DRY BEAN PROTEIN FUNCTIONALITY

S. K. SATHE, Dept. of Nutrition, Food & Movement Sciences, Florida State Univ., Tallahassee, FL 32306-2033

Dry beans are an important source of proteins, carbohydrates, dietary fiber, and certain minerals and vitamins in human food supply. Among dry beans, Phaseolus beans are cultivated and consumed in the greatest quantity on a worldwide basis. Typically, most dry beans contain 15- 25% protein on a dry weight basis (dwb) and water soluble albumins and salt soluble globulins respectively account for up to 10-30% and 45-70% of the total proteins (dwb). The dry bean albumins are typically composed of several different proteins including the lectins and enzyme inhibitors. A single 7S globulin dominates the dry bean globulin fraction and may account for up to 50-55% of the total proteins in the dry beans (dwb). Most dry bean proteins are deficient in sroteins are deficient in sulfur amino acids methionine and cysteine and are therefore of lower nutritional quality when compared with the animal proteins. Despite this limitation, dry beans make a significant contribution to the human dietary protein intake. In bean based food, the dry bean proteins also serve additional functions that may include surface activity, hydration and hydration related properties, structure, and certain organoleptic properties. This paper will provide an overview of dry bean protein functionality with emphases on nutritional quality and hydration related properties.

PARTICLE SIZE DISTRIBUTION AFFECTS THE RHEOLOGY OF MILK CHOCOLATE

G. Mongia, and G. R. ZIEGLER, Dept. of Food Science, Pennsylvania State Univ., Univ. Park, PA 16802

Molten milk chocolate is a dense suspension of solid particles of sugar, milk, and cocoa in a mixture of cocoa butter and milk fat. The concentration of suspended solids is about 67% by weight. Chocolates with higher solids content represent savings in fat for the manufacturer and lower caloric density for the consumer. However, the maximum concentration of solids in chocolate is limited by its effect on the rheological and organoleptic properties of the product.

The complex flow behavior of chocolate can be expressed in terms of two components; the Casson plastic viscosity and the Casson yield value. Each of these componeon yield value. Each of these components is significant in terms of usage and handling of the product. Several authors have studied the compositional and processing factors that influence these two parameters. However, only a few have explored the effect of particle characteristics on the flow behavior of molten chocolate. The present paper addresses the effects of the size distribution of suspended particles on the flow properties of milk chocolate.

Five milk chocolates were produced with the same composition but different mean particle diameter and size distributions. Nonfat dry milk, nonfat cocoa powder, and sugar were the source of solids in the chocolates. The particulate components were each ground separately in a jet mill. The sugar component was air classified to generate a coarse and fine fraction. The two fractions were mixed with ground nonfat cocoa and milk powders to give a large size fraction and a small size fraction of blended powders. These blends were then mixed in the ratios of 25:75, 50:50, and 75:25 by volume, to give five distinct blend distributions with the same composition. Packing densities and the Casson parameters were measured for each of the chocolates.

Particle size distribution was found to be a significant factor in influencing chocolate rheology. The effect of distribution is more noticeable on the viscosity component of the flow behavior. Casson viscosity of the chehavior. Casson viscosity of the chocolates was found to be the lowest for the 50:50 mix of the large- and small-size distributions. Plastic viscosity was related to the width of the distribution. The yield value component has a linear dependence on the mean particle diameter. The packing density of the distributions increased with the mean particle diameter size. Relationship of viscosity in dense suspensions to the particle size distribution characteristics such as diameter ratios, width of the distribution, and packing density will be discussed, as will the effect of particle size distribution on the flow behavior at low shear rate (<5/s).

IMPROVEMENTS IN STABILITY AND FUNCTIONALITY OF FATTY FISH SURIMI

S. D. KELLEHER, and H. O. Hultin, Dept. of Food Science, Univ. Of Massachusetts-Amherst, Marine Station, Gloucester, MA 01930

Pelagic fish, such as those found in the herring, mackerel, or smelt families, are found in great abundance throughout the world. The most substantial use of oils and animal feeds; little of these fish are used for human consumption. One possible avenue toward human consumption for these pelagics is through the production of surimi, which historically has been hindered due to low yields, development of oxidized odors and flavors, poor gelation characteristics, and dark color.

