Food Emulsions Milk Industry

Another example of a food emulsion is the ice cream, in which the colloidal dispersion of ice particles is achieved together with tiny entrapped air bubbles in an emulsion consisting of fats, sugar, and thickening agents (polysaccharides). 

The structure of ice cream has been studied in detail using electron microscopy. Trapped air bubbles are found to be separated by only few micrometer-thick layers of the continuous phase. 

Ice cream consists of ca. 40% air-frozen foam. The continuous phase in foam consists of sugars, proteins, and emulsifiers. A typical ice cream contains 

Ice cream emulsion has a very characteristic degree of stability. The air bubbles should remain dispersed, but as soon it melts in the mouth, the emulsion should break. This leads to the sensation of taste, which is very essential to enjoy its specialness. The sensation of taste on the surface of the tongue is known to be related to molecular shape and physicochemical properties. As soon as these molecules are separated from the emulsion, the taste sensation is recorded in the brain. Therefore, the various components must stay in the same phase after the breakup of the emulsion. Emulsifiers that are generally used have low HLB values (for W/O), and have been found to have considerable effect on the structure of the ice cream. 

The role of milk in nature is to nourish and to provide immunological protection to the mammalian young. The nutritional value of milk is high. It comes from various sources, such as human, goat, buffalo, sheep, and yak, and has been a food for humans since prehistoric times. It is also a very complex food with many thousands of different molecular species found in it. There are several factors that can affect milk composition. An approximate composition of milk can be given as follows  

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Because of the widespread applications of surface chemistry, practically all industries, knowingly or otherwise, make use of the principles of surface chemistry. Countless cosmetic and pharmaceutical products are emulsions—lotions, creams, ointments, suppositories, etc. Food emulsions include milk, margarine, salad dressings and sauces. Adhesive emulsions, emulsion paints, self-polishing waxes, waterless hand cleaners and emulsifiable insecticide concentrates are commonplace examples of emulsions, which fall within the province of surface chemistry. Other products winch function in accordance with the principles of smface chemistry include detergents of every variety, fabric softeners, antistatic agents, mold releases, dispersants and flocculants. 

The use of surfactants in the food industry has been known for centuries. Naturally occurring surfactants such as lecithin from egg yolk or soybean and various proteins from milk are used for the preparation of many food products, such as mayonnaise, salad creams, dressing, and desserts. Polar lipids such as monoglycerides have been introduced as emulsifiers for food products. More recently, synthetic surfactants such as sorbitan esters (Spans) and their ethoxylates (Tweens), sucrose esters, have been used in food emulsions. It should be mentioned that the structures of many food emulsions is complex, and in... 

Emulsions are part of the product range in the chemical and petrochemical industries, and also in the pharmaceutical, cosmetic and food industries. Widespread and well known are food emulsions such as milk and dairy products, mayonnaise, spreads, sauces and dressings. However, emulsions are also found in vanishing cream, ointments and lotions, detergents, surface coatings (e.g. of paper), bitumen and as intermediate products in a wide range of product technology [1]. 

Separation of liquids in a centrifuge. Liquid-liquid separations in which the liquids are immiscible but finely dispersed as an emulsion are common operations in the food and other industries. An example is the dairy industry, in which the emulsion of milk is separated into skim milk and cream. In these liquid-liquid separations, the position of the outlet overflow weir in the centrifuge is quite important, not only in controlling the volumetric holdup V in the centrifuge but also in determining whether a separation is actually made. 

Carrageenan has diverse industrial applications including use in toothpaste, ice cream, chocolate milk, jellies, puddings, pet foods, pharmaceutical and industrial suspensions, antiulcer treatments, shampoos, creams, lotions, and oil/water and water/oil emulsions. Carrageenan reacts with denatiu-ed proteins and has been shown to exhibit properties similar to those of the animal mucopolysaccharides, such as anticoagulant activity and induction of growth of new connective tissue. 

Because of its gelling ability, carrageenan is widely used as food thickeners and emulsion stabilizers in the food industry and is present in many dairy products including less expensive ice-cream and other dessert products providing a smooth, creamy texture. It is used as a stabilizer in foods, such as chocolate milk. 

Another parameter that influences the overall properties of the bulk emulsion is the physical state of the lipid droplets in an emulsion (17, 19, 28-31). Crystallization of lipid droplets in emulsions can be either beneficial or detrimental to product quality. Margarine and butter, the most common water-in-oil emulsions in the food industry, are prepared by a controlled destabilization of oil-in-water emulsions containing partly crystalline droplets. The stability of dairy cream to mechanical agitation and temperature cycling depends on the nature and extent of crystallization in milk-fat globules. It should be noted that because the density of the phases can change as crystallization occurs, the rate at which milkfat droplets cream can be altered as droplets solidify. Emulsion manufacturers should therefore understand which factors influence the crystallization and melting of emulsified substances, and be aware of the effect that droplet phase transitions can have on the properties of emulsions. 

Abcor (now a division of Koch Industries) installed the first industrial ultrafiltration plant to recover electrocoat paint from automobile paint shop rinse water in 1969. Shortly afterwards, systems were installed in the food industry for protein separation from milk whey and for apple juice clarification. The separation of oil emulsions from effluent wastewaters has also become a significant application. The current ultrafiltration market is approximately US 200 million/ year, but because the market is very fragmented no individual end-use segment is more than US 10-30 million/year. In the chemical and refining industries, the principal application of ultrafiltration is the treatment of oily wastewater. 

General application areas for LR-NMR are given in Table 7.27. Low-resolution pulsed H NMR has found widespread application in a variety of QC laboratories and research establishments in the food industry, polymer and chemical industries, mineral oil industry, pharmaceutical and cosmetic industries, and medical research because it offers rapid analysis without the need for difficult sample preparation [30, 199,210]. Applications of LR-NMR in the food industry, e.g. as applied to measurement of moisture in foodstuffs, were described as long as 50 years ago [211], Applications now include measuring oil or fat in cosmetics, oilseeds, chocolate and other foodstuffs, solid-fat content, droplet size in oil-inwater emulsions total moisture content in seeds, milk powder, pharmaceuticals oils in/on polymers... 

Emulsifiers and the emulsions prepared from these are used in very diverse applications. In the foodstuffs industry, fatty acid polyglycol esters or glycerol esters are used for the production of margarine and in the manufacture of cooking fats, milk powders contain emulsifiers in the form of glycerol monostearates, and special lactates and tartaric acid esters of fatty acid glycerides are present in pastries made with yeast dough and in pasta. In most countries, strict food laws limit the use of synthetic emulsifiers [41]. 

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