RU2565088C1 - Method for manufacture of dried quince - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: dried quince production method involves raw material inspection, sorting, washing, cutting and subjecting to UHF-convective drying. Drying is performed with UHF-heating power equal to 800 W and with convective blowing with air having temperature equal to 293 K in three stages. At the first stage, quinces cut into 10×10×10 mm cubes are heated with UHF field during 3 minutes with simultaneous blowing at an air flow rate equal to 1.5 m/s. At the second temporal stage, the quince cubes are heated with UHF field with simultaneous blowing at an air flow rate equal to 0.9 m/s during 15 minutes. At the second temporal stage, the quince cubes are heated with UHF field with simultaneous blowing at an air flow rate equal to 0.3 m/s during 40 minutes.

EFFECT: invention allows to obtain high quality dried quince with dry content of valuable thermolabile substances, enhance the process heat efficiency, reduce energy- and labour expenditures due to usage of staged modes of UHF-convective drying.

1 dwg, 1 tbl

Description

The invention relates to the food industry, in particular to the technology of fruit processing, and can be used for the production of dried quince.

A known method of producing a food product from quince [US Pat. RF 2500190, IPC A23L 1/212. Method for the production of food product from quince [Text] / O.I. Kvasenkov; applicant and patent holder O.I. Kvasenkov. - No. 2012136324/10; declared 08/27/2012; publ. 12/10/2013], including preparing quince fruits, cutting them, convective drying to intermediate humidity, drying in the microwave field until the solids content is at least 85%.

The disadvantage of this method are: the low quality of the finished product, the duration of the drying process and high specific energy consumption.

An object of the invention is to improve the quality of the finished product and increase the thermal efficiency of the drying process through the use of a stepped regime of microwave convective drying of quince, reducing energy costs and reducing the cost of obtaining the finished product, intensification of the drying process.

The object of the invention is achieved by the fact that in the proposed method for the production of dried quince, including inspection of raw materials, sorting, washing, cutting raw materials, microwave convective drying, it is new that drying is carried out with a microwave heating power of 800 W and convective air blowing with at a temperature of 293 K in three stages: at the first stage, the quince, cut into cubes with a size of 10 × 10 × 10 mm, is heated by the microwave field for 3 minutes while being blown with air at a speed of 1.5 m / s, at the second time stage, the quinces are heatedHF field for 15 minutes while blowing air stream with a velocity of 0.9 m / s, at a third time step quince cubes was heated by a microwave field for 40 minutes while blowing air stream with a velocity of 0.3 m / s.

The technical result of the invention is to improve the quality of the finished product through the use of stepwise modes of combined microwave convective drying of quince, increasing thermal efficiency and intensification of the drying process, in reducing energy consumption for obtaining the finished product.

In FIG. Figure 1 shows the kinetic laws of the stepped regime of combined microwave convective drying of quince: a (1) is the drying curve and a (2) is the drying speed curve; b - temperature curve; in - thermogram.

Fresh quince coming into processing, in terms of quality, must meet the technical conditions of GOST 21715-76 and meet the following requirements:

in appearance: selected fruits typical for a given pomological variety, uniform in color, without damage by pests and diseases, without damage to the skin of the fruit at the points of attachment to the fruit stem;

by maturity - fruits are uniform in maturity, but not lower than removable;

according to the size of the largest transverse diameter, not less than 70 mm.

The initial quince should be fresh, healthy, of a suitable color, with a high content of pectin, organic acids and dry soluble substances.

A method of manufacturing dried quince is as follows.

Quince fruits are washed in a fan washer. For more intensive washing of contaminated fruits in the washing tub of the machine, drilling is created by means of compressed air supplied to the perforated pipes. The washed fruits from the washing bath are moved by an inclined conveyor, in the upper part of which they are rinsed with water from the shower unit. When processing heavily contaminated fruits, you can increase the time they spend in the washing area by occasionally stopping the conveyor.

Then the washed quince is subjected to inspection and sorting, which is carried out manually on a sorting and inspection conveyor. Simultaneously with sorting, an inspection of raw materials is carried out, in which defective specimens (rotten, damaged, broken, moldy, heavily contaminated), foreign impurities and objects are removed.

