Functionality of Proteins in Food

Abstract

The property of proteins to fonn stable foams is important in the production of a variety of foods. Foam can be defmed as a two-phase system consisting of air cells separated by a thin continuous liquid layer called the lamellar phase. Food foams are usually very complex systems, including a mixture of gases, liquids, solids, and surfactants. The size distribution of air bubbles in foam influences the foam product's appearance and textural properties; foams with a unifonn distribution of small air bubbles imparts body, smoothness, and lightness to the food. Proteins in foams contribute to the unifonn distribution of fme air cells in the structure of foods. Body and smoothness of food foams is related to the fonnation of air bubbles that allow volatilization of flavors with enhanced palatability of the foods.The most widely used protein foaming agents are: egg white, gelatins, casein, other milk proteins, soy proteins, and gluten. Proteins vary significantly in their foaming properties; for example, serum albumin is an excellent foaming agent while purified ovalbumin is poor. Protein foaming agents should possess the following properties. They should stabilize foams rapidly and effectively at low concentrations; perfonn as an effective foaming agent over the pH range which exists in various foods; perfonn effectively as a foaming agent in the medium with foam inhibitors such as fat, alcohol or flavor substances.Our understanding of the functions of proteins in the fonnation of adsorbed protein films has been improved by studies in which radio-labelled proteins were used to obtain surface concentrations. Foamability and whippability of foaming agents are used interchangeably in the literature. The tenn whippability is applied when foam is obtained by a high blending or whipping treatment. The tenn foamability is applied when foam is prepared by injecting air or gas through the protein solution. The foaming properties of proteins are influenced by the source of the protein, methods and thennal parameters of processing, including protein isolation, temperature, pH, protein concentration, mixing time, method of foaming. Among many factors influencing foaming capacity (FC) of proteins the type of foaming equipment and method of agitation are important. Speed of whipping is important to foam properties and consumer acceptance.

Expansion in chickpea (Cicer arietinum L.) seed during soaking and cooking

“…Below the gelatinisation/denaturation temperature the water absorbed into the seed might be interstitial water, penetrating between the macromolecules and letting the volume expand. Another possible reason might be the restricted swelling of proteins as the temperature increases below the denaturation temperature (Zayas, 1997). Above the denaturation/gelatinisation temperature the physical properties of the seed have the same behaviour in terms of the effect of water on expansion.…”

Effects of high pressure on functionality of whey protein concentrate and whey protein isolate

“…IV). This is attributed to the previously discussed significant amount of β-lactoglobulin, which is capable of forming a thicker and more viscous film, thus improving foam stability [49].…”

Crystal Structures of Protein Glutaminase and Its Pro Forms Converted into Enzyme-Substrate Complex

“…The enzyme was discovered in culture supernatant from Chryseobacterium proteolyticum strain 9670 and purified by Yamaguchi and Yokoe (1). It was cloned and expressed in Escherichia coli (2) and investigated for its reactivity with substrate proteins such as ␣-and ␤-caseins and gluten (3), zein (4), and gliadin and ␣-and ␤-lactalbumins (5), including proteins exhibiting low solubility in aqueous solutions (6), to improve the quality of these food proteins. One of the potential applications of PG is to reduce the allergenicity of food proteins.…”