RU2348158C1 - Method of manufacturing dried parsnip roots - Google Patents

Abstract

FIELD: food products.

SUBSTANCE: method includes washing, inspection, alkaline cleaning, skinning and washing off alkaline, advanced cleaning, cutting, drying and inspection. Drying is performed in four stages. At the first stage cut parsnip roots are treated in dense layer by coolant flow at the temperature of 323 K and speed of 2.4 m/s during 10 minutes. At the second stage - by the flow at the temperature of 333 K and speed of 1.3 m/s during 15 minutes. At the third stage - by the flow at the temperature of 343 K and speed 0.6 m/s during 35 minutes. On the fourth stage - by the flow at the temperature 348 K and speed of 0.3 m/s during 15 minutes. Parsnip roots are mixed under drying process during 4 seconds. At the first stage - every 2 minutes, at the second stage - every 3 minutes, at the third and fourth - every 5 minutes.

EFFECT: quality improvement of finished product.

1 dwg, 1 tbl

Description

The invention relates to a vegetable drying and food concentrate industry, namely the production of dried parsnip roots, and can be used for the production of spices and seasonings.

A known method for the production of dried parsnip roots, which includes washing in cam or drum machines (water to product ratio 3: 1), inspection (manually rotten roots with black spots and other defects are manually removed, the roots are cleaned of side roots), alkaline cleaning ( caustic soda solution with a concentration of 3 ... 6% at a temperature of 80 ... 85 ° C for 5 min), peeling and alkali washing in a washing and cleaning machine, manual tertiary treatment, cutting or on columns (shavings) with a section of 3 × 5 mm, length not less than 5 mm, either on cubes with a face size of 5 ... 9 mm, or on plates with a thickness of not more than 4 mm, length and width of 9 ... 12 mm), drying and inspection. Parsnip roots are dried on five-belt conveyor dryers. The product enters the dryer, is laid out using a stacker, and moves along the conveyor belt, pouring from one belt to another. The initial drying temperature is 48 ... 50 ° C, the temperature in the middle sections of the dryer is 52 ... 55 ° C, at the final stage the temperature is 45 ... 40 ° C. Drying time 3.50 ... 4.13 hours. Humidity of the final product no more than 14% (in agreement with the consumer - with a mass fraction of moisture not more than 8%) [Handbook of the technologist of food-concentrate and vegetable-drying production / V.N. Gulyaev, N.V. .Dremina, 3.A. Katz et al. / Ed. V.N. Gulyaev. - M .: Light and food industry, 1984.-488. S., p. 330-332].

The disadvantages of this method is the significant energy consumption and low quality of the finished product and the duration of the drying process.

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 stepwise drying modes of parsnip roots in a dense layer using fluidization for mixing, reducing energy consumption to obtain the finished product, intensifying the drying process.

The problem is achieved in that in the proposed method for the production of dried parsnip roots, including washing, inspection, alkaline cleaning, peeling and alkali washing, post-treatment, cutting, drying and inspection, the new is that drying is carried out in four time stages: the first stage, the cut roots of the parsnip are treated in a dense layer with a flow of coolant (air) with a temperature of 323 K and a speed of 2.4 m / s for 10 min; at the second stage - by the flow of coolant (air) with a temperature of 333K and a speed of 1.3 m / s for 15 minutes; at the third stage - by the flow of coolant (air) with a temperature of 343K and a speed of 0.6 m / s for 35 minutes; at the fourth stage - by the flow of coolant (air) with a temperature of 348K and a speed of 0.3 m / s for 15 minutes; throughout the drying process, the roots of the parsnip are subjected to stirring in a fluidized bed for 4 s, and in the first stage, every 2 min; on the second - after 3 minutes; on the third and fourth - after 5 minutes.

The technical result consists in increasing the thermal efficiency and intensification of the drying process, improving the quality of the finished product through the use of stepwise drying modes of parsnip roots in a dense layer using fluidization for mixing, in reducing the energy consumption for obtaining the finished product.