Then, the treated quince is cut into cubes with linear dimensions of 10 × 10 × 10 mm. Sliced quince in cubes larger than 10 mm, for example 15 mm, significantly increases the drying time and reduces the productivity of the line. Sliced quince in cubes smaller than 10 mm, for example 5 mm, leads to severe shrinkage, which will ruin the presentation of the product.

Then chopped quince cubes are subjected to combined microwave convective drying. Moreover, quince cubes are heated at a microwave heating power of 800 W and with simultaneous convective air blowing with an initial temperature of 293 K in three time stages.

The choice of microwave power equal to 800 watts is due to the fact that if the microwave power is more than 800 watts, for example 1000 watts, the product will burn. If the field power is less than 800 W, for example 600 W, then the drying time will be increased and the line productivity will decrease.

Chopped quince cubes are blown with air with an initial temperature of 293 K to remove water vapor evaporated from the product.

The choice of the initial air temperature of 293 K is due to the fact that air is taken from industrial premises, in which, as a rule, this temperature is maintained.

The use of air as a heat carrier with an initial temperature of more than 293 K, for example 303 K, will necessitate the installation of a heater for additional heating of the air, which may impair the quality of the finished product due to its overheating, increase the cost of production and increase the amount of capital investment due to the installation of an additional heater .

The use of air with an initial temperature of less than 293 K, for example, 283 K, necessitates the installation of cooling devices for additional air cooling, which during microwave drying can cause unnecessary excessive cooling of the product and lead to an increase in energy consumption and an increase in the cost of production.

The essence of the choice of stepwise modes of combined microwave convective drying of quince consists in dividing the drying process into three stages of different duration, at each of which, depending on the law of change of current quince humidity, its rational technological drying mode is selected, i.e. The temperature of heating quince cubes with a microwave field and blowing them at a coolant velocity (air flow with an initial temperature of 293 K) assumed fixed values, the values of which were determined experimentally. Moreover, their selection at each stage must be carried out in accordance with the restrictions imposed by technological requirements on the quality of the finished product.

At the first time stage, the cut quince cubes with dimensions of 10 × 10 × 10 mm are heated with a microwave field for 3 minutes, while at the same time blowing with an air stream at a speed of 1.5 m / s (Fig. 1). In this case, physical and mechanical moisture is removed, i.e. moisture micro- and macrocapillaries, and wetting moisture. The main parameter affecting the intensity of moisture removal during this period is the coolant speed. Therefore, it is most advisable to use drying at the initial moment of drying with a high coolant velocity and a low heating temperature of the product. Drying at the first stage most fully meets this requirement.

Blowing the product with air flow at a speed of less than 1.5 m / s, for example 1 m / s, will reduce the efficiency of removal of evaporated water vapor, and therefore, reduce the efficiency of heat and mass transfer of the drying process. Blowing the product with air at a speed greater than 1.5 m / s, for example 2 m / s, will lead to overdrying of the surface layers of quince, the formation of a crust on the surface of quince, which will complicate the removal of evaporated moisture.

The duration of the first time step (3 min) was determined experimentally by analyzing the obtained drying curves. Using a longer duration of the first time step, for example 5 min, will lead to overdrying of the surface layers of quince and the difficulty of removing moisture contained in the central layers of quince. Using a shorter duration of the first time step, for example 1 min, will result in the fact that not all physico-mechanical moisture will be removed from the quince, which will entail an increase in the duration of the subsequent temporary stages of drying and a deterioration in the quality of the finished dried quince.

At the second time stage, pre-dried quince cubes are heated by the microwave field while blowing air at a speed of 0.9 m / s (Fig. 1). The duration of the second stage is 15 minutes. With the removal of physical and mechanical moisture, the velocity of the coolant, as a determining factor in the intensity of the process, loses its significance. Therefore, in the second stage, it is preferable to carry out drying at a decreasing speed and increasing temperature of the coolant. Blowing the product with an air stream at a speed of less than 0.9 m / s, for example 0.6 m / s, will not ensure the complete removal of evaporated water vapor, and therefore, will reduce the efficiency of heat and mass transfer of the drying process. Blowing the product with air flow at a speed greater than 0.9 m / s, for example 1 m / s, will lead to overdrying of the quince surface and the formation of a crust on the quince surface, which will complicate the removal of evaporated moisture.

