Recovery and Functional Properties of Soy Storage Proteins from Lab- and Pilot-Plant Scale Oleosome Production

The aim of this study was to investigate soy protein recovery feasibility after lab- and pilot-plant scale oleosome isolation. The proteins were isolated by isoelectric precipitation and by ultrafiltration. The functional properties of the recovered proteins were compared to soy protein isolate produced in our laboratory. The residual lipid content in the aqueous supernatant affected the protein recovery yields and purities. Ethanol precipitation and ultrafiltration resulted in the best protein yields, which were 25 and 26% greater than protein yield obtained by isoelectric precipitation with distilled water dilution. The protein content of the isoelectric precipitated pilot-plant supernatant was higher (98%) than the protein content of ethanol-precipitated proteins (80%). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed similar peptide profiles for laboratory and pilot-plant supernatants. Protein solubility curves between pH 3 and 8 were typical for soy protein isolate with higher solubilities for proteins obtained from pilot-plant supernatant. The soy protein isolate and ethanol-precipitated protein had the highest emulsification capacity on a dry-weight basis. These desirable functional properties of proteins recovered as co-products after oleosome isolation suggest they are highly suitable for industrial application as food ingredients and their recovery would contribute to the economics of the overall oleosome fractionation process.     

Preparation and Characterization of <Emphasis Type="Italic">Camelina sativa</Emphasis> Protein Isolates and Mucilage

Processes for the production of protein isolates from camerlina Camelina sativa were developed by modifying the procedure used for other seeds from the Brassicaceae family, such as rapeseed and mustard. The procedure consisted of defatting the seed followed by alkaline extraction at pH 11, ultra- and diafiltration using a 5-kDa membrane, isolelectric precipitation of the proteins at pH 5 and recovery of the acid soluble protein isolates (SPI) after further filtration and drying. Protein yields as precipitated protein isolate and SPI were 10.7 and 11.4%, containing 67 and 42%, respectively. Due to the high concentration of mucilage in camelina, a water-to-seed ratio of 30 had to be used for protein extraction from the hexane-defatted seed and most of the mucilage had to be removed prior to the defatting process. A rapid mucilage extraction process using water at 55 °C was developed. Camelina mucilage absorbs water and oil. Viscosity measurements of dried and redissolved mucilage showed the highest values at natural pH, and the viscosity increased rapidly above 1% solids concentration. It may be a useful product in the food and pharmaceutical industries.     

Oil-free protein isolates from full-fat,dehulled mustard flour by microfiltration

New microfiltration (MF)-based aqueous processes for the extraction of oil-free protein isolates from full-fat, dehulled mustard flour have been developed. The processes used hydrophilic MF membranes to separate oil and protein. The most successful processing sequence consisted of alkaline extraction of oil and protein from the flour at pH 11, centrifugation to remove undissolved solids, and an initial microfiltration step to separate oil and dissolved protein. This was followed by proteolytic enzyme treatment of the retentate and a second-stage MF step to recover further protein. The proteolytic enzyme treatment was designed to break aggregated proteins into smaller fractions to permit their passage through the MF membrane. The permeates from the two microfiltration steps were ultrafiltered to concentrate the protein and remove antinutritional compounds and highly fragmented peptides. With this process, 60% of the protein originally in the flour was separated from the oil phase. Approximately 40% of the protein present in the flour was recovered in the form of two oil-free protein isolates—a soluble protein isolate containing 91% protein and a precipitated protein isolate containing 100% protein. The process proves the potential of MF as an effective method of extracting oil-free protein isolates from oilseeds without the use of organic solvents. Based on a presentation at the 16th Annual Meeting of the Canadian Section of AOCS held in Winnipeg, Manitoba, Canada, September 29–October 1, 2001.     

Production of mustard protein isolates from oriental mustard seed (Brassica juncea L.)

