Protein storage temperature

The egg shell is 94% calcium carbonate [471-34-17, CaCO, 1% calcium phosphate [7758-23-8] and a small amount of magnesium carbonate [546-93-0]. A water-insoluble keratin-type protein is found within the shell and in the outer cuticle coating. The pores of the shell allow carbon dioxide and water to escape during storage. The shell is separated from the egg contents by two protein membranes. The air cell formed by separation of these membranes increases in size because of water loss. The air cell originally forms because of the contraction of the Hquid within the egg shell when the temperature changes from the body temperature of the hen at 41.6°C to a storage temperature of the egg at 7.2°C. 

The chemical stability of an amorphous formulation is usually also a function of its storage temperatme relative to Tg. The enhanced molecular mobility achieved near the glass transition translates into an increase in translational diffusion-dependent degradation pathways, such as aggregation in proteins. It should be noted that the reaction kinetics near the Tg do not obey Arrhenius kinetics, and that extrapolation of the accelerated stability data generated near the Tg to stability at the storage temperature should be viewed with extreme caution. Amorphous materials must be stored well below the glass transition (at least 10°C, and typically 40 to 50°C below Tg) to maintain their physical and chemical stability. 

The whey produced during cheese and casein manufacturing contains approximately 20% of all milk proteins. It represents a rich and varied mixture of secreted proteins with wide-ranging chemical, physical and functional properties (Smithers et al., 1996). Due to their beneficial functional properties, whey proteins are used as ingredients in many industrial food products (Cheftel and Lorient, 1982). According to Kinsella and Whitehead (1989), functional properties of foods can be explained by the relation of the intrinsic properties of the proteins (amino acid composition and disposition, flexibility, net charge, molecular size, conformation, hydrophobicity, etc.), and various extrinsic factors (method of preparation and storage, temperature, pH, modification process, etc.). 

The leaf extract of curry leaf has been reported to contain moisture (66.3%), protein (1%), fat (1%), carbohydrate (16%), fibre (6.4%) and mineral matter (4.2%). The main minerals per 100 g of leaves are calcium (810 mg), phosphorus (600 mg) and iron (2.1 mg). The vitamins in the leaves are carotene (12,600 i.u.), nicotinic acid (2.3 mg) and vitamin C (4 mg) (Anon., 1962 Kumar et al., 1999). The extract also contains oxalic acid, which reduces the availability of calcium. The contents are total oxalate (1.352%) and soluble oxalate (1.155%) (Ananthasamy et al., 1960 Walde et al., 2005). The effects of storage temperature on the nutritive value were studied by Palaniswamy et al. (2002). Reisch et al. (1994a) found the furocou-marins in the seeds. 

Denaturation of proteins may result from low concentrations and elevated storage temperatures. These conditions must also be controlled for radioiodinated proteins that are also subject to internal self-irradiation damage, which is more pronounced in I-labeled proteins than I-la-beled proteins owing to the beta radiation emission of I. To minimize such problems, radioiodinated proteins are diluted in protective protein solutions that will not interfere in the subsequent studies to be made, such as 10% normal serum or BSA at 2 mg of protein per milliliter. Aliquots are kept frozen at -20° to -70° and thawed only as needed. 

Thermal techniques such as isothermal calorimetry (ITC) and differential scanning calorimetry (DSC) have been used in formulation screens to predict the formulation with the greatest stability based on the assumption that excipients that increase the of the protein will stabilize the molecule at the recommended storage temperature. For example, a screen of preservatives performed during formulation development for interleukin-1 receptor found that the for the formulation... 

After frozen storage at several temperatures in various media. All samples were quenched in alcohol at —72° before transfer to alcohol at the stated storage temperatures, and all were thawed rapidly in a 37° water bath for assay. All samples in a given experiment were prepared, frozen, stored, thawed, and assayed simultanously. ppt = precipitated on thawing. P = protein. MEt = mercaptoethanol. 

Rates of denaturation of muscle proteins in Alaska pollack, as influenced by freezing rate and storage temperature, were studied by Matsuda... 

The state of fat in powder has a major influence on wettability, i.e. the ease with which the powder particles make contact with water. Adequate wettability is a prerequisite for good dispersibility. Free fat has a water-repelling effect on the particles during dissolution, making the powder difficult to reconstitute. Clumps of fat and oily patches appear on the surface of the reconstituted powder, as well as greasy films on the walls of containers. The presence of free fat on the surface of the particles tends to increase the susceptibility of fat to oxidation. A scum of fat-protein complexes may appear on the surface of reconstituted milk the propensity to scum formation is increased by high storage temperatures. 

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