The drawing shows the kinetic dependences of the drying process of the cubes of parsnip roots with rational operating parameters: a - diagram of the change in the velocity v _n and temperature T of the coolant over time, b - the drying curve W = f (τ) and the drying speed curve dW / dτ = f (W ) parsnip roots, where W is the moisture content of parsnip roots,%, τ - time, s; c - thermogram of the drying process of the roots of parsnip T _n = f (τ), where T _n is the temperature of the roots of parsnip.

Fresh parsnip roots were used as an object of study. Fresh root parsnip coming into processing must meet the technical specifications of OKP 97 3228 PCT RSFSR 364-77 in quality and meet the following requirements:

in appearance: the root crops are fresh, whole, healthy, unpolluted, not deciduous, uniform in shape, unkempt, with petioles of leaves no more than 20 mm;

by the size of root crops by the largest transverse diameter, mm, not less than: for varieties with an elongated shape - 20; for varieties with a rounded shape - 30;

by the content of root crops, in% by weight, not more, with minor damage by pests - 5; ugly and branched - 5; with incorrectly cut leaf petioles - 5; slightly wilted - 5; 5 mm less than the established sizes - 10;

by the presence of land adhered to root crops,% by weight, not more than - 1.

In the batch of fresh root parsnip coming after winter storage, wilted root crops are allowed in an amount of not more than 15% by weight.

Fresh root parsnip contains 83% water, 1.4% protein, 11.0% carbohydrates (including 6.5% mono- and disaccharides and 4.0% starch), 2.4% fiber, 0.1% organic acids (in terms of malic acid) and 1.5% ash. The main component of sugars in the roots of parsnips (from 2.3 to 10.6%) are sucrose, glucose, fructose; in addition, there are galactose, mannose, arabinose, xylose, rhamnose.

The solids content in the roots of parsnip is 16.8 ... 33%. Parsnip root crops contain a rich set of microelements: sodium - 8; potassium - 342; calcium - 57; magnesium - 22; phosphorus - 73; iron - 0.7 mg per 100 g of the edible part of the product. Parsnip is a rich source of vitamins. It contains in root crops: 5 ... 28 mg ascorbic acid per 100 g, 1.2 ... 1.9 mg B ₁ per 1000 g, 0.1 ... 0.9 mg B ₂ per 1000 g, 0.03 mg carotene. Dehydroascorbic acid was found in root juice. The energy value of parsnip root crops is 47 kcal / 100 g [Handbook of the technologist of food-concentrate and vegetable-drying production / V.N. Gulyaev, N.V. Dremina, Z.A. V.N. Gulyaev. - M .: Light and food industry, 1984. - 488. S., p.307-308].

The amount of crude protein (N × 6.25) in root crops is 1.1 ... 2.6%. Parsnip prevails in the composition of minerals in the ash of the parsnip; there are also calcium, phosphorus, iron, copper, etc.

Of the oxidizing enzymes in parsnip, peroxidase, phenolase, and ascorbate oxidase were found. In all parts of plants contain essential oils, but most of all in seeds (from 1.5 to 2.5%). According to many authors, root crops of parsnip contain from 70 to 350 mg of essential oils per 100 g of raw material. The number of esters in oil (ether number) of parsnip ranges from 218 ... 270.

Parsnip has a thick, fleshy root. Depending on the variety, the roots are long or short. The most common varieties of parsnip with a short root.

As can be seen from the foregoing, parsnip roots contain vitamins, organic acids, macro- and microelements, proteins, and other substances vital to the body. In this regard, it is useful for inflammatory diseases of the mucous membrane of the stomach, small and large intestines, diseases of the liver, gall bladder, kidneys, and various allergic conditions. They improve metabolism, promote the removal of cholesterol from the body and cleanse the body of radioactive and other harmful substances, enhance the activity of the heart, calm the nervous system, and increase the body's defenses.

A method of manufacturing dried parsnip roots is as follows.