A membrane-based process to produce protein isolates from seeds of oriental mustard (Brassica juncea) was developed by modifying a method originally developed for rapeseed. The optimized process consisted of extraction at pH 11, ultrafiltration with concentration factor 4, diafiltration with diavolume 3, and precipitation at pH 5. The process, based on defatted oriental mustard seed containing 45–50% protein, recovered 81% of the protein in useful products: 47.3% in precipitated protein isolate (PPI), 3.8% in soluble protein isolate (SPI), and 13% in meal residue. Mass yields were 21.9% in PPI, 2.8% in SPI, and 38.4% in meal residue. The losses in the system included ∼10% loss of nonprotein nitrogen, and <9% into permeate and transfer losses. The PPI compared favorably with soy protein isolate in typical meat products in terms of color, texture, and flavor. The work confirms that oriental mustard is a potentially useful source of edible protein.     

Comparative Biological Activities Determination of Aqueous Extracts of Hempseed Oil and Hempseed Protein Isolate Production Coproducts

Industrial hempseed is an important agricultural crop with increasing potential for food applications. The objective of this study was to determine the different biological activities of hempseed coproducts after hempseed oil extraction and hempseed protein isolate precipitation. Hempseed oil was extracted by n-hexane and the defatted meal was dried. The hempseed protein isolate was prepared by alkaline pH solubilization followed by isoelectric precipitation. Two coproducts were obtained by freeze drying the precipitate after alkaline solubilization and freeze drying the supernatant after isoelectric precipitation. The coproducts were called hempseed meal after protein isolation (HM-PI) and hempseed supernatant after protein isolation (HS-PI). The biological activities of HM-PI and HS-PI were determined by measuring their antioxidant properties, antiproliferative properties against two human colon cancer cell lines, and anti-inflammatory activities in lipopolysaccharide-induced RAW 264.7 macrophages. The results showed that HS-PI has better biological activities than HM-PI, which correlated positively with the concentrations of soluble proteins, soluble polyphenols, tannins, and flavonoids. Our results showed for the first time that coproducts of hempseed processing can be potential sources of food ingredients with health-promoting properties.     

Effects of cooking and screw-pressing on functional properties of Cuphea PSR23 seed proteins

This investigation determined the effects of oil processing conditions on some functional properties of Cuphea PSR23 seed proteins to evaluate their potential for value-added uses. Flaked Cuphea seeds were cooked at 82°C (180°F) for 30, 75, or 120 min in the seed conditioner and then screw-pressed to extract the oil. Cooked flakes and press cakes were analyzed for proximate composition and protein functional properties. Results were compared with those of unprocessed ground, defatted Cuphea seeds. Protein from unprocessed Cuphea seeds had excellent emulsifying properties, poor foaming properties, poor solubility (10%) at pH 4–7, and much greater solubility at pH 2 and 10 (57 and 88%, respectively). Solubility profiles showed that cooking the flaked seeds to 82°C for 30 min resulted in a 50–60% reduction in soluble proteins. Cooking for 120 min gave <6% soluble proteins at all pH levels. Cooking for 75 min gave good oil yields but also resulted in <10% soluble proteins at pH 2–7 and 25% soluble proteins at pH 10. Seed cooking and screw pressing during oil extraction had significant detrimental effects on the solubility of Cuphea seed protein but generally improved its foaming capacity and emulsifying activity.     

Polypeptide Profile,Amino Acid Composition and Some Functional Properties of Calabash Nutmeg (<Emphasis Type="Italic">Monodora myristica</Emphasis>) Flour and Protein Products

The aim of this work was to compare the physicochemical and functional properties of calabash nutmeg (Monodora myristica) seed protein flour with those of protein-enriched products (albumin, globulin, and protein isolate). Defatted M. myristica seed flour (MMF) was used to prepare various protein products. A NaCl extract of MMF was dialyzed against water to obtain the soluble albumin fraction (MMA) and a precipitated globulin fraction (MMG). MMF was also extracted with NaOH, the extract adjusted to pH 4.0 and the precipitated proteins collected as the isolate (MMI). Non-reducing gel electrophoresis showed that the MMF, MMG and MMI had similar composition that was dominated by 55 and 110 kDa polypeptides while MMA consisted mainly of smaller (<35 kDa) polypeptides. However, under reducing conditions, the 110 kDa polypeptide was not observed. Amino acid composition revealed an Arg/Lys ratio that increased in the extracts (1.92, 2.28 and 2.11 for MMA, MMG and MMI, respectively) relative to that in MMF (1.85). MMA had 67.5–86.5% protein solubility in the pH 4.0–6.0 range while those of MMF, MMG, and MMI were 37.7–63.8, 2.7–69.4 and 3.8–55.1%, respectively. MMA, MMG and MMI were found to be better emulsifiers based on their smaller oil droplet sizes (8–14 μm) compared with the 14–33 μm for MMF emulsion. Maximum foaming capacity was highest for MMI (205%) when compared with MMA or MMG (150%) and MMF (89%). We conclude that protein enrichment led to significantly enhanced emulsion and foam-forming properties but high solubility may have contributed to reduced emulsion stability.     

