Technical problems and opportunities in using vegetable proteins in dairy products

The food processing industry is giving increased emphasis to the production and utilization of alternate protein isolate products as functional and nutritional ingredients in an expanding number of formulated food products. Alternate protein sources such as soy and other vegetable proteins offer additional flexibility in formulating foods due to their economics, availability, functionality and nutritional properties. This paper discusses needs for developing soy and vegetable protein isolates with improved flavor, color and functionality for producing simulated dairy foods. It also considers alternative technologies for incorporating soy and vegetable proteins into the formulation so that they may function properly for forming stable solutions, emulsions, foams and gels that resemble those in their natural dairy food counterparts.     

Functional properties of oilseed proteins

The functional and physical properties, rather than the nutritional value, of protein in protein-containing products will largely determine their acceptability as ingredients in prepared foods. The nature of the protein per se, the presence of other constituents naturally present in protein-containing products, the degree to which the protein product is refined, the presence of other ingredients in a food system to which protein products are added, manufacturing conditions and a number of other factors, working singly or together, will influence the way proteins (as well as other ingredients) exert their functional characteristics. Differences in these characteristics are presented with examples of the manner in which various factors can influence functionality. Nonfunctional properties may be of interest for certain applications. Presented at the AOCS-AACC Joint Protein Short Course, French Lick, Indiana, July 13–16, 1969.     

Textured and shaped oilseed protein food products

The major emphasis in developing textured and shaped protein foods has been with the use of soy proteins. The availability at a low stable price, the high protein content and quality, and the inherent chemical properties of the protein allowing for unique structure development are major reasons for its strong world-wide use. The changing economic trends of many basic protein foods are creating a need for the use of unique textured proteins either as ingredients in existing foods or allowing improved functionality in new products. The two main procedures for texturing and shaping oilseed protein are spinning of protein isolates, and direct extrusion of flour. The spinning technique is more expensive and has greater product functionality in contrast to the direct extrusion method. Consumer acceptance is in large part correlated with the technological success of imparting desirable colors, flavors and textural properties in the finished food product. Examples of these variations are given. The use level of these textured proteins, particularly in meat products, are restricted by labeling standards. The present regulations are not clearly defined. Current proposals for labeling textured vegetable proteins when used with meat products involve standards on a ratio to meat basis. One of 21 papers presented at the Symposium, “Oilseed Processors Challenged by World Protein Need,” ISF-AOCS World Congress, Chicago, September 1970.     

Designing vegetable proteins to fit market needs

The needs and wants of the market are discussed as well as the regulatory practices that frequently inhibit the fulfillment of the market’s requirements. The advantages and short comings of the various types of protein ingredients are described, and appeals are made to the soy protein-producing industry to protect the integrity of traditional products by recommending extension of meat and other products in such a manner as to preserve their traditional character. Improved technical service offered to the food processors can bring added assurance to the consumer of a continuing supply of quality traditional products. The soy protein industry must continue the development of their own products so that broader application is possible. The inherent nutritional and functional values of soy proteins are such as to make a new generation of textured products, and improvement in the functional properties of concentrates and isolates a very realistic goal. Compatibilities of soy proteins with other proteins and ingredients are discussed; suggestions are made that the inherent synergism in many of these combinations is an untapped developmental area that will enable us to design protein ingredients for specific applications and thus benefit the consuming public, as well as the food processing industry.     

Cleaning UF membranes with simple and formulated solutions

The ultrafiltration membranes fouled by proteins are typically cleaned by consecutive soaking in alkali, surfactant and oxidizing solutions. We combined all three chemicals into a formulated cleaning agent and examined its efficiency to restore the water flux without damaging the membrane or enhancing protein fouling. Lower concentrations of ingredients in the composite were required to restore the water flux to the initial level. The membrane after the cleaning remained intact and subsequent filtration left trace protein amount on the membrane surface. We propose a mechanism of cleaning based on a fast penetration of alkali and oxidizing ingredients through a fouling layer and efficient micellation of detached foulants with surfactant.     

