View this article in RussianYear by year more and more refrigeration enterprises prefer to manufacture frozen food. This fact is due to, first, because frozen products have a long period of storage. Secondly, they retain chemical composition and organoleptic characteristics without essential changes after freezing, and thirdly, low-temperature processing is ecologically secure.
Besides last two aspects have more relation to the technology of freezing by liquefied and compressed inert gases.
The methods of freezing of food products are represented in figure 1.
Figure 1. Methods of freezing of food products
Common freezing ways are characterized by less security, and by less quality of products because of forming of bigger ice crystals. However common freezing ways consumes less energy and can be applied for freezing of lumpy raw materials (for example, meat blocks, meat half-blocks, meat quarters, and fish in blocks). Ways of freezing have been represented in the right part of figure 1, are usually applied for freezing of small-sized and crushed raw materials. This fact is due to usage of liquefied and compressed inert gases (in the next just “liquefied gases”), which are manufactured from atmosphere air using special stationary gas-liquid machine, which cuts much costs of manufacture of liquefied gases.
The refrigeration technology of food products doesn’t restricted by just application of freezing technology. Also different ways cryoprocessing has the wide spreading in other ways of different manufacture.
The perspective methods of cryoprocessing have been represented in figure 2.
Figure 2. Perspective methods of cryoprocessing
The represented methods of cryoseparation (fig. 2) are related to cryoprocessing with some exaggeration. The air-cryoseparation is directly related to cryoprocessing (because there are cryotemperature or a liquid gas is used), and the other ways of cryoseparation conditionally are related to cryoprocessing. They are called like that just because the separation technology uses cryofrozen products as raw materials. For example, Russian scientists have [1] developed methods of cryocrushing and of cryoseparation, which temperatures are being maintained in the range of -25 °С till -100 °С.
In the difference of cryoseparation, ways of cryocrushing are classified by the application of a type of milling machine with the difference of dispersion of finish product. The current ambiguity of the concept “cryoprocessing” causes frequent disputes about an ability of its application as a scientific term. Some scientists prefer to attribute to cryoprocessing the processes are being made at the temperature of liquid nitrogen (-196 °С), others scientists – on the base of usage of liquefied gases (despite the temperature of carbon dioxide is not lower of -78 °С), and else some scientists – on the base of separation on moderate low (till -120 °С) and cryo- (the temperature is lower -120 °С). It’s necessary to note that the term “cryoscopic temperature” hasn’t anything general with cryotemperatures. Authors prefer to attitude to cryoprocessing technology the next: when liquefied gases with cryotemperature are used (including carbon dioxide with the condition that its temperature is not higher than -72…-78 °C) and in usage of other refrigerants with temperature is lower than -120 °С (for example, when the low-temperature air is used).
The following text contents the most perspective technologies, which can improve the refrigeration technology of food products.
Considering exist tendency, the volume of frozen food products manufacture will be growing in the future. It’s necessary to note that the market of frozen food has not sufficiently satisfies the need in season fruits, many of which are cryolabile and that’s why they need in application of cryoprotectants. Authors’ research allows to decrease the essential loss of products’ quality [2]. The manufacture of frozen salads from small-chopped or cryocrushed (dispersion 5…10 mm) fruits is perspective, as well. The manufacture of such fruit salads could to enrich the ration of nutrition of people by micro- and macro-elements, also to use frozen cryocrushed fruits in manufacture, for example, of milk and milk-confectionery food, that would allow to increase their the nutrition value and organoleptic characteristics.
At present the improvement of refrigeration technologies is separated from improvement of refrigerator techniques (that, possible, due to a great diversity of non-type projects of technological lines of frozen food manufacture and due to a great competition in the market of refrigeration technique). In our opinion, it is due to the high manufacturability and the technical value of refrigeration technique, which allows to improve the quality of finished products considerably and to decrease self-cost.
The cryomolding technology is left a non-sufficient attention of food enterprises. Cryomolding technology allows to manufacture semi-finished products with better outer form, better taste and aromatic characteristics, that again proves a high efficiency of application of low temperature from the viewpoint of quality of food products. It is perspective to apply the cryomolding technology for the processing of meat and meat-vegetative raw materials. This technology is not more difficult than cryofreezing.
The proposed technological process of cryomolding has been represented in figure 3.
Figure 3. The technological process of cryomolding
The application of high pressure for pressing and molding stages can prevent formation of crystals (solid phase of water). It is known that a great growth of local pressure can activate the increase the viscosity of water and decrease the cryoscopic temperature. Therefore being decreased pressure allows to form small crystals.
Excepting perspective low temperature technologies, the refrigeration storage is also perspective scientific direction. The manufacturing plants and depots for the storage apply Modified Atmosphere Packaging (MAP) and Regulated Atmosphere Packaging (RAP) which require high energy costs and a long creation of storage regime (from 6 to 48 hours depending from the volume of storage room and the composition of modified environment). Refrigeration storage doesn’t have these lacks.
Thus the refrigeration technologies of food products in the modern stage of manufacture have a great potential of development because there is a tendency of increasing of manufacture volumes and of frozen food consumption. That is due to, first, high quality of frozen food, second, the decrease of the consumption of genetically modified products and products which manufacture is based on the application of harmful preserving agents.
References
- Rogov I.A., Babakin B.S., Fatykhov U.A. The cryoseparation technology of raw materials of biologically origin. – Monograph, Russia, Ryazan, Nashe Vremya Publisher, 2005, 288 p.
- Syazin I.E. The Improvement of cryopreservation and cryoseparation technologies. – Abstract of dissertation for first level of postgraduate degree, Russia, Krasnodar, 2013, 23 p.
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