ERRC, Wyndmoor, PA, USA
It was demonstrated that food products containing extruded whey protein isolate (WPI) possess beneficial nutritional properties and desirable texture. The effects of extrusion on the protein compositional profiles and molecular structures of WPI, however, remain poorly understood. In this work, we studied the effect of extrusion conditions including moisture and temperature on the protein compositional profiles by SDS-PAGE in the presence and absence of reducing agent, 1, 4-dithiothreitol (DTT). The molecular structural changes were investigated using circular dichroism (CD), FTIR and fluorescence spectroscopic techniques. The results showed that the extrusion moisture bears a clear positive effect on the water solubility of the proteins, but only negligible impact on the protein secondary structures. Increasing extrusion temperature, on the other hand, not only significantly reduces the water solubility but also considerably alters the protein composition and structures through the combination of shear and thermally- induced aggregation and denaturation. Quantitative analysis from gel electrophoresis suggested that among the two major protein components in WPI, β-lactoglobulin appears to undergo a greater conformational loss as a function of extrusion temperature compared to α-lactalbumin, presumably due to the formation of intermolecular disulfide bonds.
Functional Implications of Texturized Whey Proteins. C.I. Onwulata, P.X. Qi, A.E. Thomas, P.M. Tomasula, USDA,ARS, ERRC, Wyndmoor, PA, USA
Whey proteins are used in many food products to enhance nutrient content. Recent research findings are showing improved health benefits of whey proteins such as superior immune response. As spray dried whey protein powders, only limited amounts, less than 5 wt% can be used in formulated foods before unacceptable taste and textural thresholds are reached. To improve the physical compatibility of whey in formulations, and to boost the amounts that can be added up to 25 wt%, it was necessary to modify whey proteins functional groups and their conformation. We have used the extrusion processing conditions of moderate shear and temperatures (<100°C) to partially denature whey protein isolates. The process modification resulted in apparent loss (~15%) of secondary structures confirmed with Atomic Force Microscopy, and complete loss of globular structure at 75°C, and conversion to true random-coiled structure state at 100°C. High temperature extrusion formed distinct and uniform densely-packed structures which improved textural, functional, and nutritional properties. These textured whey protein isolates were used in formulated snack-type products.
PCP 3: Bioactive Peptides in Human Health and Diseases
Chair(s): H. Kumagai, Nihon University, Japan; H. Ibrahim, Kagoshima University, Japan; and J. Wu, University of Alberta, Canada
Squeezing New Therapeutic Peptides Out of Egg Albumin. Hisham Ibrahim, Kagoshima University, Faculty of Agriculture, Kagoshima, Japan
Increasing attention is being focused on the science of bioactive peptides derived from food proteins. These peptides are inactive within the sequence of the protein molecule and can be liberated by gastrointestinal digestion or proteolytic enzymes. This science involves the exploration of bio-activities of peptides from natural foods to formulate novel candidates for human health that may reduce the risk of disease. Egg albumen is a valuable source of bioactive proteins with diverse structural entities and many of them possess specific biological activities that represent potential ingredients of health-promotion. Thus, egg proteins offer tremendous opportunities for peptide drug discovery and hope for the treatment of emerging human diseases. In this work I will introduce our gastrointestinal simulation approach to uncover the potential bioactive peptides encrypted into egg albumin. Specifically, exploring novel bio-active peptides in egg albumin which heralding a fascinating opportunity for its potential candidacy as anti-infection and anti-oxidative bio-peptides for the treatment and risk reduction of emerging human diseases.
Occurrence of Pyroglutamyl Peptides in Wheat Gluten Hydrolysate and Its Beneficial Activity - Moderation of Hepatitis. K. Sato1, M. Nagata1, H. Sanada2, Y. Egashira2, S. Ono3, Y. Suzuki4, Y. Kido1, P.Y. Park1, K. Hashimoto1, Y. Nakamura1, 1Graduate School of Life and Environment Sciences, Kyoto Prefectural University, Kyoto, Japan, 2Faculty of Horticulture, Chiba University, Chiba, Japan, 3Faculty of Engineering, Toyama University, Toyama, Japan, 4Nisshin Pharma Inc., Tokyo, Japan
Gluten is formed from gliadin and glutenin during bread making and responsible for firmness of dough. Wheat gluten hydrolysate (WGH) has been considered as a stable glutamine source and prepared in an industrial scale. Beyond its nutritional value, there is an episode suggesting that ingestion of WGH could improve hepatitis of patients. The objective of the present study was to characterize peptides in WGH and confirm beneficial effect against hepatitis by animal models and identify the active compound in WHG. Up to half of glutamine residues in some WGH preparations were distributed in indigestible pyroglutamyl peptide fraction. Ingestion of WHG can improve galactosamin-induced acute hepatitis in rat model. Peptides in WHG were fractionated on the basis of amphoteric nature of sample peptide by the method of Hashimoto et al. The acidic peptide fractions showed significant moderation of the hepatitis. Peptides in the active fraction predominantly consisted of free pyroglutamic acid, pyroGlu-Leu, pyroGlu-Ile, pyroGlu-Gln, and pyroGlu-Gln-Gln. Among them, pyroGlu-Leu significantly suppressed the hepatitis, which can at least partially be responsible for the beneficial effects of WHG.