Preparation and characterisation of protein hydrolysates from Indian defatted rice bran meal

Rice bran meal is a very good source of protein along with other micronutrients. Rice bran meal has been utilized to produce protein isolates and respective protein hydrolysates for potential application in various food products. De-oiled rice bran meal, available from Indian rice bran oil extraction plants, was initially screened by passing through an 80-mesh sieve (yield about 70%). A fraction (yield-30%) rich in fibre and silica was initially discarded from the meal. The protein content of the through fraction increased from 20.8% to 24.1% whereas silica content reduced from 3.1% to 0.4%. Rice bran protein isolate (RPI) was prepared by alkaline extraction followed by acidic precipitation at isoelectric point. This protein isolate was hydrolysed by papain at pH 8.0 and at 37 degrees C for 10, 20, 30, 45 and 60 minutes. The peptides produced by partial hydrolysis had been evaluated by determining protein solubility, emulsion activity index (EAI), emulsion stability index (ESI), foam capacity and foam stability (FS). All protein hydrolysates showed better functional properties than the original protein isolate. These improved functional properties of rice bran protein hydrolysates would make it useful for various application especially in food, pharmaceutical and related industries.     

Plastics from an Improved Canola Protein Isolate: Preparation and Properties

Canola meal proteins were solubilized from canola flour at pH 12 using sodium hydroxide solution. Proteins were then precipitated sequentially at pH values ranging from 11 to 3 in decrements of 1 pH unit. The weight distribution and the properties of these fractions were analyzed. The majority (>76%) of the recovered proteins were precipitated at pH values at or below 7. Another substantial fraction was precipitated at pH 11. The functional and thermal property (differential scanning calorimetry) analyses showed that this protein fraction exhibits the highest water holding capacity and lowest melting point. The plastics prepared with refined protein isolates (with pH 11 fraction removed) showed higher water resistance, tensile, and flexural strength, toughness, and elongation values compared to those prepared with standard canola protein isolates. This shows that mechanical and water resistance properties of protein-based plastics can be enhanced using improved protein isolates.     

Sunflowers: America’s neglected crop

The sunflower,Helianthus annuus, is a crop which has been neglected in American agriculture. Sunflower oil from seed grown in the northern U.S. typically contains 70% linoleic acid and has a high ratio of polyunsaturated to saturated fatty acids. This makes it desirable as an edible oil in light of evidence linking saturated fats to high blood cholesterol and incidence of heart disease. In contrast sunflower oil from seed produced in the South generally contains 40–50% linoleic acid. Preliminary studies indicate that southern oil with a lower content of linoleic acid is slightly more stable than northern oil. The effect of planting dates, location and environmental temperatures on the fatty acid composition of northern and southern sunflower oils is reported. Studies also show that potato chips fried in sunflower oil are more flavorful after storage for four weeks than similarly treated chips fried in cottonseed-corn oil mixtures. Sunflower protein is highly digestible (90%) and possesses a high biological value (60%). Protein isolates prepared by the conventional method of extraction are greenish in color due to oxidation of chlorogenic acid. However research underway indicates that development of a nearly white isolate is possible. Analysis of chemical, physical and organoleptic properties indicate that dehulled sunflower kernels can be used in various food products. Defatted meal also can be used as a partial wheat substitute in bread and other bakery products. Presented at the AOCS Meeting, Atlantic City, October 1971.     

