Properties of foodstuffs

Besides texture and color, flavor (taste and smell) is an important property of foodstuffs. Smell is caused by volatile compounds coming into contact with a distinct area in the nose, the so-called "regio olfactoria" [1], Volatile flavor compounds are denoted odorants or odor compounds, if they have been perceived nasally (before eating) and aroma compounds if they have been perceived retronasally via the throat (during eating). Therefore, in the literature the terms flavor, odor or aroma compounds are often synonymously used. 

In the last part of the book some examples are reported on the importance of the contribution of chemical studies to fields that are of increasing concern for the public opinion such as health, food, and the environment. One of these describes investigation of the protein-tannin interaction in order to better understand organoleptic properties of foodstuffs, and in particular those of red wine. 

Others (such as flavors, other food products added in small quantities, e.g., plant proteins added to meat products, enzymatic products which modify physicochemical and sensory properties of foodstuffs)... 

The formation of inclusion complexes of lipids inside the amylose helix is not the only important factor regulating the functional properties of foodstuffs. The adsorption of lipids on starch surfaces can prevent the separation of components in frozen starch noodles. Such surface sorption reduces the viscosity and adhesiveness of the starch.888 The latter property can also be important in the microencapsulation of medicines. For example, a complex of cornstarch with glucolipids has been patented as an excipient for 3-(p-chlorobenzyl)-6-methoxy-2-methylindole-l-acetic acid.889... 

Rhodium tetraacetate, as catalyst, in O-alkylation 666 Rhodococcus 978 Ring current effects 336 Ring inversion, cone-to-cone 1385, 1386 Ring-walk isomerization 283 Ripening, state of, effect on organoleptic properties of foodstuffs 913 River water, analysis of 946, 947, 962, 977 Road particulate matter, phenoUc compounds in 938... 

Maltini, E. 1974. Thermophysical properties of frozen lemon juice related to freeze-drying problems. Current studies on the Thermophysical Properties of Foodstuffs, HR-IIFCl-2. Bressanone, Italy, pp. 201-207. 

The rheological properties of foodstuffe are important in food process engineering since they are the essential parameters in plant design (pumping requirements, pipe and valve dimensions, and mixing operations, etc.) and in the calculation of basic heat, mass, and momentum transfer (Szczesniak, 1977). 

In sensory evaluation consumers estimate fruit firmness on the basis of the deformation resulting from physical pressure applied by the hand and fingers. The toughness or tenderness of meat is subjectively evaluated in terms of the effort required for the teeth to penetrate and masticate the flesh tissues. Therefore, determination of rheological properties of foodstuffs is important in evaluation of consumer-determined quality by correlating rheological measurements with sensory tests. 

Already at an early stage in the development of surfaee and colloid science emulsions received a lot of attention. It was primarily clear that the properties of foodstuffs like milk, butter, and sauces contained dispersions of one liquid phase in another either oil (as fat) in water or water in oil (fat). Pioneering studies were performed by Baneroft in the first quarter of this century and his studies were followed up by Harkins and others, leading to a phenomenologieal knowledge that is still relevant today. Attempts were also made to understand and rationalize the experimental findings, but in this aspect progress was much slower. 

It follows that foods can have an expanded role in human health that goes well beyond providing an adequate source of nutrition. This concept has served to blur the distinction between pharmaceuticals and foods, bringing new companies into the food area and making food companies more conscious of the health-promoting properties of foodstuffs. 

Figure 4.3. Integrated modeling strategy of the physical-chemical properties of foodstuffs and the development of the bacterial populations undergoing a manufacturing process...

Occurrence and sensorial properties of alkoxypyrazines contained in foodstuffs and wines 98CLY402. 

For size analyses of particles larger than Vte y, the geometric properties of uniformly constructed physical barriers such as sieves are commonly used. Though this technique of finished product size control dates back to at least 2500 BC when the Egyptians constructed woven cloth sieves for preparation of foodstuffs, it is only within the... 

