Development of new methods and systems for control of physical properties of dairy products is a promising trend in the food industry. Using new methods of control improves product quality and helps to reduce manual labor at dairy plants. The aim of this study was to develop a methodology for monitoring of milk coagulation with combined infrared koagulograph. Whole unpasteurized milk was the object of our study. Chymosin solution with activity of 8,000 units under the CHY_MAX trademark was used as a coagulant. To control the process of rennet coagulation we used a combined nephelometer-turbidimeter of our own design. The technique of coagulation monitoring is based on receiving turbidimetric and nephelometric data from multiple optical sensors operating in the near infrared region of the spectrum. Data were recorded using a laboratory complex based on universal multichannel ZET210 data collection device. The flux data from the sensors were recorded in the database and displayed using the applied KoaguMilk software of our own design. Possible photocell set for the coagulograph is also described in the paper. As a demonstration of the method possibilities the dependence of coagulation on chymosin concentration has been analysed. The data on the effect of the rennet concentration on coagulation rate obtained under this study are found to be corresponding to the conventional data. This proves applied effectiveness of our optical method for milk clot structuring under the rennet coagulation. We obtained diagrams for dependence of the IR radiation flow on time under the rennet coagulation, showing a decrease in the degree of flux transmission in direct and sidewise scattering and increase in backscattering at the active stage of milk coagulation.

From the technological point of view, one of urgent problems is the study of milk coagulation for samples containing a close to natural amount of fat. This paper is devoted to theoretical and experimental study of flocculation and gelation processes in model samples of reconstituted milk containing different amounts of casein (2.5% and 5% by weight) and fat (0%, 2.5% and 5% by weight). Experimental study of the viscoelastic properties of milk clot during its formation was made with a dynamic rheometer of our own design characterized by reciprocal translational displacement of the cell relative to the stationary probe. A simplified kinetic mod el of the clot formation process is developed. Flocculation stage of this process is described as growth of fractal aggregates with fractal dimension D = 2.22. In this case, the average size of the aggregates increases faster than the average distance between them, and if the initial concentration of the casein micelles is sufficient, the system reaches percolation stage, i.e. formation of continuum gel. The next stage is strengthening of the clot due to formation of additional bonds. Based on the proposed model the presence of min imum micelle concentration for gelation is explained. A possible explanation for the proportionality of the elastic modulus and th e loss modulus for gel network is suggested. It is found that decreasing the micelle concentration leads to the lowering of the number of additional bonds per unit volume at the clot formation stage and proportional decrease of the clot strength. For example, at any fat concentration the clot strength wherein the initial micelle concentration twice as much is approximately two times higher. The fat concentration increase also leads to the increase in the clot strength both by reducing the volume available to micelles and by increasing the stiffness of the casein chains due to decreasing of their lengths. In addition, protein-coated fat globule surfaces may seem to become the seed centers for flocculation and the formation of additional bonds, thereby increasing the rates of these processes.

A device for investigation of rheologic properties of viscoelastic foodstuff media is developed. The device combines advantages of such devices as Formograph and dynamic rheometer, allowing both to define the gelation time and to estimate relations between viscous and elastic properties of foodstuff media.

Temperature dependence of reconstituted skim milk coagulation on its initial acidity and concentration of calcium ions is investigated. It is shown that the temperature of milk coagulation decreases with increase of both milk acidity, and ionised calcium concentration in milk. Moreover, there is a possibility to change the temperature of milk coagulation by simultaneous variation of both specified parameters.On the basis of the experimental data some hypotheses are formulated and the physical and chemical model is offered describing heat-acid and heat-calcium milk coagulation within the limits of the uniform scheme.

Based on the hypothesis of an additional electrostatic stabilization of the colloidal caseinate-calcium-phosphate complex of milk with a lack in the activity of calcium ions, the method of magnesium enrichment of milk proteins during their coagulation is proposed. The fact of the transition of magnesium ions added to the milk with a low concentration of calcium ions into the milk clot during rennet coagulation is experimentally confirmed. The possibility of enrichment of milk clot with other metal ions, for example with iron, is considered.

The research deals with the influence of vegetable filler dose, fat content in the product and the mass melting point on the product flavor and taste, its texture and penetration firmness. The possibility of using vegetable raw-material in the processed cheese product manufacture is shown. It imparts specific flavor, good texture and original color to the product. The dependences of joint influence of suspension in the amount of 10-30 %, the fat content in the product solid (20-60 %), the mass melting point (70-90 oC) on the product flavor, consistence and penetration firmness were studied. The suitable regression equations were obtained.

Basing on analysis of experimental data the model defining contribution of calcium ions into colloid stability of casein micelles in milk is proposed. The algorithm is developed for quantitative calculation of the beginning of flocculation in the micellar system.