Reduction of Allergenicity and Improvement of Sensory Properties of Rice By Enzymatic Reaction During Cooking. H. Kumagai, Nihon University, 1866 Kameino, Fujisawa-shi 252-8510, Japan
Rice allergy is a serious problem especially for those where rice is consumed as a staple food. Different from patients with milk and egg allergies, children with rice allergy are unlikely to outgrow it, and are sometimes allergic to other cereals such as wheat, which makes their quality of life low during their lifetime. Although hypoallergenic rice products have been developed by the combination of several techniques such as enzymatic hydrolysis of allergens in degassed rice grains with surfactant or solubilization of allergens by salt solution under high pressure, their commercial availability is limited and their price is relatively high for daily use. We found that certain enzymes added to rice just before heating were active during cooking and could hydrolyze allergens. As some of the rice-improving substances used for large-scale cooking of rice contain enzymes, enzymatic treatment during cooking may not only reduce the allergenicity of rice but also improve the sensory properties of rice. Therefore, this study was aimed at examining the effect of enzymatic treatment on the allergenicity and sensory properties of cooked rice. The rice allergenicity was reduced and the sensory properties of cooked rice were somewhat improved by the addition of enzymes during cooking.
Anti-inflammatory Activity of Naturally Present Soy Peptides. E. de Mejia, V. Dia, University of Illinois, USA
Soybean contains several naturally present bioactive peptides. The objective of this study was to determine the in vitro anti-inflammatory activity of three naturally present soy peptides using RAW 264.7 macrophages. Isolation and purification was achieved by ion-exchange chromatography, ultrafiltration and size exclusion chromatography. The identity of the peptides was established by Western blot, HPLC, MALDI-TOF and LC/MS-MS. Fractions from both chromatographic techniques consistently showed three peptides with positive immunoreactivity against lunasin mouse monoclonal antibody. Treatment of RAW 264.7 macrophages with 100 µM of pure lunasin decreased the production of NO (92.6 ± 0.8%) and PGE2 (10.1 ± 4.5%), and the expression of iNOS (27.8 ± 2.1%) and COX-2 (41.4 ± 16.7%). Other two peptides, 8 and 14 kDa, had differential inhibition of COX-2/PGE2 and iNOS/ NO pathways. Possible mechanisms of action will be discussed. This newly discovered property of soy peptides might contribute to the suppression of inflammation in vivo.
Regulation of Vascular Contraction by Peptides. Toshiro Matsui, Kyushu University, Fukuoka, Japan
Peptides, which are condensed amino-acids, have been well-documented as physiologically functional compounds in nature. To date, many functional food products with a health claim can be available in Japan. One of the successful products is an antihypertensive food including angiotensin I-converting enzyme (ACE) inhibitory peptides. However, their underlying mechanism of antihypertensive peptides still remains unclear, since some peptides did not show any inhibition effect on circulating ACE activity in human. We have thus investigated their physiological potentials on local blood pressure systems. We mainly focused on the vascular response of small di- and tri-peptides in rat thoracic aorta or cells, because they are favorably absorbed through intestinal peptide transporter, PepT1. In a series of our studies, we have clarified some physiological functions such as intact absorption into human circulatory blood systems and endothelium-independent vasorelaxant action via blocking of L-type voltage-gated Ca2+ channel. Among active tri-peptides, His positioned at the N-terminal as well as aromatic residues at the C-terminal was found to be essential for exerting the effect. These findings suggest that vasoactive small peptides may have an ability to improve vessel-related diseases including hypertension, diabetes or sclerosis.
Structure and Activity Relationship Study of Bioactive Peptides and Its Application in Generation of Novel Peptides. J. Wu, K. Majumader, University of Alberta, Edmonton, AB, Canada
Many kinds of bioactive peptides from various food proteins have been reported which have greatly advanced our understanding the structure and activity relationships of bioactive peptides. Through Quantitative Structure and Activity Relationship (QSAR) study, we have established the structural requirements of ACE inhibitory peptides; we have also preliminarily demonstrated that QSAR study could further facilitate the course of the discovery of new peptides with enhanced activity. However, the potential of QSAR models in revealing the most potent peptides has not yet been fully explored. We hypothesize that the most potent ACE inhibitory peptides can be produced through an integrated in silico digestion and QSAR study. In combination with computational technology, the potent peptide sequences in the protein structure have specifically released and their presences in the hydrolysate have been characterized by using LC-MS. The resulting scientific rationale could be applied to a wide range of bioactive peptide studies, and represents a quantum leap in the ability to discover new health-promoting bioactive peptides from food proteins.