Parsnip roots, previously washed (in running water with a water: product ratio of 3: 1) and inspected (manually decayed roots with black spots and other defects, simultaneously clean the roots of side roots), are subjected to alkaline cleaning (caustic soda solution with concentration of 3 ... 6% at a temperature of 80 ... 85 ° C for 5 min), remove the skin and wash off alkali in a washing and cleaning machine. Then the roots of the parsnip are manually cleaned and cut either into columns (shavings) with a section of 3 × 5 mm, a length of at least 5 mm, or into cubes with a face size of 5 ... 9 mm, or on plates with a thickness of not more than 4 mm, length and width 9 ... 12 mm). Parsnip roots treated in this way are placed in the working chamber of the dryer and dried in four time steps (drawing, a). At the first stage, the cut roots of the parsnip are treated in a dense layer with a flow of coolant (air) with a temperature of 323 K and a speed of 2.4 m / s for 10 minutes.

At the second stage, parsnip roots are treated in a dense layer with a coolant (air) flow with a temperature of 333K and a speed of 1.3 m / s for 15 minutes.

At the third stage, parsnip roots are treated in a dense layer with a flow of coolant (air) with a temperature of 343 K and a speed of 0.6 m / s for 35 minutes.

At the fourth stage, parsnip roots are treated in a dense layer with a flow of coolant (air) with a temperature of 348K and a speed of 0.3 m / s for 15 minutes.

The following approach is proposed to justify the choice of stepwise drying modes of parsnip roots. Its essence consists in dividing the drying process into several temporary (different in duration) stages, at each of which, depending on the law of change in the current humidity of the parsnip, its rational technological mode of drying is selected.

The choice of the law of the temperature and velocity of the coolant and the time of their impact on the product is the main task of controlling the drying process. To solve it, information is required on the preference of various combinations of control actions at each stage of the process. Consider the case when the control variables temperature T and velocity v of the coolant at the inlet to the bulk product layer are piecewise constant functions of time. This allows us to consider convective drying of the product as a process having known time intervals: [0, τ ₁ ]]; [τ ₁ , τ ₂ ]; ([τ _n-1 , τ _n ], at which the temperature and velocity of the coolant take fixed values. Moreover, the choice at each interval must be made in accordance with the restrictions imposed by technological requirements on the quality of the finished product.

This mode of stepwise (four-stage) heat supply, i.e. the alternation of temperature and hydrodynamic processing in a dense layer and a change in the duration of the stages is due to the following. At the beginning of the drying process, mechanically bound moisture is removed, i.e. moisture of microcapillaries, macrocapillaries and wetting. 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 a high speed and low temperature at the initial moment of drying. Drying at the first stage most fully meets this requirement.

As the indicated moisture is removed, the velocity of the coolant, as a determining factor in the intensity of the process, loses its significance. With further drying, osmotic, poly- and monoadsorption moisture is removed, the removal rate of which is most affected by the temperature of the coolant, since only the temperature of the coolant determines the intensity of internal moisture transfer. Therefore, in the second, third and fourth stages, drying is preferable to carry out at a decreasing speed and increasing temperature of the coolant. Thus, if at the beginning of the process the drying speed is mainly limited by the coolant speed, then by its temperature. This leads to a change in the ratio of the durations of the drying stages.

Adapted in accordance with the basic kinetic laws of the drying process, the coolant supply at the four 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.

Throughout the entire drying process, the roots of the parsnip are subjected to stirring in a fluidized bed for 4 s, and in the first stage, every 2 min; on the second - after 3 minutes; on the third and fourth - after 5 minutes. The use of air mixing allows more uniform drying of the roots of parsnip.

Drying the roots of parsnip is carried out to a final moisture content of the finished product of 14%. Such treatment of parsnip roots can increase the energy efficiency of the process, reduce the drying time of the parsnip and improve its quality.

A method of manufacturing dried parsnip roots is illustrated by the following example.

An example implementation of a method of manufacturing dried parsnip roots.

