Treatment effect

The heating is the main technique of processing of milk, whether pasteurization, boiling, condensation, or preparation of dried milk. Heat treatment leads to certain changes milk proteins, including the deployment of polypeptide chains and the gap disulfide bonds. It is known that after boiling reduces clotting and change the physical properties of milk proteins [53]. This applies particularly to thermo labile proteins. Lability of proteins heat can be evaluated according to various criteria; one of them is the immunological reactivity.
Ratner et al. [54] have managed to raise awareness of Guinea pigs by feeding them pasteurized skimmed milk (but not milk, denatured by heat treatment). In [43, 55, 56] studied proteins are subjected to heat treatment of milk and released condensed milk without sugar. It was discovered that alpha-casein - thermostable protein, its antigenic properties was reduced to until the temperature does not exceed 100 degrees C. alpha lactalbumin was moderately thermolabile protein, its antigenic properties somewhat lessened when heated to 60 degrees C and completely disappeared in the preparation of condensed milk without sugar. Beta-lactoglobulin only partially subjected denaturation at a temperature of 100 C, thereby occupying an intermediate position between the alpha casein and alpha-lactalbumin. It is possible that the relative stability of beta-lactoglobulin related to the formation of more stable complex with lactose [12]. According to Luz, and Todd [57], serum albumin cow's milk is the most heat-sensitive proteins, while casein, beta-lactoglobulin, alpha-lactalbumin partially keep their antigenic properties of condensed milk without sugar. Using immunodeficiency-noworemixeme analysis Hanson and Mansson [16] found that casein is sustainable at a temperature of 120 C for 15 min, beta-lactoglobulin, alpha-lactalbumin resistant to temperatures up to 100 C, while whey proteins have been denaturation already at 70-80°N In experiments on Guinea pigs Cole and sound way [58] found that serum proteins of milk partially keep their antigenic properties after heat treatment, and alpha-lactalbumin has more expressed antigenic properties than beta-lactoglobulin.
Saperstein [35] analyzed the different designs available condensed milk without sugar and found that the reaction of precipitation with antigens was positive in some samples and negative in others; this suggests that the denaturation of proteins of milk is uneven. In the same work Guinea pigs subjected to passive sensitization by anticorodal to alpha lactalbumin or beta-lactoglobulin; in animals have evolved anaphylactic shock in response to intravenous them condensed milk, diluted to standard concentration. Therefore, these proteins are partially preserved allergenic properties in concentrated milk.
Exploring patented milk formulas methods reaction precipitation and passive cutaneous anaphylaxis, Saperstein and Anderson [59] found that is responsible for the antigenic properties of the structure of the molecule casein, alpha-lactalbumin, beta-lactoglobulin not inactivated under the influence of heat treatment in the process of manufacturing mixtures. Serum albumin cow's milk was immunological inactive in liquid dairy mixes and active in dry mixtures. Gamma globulin were active only in the fresh pasteurized milk, i.e. with minimal heat treatment.
Crawford [60]using double oral test passive transfer of hypersensitivity, has established that the thermal denaturation of liquid or powdered infant formula before their use significantly reduces the allergenic properties of beta-lactoglobulin, alpha-lactalbumin, but does not change the properties of alpha-casein. On the other hand, reception pasteurized milk (skim or homogenized) often led to the emergence of reactions on the sites passively sensitised to the three specified protein fractions: alpha-casein, beta-lactoglobulin, or alpha-lactalbumin.
Crawford and Grogan [37] using the method of double diffusion gel rabbit anticorodal found that denaturirovannogo heating milk completely lost their ability to react with anticorodal against the alpha-lactalbumin, and its activity in relation to antisyware against Alfa-casein and beta-lactoglobulin sharply declined. Along with this Nagel et al. [61], researching sensitive to milk patients positive for raw milk proteins, found that the skin reaction has fallen slightly, when tried out with cooked whole cow's milk, casein, beta-lactoglobulin, or alpha-lactalbumin.
Based on the above data, it can be argued that the thermal denaturation of cow's milk does not lead to the loss of the allergenic properties of proteins. Apparently, the sick, the only susceptible to temperature-sensitive protein fractions such as serum albumin or gamma-globulin, it is most expedient to use the boiled milk. In table. 4 summarizes the properties of the major protein fractions of milk.
Antigenicity of casein after trypsin digestion becomes much lower than before treatment; these data were obtained on Guinea methods of passive cutaneous anaphylaxis and inhibition reaction precipitation [62]. Change antigenic properties of casein was confirmed also by the fact that the title of hemagglutinin to the casein content in the blood serum of children receiving milk with hydrolyzed casein, was lower than at feeding ordinary infant formula [63]. It should be noted that in rare cases allergens are not native, namely digested proteins of milk [64].
In 1911 it was noted that UV irradiation reduces the antigenic properties of proteins [65]. Later it was determined that gamma rays are even more effective in this respect, but is not as effective as the heating [37, 53]. Samples of raw skimmed milk processed by radiation 5, 58 and 9.30 Mrad (55 800 and 93 000 Gr), had the same antigenic activity as milk after heating for 35 to 77 C and 89 C, correspondingly [53].