SU947596A1 - Grape drying method - Google Patents

Description

The invention relates to the technology of producing dried fruits. And can be used in fruit canning plants for drying grapes to ishmiche varieties.

Nowadays, in the main areas of production of dry grape varieties of the Sabz type, mainly solar drying of the grapes after cooking them with a 0.5% alkali solution for 23 s is used to remove a year of venting from the surface in order to speed up the drying process. After frying, a bunch of grapes are washed with water to remove alkali and laid in one bunch in specially prepared areas. In the process of drying the bunch is turned over from time to time. All these operations are performed manually. Dried years are again manually separated from the ridges. In this form, dry grapes are still HQ suitable for use due to contamination with various debris, pieces of soil and microflora. Therefore, they are sent to a plant that is specially engaged in processing dry grapes. There, the years are separated by the year-olds, removed

rubbish, pieces of earth, etc., washed, dried in dryers and packed.

The disadvantages of solar drying include high labor intensity, long process time (10-15 days), increased water consumption, dependence on weather conditions and poor quality of the finished product, since as a result of a 10-year increase in dryness, sucrose inversion occurs and accumulation of excess quantities of reducing substances. In addition, the need for .Specialized

15 land plots for Drying the grapes (for each 1000 tons of production, up to 150 hectares of land is required) is a serious obstacle to increasing the production of dry crops. In addition, the need for special factory processing of dried grapes complicates and increases the cost of its production.

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In connection with this, attempts have been repeatedly made to develop a technology for producing dry grapes, which allows for an increase in productivity, a lower cost of production.

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the finished product and at the same time improve its quality.

The known method of convective fruit, which is carried out in two stages. At the first stage (submerging), drying is carried out at 50-55 ° C for 4-5 hours, and at the second (dry) state - at BO-EO C for 152 O h 1.

This method allows to reduce the duration of the drying process and partially mechanize the process, however, it does not ensure the production of dry grapes of high quality due to the removal of sugar to the surface of the NIN and its caramelization.

The closest to the proposed technical essence and the achieved result is the method of convective drying of grapes by blowing it with air in several stages. In this method, in the first stage (sub-injection), the grapes are blown with air with a temperature of 30–35 ° C and a moisture content of 5–15 g / kg d.s. at a speed of 3.5-5 m / s for 3-4 hours and at two subsequent stages (drying), the grapes are first purged with air at a temperature of 85-90 s and a moisture content of 60-80 g / kg d.v. within 3 h to absolute humidity of grapes 20-30%, and then the air temperature and its moisture content is reduced to 515 g / kg d.s. respectively, and process the material within 1-2 hours to an absolute moisture content of the vineyard 10-12% 2.

A significant disadvantage of this method is the lack of a blanching effect at the initial stage of drying (during the basement). This leads to cracking of the years and the release of juice, which results in the loss of dry substances (sugars and various organic acids) and caramelization of sugar with the formation of a crust on the surface of the grapes, which prevents intensive drying. All this greatly affects the quality indicators of dry grapes. In addition, the isolation of juice, especially from the year of infertile varieties having a high sugar content and caramelization of sugar, causes the adhesion of the year, which often form fairly dense agglomerates that it is practically impossible to carry out the drying process.

In addition, carrying out the initial stage of drying (filling) with an air speed of 3.5–5 m / s leads to the need to use powerful Ventilation plants in one of the dryer zones, which naturally causes a considerable increase in energy consumption.

The purpose of the invention is to improve the quality of drying.

The goal is achieved by the fact that in the first stage airflow is carried out for 55-65 minutes at an air temperature of 95-105 ° C and its moisture content of 20-30 g / kg dw, then at each of the subsequent stages the air temperature is reduced by, and moisture content is increased by 510 g / kg d.s. with the duration of each stage 2-2.5 hours and with the last stage at an air temperature of 55-65 s and a moisture content of 60-65 g / kg dw.

Processing fresh air with hot air at the initial stage of drying ensures the removal of wax deposits, rapid heating of the year and the appearance of small cracks on the surface (blanching effect), which leads to a more intensive supply of moisture to the evaporation surface and accelerations of the drying process without rupture of fruit. In addition, blanching contributes to the destruction of oxidative enzymes, thereby providing better preservation of vitamin C.

. The mode of carrying out the first stage of drying is due to the following reasons.