Parsnip roots, previously washed (in running water with a water: product ratio of 3: 1) and inspected (manually decayed roots with black spots and other defects, simultaneously clean the roots of side roots), are subjected to alkaline cleaning (caustic soda solution with concentration of 3 ... 6% at a temperature of 80 ... 85 ° C for 5 min), remove the skin and wash off alkali in a washing and cleaning machine. Then the roots of the parsnip are manually cleaned and cut into cubes with a face size of 5 ... 9 mm. The thus treated cubes of parsnip roots are placed in the working chamber of the dryer and dried in four time steps (drawing, a).

At the first stage, the drying of the parsnip roots is carried out in a dense layer by a flow of coolant (air) with a temperature of 323 K and a speed of 2.4 m / s for 10 minutes At the beginning of the drying process, mechanically bound moisture is removed, i.e. moisture of microcapillaries, macrocapillaries and wetting.

The technological parameters of the coolant (temperature 323K and speed 2.4 m / s) and the duration of the first stage (10 min) are interrelated and their choice is due to the fact that they are complexly aimed at removing mainly mechanically bound moisture, the evaporation of which dominates at the very beginning of the drying process. 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 speed (2.4 m / s) and a low temperature (323K).

The use of a coolant velocity of less than 2.4 m / s, for example 1.8 m / s, will reduce the hydrodynamic effect of tearing the liquid film from the surface of the product and, as a result, reduce the evaporation efficiency.

The use of a coolant velocity of more than 2.4 m / s, for example 2.8 m / s, will lead to the soaring or even entrainment of particles of parsnip roots, which will cause increased energy consumption during fan operation.

The use of a coolant with a temperature of less than 323K, for example 318K, will lead to insufficiently rapid heating of the liquid film and, as a result, to a decrease in the efficiency of its evaporation.

The use of a coolant with a temperature of more than 323K, for example 330K, will lead to increased energy consumption and incomplete use of the energy potential of the coolant.

An analysis of the drying curves and the drying speed of the parsnip roots (drawing, b) shows that there are three periods: heating, constant and decreasing drying speeds. Analysis of the drying curve of the parsnip roots (drawing, b) shows that the duration of the warm-up period is very significant and amounts to 9 ... 10 min. It is this consideration that justifies the choice of the duration of the first stage - 10 minutes.

With a shorter duration of the first stage, for example 8 min, mechanically bound moisture did not have time to completely evaporate and the cubes of parsnip roots tended to stick together and clump. With a longer duration of the first stage, for example, 14 min, mechanically bound moisture completely evaporated, and further heat supply was not rational from an energy point of view.

At the second stage, the drying of the parsnip roots is carried out in a dense layer by a flow of coolant (air) with a temperature of 333K and a speed of 1.3 m / s for 15 minutes Technological parameters of the coolant (temperature 333K and speed 1.3 m / s) and the duration of the second stage (15 min) are interrelated and their choice is due to the fact that they are complexly aimed at removing mainly osmotically bound moisture. For intensive removal of osmotically bound moisture, it is advisable to increase the temperature of the coolant and reduce its speed. Therefore, it is most advisable to use a coolant at a speed of 1.3 m / s and a temperature of 333K at this moment of drying.

The use of a coolant with a speed of less than 1.3 m / s, for example 1.0 m / s, will reduce the efficiency of evaporation of osmotically bound moisture.

The use of a coolant with a speed of more than 1.3 m / s, for example 1.8 m / s, will lead to the fact that the coolant has been in contact with the particles of the parsnip roots for some time and does not have time to give its heat to them: this will cause increased energy costs for the process drying.

The use of a coolant with a temperature of less than 333K, for example 326K, will lead to insufficiently fast heating of the particles of parsnip roots and, as a result, to a decrease in the evaporation efficiency.

The use of a coolant with a temperature of more than 333K, for example 340K, will lead to increased energy consumption and incomplete use of the energy potential of the coolant.