Techniques used to overcome the inherent problems associated with the manufacture oms associated with the manufacture of fatty fish surimi will be discussed. Early contact between the fish muscle tissue and antioxidants (ascorbate and tripolyphosphate) was found to be crucial in reducing oxidative odors detected using both chemical and sensory indicators. Addition of antioxidants at the mincing operation, a point of cell breakage, reduced the TBARS values to 4.1 umol/kg, compared to a control value of 41.5 umol/kg, and sensory values improved 4.6 points on a 9 point scale. Color improvements were found when particle size of the tissue was substantially reduced from sizes normally found during the mincing operation (5mm to microscopic). Heme pigment in the leach water increased 18% upon particle size reduction. Close correlation was found between leached heme pigment, protein losses, and improvement in "L" and "b" values. The above methods used to produce a more stable product also improved gel strain and stress values. Using process adjustments surimi of, or approaching, "AA" grade produced from Atlantic mackerel light muscle.

OPTICAL LUMINESCENCE STUDIES OF STRUCTURE AND DYNAMICS OF MUSCLE PROTEINS

R. D. LUDESCHER, I. K. Chandy, and C. A. Rebello, Dept. of Food Science, Cook College and New Jersey Agricultural Exp. Station, New Brunswick, NJ 08903-0231

Vertebrate skeletal muscle is an elaborate protein architecture of interdigitated thicin architecture of interdigitated thick, myosin- containing and thin, actin-containing filaments that converts chemical energy in the form of ATP to mechanical movement. Although the atomic structures of many of the components of this system are known (myosin, actin, tropomyosin, troponin C) and models of the filament systems are postulated (especially for the thin filament), the specific details of how these proteins convert chemical energy into force and regulate force generation to bring it under nervous control are still moot. This paper will review the author's use of optical luminescence to monitor the local segmental and large scale domain dynamics of the skeletal muscle proteins myosin, actin, and tropomyosin on time scales ranging from nanoseconds to milliseconds, outline how this information contributes to current theories of force generation and its regulation, and speculate about how this information may provide insight into the functionality of these proteins in muscle foods. (Research supported by the NJAES and by grants from the American Heart Association-- New Jersey Affiliate and the Muscular Dystrophy Association.)

GLASSY STATES AND GLASS TRANSITIONS IN PROTEINS

S. PARIDA, J. Cao, R. Puri, and R. D. Ludescher, Dept. of Food Science, Cook College and New Jersey Agricultural Exp. Station, New Brunswick, NJ 08903-0231

The glass transition temperature (Tg) acts as a reference temperature(Tg) acts as a reference temperature for food stability; below Tg foods are stable due to negligible rates of chemical and physical deterioration while above Tg these rates increase dramatically. Typically, the Tg and thus the physical state of foods is determined by sugars and carbohydrate polymers. Protein functionality in low moisture foods, however, also depends on physical state. Proteins are thought to undergo transitions from rigid glassy to soft rubbery states in a manner analogous to amorphous, synthetic polymers. Although such behavior is manifest in some denatured proteins that are indeed amorphous (gelatin is the classic example), it is not clear to what extent such transitions occur in native, folded proteins with considerable internal structure. The specific objectives of our research are to determine whether dry and partially hydrated proteins in their native folded states are glassy and undergo glass to rubber transition at distibber transition at distinct temperatures and to determine how denaturation modulates the glass to rubber transition in dry and moist proteins. This paper will review the literature on glassy states and glass transition in food proteins, evaluate the extent to which native, folded proteins act like amorphous polymers that undergo glass-to-rubber transitions, and present data describing how denaturation plays a role in modulating the distinct transition from a glassy to a rubbery state in model protein systems.

THE ROLE OF FAT REPLACERS IN FUNCTIONALITY OF REDUCED FAT CHEESES

M.A. DRAKE1, and B.G. Swanson2, 1Dept. Food Science and Technology, Mississippi State Univ., Mississippi State, MS 39762, 2Dept. Food Science and Human Nutrition, Washington State Univ., Pullman, WA 99164-6376

Consumers have continually demanded reduced and low fat cheeses. The reduction of fat in cheese adversely affects both flavor and texture. One way to correct the loss of quality associated with fat reduction is the use of fat replacers. Fat replacers fall into two categories: non-polar and fat-soluble fat substitutes and polar water-soluble fat mimetics. Sucrose polyesters, a fat substitute, and four fat mimetics were successfully incorporated into reduced fat Cheddar cheeses.

