Effects of the ultra-jet and laser treatments on contamination of raw milk

Two new methods of treating raw milk: the ultra-jet one and application of laser and their impacts on the raw milk contamination were studied. Treatment of raw milk by the ultra-jet technology and by laser actually is not applied, and scientific research of the item is needed. The authors carried out investigations of the bactericide effect on the hydro-technological media after ultra-jet treatment. The bactericide-sterilzing effect of the ultra-jet treatment was proved. It was offered to use water treated in such a way on an industrial scale. The technology has been patented. The laser action leads to the appearance of dependence from the dose of irradiation in micro-organisms, changes of morphological and biochemical properties up to the loss of viability. As a result, shelf life increases and milk products quality improves. Two types of milk were applied in experimental work: the raw whole milks with fat levels 1.5 and 3.2 %, the milk taken before the treatment was used as a control. The results of the study demonstrate that both methods give reduction of the somatic cells count in milk - from 500 thousands/cm3 (initial quantity) to 300 thousands/cm3. The quantity of the mesophilic aerobic and facultative-anaerobic microorganisms became lower by two orders e.g. by 100 %. After the treatment by the methods studied the coli-bacteria were absent in 1 cm3 of milk (before the treatment - in 0.001 cm3). For extending shelf life of the raw whole milk the most optimal doses of the laser irradiation are considered to be 0.2-0.8 Mrad, that provide hundreds of thousands times reduction of contamination and at the same time do not cause changes of taste, color and odor of the milk. Irradiation with the doses of 1.0-3 Mrad together with cooling at the temperature from the 0 to -2 °C eliminates possibilities to develop in irradiated milk products for the pathogenic and toxicogenic microorganisms.

milk, laser treatment, ultrasonic treatment, microbiological contamination, inactivation of microorganisms, somatic cells