Dietary Fatty Acid Metabolism is Affected More by Lipid Level than Source in Senegalese Sole Juveniles: Interactions for Optimal Dietary Formulation

This study analyses the effects of dietary lipid level and source on lipid absorption and metabolism in Senegalese sole (Solea senegalensis). Juvenile fish were fed 4 experimental diets containing either 100 % fish oil (FO) or 25 % FO and 75 % vegetable oil (VO; rapeseed, linseed and soybean oils) at two lipid levels (~8 or ~18 %). Effects were assessed on fish performance, body proximate composition and lipid accumulation, activity of hepatic lipogenic and fatty acid oxidative enzymes and, finally, on the expression of genes related to lipid metabolism in liver and intestine, and to intestinal absorption, both pre‐ and postprandially. Increased dietary lipid level had no major effects on growth and feeding performance (FCR), although fish fed FO had marginally better growth. Nevertheless, diets induced significant changes in lipid accumulation and metabolism. Hepatic lipid deposits were higher in fish fed VO, associated to increased hepatic ATP citrate lyase activity and up‐regulated carnitine palmitoyltransferase 1 (cpt1) mRNA levels post‐prandially. However, lipid level had a larger effect on gene expression of metabolic (lipogenesis and β‐oxidation) genes than lipid source, mostly at fasting. High dietary lipid level down‐regulated fatty acid synthase expression in liver and intestine, and increased cpt1 mRNA in liver. Large lipid accumulations were observed in the enterocytes of fish fed high lipid diets. This was possibly a result of a poor capacity to adapt to high dietary lipid level, as most genes involved in intestinal absorption were not regulated in response to the diet.     

Healthier lipid combination as functional ingredient influencing sensory and technological properties of low‐fat frankfurters

Oil (healthier lipid combination of olive, linseed and fish oils)‐in‐water emulsions stabilized with different protein systems (prepared with sodium caseinate (SC), soy protein isolate (SPI) and microbial transglutaminase (MTG)) were used as pork backfat replacers in low‐fat frankfurters. Composition (proximate analysis and fatty acid profile), sensory analysis and technological (processing and purge losses, texture and colour) properties of frankfurters were analysed as affected by the type of oil‐in‐water emulsion and by chilling storage (2°C, 41 days). Frankfurters produced with oil combinations had lower levels of saturated fatty acids (SFA, 19.3%), similar levels of MUFA (46.9%) and higher levels of PUFA (33.6%) than control frankfurters (all pork fat) (39.3, 49.5 and 10.6%, respectively). PUFA/SFA and n‐6/n‐3 PUFA ratios in control sample were 0.27 and 9.27; in reformulated frankfurters the PUFA/SFA ratio was higher (1.7) and the n‐6/n‐3 PUFA ratio was lower (0.47). In general, frankfurters had good fat and water binding properties. Colour parameters were affected by formulation and storage time. Compared to control sample, frankfurters made with oil‐in‐water emulsions had higher (p<0.05) hardness, springiness and chewiness values. Emulsified oil stabilizing systems did not affect sensory characteristics of frankfurters, and all products were judged as acceptable.     

Barley Protein Isolate: Thermal, Functional, Rheological, and Surface Properties

Barley protein isolate (BPI) was extracted in 0.015 N NaOH in a 10:1 ratio solvent:flour and was precipitated by adjusting the pH to 4.5 and freeze-dried. The thermal properties of BPI were determined using modulated differential scanning calorimetry (MDSC). BPI with 4% moisture content exhibited a glass transition (T _g) with 140 °C onset, 153 °C middle, and 165 °C end temperatures and a ΔC _p of 0.454 J/g per °C. The high moisture content sample (50%) showed a T _g at 89, 91, or 94 °C and 0.067 ΔC _p. Acetylation had no apparent effect on the foaming and emulsifying properties of protein from barley flour but exhibited the least-stable foam among BPI samples. Foaming capacities of both barley protein isolates were ∼12% less than that of acid-precipitated soy protein isolate reported in the literature. Acetylated BPI showed the highest surface hydrophobicity compared to the other samples. The surface-tension test confirmed that unmodified and modified BPI possessed surface activity. BPI phosphorous oxycloride-crosslinked was the most effective in lowering the surface tension of aqueous NaCl, while the crosslinked BPI was the least effective. The G′ value of BPI suspension was greater than G″ at all frequencies from 0.1 to 100 rad/s. The strain value at which linear behavior ceased and nonlinear behavior began ranged from 3 to 10%. Names are necessary to report factually on available data; however, the United States Department of Agriculture (USDA) neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Sunflower Protein Concentrates and Isolates Prepared from Oil Cakes Have High Water Solubility and Antioxidant Capacity