Chemistry and characteristics of enzyme-modified whipping proteins

Protein derivatives exhibiting aerating and whiping properties are produced by the action of a proteolytic enzyme on a suitable protein substrate, viz., wheat gluten, soy protein or casein. Various proteolytic enzymes can be utilized in the manufacture of the modified protein derivatives, but those enzymes displaying maximum proteolytic activity in the acid pH range produce whipping proteins with optimum aerating functionality and maximum stability characteristcs. Reaction parameters for the hydrolysis include: type of enzyme, enzyme concentration, temperature, pH and time of reaction. By careful control of these variables, modified proteins with unique and exceptional whipping properties can be produced. Enzyme-modified whipping proteins are bland, light cream-colored, spray-dried powders, soluble in hot or cold water, and functional over the entire pH range. Depending upon the source, protein and conditions of manufacture, products can be produced with a protein content ranging from as low as 50% to as high as 85%, and a whipping functionality equal to or twice that of egg albumen. Unlike egg albumen, these products do not coagulate to any appreciable degree when heated, and depending upon the specific end use of the product, this property may be either an advantage or disadvantage.     

Methods of studying functional characteristics of vegetable proteins

In a functional characterization, a set of data is obtained which gives information on the fields of application for a certain protein ingredient. This fingerprint can be used as a guideline in product development and restricts the amount of tests on large scale. The function of a protein in a complex food system can be better understood if a functional characterization is combined with a microstructural investigation. This may be especially important in cases where proteins act by indirect functionality, i.e., when the prescence of one protein changes the function of another component. In order to improve the efficiency of functional characterizations, methodologies need to be further developed. This is especially important for characterization of gels, emulsions, and mixtures of structures.     

耐水胶合板用环保乳清蛋白基水性胶粘剂

乳清蛋白是干酪加工过程中所产生的一种副产品,除被用作食品添加剂外,仍有相当数量乳清蛋白并未得到有效利用。为了实现乳清蛋白的高附加值利用,本文以乳清蛋白为原料,研制了具有良好耐久性和环保的乳清蛋白基胶合板用水性胶粘剂,并评价了变性处理、改性剂种类及其用量对乳清胶粘剂的胶合性能及游离甲醛释放量的影响。结果表明,热变性使乳清蛋白胶粘剂的胶接耐久性提高;不同改性剂对乳清蛋白胶粘剂的性能影响不同。采用1％多异氰酸酯改性胶接耐久性最好;采用0．15％戊二醛／1％乙二醛改性胶接强度最高。中试结果表明,所研制的耐水性环保乳清蛋白基胶合板胶粘剂的干胶接强度达到1．98MPa,煮－烘－煮28h后湿胶接强度为1．14MPa,游离甲醛释放量仅为0035mg／L（干燥器法）,达到了1ISK6806--2003环保结构胶合板用胶粘剂要求。     

Processing of leaf proteins into food ingredients

Many process alternatives are possible. Most of them are currently being investigated by laboratory or pilot tests. The successful future of some of these processes is certainly connected to the quality of the end product vs. market requirements and consumer acceptability. The status of development of the processes does not allow any economic forecast on profitability, but it is reasonable to think that the simplest techniques to produce acceptable leaf protein isolate and sufficient control on processing conditions could be profitable. These processes need further technological development and the end product market needs to be investigated further, but leaf proteins could be an alternative and complementary source of proteins for food ingredients in the predictable future.     

Soy protein ingredients prepared by new processes—Aqueous processing and industrial membrane isolation

The production of food ingredients from undefatted soybeans by aqueous processing and isolation of protein from soy flour by ultrafiltration membranes has been demonstrated adequately during the past decade. These relatively new techniques offer significant advantages over conventional soy processing methods. Aqueous processing requires no petroleum-based solvent and consequently provides increased safety and flexibility of operation (because start-up and shutdown are safe and easy). It also provides opportunities for removal or deactivation of undesirable constituents of raw materials with appropriate water-soluble chemicals. It is, however, less efficient in oil extraction, and demulsification is required to recover clear oil when emulsions form. Ultrafiltration processes recover protein directly from soy flour extracts and thereby avoid generation of the whey which results from the conventional isoelectric precipitation. These processes have the advantages of increased isolate yield (as whey proteins are recovered in the isolate), and produce products having enhanced functionality and nitrogen solubility. The two processing techniques have subsequently been combined to obtain a single procedure with the advantages of each. Extracts from undefatted soybeans have been membrane processed with and without separating the oil to produce a variety of new soy protein ingredients.     

