Whole egg yolk

Proteins present in whole egg, yolk, and albumen (egg white) are excellent sources of nutrients, and they possess valuable functional properties. Shell eggs consist of 8-11% shell, 56-61% albumen, and 27-32% yolk. The solid content of albumen is about 11-13%, depending on the strain and on the age of the hens, and the solid content of yolk is about 52-53.5%. Albumen solids contain mainly protein, whereas lipids are the major constituents of egg yolk (92). Yolk can be separated by centrifugation into sedimented granules and a supernatant, plasma. The granules contain the major part of the yolk proteins. The main proteins in albumen and yolk are ovalbumin, ovotransferin, lysozyme, ovomucoid, ovomucin, and immunoglobulin Y (93). 

Phospholipase Ai activity is routinely measured by titrimetry in a pH-stat using substrate emulsions of whole egg yolk [31], purified long-chain lecithin in the presence of detergents to facilitate formation of micelles [321 and radiolabeled... 

The fat content of egg yolk is approximately 31.8 to 35.5% that is, about a third of the whole egg yolk. Lipids occur in different particles (granules, LDL-micelles) and are almost completely associated with proteins. An overview is provided by Temes (2001). About 70% of the dry mass consists of lipids. Differences in the Upid composition are not only genetically determined, but also occur due to the animals age and diet. The contents of long-chain (C20 and C22) polyunsaturated FA (PUFA) of n-6 and n-3 were 20 to 25% higher in the lipids of egg yolk from younger hens (Nielsen, 1998) (Table 14.1). 

A comparison of the FA spectrum of TAG from the whole egg yolk with the phospholipid fraction shows that the concentration of stearic acid is reduced, whereas the proportion of more highly unsaturated FA in the phospholipid fraction increases markedly. Oleic acid (20 to 27% in the phospholipid fraction) is present only half as frequently as in the TAG. The concentration of palmitic acid (approximately... 

Table 1 shows the various physical properties for components of eggs (4). Specific gravity of whites, yolks, and whole egg is the same, ie, density is 1035 kg/m (64.6 Ib/ft = 8.63 Ib/gal) for all three types of egg products shown. The viscosity of blended Hquid egg components varies over a wide range of temperatures at temperatures higher than those indicated in Table 1, the protein starts to denature and coagulate, increasing viscosity. 

Frozen Egg Products. Frozen egg products include egg white, plain whole egg, whole egg with yolk added (ie, fortified), plain egg yolk, fortified whole egg with com symp, sugared egg yolk, salted egg yolk, salted whole egg, and scrambled eggs and omelets. Egg products are frozen in a blast freezer at —40 C for up to 72 h, and then held for storage at —24 C (see Refrigeration and refrigerants). They are used by large and small bakeries and for other uses. 

Dried Whole Egg and Yolk. Dried plain whole egg and yolk products are either dried as is, or have the glucose removed to improve stabiHty and shelf life of the product. Glucose is removed before drying by use of glucose oxidase or by yeast fermentation (see Yeasts). Bacterial fermentation is not used because of off-flavor and off-odor development. 

Dried whole egg and yolk products with glucose are less stable, and are usuaUy held under refrigeration until used. The whole egg product has more glucose than the egg yolk and therefore is less stable. 

Dried whole egg and yolk products should be spray-dried so that a minimum amount of heat is imparted to the product during drying. Sodium siHcoaluminate [1344-00-9] or siHcon dioxide [7631-86-9] is added at a level of less than 2.0% to give free-flowing and noncaking characteristics. 

Dried blends of whole egg and yolk with carbohydrates have sucrose or com symp added to the Hquids before spray-drying. Such carbohydrates (qv) preserve the whipping properties of whole egg and yolk by keeping the fat in an emulsified state. Com symp also gives anticaking characteristics, better flowabiHty, and improved dispersibiHty in water. Dried blends of egg and carbohydrate function weU in emulsified, as weU as unemulsified, sponge cakes. 

Imitation whole egg having a low cholesterol content contains egg white as a base nonfat milk and vegetable oil, substituting for egg yolk, are added to give a composition similar to whole egg. These are in frozen, Hquid, or dried forms. 

Low cholesterol egg products are formed by extraction of cholesterol from the egg. Attempts have been made to extract cholesterol by using hexane or by supercritical CO2 extraction methods (24,25). A whole egg product in which 80% of the cholesterol is removed by a process using beta-cyclodextrin, a starch derivative, added to egg yolks has been introduced. The cyclodextrin binds up to 80% of the cholesterol, the mixture is centrifuged, and the Hquid separated. The cholesterol-reduced yolk is then blended with egg white, pasteurized, and packed in asceptic containers to give a Hquid whole egg product having a shelf Hfe of 60 days under refrigeration (see Eood packaging). 

Most egg white sohds are desugared. Whole egg and yolk products are desugared if specified on purchase (SOP). 

Spray dryers may lose dried egg products out of the stack. Cyclone-type coUectors, usually used as the secondary coUector, are not properly designed to coUect products efficiently. A weU-designed cyclone coUector recovers only 85—90% of spray-dried egg white, with 10—15% lost out of the stack, and 94—95% of egg products co-dried with carbohydrates. Bag-type coUectors are needed for 100% recovery of both these products. Plain whole egg and plain egg yolk products are capable of being coUected almost 100% with a cyclone coUector, but a bag coUector is advised (see Airpollution control methods). 

Francis 1 (J. Zitterer) Moravian gallery 1792 Egg yolk/ whole egg [43]... 

Whole egg and egg yolk HMDS Hexadecanenitrile, octadecanenitrile, cholesterol derivatives (TMS derivative) 28, 29, 30... 

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