Foods systems, functional properties

As presented, data are available on assessment of water absorption in simple systems and on the incorporation of protein additives into some food systems. Functional properties in... 

The main unique feature of osmotic dehydration, compared to other dehydration processes, is the penetration of solutes into the food material. Through a calculated incorporation of specific solutes into the food system, it is possible, to a certain extent, to change nutritional, functional, and sensory properties, making it more suitable to processing by... 

Maltini, E., Torreggiani, D., Rondo Brovetto, B., and Bertolo, G. 1993. Functional properties of reduced moisture fruits as ingredients in food systems. Food Res. Int. 26, 413-419. 

Compositional differences in the pea seeds influence the quality of the end products. Pea flours have been used for protein enrichment of a number of cereal-based products however, undesirable sensory characteristics may limit their use, in spite of improved functional effects in food systems. The production of volatile compounds during cooking and baking of foods with pea supplementation affects their acceptability. Enzyme systems active in unheated pea flours may contribute to their functional properties, but adversely affect the sensory quality of the food. 

The present research was conducted to evaluate selected physicochemical properties of the dry roasted and air-classified navy, pinto, and black bean flour fractions. Studies were conducted to determine the chemical composition and to characterize the functional properties of dry-roasted bean flour fractions and to evaluate the suitability of the flours for use in foods systems. 

Dry bean flour fractions produced by dry roasting, milling and air classification resulted in versatile food ingredients. Fractions possessed good functional and nutritional properties which were found to be acceptable in a variety of food systems. These processes and products appear to have potential for improving nutritive status through improved dry bean utilization. 

Kolakowska, A. (2002). Lipid oxidation in food systems, in Sikorski, Z.E. and Kolakowska, A., eds., Chemical and Functional Properties of Food Lipids, CRC Press, Boca Raton, 133-166. 

FIGURE 5.6 Physico-chemical and protein-related functional properties of defatted morama bean flours and their potential applications in food systems (adapted from Maruatona, 2008). 

Soy protein is a low-cost food protein with good nutritional value, but its uses in foods are limited because of inferior functional properties as compared to those of commonly used animal proteins such as casein and albumin (1.2). Therefore, modifications are often required to make soy protein more suitable for food use. Improved functional properties, particularly in the pH range of 3 to 7 where most food systems belong, have been achieved by non-enzymatic methods, including succinylation (3-5), deamidation (6.7), and phosphorylation (8.9). 

Model System (or Model Test) - An evaluation of one or more functional properties that does not mimic completely the steps and ingredients of an actual food preparation. 

Utility System (or Utility Test, or Food Test) - An evaluation of a functional property that mimics food preparation in all its particulars. 

Protein is utilized in many foods for the particular characteristics that it contributes to the final product (1 ). In order for protein products to maintain or enhance the quality and acceptability of a food, the protein ingredients should possess certain functional properties that are compatible with the other ingredients and environmental conditions of the food system. Consequently, an important aspect of the development of new protein additives and their incorporation into food systems is the establishment of their functional properties. Functional properties of proteins are physicochemical properties through which they contribute to the characteristics of food. Study of functionality should provide information as to how a protein additive will perform in a food system (, A). These properties are... 

Relationships with other properties. In any food system and possibly in simple systems, the protein ingredient is likely to perform several functions, most of which are being discussed in... 

Environment. The physical and chemical environments have been shown to affect the functional performance of proteins. Factors, such as concentration, pH, temperature, ionic strength, and presence of other components, affect the balance between the forces underlying protein-protein and protein-solvent interactions (9). Most functional properties are determined by the balance between these forces. Although the comparison of discrete data from various studies might be of limited value, consideration of the response patterns of protein additives to changes in the environment of simple and/or food systems might be fruitful. 

Hutton, C. W. "Functional properties of a soy isolate and a soy concentrate in simple systems as related to performance in a food system" Dissertation, The University of Tennessee, Knoxville, Tenn., 1975. 