Implications of fat replacement for nutrition and food intake

The expanding development and marketing of fat replacers and reduced-fat foods is primarily directed at nutritional concerns regarding excessive fat and energy consumption. Existing and proposed ingredients used to replace fat span a range of physical and chemical properties, with varied functionality and differences in their potential physiological effects. Although the safety and functionality of such ingredients and technologies have been scrutinized by industrial and governmental bodies, there has been rather less consideration given to assessments of their likely effects on food intake and nutritional status. It is often assumed that products made using fat replacement technologies would help to reduce fat intake and aid in weight control, despite little research directly assessing the effects of purchase and consumption of these products by normal consumers in the domestic environment. This review considers existing and proposed fat replacers and reduced-fat foods, focusing on their potential beneficial and adverse influences on diet and nutrition, highlighting the possible implications for fat intake and energy balance.     

Effect of canola meal fermentation and protein extraction method on the functional properties of resulting protein products

The present study investigated the effect of solid-state fermentation (SSF) of cold-pressed (CP) and hexane-extracted (HE) canola meals with Aspergillus niger NRRL 334 and Aspergillus oryzae NRRL 5590 on the functionalities of protein products extracted from them. After SSF, proteins were recovered using alkaline extraction-isoelectric precipitation (AE-IP) or salt extraction-dialysis (SE). SSF of the two meal types reduced the protein content of the extracts produced by AE-IP. There were varied effects to solubility, foaming, and emulsifying properties as a result of SSF under the combined influence of functionality pH, strain, meal type, and protein extraction method. The protein isolate produced from CP meal using SE had increased solubility at pH 7 (from 51.8% to 90.7%) when the meal was fermented with A. oryzae. Both strains resulted in an over twofold increase in the emulsifying activity index (at pH 7) of AE-IP products from CP meal. For both protein extraction methods, the protein products from A. niger fermented HE meal had better foaming capacity (FC) at pH 7 than the controls (non-fermented), but reduced FC at pH 3. Overall, regardless of meal fermentation, the SE products were richer in protein and had higher oil holding capacity (OHC), whereas the water holding capacity (WHC) was higher for AE-IP isolates. SSF of the meals generally improved the O/WHC of the extracted proteins. The findings suggest that canola protein functionality could be effectively modulated by SSF with different microbial strains under various processing conditions to enhance their applicability in the food industry.     

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.     

A review of lecithin chemistry and glandless cottonseed as a potential commercial source

Industrial lecithin can be fractionated as phospholipids and glycolipids after neutral lipids and protein-containing contaminants are removed. The polar lipids are very reactive and are difficult to extract and purify from oilseeds. Their purity and special properties can be improved by a number of methods including solvent fractionation, hydrogenation, sulfonation, and ethoxylation. Studies are determining the role of the polar lipids of lecithin in (a) the synthesis of triglycerides in maturing seeds, (b) the structure of biological membranes, and (c) the molecular basis of the functionality of food ingredients. Lecithin, having both polar and nonpolar groups, has high surface activity and is reactive with both oil and protein, making it an excellent emulsifying agent in food systems; lecithin also slows autoxidation and enzyme hydrolysis of fats. Cottonseed lecithin is low in linolenic acid, prevents flavor deterioration of soybean oil and can be used to stabilize sunflower oil against color change during high temperature use. Gossypol binds to lecithin in oil from glanded cottonseed economically negating it as a commercial source of this product. New cultivars producing glandless, or gossypol-free cottonseed, may have potential as commercial sources of edible lecithin.     

Photosynthesis and application of polyfunctional poly(n-butyl acrylate) elastomers for use in epoxy resin toughening

Medium molecular weight, novel polyfunctional elastomers, namely epoxy groups on poly(n-butylacrylate) (ETPnBA) and carboxyl groups on poly(n-butylacrylate) (CTPnBA) were photosynthesized for evaluation as the toughening agents in epoxy resins. The effect of the functionality and kind of functional group of the elastomers upon the toughening of epoxy resins modified with these rubbery copolymers as a second phase was investigated by tensile tests, impact test, and electron microscopy. It was found that there exists an optimum functionality of elastomers for maximum impact resistance in epoxy groups (ETPnBA) and carboxyl groups (CTPnBA) copolymer-modified systems. Studies on morphology of the modified epoxy resin system indicated that the better toughening effects of multiple distribution of particle sizes. The aggregation of rubber particles occurring in carboxyl group CTPnBA modified epoxy resin caused a loss of toughness.     