Increasing the applications of industrial by-products is of great interest. Therefore, in the present study, sunflower oil cake from a local oil manufacturing company was used to obtain soluble protein concentrates and isolates with different content of phenolic compounds. All the extraction procedures evaluated resulted in concentrates and isolates with water solubility higher than 75% but with different chemical composition, color and physicochemical properties (i.e. surface hydrophobicity, thermal stability, and polypeptide composition). Since no extraction process led to a complete extraction of phenolic compounds, all the products exhibited antioxidant activity, which depended on the concentration of such compounds. Phenolic compounds give a dark color to sunflower protein concentrates and isolates; nevertheless their final color tone was more dependent on the conditions used in the preparation process than on the amount of phenolic compounds in the product. The results demonstrate the value of sunflower industrial oil cake as a source of proteins with high water solubility, good physicochemical properties and antioxidant activity.     

Preparation of alginate/soy protein isolate blend fibers through a novel coagulating bath

Alginate and soy protein isolate blend fibers were prepared by spinning their solution through a viscose‐type spinneret into a novel coagulating bath containing aqueous CaCl₂, HCl, and ethanol. The structures and properties of the fibers were studied with the aids of infrared spectra (IR), X‐ray diffraction (XRD), and scanning electron micrograph (SEM). Mechanical properties and water‐retention properties were measured. And with the sample of AS1 fiber (soy protein isolate weight content was 10%), the effects of the composition of the novel coagulating bath were also studied. The best values of the tensile strength of AS1 were 14.1 cN/tex in the dry state and 3.46 cN/tex in the wet state, respectively. Both the dry state and wet state breaking elongation were also having the best value 20.71% and 56.7% with AS1. Mechanical properties of the AS1 enhanced with the CaCl₂ content increased in the coagulating bath. When the HCl content was 1%, the mechanical property of the fiber was best. Ethanol in the coagulating bath increased the wet mechanical properties of the fiber by 41.2% (tensile strength) and 45.1% (breaking elongation) when the ethanol weight content in the coagulating bath was 50%; but it had little effect on the dry mechanical properties. And the water‐retention value (WRV) of blend fibers decreased as the amount of soy protein isolate was raised. The structure analysis indicated that there were strong interaction and a certain level of miscibility between alginate and soy protein isolate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 425–431, 2006     

Protein-Based Microencapsulation with Freeze Pretreatment: Spray-Dried Oil in Water Emulsion Stabilized by the Soy Protein Isolate–Gum Acacia Complex

Spray-dried microparticles with lipid cores that dissolve β-carotene were prepared using a technique based on the complexation of soy protein and gum acacia. A freeze-pretreatment was applied to modify the resultant properties of the dried particles. An oil in water emulsion stabilized by soy protein isolate was mixed with gum acacia. The pH of the solution was adjusted to a selected value; this solution was frozen and thawed under controlled thermal protocols, then spray-dried to obtain the final products. Complexation was induced on the surface of the oil droplets owing to electrostatic interactions that occur below the isoelectric point (ca. pH 4.0) of the employed soy protein isolate. The freeze-pretreatment prior to spray-drying was expected to induce this interaction by freeze concentration and to control the kinetics of complex formation. When solutions with a pH of 4.0 and 3.0 were spray-dried, the encapsulation of β-carotene had similar efficiencies. The freeze-pretreatment was observed to have a significant effect on the specimens prepared from the solution with a pH of 4.0. Slow freezing conditions successfully improved the encapsulation efficiency and simultaneously reduced the amount of surface oil. Moreover, this pretreatment augmented the mass transfer resistance of the shell matrix, so that the release rate of dissolved β-carotene in the lipid core could be retarded.     