Yields and instrumental firmness of cheeses containing sucrose polyesters (SPE) in place of milkfat were not significantly place of milkfat were not significantly different from full fat cheeses (P<0.05). The selection of different fatty acids for synthesis of SPE resulted in SPE with different functional profiles. Protein and carbohydrate-based fat mimetics increased yields and decreased rubberiness in 60% reduced fat cheeses (P<0.05). Viscoelastic properties of low fat cheeses containing carbohydrate-based fat mimetics were more similar to full fat cheeses than low fat cheeses without fat mimetics. The use of lecithin in 33% reduced fat cheeses resulted in texture scores from trained dairy judges that were not different from full fat cheeses (P<0.05). Microstructure and viscoelastic properties of reduced fat cheeses with lecithin were more similar to full fat cheeses than control reduced fat cheeses with no added lecithin. Fat replacers can be used to improve quality and functionality of reduced fat cheeses.

PLASMA AS A SOURCE OF FUNCTIONAL FOOD ADDITIVES

T. C. LANIER, and I. S. Kang, Dept. of Food Science, North Carolina State Univ., Raleigh, NC 27695

Plasma, the platelet-free fluid menstrum of meat animal blood, is little used for human food. Objections to blood products as food additives are usually for esthetic or religious reasons. Yet some ethnic groups have traditionally enjoyed specialty ?blood' sausage products. Bovine plasma is now being marketed for its heat gelation and protease inhibitory prat gelation and protease inhibitory properties in meat, poultry, and seafood applications. Difficulties in the sanitary collection of blood have hindered the utilization of plasma from other species. Efforts are now underway to fractionate plasma into more active and functional components. Examples of potentially functional fractions include transglutaminase (factor XIIIa), a2-macroglobulin, kininogen/cystatins, and fibrinogen. This approach to the food utilization of plasma promises to open many new applications by reducing esthetic objections as well as organoleptic concerns of off-flavors or discoloration. Fractionation additionally presents a means of adding greater value to, and meeting market demands for, a resource presently restricted by the difficulties of sanitary blood collection.

PERSPECTIVES OF STARCH FUNCTIONALITY IN FOOD SYSTEMS

R. D. WANISKA, Cereal Quality Laboratory, Dept. of Soil & Crop Sciences, Texas A&M Univ., College Station, TX 77843-2474

Starch is a hydrocolloid that provides unique functional properties to many food systems. Native starch from cereals and tubers are insoluble; thus, yielding lower viscosity food systems initially, compared to the same system after processing. Starches are used in many food systems for their thickening or gelling effects, which occur after gelatinization of native starch. During processing, starch gelatinization occurs after minstarch gelatinization occurs after minimum temperature, pressure, time, and plasticizer conditions are attained. The molecular, aggregate, or microgel nature of starch in the gelatinized starch granule and in the leached or dispersed materials change dynamically in food systems. Analytical measurements of starch content and composition are important but do not predict functionality in complex food processing systems. Measurements of the changes in starch functionality during and after gelatinization and during storage are related to product qualities and shelf-stabilities. Monitoring starch functionality during processing provides greater control of finished product characteristics. Examples of functional measurements of starch will demonstrate some of the tools available and their interpretation.

TURBIDIMETRIC ANALYSIS OF GEL FORMATION

J. A. MESSER, and T. P. Moody, Dept. of Biochemistry and Molecular Biology, Univ. of New Hampshire, Biological Center, Durham, NH 03824

Model gel-forming systems are constructed that consist of species for which the turbidity can be calculated. These species include particles that can be described as spheres, long rods or long random coils. Another species in these models consists of reflective regions. It is assumed that the reflective regions are aggregated material that is large, relative to the wavelength of the incident light, in more than one dimension. T light, in more than one dimension. The principle dimension of the long rods and long random coils may be significantly less than, on the order of, or much greater than the wavelength of the incident light. Given experimental turbidimetric data and estimates of the mass concentration of gel for a real gel-forming system, a model gel-forming system can be constructed that matches the turbidimetric characteristics of the real system. An example is presented of a model system that was constructed to match the turbidimetric characteristics of a real system.

