Foamy structure

When air mixes up with a liquid theoretically receive foam. For the frozen desserts, such as ice cream, fats and particles of fat are very important for reception of the necessary foamy structure. A degree of hardening of fat together with quality of foam influence a consistence, taste and stability at storage of ice-cream, and also cause its properties at fusion.

   In a mix some destabilization of fat and its hardening of fat is necessary for change of structure of foam. The optimum foamy structure turns out in that case when the necessary level to watch the fat is reached.

   Yet up to the end it is clear, how passes process of destabilization of fat in freezer, but it is possible, that at passage through freezer the further proceeds desorbtion of proteins to which fatty balls are exposed during maturing. Except for it, as a result of intensive mechanical influence the most part of membranes of fatty balls collapses and are released particles of fat. It conducts to step growth of water repellency of all fatty phase. Also some of liquid fat at the same time is released Propensity of fat to agglomeration and formation of clod thus is shown, that in part is called as a phenomenon of hardening of fat. Lumps of fat push away water and take a boundary position between water and air and by that form stabilizing membrane around air bubbles. The foamy structure thus is created.

   As a whole it is possible to tell, that destabilization of fat in steps can be varied from absolutely small up to extreme. As a result of it on any other business it is shown agglomeration of fats: it or is not present absolutely or it can result in formation of fatty lumps which stabilize foamy structure, and down to occurrence large clods, similar to slices of oil. The foamy structure can be from soft up to dense. The Fig. 5 serves as a simple illustration to this.

   Various factors can influence process of hardening of fat in freezer, thus this process is affected with the following moments:


   As it was marked earlier, monohlycerides increase a degree desorbtion a protein with particles of fat during maturing ice cream. If in ice-cream would not be monohlycerides would not be and desorbtion of proteins, particles of fat would be too stable and there would be no agglomeration during process of freezing. Due to entering of 0,3-0,4 % monohlycerides for 10 % ice cream can be achieved perfect conditions for process of hardening of fat. Because of too high dosage monohlycerides is too strongly pronounced effect of stabilization and hardening of fat can arise.


   The contents of fat also is important for process of its hardening. As against monohlycerides fats do not play the important role at destabilization of fats. It is a question concerning concentration in a product. If the contents of fat in ice-cream raises, the average distance between fatty balls becomes less, that conducts to their more often collision in time of freeze. Thus process of agglomeration is expressed more brightly.

   Temperature on output from freezer

   The below the temperature on output is more formed crystals of ice. Mechanical friction in a mix raises, that results in the greater destabilization of fats and destruction of fats of balls. Except for it concentration of fatty balls in the stayed liquid phase raises also, that besides results in a congestion of fatty balls.

   Thus higher temperature on output from freezer causes smaller quantity of crystals of ice, smaller agglomeration of fat and provides foamy stability. At low temperatures on output more crystals of ice and process of hardening of fat are formed is more active. (Fig. 6).

   Naturally, for each kind of ice cream there is an appropriate degree of hardening of fat (destabilization of fat or agglomeration of fat). Sometimes it is impossible to achieve optimum effect, as industrial conditions are not ideal. At strong hardening fat there is one more effect which consists that destabilization of fat comes too far that results in transformation of separate phases, on knifes, in pipelines, in corners extruder are marked oil stratifications. Table 2 illustrates influence of various conditions on effect of hardening of fat in ice cream.

   Sometimes for the research works, process of measurement of a degree of hardening of fat is interesting, that it is possible for the several reasons. Sometimes it is possible to measure chloroform in extruded parts of fat in the fused ice-cream (Stistrap and Andreasen, 1962) to define quantity of agglomerated fat. Except for it, it is possible to define size of fatty agglomerations under a microscope or with the help of the electronic device for the account of particles.

   Temper of ice cream

   When ice cream leaves from freezer and is packed up, it only has in part frozen. In dependence from type of ice cream the quantity of water varies between 30 and 60 %. The further process of freezing during which about 85 % of crystals are formed, name temper. It occurs at once after output of ice cream from freezer.

   At temper it is necessary to achieve temperature of-20 degrees in the center of ice cream. The faster this temperature will be achieved, the there will be a distribution of crystals in regular more intervals and it is better quality of ice cream.

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