The duration of the second time step (15 min) was determined experimentally as a result of the analysis of the obtained drying curves. Using a longer duration of the second time step, for example 20 minutes, will lead to overdrying of the surface layers of quince and the difficulty of removing moisture contained in the central layers of quince. Using a shorter duration of the second time stage, for example 10 minutes, will lead to the fact that not all osmotic moisture will be removed from quince, which will entail an increase in the duration of subsequent temporary stages of drying and a deterioration in the quality of the finished product.

At the third time stage, pre-dried quince cubes are heated with a 800 W microwave field while simultaneously being blown with an air stream at a speed of 0.3 m / s (Fig. 1) for 40 minutes. As the osmotic moisture is removed, the velocity of the coolant, as a determining factor in the intensity of the process, loses its importance, due to the fact that temperature as the factor determining the intensity of internal moisture transfer has the greatest influence on the intensity of removal of polyadsorption moisture.

Blowing the product with an air stream at a speed of less than 0.3 m / s, for example 0.2 m / s, will not ensure the complete removal of evaporated water vapor, and therefore, will reduce the efficiency of heat and mass transfer of the drying process. Blowing the product with air flow at a speed greater than 0.3 m / s, for example 0.5 m / s, will lead to overdrying of the quince surface layers and the formation of a crust on the quince surface, which will complicate the removal of evaporated moisture.

The duration of the third time step (40 min) was determined experimentally as a result of the analysis of the obtained drying curves. Using a longer duration of the third time step, for example, 50 minutes, will lead to overdrying of the quince surface layers and make it difficult to remove moisture contained in the quince central layers. Using a shorter duration of the third time stage, for example, 35 minutes, will lead to the fact that not all polyadsorption moisture will be removed from quince, which will entail an increase in the duration of subsequent temporary stages of drying and a deterioration in the quality of the finished product.

The moisture content of the dried product is 23% according to GOST 28502-90. Adapted in accordance with the basic kinetic laws of the drying process, the coolant supply at the three stages of drying the product allows you to choose rational drying modes taking into account changes in the moisture content of the product during the drying process. The table shows the chemical composition of the original quince and dried quince cubes according to the proposed three-stage drying method.

The production method of dried quince is illustrated by the following example.

Quinces are washed in a washer. Then washed quince is subjected to inspection and sorting, which is carried out manually on the sorting and inspection conveyor. Next, quince is cut into cubes 10 × 10 × 10 mm in size. Then, the quince cubes cut are subjected to combined microwave convective drying, the quince is heated by a microwave field with a power of 800 W while air blowing with an initial temperature of 293 K in three time steps.

At the first time stage, the quince cut into cubes is heated by the microwave field for 3 minutes while at the same time being air-blown at a speed of 1.5 m / s for 3 minutes. In this case, physical and mechanical moisture is removed, i.e. moisture micro- and macrocapillaries, and wetting moisture.

At the second time stage, the pre-dried quince cubes are heated with a microwave field while air-blown at a speed of 0.9 m / s for 15 minutes. In this case, osmotic (intracellular) moisture is removed.

At the third time stage, quince cubes are heated with a microwave field while blowing air at a speed of 0.3 m / s. The duration of the third stage is 40 minutes. At the same time, poly- and monoadsorption moisture is removed from quince.

Analysis of the data given in the table shows that dried quince has a high content of valuable nutrient thermolabile substances. This indicates the correct choice of soft, gentle temperature-hydrodynamic drying regimes. Such processing of quince allows to increase the energy efficiency of the process, reduce the drying time of quince and increase its quality.

Thus, the use of the proposed method for the production of dried quince allows you to:

- receive dried quince of high quality with a high content of valuable thermolabile substances (vitamins, monosugar, amino acids, etc.);

- increase the thermal efficiency of the process;

- reduce energy and labor costs for the production of dried quince due to the use of stepwise modes of microwave convective drying;

- reduce the cost.

Claims (1)

Method for the production of dried quince, including inspection of raw materials, sorting, washing, cutting raw materials, microwave convective drying, characterized in that the drying is carried out with a microwave heating power of 800 W and convective air blowing at a temperature of 293 K in three stages: in the first stage, cut with 10 × 10 × 10 mm cubes, the quince is heated by the microwave field for 3 minutes while blowing air at a speed of 1.5 m / s, at the second time stage, the quinces are heated by the microwave field while blowing with the air flow at a speed of 0 9 m / s for 15 minutes, at the third time stage, quince cubes are heated with a microwave field while blowing air at a speed of 0.3 m / s for 40 minutes.

Images