Heat-coagulation

Water Treatment Industrial CleaningPipplications. Boiler and cooling tower waters are treated with lignosulfonates to prevent scale deposition (78). In such systems, lignosulfonates sequester hard water salts and thus prevent their deposition on metal surfaces. They can also prevent the precipitation of certain iasoluble heat-coagulable particles (79). Typical use levels for such appHcatioas range from 1—1000 ppm. 

Figure 14.3 SDS-PAGE of recovery of lysozyme in the presence of BME. Lane M, molecular weight marker lane 1, FFPE lysozyme tissue surrogate lane 2, a 75 mg/mL solution of lysozyme heat coagulated for 10 min at 100°C in 10 mM sodium phosphate buffer, pH 7.4. Both preparations were resuspended in 20mM Tris-HCl, pH 4, with 2% SDS and 0.5 M BME, and heated at 100°C for 20min followed by a cycle of heating at 60°C for 2h. For more detail, see Reference 25.

Figure 9.1 The time needed (t ) at various temperatures (T) to inactivate some enzymes and cryoglobulins to kill some bacteria and spores to cause a certain degree of browning to convert 1 % of lactose to lactulose to cause heat coagulation to reduce available lysine by 1 % and to make 10% and 75% of the whey proteins insoluble at pH 4.6 (from Walstra and Jenness,...

Cross-linking of proteins. Covalent cross-linking of caseins is evident (by gel electrophoresis) after even 2 min at 140°C and it is not possible to resolve the heat-coagulated caseins by urea- or SDS-PAGE. 

All the heat-induced changes discussed would be expected to cause major alterations in the casein micelles, but the most significant change with respect to heat coagulation appears to be the decrease in pH - if the pH is readjusted occasionally to pH 6.7, milk can be heated for several hours at 140°C without coagulation. The stabilizing effect of urea is, at least partially,... 

Figure 9.21 Effect of pressure (Rannie homogenizer) on the heat coagulation time (at 140°C) of milk, unhomogenized ( ) or homogenized at 3.5 MPa (A) 10.4 MPa ( ) or 20.7/3.5 MPa ( + ) (from Sweetsur and Muir, 1983).

Pyne, G. T. 1958. The heat coagulation of milk II. Variations in sensitivity of casein to calcium ions. J. Dairy Res. 25, 467-474. 

Much is known of protein functionality in terms of water solubility and dispersibility, the heat coagulation (or heat-setting) property, water... 

An acetone powder of Savoy cabbage leaves (prepared by heat coagulation and acetone precipitation and available from commercial sources) is suspended in diethyl ether and then filtered. The residue is dispersed in sodium acetate and calcium chloride at pH 5.0, and the insoluble matter is separated by centrifugation at 13,000 g for 10 min at 4°C. The supernatant contains all the phospholipase D activity and in our laboratory s experience can be used successfully in any experiment requiring this enzymatic activity. It can be maintained at -20°C for 1-2 weeks. 

McCrae, C., Muir, D. 1992. Heat stability of recombined milk influence of lecithins on the heat coagulation time-pH profile. J. Dairy Res. 59, 177-185. 

Farkye, N.Y. 2004. Acid- and acid/rennet-curd cheeses. Part C Acid-heat coagulated cheeses. In Cheese Chemistry, Physics and Microbiology, Vol. 2, Major Cheese Groups, 3rd edn (P.F. Fox, P.L.H. McSweeney, T.M. Cogan, T.P. Guinee, eds.), pp. 343-348, Elsevier Academic Press, Amsterdam. 

Table 3-7 Heat Coagulation Temperatures of Some Albumins and Globulins and Casein...

Simple proteins yield on hydrolysis, only amino acids. These proteins are further classified based on their solubility in different solvents as well as their heat coagulability. 

The amount of heat required to sterilize depends upon the magnitude (I), duration (t), and amount of moisture present, t l/T. For example, heat coagulates protein in the living cell. The temperature required for this phenomenon to occur is inversely proportional to the moisture present. 

Procedures for the direct weighing of precipitated or heat-coagulated protein of serum (D8) are uneconomic. Turbidity methods have been discussed in relation to total globulin, and near- and far-ultraviolet spectrophotometry in relation to albumin. Of these, spectrophotometry at about 215 nm is the method of choice. A simple and direct fluorimetric method (K33) should also prove useful. BPB staining of serum on paper, after protein concentration by the Weiss ring-oven technique, has been tried. This is a rapid technique (F3), but the color, confined as it is to a line, is difficult to quantitate, so that the method is insensitive and unsatisfactory in its present form. 

Definite traces of heat-coagulable protein frequently are excreted, notably during the time of maximum nitrogen excretion (C21). 

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