When the air temperature is below 9 5C, simultaneously with the process of intensive moisture release (filling), the blanching process does not occur, and at a temperature above 105 ° C, the heat supply intensity exceeds the energy costs of moisture removal, resulting in overheating for a year. Air moisture content in the range of 2030 g / kg dw. provides effective holding of basement without overheating for a year and their steaming. At the time of a lower temperature treatment of less than 55 minutes, blanching does not occur with accumulation in its entire volume, and exceeding 65 minutes leads to overheating year, especially the moisture content that has material by this time, which causes a significant reduction in quality indicators. the finished product due to cracking a year and the release of juice.

A gradual decrease in air temperature and an increase in its moisture content by 5-10 g / kg d.s. every 2-2.5 hours it is necessary to prevent overheating a year, which occurs due to the intensity of internal diffusion processes and a decrease in the intensity of evaporation of moisture, which leads to caramelization of the surface and color change a year.

Decrease in air temperature to 5 55-65 s and increase its moisture content to 60-65 g / kg.sv. at the last stage of drying, it ensures the achievement of a uniform-moisture content of the product in the whole volume, and, consequently, obtaining a uniform in quality dry grapes.

The invention is illustrated by examples of experimental industrial drying of a raisin grape variety.

Example 1: White raisins are dried on a plastic belt conveyor dryer with the conveyors arranged one above the other. Grapes layer in one bunch continuously moving inclined loading conveyor is fed to the upper belt of the dryer, where high-temperature processing of the grapes with air with a temperature and moisture content of 20 g / kg s.v. and 0.6 m / s for 55 min. Visual observations have shown that, at the end of this treatment, the grapes are covered with a fine grid of cracks, which is characteristic of blanched fruit. Then at each of the subsequent stages of air temperature. reduced by, and the moisture content increased by 5-10 g / kg d.s. every 2 hours. At the last stage, the drying is carried out at an air temperature and its moisture content of 60 g / kg dw. With these parameters. Air drying is completed. The total drying time is 9 hours. Then the dried grapes on the drums are separated from the ridge and stalk and packed.

Example 2; On the same dryer, white raisin is dried in one layer

bunch. The initial air temperature is 25 g / kg r.v., the velocity is 0.6 m / s. Drying time in the first stage 60 min. After this treatment with high-temperature air, the grapes, as in the first burn, are covered with small cracks. On ka: from the subsequent stages, every 2-2.5 hours, the air temperature is lowered by, and its moisture content is increased by 5-10 g / kg s .. in. At the last stage, the following drying mode is maintained: air temperature, moisture content 62 g / kg dw. General

drying time 10 hours

Example 3. Similar results were obtained during the drying of black raisin, which is dried on the same five-dryer. The air temperature at the first stage is 105 s, the moisture content is 30 g / kg d.v., the speed is 0.6 m / s, the time is 65 min.

At subsequent stages, the drying mode is changed every 2-2.5 hours.

At the same time, the air terarature is reduced by as well. moisture content increased by 7-10 g / kg d.s. at every stage. Drying finish at air temperature and moisture content of 65 g / kg dw. The total drying time is 11 hours.

In all three examples, the dried grapes in all respects not only meets the requirements of the current GOST, but also surpassed it.

due to the higher content of CcixapOB, organic acids and vitamin C.

Data on the drying mode for the three examples described are tabulated.

Total drying time

As can be seen from the table of intensification, the finished product of high quality of the drying process can be dried.

grape varieties of grapes for 9-11 h. In addition, the proposed method

(instead of 10-15 days according to the existing, it gives the opportunity to reduce

nowadays the technology is gaining manual labor and reduce the cost price

no dry kishmish) and at the same time half-dry, as well as mechanize, and

10 h

9 h

Claims (2)

11h 94759 to automate the production process. Formula of the invention The method of drying the grapes by blowing it with air in several stages with changing air parameters from stage to stage, and with the aim of improving the quality of drying, 10 NIN airflow is carried out for 55-6 minutes at an air temperature of 95-105 C and its moisture content of 20-30 g / kg dB, for-5 6. "At that of each of the subsequent stages, the air temperature is reduced by 812С, and the moisture content is increased . at 5-10 g / kg r.v. with a duration of each stage of 2-2.5 hours and with the last stage with an air temperature of 55-65 ° C and a moisture content of 60-65 g / kg d.s. Sources of information taken into account during the examination 1. Genin L.I. Technology of drying potatoes, vegetables and fruits. M., Pishepromizdat, 1960, p. 118. 2. USSR author's certificate number 651775, cl. A 23 B 7/02, 1975.