Characterization of laurel fruit oil from Madeira Island,Portugal

The fixed oil extracted from Laurus spp. fruit from Madeira Island, Portugal, is used in local traditional medicine for a wide variety of health complaints. Physical properties, density and refractive index, as well as the TAG FA composition, sterols, and waxes were determined. The oil was found to have an unusually high content of volatiles (ca. 10%), with trans-ocimene and germacrene D predominating. Oleic (30%) and linoleic (20%) acids were the main unsaturated FA, whereas lauric (18%) and palmitic (up to 22.5%) acids were the main saturated FA in the neutral lipid fraction. The oil had a sterol content on the same order as olive oil, with β-sitosterol (84%) predominating. Two sesquiterpene lactones, dehydrocostuslactone and costunolide, accounted for 5% of the overall composition. Madeira laurel oil is not currently used as an edible oil because of its very strong flavor. Its claimed medicinal properties have not yet been validated, and this is the first report on the characterization of the commercial product.     

Effect of Alcalase™ on olive pomace protein extraction

The effect of Alcalase^™ treatment on olive pomace protein extraction has been studied. Alcalase improves protein extraction from 5 to 30% of total protein. This improvement is not accompained by an increase in degree of protein hydrolysis, probably because protease activity is inhibited by secondary metabolites and the substrate is highly denatured and resistant to hydrolysis. The increase in protein extraction is attributed to fiber solubilization as a result of secondary activities of Alcalase. Protein extracts with a high content of soluble fiber have improved functional properties, with respect to olive pomace, such as water and oil absorption. Emulsifying and foaming activities were inappreciable. The products obtained represent a suitable source of soluble fiber and protein and may contribute to the improvement of the economic status of olive pomace by-product.     

Functional Properties of Soy Protein Isolates Prepared from Gas-Supported Screw-Pressed Soybean Meal

White flakes (WFs) are obtained from dehulled flaked soybeans by extracting oil with hexane and flash- or downdraft-desolventizing the (defatted) flakes, and WFs are the normal feedstock used to produce soy protein ingredients. Gas-supported screw pressing (GSSP) is a new oilseed crushing technology in which traditional screw pressing is combined with injecting high-pressure CO₂, thereby producing hexane-free, low-fat, high-PDI soybean meal. The objectives of the present study were to evaluate yields, compositions, and functional properties of soy protein isolates (SPIs) produced from GSSP soybean meal and to compare these properties to those of SPIs produced from WFs. GSSP meals produced SPIs in significantly higher yields (59.7–63.1% vs. 51.6–61.1%), with greater free (0.05–0.40%) and bound fat (3.70–4.92%) contents than did WFs. There were no significant differences in protein contents of the SPI; all exceeded 90% protein content (db). SPIs prepared from GSSP meals had similar or slightly lower water-solubilities compared to SPIs prepared from WFs. SPIs prepared from GSSP meals had higher water-holding capacities and viscosities, and significantly better emulsifying and fat-binding properties compared to SPIs prepared from WFs. SPIs prepared from WFs had significantly better foaming properties compared to SPIs prepared from GSSP meals, which were attributed to the lower fat contents of SPIs prepared from WFs.     

Gas barrier and wetting properties of whey protein isolate‐based emulsion films

The aim of this research was to investigate the effect of rapeseed oil concentration (1–3% w/w) on the water vapor, oxygen and carbon dioxide permeability, water vapor sorption and surface properties of whey protein isolate emulsion‐based films. The water contact angle as affected by oil content, film side and time was analyzed. The effect of temperature (5 and 25°C) on the water vapor permeability (WVP), water vapor sorption kinetics and diffusion coefficient was also studied. The results showed that the incorporation of a lipid phase to whey protein film‐forming solutions was able to decrease the WVP, water hydrophilicity (increasing water contact angle) and water transfer of whey protein films. However, the films containing oil were more permeable to oxygen and carbon dioxide. Significantly higher values of WVP and diffusion coefficient were obtained at 5°C than at 25°C, indicating that storage temperature should be taken into account when designing the composition of edible films and coatings for food applications. POLYM. ENG. SCI., 59:E375–E383, 2019. © 2018 Society of Plastics Engineers