FLOW CHARACTERISTICS OF HEATED DISPERSIONS OF COMMERCIAL MILK PROTEINS AND CARRAGEENANS

RANJAN SHARMA1, E. Allen Foegeding2, and Peter A. Munro1, 1New Zealand Dairy Res. Ins., Palmerston North, New Zealand, 2Dept. of Food Sci., North Carolina St. Univ., Raleigh, NC 27695, USA

Milk proteins and carrageenans are commonly used as functional ingredients in food products. Although there are several reports covering functionality of the two ingredients at concentrations at which they form gels, there is limited information at low concentrations where the gelation is not the main functionality. The present work looks at the flow characteristics of dispersions of milk protein concentrate (MPC), sodium caseinate (SC), and whey protein concentrate (WPC) with k, i, and l-carrageenans at concentrations that are commonly used for liquid nutritional prodummonly used for liquid nutritional products.

Dispersions of milk protein and carrageenan containing 5% (w/v) protein and 0.02 to 0.10% (w/v) carrageenan were heated at 121·C for 16 min, cooled to room temperature and evaluated for flow characteristics, viscosity, and particle size.

All protein and carrageenan dispersions individually showed Newtonian flow behavior. The mixed dispersions of the three proteins and i- and k-carrageenans at all concentrations of carrageenan also showed Newtonian or Linear flow behavior. The dispersions containing MPC or SC and k-carrageenan showed flow behavior that ranged from Newtonian to non-Newtonian (pseudoplastic) to gels. Up to 0.04% (w/v) k-carrageenan, the mixed dispersions containing MPC were Newtonian but at ³0.06% (w/v) they formed thermally reversible gels. For SC containing dispersions, the flow characteristics changed from Newtonian at 0.02% k-carrageenan, to non-Newtonian (pseudo, to non-Newtonian (pseudoplastic) at 0.04% (w/v) k-carrageenan, to thermoreversible gels at higher carrageenan concentrations. At all concentrations of k-carrageenan, WPC containing dispersions were Newtonian fluids.

To determine synergism between protein and carrageenan, apparent viscosity values of mixed dispersions, i.e. dispersions containing both protein and carrageenan were compared with sum of viscosities of protein and carrageenan dispersions alone. Mixed dispersions of MPC and SC with k-carrageenan showed higher apparent viscosity values than those obtained for protein or carrageenan alone, suggesting synergistic interactions. The increase in viscosity was directly proportional to k-carrageenan concentration. Mixed dispersions of WPC and k-carrageenan showed lower apparent viscosity values compared to the sum of viscosities of WPC and carrageenan, indicating no synergism. At all concentrations of i-carrageenan, mixing with MPC resulted in a viscosity value which was lower than the sum of individual viscosities. For dispersions containing SC and i-carrageenan, there was no synergism up to 0.06% carrageenan but synergism was noted above that concentration. Similar results were obtained for WPC and i- carrageenan. Mixed dispersions of milk proteins and l-carrageenan showed no synergism at all concentrations of carrageenan.

DEVELOPMENT OF NEW FOOD APPLICATIONS FOR PROTEINS AT NEW FOOD APPLICATIONS FOR PROTEINS AT ATO-DLO: VALORIZATION OF PEA PROTEIN BY ENZYMATIC HYDROLYSIS

K. B. MERCK*, D. Tezera, J. C. A. Hustinx, J. M. Vereijken, ATO-DLO, Dept. of Industrial Proteins, P. O. Box 17, 6700 AA Wageningen, The Netherlands

ATO-DLO, the Agrotechnological Research Institute of The Netherlands, is an organization for fundamental and applied-scientific research for agriculture and horticulture and for the food- and non-food industries on the basis of agro-raw materials. In the Department of Industrial Proteins, we aim at improving and extending the applicability of proteins in food and non-food products. In the food section, we focus on the industrial isolation of proteins, the improvement of existing applications, and the development of new applications. The type of research carried out in the food section is explained by shortly describing some of the projects.

One of the projects concerns the valorization of pea protein by means of enzymatic hydrolysis. Although pea is grown all over Europe, the use of pea protein is limited. For its use as a functional ingredient in food products, functional properties have to be improved. To that end, pea protein isolate was subject to limited enzymatic hydrolysis, resulting in hydrolysates with improved solubility, foaming and emulsifying properties, depending on the extend of hydrolysis and the enzyme used.