Analysis of the drying curve of the roots of parsnip (drawing, b) shows that the duration of removal of osmotically bound moisture is 15 minutes It is this consideration that justifies the choice of the duration of the second stage - 15 minutes.

With a shorter duration of the second stage, for example 12 minutes, the osmotically bound moisture did not have time to completely evaporate. With a longer duration of the second stage, for example, 18 min, the osmotically bound moisture completely evaporated, and further heat supply was not rational from an energy point of view.

At the third stage, the drying of the parsnip roots is carried out in a dense layer by a flow of coolant (air) with a temperature of 343 K and a speed of 0.6 m / s for 35 minutes The technological parameters of the coolant (temperature 343K and speed 0.6 m / s) and the duration of the third stage (35 min) are interrelated and their choice is due to the fact that they are complexly aimed at removing mainly polyadsorption bound moisture. For intensive removal of polyadsorption bound moisture, it is advisable to increase the temperature of the coolant and reduce its speed. Therefore, it is most advisable at this time of drying to use a coolant at a speed of 0.6 m / s and a temperature of 343K.

The use of a coolant with a speed of less than 0.6 m / s, for example 0.4 m / s, will lead to a decrease in the evaporation efficiency of polyadsorption bound moisture.

The use of a heat carrier with a speed of more than 0.6 m / s, for example 0.8 m / s, will lead to the fact that the heat carrier has been in contact with the particles of the parsnip roots for a short time and does not have time to give up its heat to them: this will cause increased energy consumption for the process drying.

The use of a coolant with a temperature of less than 343K, for example 338K, will lead to insufficiently fast heating of the particles of parsnip roots and, as a result, to a decrease in the evaporation efficiency.

The use of a coolant with a temperature of more than 343K, for example 350K, will lead to increased energy consumption and incomplete use of the energy potential of the coolant.

Analysis of the drying curve of parsnip roots (drawing, b) shows that the duration of removal of polyadsorption bound moisture is 35 minutes It is this consideration that justifies the choice of the duration of the third stage - 35 minutes.

With a shorter duration of the third stage, for example, 30 min, the polyadsorption bound moisture did not have time to completely evaporate. With a longer duration of the third stage, for example 40 min, the polyadsorption bound moisture completely evaporated, and further heat supply was not rational from an energy point of view.

At the fourth stage, the drying of the parsnip roots is carried out in a dense layer by a flow of coolant (air) with a temperature of 348 K and a speed of 0.3 m / s for 15 minutes The technological parameters of the coolant (temperature 348K and speed 0.3 m / s) and the duration of the third stage (15 min) are interrelated and their choice is due to the fact that they are complexly aimed at removing mainly monoadsorption bound moisture. For intensive removal of monoadsorption bound moisture, it is advisable to increase the temperature of the coolant and reduce its speed. Therefore, it is most advisable at this time of drying to use a coolant at a speed of 0.3 m / s and a temperature of 348K.

The use of a coolant with a speed of less than 0.3 m / s, for example 0.1 m / s, will reduce the efficiency of evaporation of monoadsorption bound moisture.

The use of a heat carrier with a speed of more than 0.3 m / s, for example 0.5 m / s, will lead to the fact that the heat carrier has been in contact with the particles of the parsnip roots for a short time and does not have time to give its heat to them: this will cause increased energy costs for the process drying.

The use of a coolant with a temperature of less than 348K, for example 341K, will lead to insufficiently fast heating of the particles of parsnip roots and, as a result, to a decrease in the evaporation efficiency.

The use of a coolant with a temperature of more than 348K, for example 353K, will lead to increased energy consumption and incomplete use of the energy potential of the coolant.

Analysis of the drying curve of parsnip roots (drawing, b) shows that the duration of the removal of monoadsorption bound moisture is 15 minutes It is this consideration that justifies the choice of the duration of the fourth stage - 15 minutes.

With a shorter duration of the fourth stage, for example 10 min, monoadsorption bound moisture did not have time to completely evaporate. With a longer duration of the fourth stage, for example, 20 min, monoadsorption bound moisture completely evaporated, and further heat supply was not rational from an energy point of view.