Use of gasification residues in aerated autoclaved concrete

Two fine-grained residues produced by gasification of wastes were tested for their suitability in aerated autoclaved concrete (AAC). AAC typically has additional aluminium powder added to the raw ingredients to facilitate the formation of small gas bubbles which provide a low-density product. Both gasification residues had high amounts of metallic aluminium and thus were well suited for this application. Studies were conducted to determine whether the residue addition would eliminate the need for the extra aluminium powder for creating air voids. Simultaneously, the residues replaced some of the aggregate ground in the process, thus enabling savings in energy consumption. Initial laboratory tests determined how much residue could be added and what type of concrete mixture proportioning was needed. Multiple properties were tested on AAC with 10% residue addition, with and without the additional aluminium powder. After laboratory investigations, full-scale tests were done at the Siporex AAC factory in Finland. These tests revealed that the residues offer a promising resource for economic production of AAC without detrimental effects to the final products.     

The Ionic Modification of the Surface Charge and Isoelectric Point of Soy Protein

The effect of anionic and cationic binding on the surface charge of soy proteins was measured by electrokinetic analysis. All of the ions investigated suppressed the surface charge of the protein; however, certain multivalent ions such as Al (III), Fe (III), hexametaphosphate and tripolyphosphate also altered the isoelectric point of the protein. The results indicated the unpredictability of ionic effects on protein functionality, thus emphasizing the importance of making measurements of protein charge.     

Cottonseed protein food products

Upward trending world population and increasing costs for traditional food proteins provide many incentives for utilization of oilseed proteins directly in human diets. Cotton, as one of the world's major oilseed crops, represents a potential source of food protein. Acceptability of oilseed protein products in terms of functional properties in food systems and nutritional value will largely determine the extent of their utilization by the food industry. Liquid cyclone process cottonseed flour, defatted glandless cottonseed flour, storage protein isolates, and cottonseed whey proteins have been evaluated by various functionality tests and in a number of food systems. The cottonseed flours have been subjected to processing by extrusion texturization. Human feeding studies have also been conducted. Results indicate a good potential for use of cottonseed protein products in a variety of food systems.     

Studies on cellulose acetate–polysulfone ultrafiltration membranes: I. Effect of polymer composition

Ultrafiltration techniques have particular advantages for simultaneous purification, concentration and fractionation of macromolecules. Studies are presented on novel ultrafiltration membranes, based on cellulose acetate and polysulfone blends, for the separation of proteins and heavy metal ions. The effects of polymer composition on pure water flux, water content, molecular weight cut‐off and hydraulic resistance are discussed. Scanning electron microscopy images of the membranes show the presence of segregated individual domains of cellulose acetate and polysulfone. The molecular weight cut‐off obtained from the protein separation studies is also presented. Applications of these membranes for separating metal ions from aqueous streams are discussed. Copyright © 2005 Society of Chemical Industry     

A Review on Quantitative Multiplexed Proteomics

Over the last few decades, mass spectrometry-based proteomics has become an increasingly powerful tool that is now able to routinely detect and quantify thousands of proteins. A major advance for global protein quantification was the introduction of isobaric tags, which, in a single experiment, enabled the global quantification of proteins across multiple samples. Herein, these methods are referred to as multiplexed proteomics. The principles, advantages, and drawbacks of various multiplexed proteomics techniques are discussed and compared with alternative approaches. We also discuss how the emerging combination of multiplexing with targeted proteomics might enable the reliable and high-quality quantification of very low abundance proteins across multiple conditions. Lastly, we suggest that fusing multiplexed proteomics with data-independent acquisition approaches might enable the comparison of hundreds of different samples without missing values, while maintaining the superb measurement precision and accuracy obtainable with isobaric tag quantification.