Identification of a Cholesterol-lowering Protein Component in Soy. C. Schasteen, C. Jankovich, J. Wu, B. Pierce, B. Tulk, M. Mekel, D. Butteiger, E. Krul, Solae, Saint Louis, MO, USA
One possible mechanism to lower circulating cholesterol, a key benefit of soy in the diet, is to bind bile acids (BA) in the digestive tract. Cholesterol is the precursor of bile acids which are used in digestion to emulsify fat and aid in lipid uptake. BAs are effectively reabsorbed back into the body, however, an accepted mechanism to lower cholesterol is to reduce the BA reabsoprtion (increase BA excretion). BA excretion results in a decrease in serum cholesterol levels as the liver upregulates its uptake of plasma cholesterol for BA synthesis. Solae has an in vitro BA binding assay (BABA) that quickly measures soy's bile acid binding capacity and has shown that a Solae soy protein isolate, SPI, effectively binds BAs. Solae SPI has also been shown to lower circulating cholesterol in the male Syrian hamster, an accepted animal model of human lipid metabolism. BABA has been used to isolate the active component in soy and determine a molecular mechanism for soy's ability to reduce cholesterol. Solae SPI binds bile acids in our in vitro assay and this agrees with the increase in fecal BAs seen in hamsters suggesting that one of the mechanisms by which soy protein lowers cholesterol is via bile acid binding. We are currently fractionating Solae SPI to determine the molecular BA binding motifs in soy protein responsible for its inherent cholesterol lowering activity. Human clinical studies are being implemented to validate the results seen to date with in vitro BABA and in vivo animal models.
Multifunctional Peptides from Flaxseed Proteins: Antioxidant Properties and Suppression of Lipopolysaccharide-Induced Nitric Oxide Production in Macrophages. C.C. Udenigwe1, W.-C. Hou2, R.E. Aluko1,3, 1Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba, Canada, 2Graduate Institute of Pharmacognosy, Taipei Medical University, Taipei, Taiwan, 3The Richardson Centre for Functional Foods and Nutraceuticals, University of Manitoba, Winnipeg, Manitoba, Canada
This study explores the production of peptides with potential human health benefits from flaxseed proteins (FP). A protein isolate was produced from defatted flaxseed meal followed by hydrolysis with pepsin, alcalase, ficin, trypsin, pancreatin, thermolysin and papain under optimum conditions. The protein hydrolysates were processed by ultrafiltration and ion-exchange chromatography to isolate low molecular weight and cationic peptide fractions. These peptides showed antioxidant properties in scavenging 2,2-diphenyl-1-picrylhydrazyl, superoxide anion, hydroxyl radicals and nitric oxide (NO), and also inhibited the activity of semicarbazide-sensitive amine oxidase. These results show that the peptides possess the potential for treatment of human diseases arising from oxidative stress. Antioxidant activities of these peptides were found to be dependent on the proteolytic treatments as well as the size of the peptides. The <1 kDa peptides from pepsin, ficin and papain FP hydrolysates also inhibited lipopolysaccharide-induced NO productions in RAW 264.7 macrophages; thus, these peptides may act as anti-inflammatory agents. These bioactive properties could encourage increased value-added utilization of flaxseed meal proteins for the formulation of therapeutic products.
Effects of Dietary Soy Protein on the Body Fat-reducing Potential of Conjugated Linoleic Acid in Rats. Kazunori Koba1, Asuka Akahoshi2, Kazunari Tanaka1, Michihiro Sugano3, 1University of Nagasaki, Siebold, Nagayo, Nagasaki, Japan, 2Prefectural University of Kumamoto, Kumamoto, Japan, 3Professor Emeritus, Kyushu University, Fukuoka, Japan
Conjugated linoleic acid (CLA) appears to reduce body fat in various animals. The magnitude of the effect differs among animal species, and humans are the least responsive. We previously suggested that the body fat-reducing potential of CLA could be increased by a combination with soy protein (SPI) instead of casein (CAS) in rats. Recently, β-conglycinin (CON), one of the main components of SPI has been shown to reduce serum triglyceride level more than SPI itself. Therefore, we examined how the combination of CON and CLA affects the lipid metabolism in rats. The rats were fed diets containing either 20% protein (CAS, SPI or CON) with 1% linoleic acid or CLA (9c,11t, 34%; 10t,12c, 36%). After 4 wk of feeding, dietary CON as compared with CAS and SPI lowered the body weight gain, which is due to decreased food consumption. Dietary SPI and more so CON decreased perirenal adipose tissue weights. This trend was more evident in combination with CLA irrespective of dietary protein. Serum triglyceride level decreased in the order of CAS, SPI and CON, and CLA tended to decrease the level further. The results suggested that body fat-reducing potential of CLA was more evident in combination with CON than with SPI. This effect could be partly due to decreased fatty acid synthesis and increased β-oxidation in the liver.
