SU1712749A1 - Method of refrigerated processing of piece foodstuff - Google Patents

Abstract

The invention relates to refrigeration technology, and specifically to methods for cooling meat in half carcasses. The purpose of the invention is to reduce shrinkage of food during refrigeration processing. The method involves supplying a cooled stream of air to flushing the product, taking away after washing the product of a warmed and humidified stream of air, dividing into two streams, directing one of them to cooling and the other to mixing. During the cooling process in a mixed flow, the amount of heated and humidified air is maintained between 0.35 and 0.5 cooled air flow to set the temperature of the mixed flow below the dew point temperature. 1 il.sls

Description

The invention relates to refrigeration technology, and specifically to methods for cooling meat in half carcasses.

. The purpose of the invention is to reduce shrinkage. food during refrigerated processing.

The goal is achieved in that the method provides for the supply of a cooled air flow to the washing of the product, the intake after washing the product of the heated and humidified air flow, separation into two streams, the direction of one of them to cooling, and the other to mixing. During the cooling process in the mixed flow, the amount of heated and humidified air is maintained within 0.35-0.5, the cooled air flow to set the temperature of the mixed flow below the dew point temperature.

When mixing the cooled and dried air flow with warm and humidified due to heat and mass exchange with a piece food product within 0.35 - 0.5, when the temperature of the mixed stream becomes lower than the dew point temperature of this stream, and when this stream is fed to the washing of the food product, mass transfer between the food product and the air flow decreases sharply, and the heat exchange increases or maintains its value.

Thus, as a result of mixing the flows of cold and warm and humidified air at the specified ratio, when the temperature of the mixed flow is below the dew point temperature, the relative humidity in the volume of the mixed flow will be 100%. Moreover, the volume will release moisture in the form of a dispersed ice medium or water droplets due to the preservation of the absolute humidity of the flows.

The drawing schematically shows a device for carrying out the method of refrigerating processing of piece food products.

The device contains air cooler 1 with fan, cold air supply duct 2, fan 3, heated and humidified air supply duct 4, mixed air flow supply duct 5, mixed air flow supply nozzle 6, mixed air flow nozzle 6, suspension path 8, nozzle 9 uniform intake of warm and humid air, separation duct 10 with a flap 11,

The method is carried out as follows.

The piece food product 7 is loaded onto the suspension path 8 and air cooler 1 with a fan and fan 3 is put into operation. A pressure gradient forms between the nozzle 6 for supplying the mixed air flow and the nozzle 9 for the heated and humidified air, which results in washing the food 7 air flow from the bottom up (in figure 1 is shown by arrows).

The wash is warm relative to the temperature of the supplied air stream, a piece food product (for example, half-carcasses), the air is moistened and warm, taking heat from the product 7. This warm and humid air through the air inlet 9, which has an air distribution grille, which has a living cross section of 15 % enters the separation duct 10, where it is divided into two streams by means of the valve 11. One stream enters the air cooler 1 with a fan., The second - into the fan 3. The flow rate is regulated, for example, by changing the number of revolutions of the electric motors, the air cooler fan 1 and the fan 3, as well as the change in the position of the valve 11. When passing through the air cooler 1 The warm and humid air flow is cooled, reducing its enthalpy, absolute and relative moisture content. At the same time, the second flow passes through the fan 3, keeping the temperature and humidity. This second stream receives additional kinetic energy. After passing through air cooler 1 and

the fan 3 flows through the air ducts 2 and 4, respectively, of the supply of cold air and the heated and humidified air enter the duct 5 of the mixed air flow, where they are mixed. In the course of cooling in a mixed flow, the amount of heated and humidified air varies from 0.35 to 0.5 of the air flow supplied to the cooling in order to set the temperature of the mixed flow below the dew point temperature, i.e. so that the water vapors in the air completely saturate it and condense in the mixed flow itself, create a kind of mist.

The invention is illustrated by the following examples.

PRI me R 1. Freezing of half-carcasses weighing 85 kg, having a heat content of 360 kJ / kg, to a heat content of 10 kJ / kg, i.e. cooling from 37 to 8 ° С. The freezing time was 20 hours. The average temperature of the air flow coming from the air cooler per cycle is -25 ° C, and the degree of saturation is 96%. The average temperature of the air entering the cycle at the air cooler is -20 ° C, the temperature at the surface of the air-cooler pipes is -40 ° C.

The heat transfer coefficient between the finned tube air cooler and the air flow according to experimental data is equal to 8, the average temperature difference was 5 ° C.

The amount of heat (Q) that must be removed from the side to reduce its enthalpy to 10 kJ / kg

Q (11 - i2) m (360 -10) -85 29750 kJ.

The required mass of pumped air (mi) to remove this heat (external heat gains were practically absent).

Q with -mi-At,

from where

Q29750 sang

   kg

mi

The density of the air is 1.4 kg / m, the total volume of air (Q) required to remove heat is

0 - - 4250mZ

Volumetric flow rate of the cooled air pumped through the air cooler, based on the fact that in 20 hours (72000 s) it is necessary to pump 4250

0 (ji -l2) mi

M

with at At-T

T

4250

m

"" 0.6 72000

EXAMPLE 2. The half-carcass was frozen on the proposed device with an estimated air flow rate of 216 and the fan 3 turned off. The freezing time was 20.5 hours, shrinkage 1.72%.

EXAMPLE 3. The half-carcass was frozen at a flow rate of cooled air 216, with an average inlet temperature of 20 ° C and exit from the air cooler 1-25 ° C, and also with a change in air flow through fan 3 to 75, 6 m / h per cycle to set the temperature of the mixed stream below the dew point temperature by 0.5 ° C. The freezing time was 20.3 h, the shrinkage was 0.81% (75.6 was 0.35 of 216 m / h).

EXAMPLE 4. The half-carcass was frozen as in Example 2, but with a change in air flow through fan 3 to 108 per cycle in order to set the mixed temperature, the flow below the dew point temperature of this flow is not less than 0.5 ° C. The freezing time was 20 hours, shrinkage was 0.79% (108 was 0.5 of 216).

In all experiments, the half carcass was selected by weight in the order of 84.5 - 85.5 kg.

EXAMPLE 5 Freezing was carried out as in Example 2, but with a change in air flow through fan 3 to 64.8 m / h per cycle. As a result of the experiment, the drying was 1.12%, the freezing time was 20, 4 hours (64.8 is 0.3 of 216).

EXAMPLE 6. Freezing was carried out as in Example 2, but with a change in the air flow through fan 3 to 118.8 per cycle. The freezing time was 20 hours. A shrinkage was 1.09% (118.8 was 0.55 out of 216 m / h).

five

The expected economic effect from the introduction of the proposed invention according to preliminary estimates for only one cell with a capacity of 50 tons will be 12 thousand rubles. in year.

0

Claims (1)

Formula of the Invention A method of refrigerating processing of piece food products, which involves cooling the air, mixing it with 5 with air heated and humidified after washing the product in the chamber, supplying the mixed flow to the product, taking air from the chamber, dividing it into two streams, directing one of them to cooling, 0 and another for mixing, characterized in that, in order to reduce food drying during refrigeration, the amount of warm and humidified air in the mixed stream is maintained between 0.35 and 0.5 cooled air flow during cooling in order to set the temperature of the mixed flow below the dew point. (X) Z 2 / / / Mhj