The choice of the hydrodynamic (high-speed) mode of drying the cubes of parsnip roots with air (at the first stage of drying, the velocity of the coolant when drying in a dense layer is 2.4 m / s for 10 minutes, at the second stage - 1.3 m / s for 15 minutes; in the third stage - 0.6 m / s for 35 minutes; in the fourth stage - 0.3 m / s for 15 minutes) was selected experimentally and depended on the nature of the humidity change of the cubes of parsnip roots during drying. With drying, the moisture content of the cubes of parsnip roots decreased, their mass also became less. When drying the roots of parsnip, shrinkage was observed, i.e. reducing the size of the cubes. Therefore, for uniform processing of cubes of parsnip roots, an adjustable heat supply was required, which was provided by this law of change in the coolant speed (Fig. 1, a, see type A, B, C and D). Failure to comply with this time and speed regimes led either to overdrying and burning of the parsnip roots, or, conversely, to underdrying and obtaining a product with high humidity, which was a violation of the applicable specifications.

The temperature regime for drying the cubes of parsnip roots was selected experimentally and depended on the nature of the change in moisture of the product during drying. With drying, the moisture of the cubes of parsnip roots decreased, their temperature increased. In order for the temperature of the parsnip roots not to exceed the maximum permissible temperature (above which the thermal decomposition of valuable nutrients was observed: melanoid formation, thermolysis, etc.), a gradual and controlled change in the temperature of the coolant was required to achieve uniform processing of cubes of parsnip roots. Failure to comply with this time and temperature conditions led either to overdrying and thermal decomposition of the roots of the parsnip, or, conversely, to underdrying and obtaining a product with high humidity, which was a violation of the current technical conditions.

Throughout the entire drying process, the roots of the parsnip are subjected to stirring in a fluidized bed for 4 s, and in the first stage, every 2 min; on the second - after 3 minutes; on the third and fourth - after 5 minutes. At the same time, the coolant flow turbulizes the product layer, mixes it and evens out the average moisture content of the parsnip roots particles in the volume of the layer. As a result of collisions of particles of parsnip roots with stirring, gas layers are also disturbed and stagnant zones are eliminated.

Using a pseudo-boiling layer to mix the particles of parsnip roots allows for more uniform drying. Using a mixing time of less than 4 s, for example 2 s, will not allow uniformly mixing the layer of particles of parsnip roots. Using a mixing time of more than 4 s, for example 6 s, will lead to unnecessary, unnecessary energy consumption for mixing the layer of particles of parsnip root.

The use of a different time interval between mixing (2 min at the first stage of drying, then 3 min at the second stage of drying and 5 min at the third and fourth stages of drying) is due to the different rate of change in the adhesion properties of parsnip roots. If, at the beginning of drying, the cubes of parsnip roots stick together well due to high humidity and need to be mixed more often to prevent conglomeration, then, as surface moisture evaporates, the stickiness of their surfaces decreases, so there is no need to mix too often. Another argument in support of the proposed mixing time intervals is different heating rates (see Fig. 1, c) of the cubes of parsnip roots: cubes located on the surface of the gas distribution grid, i.e. directly in contact with fresh coolant, and cubes of parsnip roots located in the upper part of the layer. The difference between the temperatures of these layers decreases as drying and the need for frequent mixing also disappears. These time intervals were established experimentally.

Thus, the best option for drying the roots of parsnips for all quality and energy indicators is the above method with the rationale for each parameter. This is due to the uniformity of drying over the entire volume of the cubes and the intense evaporation of moisture from their surface. A reduction in the rate of internal heat transfer is achieved in comparison with the rate of movement of moisture and its evaporation from the surface of cubes of parsnip roots of this size.