An understanding of non-Newtonian behaviour is important to the chemical engineer from two points of view. Frequently, non-Newtonian properties are desirable in that they can confer desirable properties on the material which are essential if it is to fulfil the purpose for which it is required. The example of paint has already been given. Toothpaste should not flow out of the tube until it is squeezed and should stay in place on the brush until it is applied to the teeth. The texture of foodstuffs is largely attributable to rheology. 

Many materials of practical interest (such as polymer solutions and melts, foodstuffs, and biological fluids) exhibit viscoelastic characteristics they have some ability to store and recover shear energy and therefore show some of the properties of both a solid and a liquid. Thus a solid may be subject to creep and a fluid may exhibit elastic properties. Several phenomena ascribed to fluid elasticity including die swell, rod climbing (Weissenberg effect), the tubeless siphon, bouncing of a sphere, and the development of secondary flow patterns at low Reynolds numbers, have recently been illustrated in an excellent photographic study(18). Two common and easily observable examples of viscoelastic behaviour in a liquid are ... 

General properties. The solvent should be nontoxic for applications such as the manufacture of foodstuffs. Even for the manufacture of general chemicals, the solvent should be preferably nontoxic for safety reasons. Safety also dictates that the solvent should preferably be nonflammable. Low viscosity and high freezing point will also be advantageous. 

Thickening agents can be of natural or synthetic origin. Various natural gums and starches have been used traditionally in many printing styles. The materials from which they are extracted are valuable sources of foodstuffs, so availability and cost can depend on fluctuating demand from the food industry. The properties required of an ideal thickener can be summarised as follows [352] ... 

The Website http //www.ediblewild.com/nettle.html lists many more properties of stinging nettles - particularly impressive being the number of ways to consume nettles in the form of edible foodstuffs, drinks and beers. 

From the legal point of view, antioxidants are substances which prolong the shelf-life of foodstuffs by protecting them against deterioration caused by oxidation, such as fat rancidity, colour changes and loss of nutrient value. Hundreds of compounds, both natural and synthesised, have been reported to possess antioxidant properties. Their use in food, however, is limited by certain obvious requirements, not the least of which is adequate proof of safety. 

The development of multiclass methods for the detection of antibacterials and coccidiostats in food samples has shown a growing interest during the last years since the regulations concerning the presence of such chemicals in animal-derived foodstuffs is becoming more and more stringent. The challenges that these types of analyses pose to the analysts mainly have to do with the complexity of the matrix and the different physicochemical properties of the antibacterial families. Therefore, very often, a purification and preconcentration step is required prior to analysis in order to minimize matrix effects and reach the desired sensitivities [192, 193]. 

While in ancient times, the sensorial properties of a flavour for foodstuffs were of major importance, modern flavours have to perform like multifunctional systems. Physical form, chemical and mechanical stability and controlled release mechanisms are meanwhile essential criteria for the flavour quality. All these properties have to be addressed by a flavourist in close cooperation with technologists. Therefore, knowledge about food product properties must lead to a careful and intelligent evaluation of the flavour system as an important driver for the success of the final product. 

The term food colloids can be applied to all edible multi-phase systems such as foams, gels, dispersions and emulsions. Therefore, most manufactured foodstuffs can be classified as food colloids, and some natural ones also (notably milk). One of the key features of such systems is that they require the addition of a combination of surface-active molecules and thickeners for control of their texture and shelf-life. To achieve the requirements of consumers and food technologists, various combinations of proteins and polysaccharides are routinely used. The structures formed by these biopolymers in the bulk aqueous phase and at the surface of droplets and bubbles determine the long-term stability and rheological properties of food colloids. These structures are determined by the nature of the various kinds of biopolymer-biopolymer interactions, as well as by the interactions of the biopolymers with other food ingredients such as low-molecular-weight surfactants (emulsifiers). 

Fungal enzymes have been used for hundreds of year to prepare and modify foodstuffs. However, modern industrial enzyme technology probably started with Takamine (53) and his work with A. oryzae. Today many industrial enzymes used to modify functional properties of foods and food ingredients are of fungal origin (54). 

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