Analysis of Shrinkage Phenomena in the Process of Cheese Vacuum Drying

The work is devoted to the study of the shrinkage phenomena during the vacuum dehydration of the cheese varieties “Sovetskiy” and “Gollandskiy”. During the research, the dependences of the cheese shrinkage coefficient on the initial mass fraction of moisture were obtained. It was found that when the mass fraction of the cheese moisture increases, an increase in the shrinkage coefficient of the product occurs. The greatest increase in the cheese shrinkage coefficient is observed when the mass fraction of moisture is more than 50%. It was established that with increasing temperature and heat load, the moisture content on the cheese surface rapidly decreases, while in the central layers it changes more slowly. Shrinkage at elevated temperatures is less; however, dry cheese has a large mass fraction of moisture. It was found that an increase in the difference in the mass fraction of moisture between the inner and surface layers is accompanied by an increase in the difference between the actual shrinkage and possible shrinkage corresponding to the amount of liquid removed. The coefficients of shrinkage in the volume of the “Sovetskiy” and “Gollandskiy” cheese varieties were calculated: they lie in the range of 0.017–0.004 and 0.006–0.003, respectively. The dependences of the cheese shrinkage coefficients on the drying layer thickness, shape and size of grinding were obtained. Keywords: cheeses, vacuum drying, shrinkage

Analysis of the cheese components’ influence on the dehydration process under reduced pressure

This work is aimed at studying the influence of various components’ content on the process of vacuum dehydration. It was found that with an increase in the proportion of fat in dry matter from 10 to 20 %, the duration of disinfection increases by 4 %. The further grows of the fat proportion from 20 to 50 increases the process duration by 54 %. It was revealed, when cheeses, with the fat proportion equal from 10 to 50 %, a change their fat proportion by 1 %, the duration of dehydration decreases by 4.25 minutes, and the drying rate grows by 0.0065 %/min. It has been discovered that with an increase in the table salt concentration with the same mass fraction of cheese moisture 53–55 %, a decrease in the rate of dehydration is observed as well. In the period with a constant drying rate at a concentration of sodium chloride of 1 %, the drying speed is 0.98 %/min; 2 % – 0.8 %/min; 3 % – 0.72 %/min; 4 % – 0.54 %/min. The amount of water activity in cheeses was investigated. It was established that with an increase in the concentration of table salt from 1 to 4 %, the water activity of cheese before drying changes by 0.131; after drying – by 0.174.