Milk protein system. The nomenclature and physico-chemical properties of the major milk proteins and their subunits have been provided by Whitney et al. (13) and Brunner (1 ). The conformation and related properties of the individual proteins and their subunits and aggregates have been reviewed by Morr (15) with special reference to their functional properties in food systems, and drawing heavily upon previous considerations by Bloomfield and Mead (16) and Slatterly (17). 

Emulsification properties in model food systems. Pearson et al. (25) investigated the emulsification properties of caseinate and NFDM in model emulsion systems produced by blending soybean oil into an aqueous buffer system as a function of pH and ionic strength (Figures 7 and 8). They found that caseinate exhibited good emulsification properties under all pH and ionic strength conditions studied, but was particularly effective at pH 10.4. 

That is, we must learn how amino acid content and molecular configuration of food proteins are related to their functional properties. This goal is made more difficult by the fact that secondary, tertiary, and quarternary structures of proteins are likely to be quite different when exerting functional effects in food systems as compared to structures of the same proteins in dilute solutions and in their native states. The way in which specific actions of proteases affect protein structure must also be studied so that correlations with changes in functional properties can be made (61). 

Functionality, or functional property, is defined as any property of a substance, besides the nutritional ones, that affects its utilization (7). Functionality, and particularly the role of proteins in its properties, is currently a high-priority area of research. Scientists working on functionality need to understand the physlcochemistry of its properties and collaborate in research on methods of testing it so that comparisons of data from different laboratories can be made and model tests of functional properties can be coordinated with actual food systems. 

This book updates and presents new information on the physicochem-istry of functionality, the roles and use of proteins for improving the functional properties of foods, and the application of data from model test systems to actual food ingredients. This volume should be useful to food processors, engineers, chemists, physicists, and others engaged in these or related areas of research. It also is hoped that this book will stimulate its readers to expand research on functionality. 

The most important feature affecting the functional and organoleptic properties of a protein is its surface structure. Surface structures affect the interaction of a protein with water or other proteins. By modifying the structure of the protein, particular functional and organoleptic properties are obtained. Functional properties of a protein are physicochemical characteristics that affect the processing and behavior of protein in food systems (Kinsella, 1976). These properties are related to the appearance, taste, texture, and nutritional value of a food system. Hydrolysis is one of the most important protein structure modification processes in the food industry. Proteins are hydrolyzed to a limited extent and in a controlled manner to improve the functional properties of a foodstuff. 

It is often best to begin with purified proteins when studying the relationships between protein structure and function at the molecular level. The presence of multiple proteins often complicates data interpretation, as it is not clear if effects are due to protein interactions, variations in the ratio of proteins, or to other factors. In these studies it is advisable to select tests based on a fundamental physical or chemical property, since results are less likely to vary with the test conditions or instrumentation used. Unfortunately, it becomes less likely that the property under study will relate directly to function in a food system when such simplified (often dilute) systems are used. Something as seemingly insignificant as protein concentration in the model system can have a large influence on the results obtained. Also, the relative importance or contribution of a functional property to a complex food system can be misinterpreted in a purified model system. 

Expressible moisture and water uptake ability measure different properties. Figure B5.3.2 shows the very different cation and anion dependencies of these methods using fish samples. Figure B5.3.3 shows that the pH profiles are also different. It is also apparent that WUA is often >100%, while expressible moisture must, of necessity, be <100%. Figure B5.3.4 shows an example where expressible moisture was actually correlated with a separate and independent functional measurement. In this case, the binding of cooked fish muscle as determined by a subjective sensory panel pulling samples of fish apparently paralleled the moisture retention of the raw fish (moisture retention = 1 - expressible moisture). Ideally, functional properties should show such correlations with other properties of interest in food systems. 

Proteins are important from the nutritional and technological points of view. Proteins affect every property that characterizes a living organism, and they play different roles in the human body. Proteins are also very important in food technology and are responsible for many food properties. The physical properties of proteins and their interactions with other components contribute significantly to the functional behavior and quality of several food products, such as cheese, bread, and meat products (9). An overview of the functional roles of proteins in different food systems is presented in Table 2. Food preferences by human beings are based not on nutritional quality but on sensory attributes to the food, such as appearance, color, flavor, texture, and... 

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