In this case, the heating of the cubes of parsnip roots occurs more slowly than moisture evaporates from them, which completely eliminates overheating of the product and ensures its high quality. From the energy point of view, the proposed option allows us to provide the most rational energy consumption per 1 kg of the obtained product, which is explained by the hydrodynamics of the process, which changes in time not only by pulsating changes in speed with alternating drying time intervals in a dense and fluidized bed, but also by the selected equivalent particle size. In this case, the pressure drop in the product layer, corresponding to the mass and heat flow of the coolant for a given processing mode, provides minimal energy consumption for obtaining a quality product. The drying time of parsnip roots is 75 minutes according to the proposed technology and 3.50 ... 4.13 hours according to the factory. The quality of the dried roots must meet the requirements of GOST 16731-71 “White roots of parsley, celery, dried parsnip”. They were investigated by organoleptic and physico-chemical indicators. Determination of these indicators allows you to identify structural changes in dried roots that occur during its drying, and to assess the quality of the resulting product. Organoleptic and physico-chemical characteristics of dried parsnip roots in the table.

Evaluation of the effectiveness of the method of production of dried parsnip roots according to the proposed and factory technology was carried out according to the value of specific energy consumption per 1 kg of finished product.

The value of specific energy consumption per 1 kg of dried parsnip roots, prepared according to the factory technology, is 5160 kJ / kg. The value of specific energy consumption per 1 kg of dried parsnip roots, prepared according to the proposed technology, is 4530 kJ / kg.

Organoleptic and physico-chemical characteristics of dried parsnip roots prepared according to the factory and proposed technology The name of indicators Characterization of dried white roots cooked according to factory technology proposed technology Appearance Cubes with a face size of 5 ... 9 mm White roots in the form of chips, cubes or plates. Cubes with a face size of 5 ... 9 mm Consistency Shavings and plates are elastic, for dried white roots with low humidity - fragile. Hard cubes Taste and smell Peculiar to dried parsnips without extraneous smacks and odors Color White with a yellowish tint A brownish shade is allowed - for the second grade Shape and dimensions:
shavings Evenly sliced with a thickness of not more than 3 mm, a width of not more than 5 mm and a length of not less than 5 mm. cubes Evenly chopped side sizes 5 ... 9 mm records Evenly sliced not more than 4 mm thick, not more than 12 mm long and wide Moisture content, % 14.0 Mass fraction of chips, cubes or plates fried, with black spots and remnants of the skin,% 6 6 including the mass fraction of chips, cubes or plates with black spots and skin residues,% 3 3 Mass fraction of metallic impurities (particles not more than 0.3 mm in the largest linear dimension),% 0,0003 Mass fraction of mineral impurities (sand),% 0.01

Thus, the above analysis shows the high thermal efficiency of the proposed technology for the production of dried parsnip roots compared to the factory technology.

The proposed method for the production of dried parsnip roots has the following advantages:

- a significant reduction in the drying time from 3.50 ... 4.13 hours in the factory technology to 75 minutes in the proposed;

- obtaining dried parsnip roots with a higher content of valuable nutrients (proteins, carbohydrates, etc.);

- a significant reduction in energy consumption for the process of drying the roots of parsnip.

Claims (1)

A method for the production of dried parsnip roots, including washing, inspection, alkaline cleaning, peeling and alkali washing, post-treatment, cutting, drying and inspection, characterized in that the drying is carried out in four time steps: at the first stage, the cut parsnip roots are processed in a dense layer air flow with a temperature of 323 K and a speed of 2.4 m / s for 10 min; at the second stage, with a coolant flow of air with a temperature of 333 K and a speed of 1.3 m / s for 15 minutes; at the third stage - with a flow of air coolant with a temperature of 343 K and a speed of 0.6 m / s for 35 minutes; at the fourth stage - with a flow of air coolant with a temperature of 348 K and a speed of 0.3 m / s for 15 minutes; throughout the drying process, the roots of the parsnip are subjected to stirring in a fluidized bed for 4 s, and in the first stage, every 2 min; on the second - after 3 minutes; on the third and fourth - after 5 minutes.

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