AM 3 / PCP 3.1: Alternative Sources in Aquafeeds
Chair(s): N. Vary, Canadian Food Inspection Agency, Canada; and K. Liu, USDA ARS, USA
The Beneficial Effect of Probiotics in Cultured Fish. T. Nakano, T. Yamaguchi, M. Sato, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi, Japan
In aquaculture, it is known that prevention of disease is more important than medical treatment. Part of disease prevention could come from daily diet. This concerns functional constituents, that is, food factors of feed other than essential constituents. Those functional feed ingredients have three categories; probiotics, prebiotics and biogenics. Probiotics (e.g. lactic acid bacteria) are defined as components of microbial cells or products from microbes that affect the host health. Prebiotics (e.g. oligosaccharides) are recognized as a nondigestible food ingredient that promotes the growth of beneficial intestinal microbes. Biogenics (e.g. polyphenolic compounds and vitamins) are defined as ingredients that modulate several functions of the body. Recently, some kinds of probiotics, in the wide sense, are often used under the assuming that they are equivalent to probiotics, prebiotics and biogenics are matched. Here, we will present some results of the effect of one of biogenics, polyphenolic procyanidins from grape seed, on the fish health. We found that procyanidins might improve antioxidant defense ability of fish. The use of probiotics in aquaculture should be regarded as a milder supplement therapy for fish and an environment-friendly method of aquaculture. We expect that ideal supplements for aquafeeds might be developed by the research of probiotics in the near future.
Nitrogen Utilization from Poultry Processing Co-products used in Diets for Florida Pompano. M. Riche, T. Pfeiffer, USDA, ARS, Fort Pierce, FL, USA
Feed represents the highest variable cost associated with fish production. High quality fishmeal (FM) continues to be the principal source of protein for fish, particularly carnivorous species that typically have dietary protein requirements of 40% or more. FM continues to be an expensive protein, with tight supplies when available, and little relief in sight. Replacement of FM with alternative protein sources will increase sustainability and profitability of the aquaculture industry. At the NOAA-USDA Alternative Feeds Initiative stakeholder's meeting in April 2008, poultry processing co-products were identified as top-tier candidates for evaluation as FM replacements in aquafeeds. However, one constraint to greater utilization of these co-products is the observed high variation in both quality and digestibility. It is well established processing conditions can affect amino acid availability in rendered products, and chemical composition and protein digestibility vary by product source. The goal of food fish production is the efficient conversion of dietary protein, measured as nitrogen (N), into salable fish flesh. This presentation reports on protein digestibility, amino acid availability, N excretion, and N retention in Florida pompano fed diets substituting five different poultry processing co-products as partial FM replacements.
Improvement of Nutritional Value of Lipid Sources by Monoacylglycerol Supplementation in Kuruma Prawn. Manabu Ishikawa, Shunsuke Koshio, Saichiro Yokoyama, Shinichi Teshima, Faculty of Fisheries, Kagoshima University, Kagoshima City, Kagoshima, Japan
This study presents effects of dietary lipid sources and monoacylglycerol (MG) supplementation on the growth and body lipid profiles for M. japonicus juveniles and larvae. Two feeding trials were conducted with 9 treatments (3x3), 3 lipid sources, triacylglycerols (TG), ethyl esters (EE), free fatty acids (FFA) and 3 supplements (control, Glycerol, MG). EE, FFA and MG were prepared from squid liver oil (SLO). In juvenile experiment, nine test diets were fed to prawns (body weight 0.4g) in triplicate 54-liter tanks. After 30 days feeding trial, body weight gain (BWG) and survival among the different treatments were statistically analyzed. Test prawn carried out to determine body fatty acid contents and the apparent digestibilities of dietary fatty acids. Results showed that there was a significant difference in BWG between the prawns fed the TG diets and those fed the EE diet. However, Supplementation of MG or glycerol trend to improve the growth of prawn in EE and FFA treatments. There were no significant differences in survival and total lipid content among the treatments. In larval experiment, similar trends were shown in the growth of the prawn. But glycerol supplementation was not effective for the improvement of larval growth.