E. D. BASTIAN and L. S. Ward, Univ. of Minnesota, St. Paul, MN.

Beta-casein has been isolated by utilizing the propensity of casein to flocculate when treated with chymosin, and for beta-casein to become more soluble at cool temperatures. By examining different commercial caseinates, we observed approximately 5-30% of the beta-casein existing in a form altered such that it separated on monoQ ion-exchange chromatography and on isoelectric focusing. The N-terminal amino acid sequence of the unknown protein was identical to beta- casein. Mass spectroscopy of isolated beta-casein A2 was compared to the unknown protein fraction and was shown to be 82 daltons greater, suggesting that a phosphate had been removed from the unknown protein. Further work using 31P-NMR showed that the unknown protein had only four phosphate residues. We concluded that the unknown fraction of protein was mono- dephosphorylated beta-casein. Because this fraction comprises a variable, and sometimes large, portion of beta-casein in commercial caseinates, the functionality of such caseinates also will be variable.

M. A. BALÁA and D. L. Marshall, Dept. of Food Science and Technol., Mississippi St. Univ., Box 9805, Mississippi State, MS 39762, Mississippi State, MS 39762

The addition of preservatives to foods is a useful approach towards inhibiting food poisoning and spoilage micro-organisms. However, chemical preservatives face regulatory guidelines and consumer acceptance. Processors face a dilemma when they attempt to prevent microbial deterioration, while also being aware that consumer acceptance may be lower due to the rejection of chemical food additives. Processors await natural preservative systems that appeal to consumers. Glycerol monolaurate, "monolaurin", is a naturally occurring glycerol ester of lauric acid that exhibits antimicrobial activity against a wide variety of Gram position bacteria.

Monolaurin is a GRAS compound with potential uses in foods, cosmetics, and pharmaceuticals. It has been recommended as a preservative potentiator in multi-functional preservative systems. This review paper presents our evaluation of monolaurin in model food systems and foods. Other relevant work will also be presented.

C. WANG, Y. L. Xiong, X. Lou, and S. D. Mims, Community Research Service, Kentucky St. Univ., Frankfort, KY 40601; and Dept. of Animal Science, Univ. of Kentucky, Lexington, KY 40546

Paddlefish, Polyodon spathula, a fresh water cartilaginous fish, seems well suited for surimi production due to its low heme and fat content, firm texture, andeme and fat content, firm texture, and lack of bones. Our research characterized the gel-forming properties of paddlefish surimi through biochemical and rheological analyses. Surimi gels were induced by one-stage heating at 40, 50, 55, 60, or 70·C for 30 minutes, or by two-stage heating with pre-incubation at these temperatures followed by heating at 90·C for an additional 30 minutes. Surimi gels formed at 60·C exhibited the highest rigidity and elasticity. Pre-incubation of surimi paste at around 40·C caused the breakdown of myosin heavy chain and a marked decrease in the strength of gels prepared by two-stage heating. The gel- weakening of heating at 40·C was essentially prevented by the addition of 1-2% bovine plasma powder (which contains protease inhibitors). These results indicate that highly functional gels could be produced from paddlefish surimi through optimization of the heating process and/or addition of inhibitors.

A. P. HANSEN, Dept. of Food Science, North Carolina State Univ., Box 7624, Raleigh, NC 27695-2951

The effect of vanillin, citral, benzaldehyde, d-limonene, aldehydes, methyl ketones, and methyl esters and etc. reacting with milk proteins. Whey proteins are the most reactive of the milk proteins. Casein will bind certain flavors but as concentrations is increased flavor loss does notions is increased flavor loss does not change. Beta-lactoglobulin is the most reactive with most flavors and binds more flavor as concentrations is increased. Heat denaturation of Beta-lactoglobulin also opens up more binding sites and therefore causes greater binding of the flavor compounds.

The interactions of flavor compounds with low density polyethylene (LDPE) and polypropylene (PP) reveal that lipophilic flavors have a greater tendency to bind to packaging material. Both LDPE and PP show similar trends in binding of lipophilic flavors. LDPE sorption of aldehydes C7-C10 range from 11-63% whereas PP is 17-63%. LDPE sorpiton of methyl ketones C7-C10 range from 1.5-43% whereas PP is 4.2-73.7%. LDPE sorption of methyl esters C7-C9 is 6.0 to 42% whereas PP is 13 to 79.5%. LDPE sorption of sulfur compounds ranges from 8.5 to 21% whereas sulfur compounds range from 38.7 to 48.6%. As flavor compounds got more lipophilic the sorptions inipophilic the sorptions increased until about C12 which may be due to molecular size hinderance. The more polar compounds were not a problem with LDPE or PP related to sorption or loss of flavor into packaging material.