RU2313953C1 - Method for producing of extruded foods - Google Patents

Abstract

FIELD: food-concentrates industry, in particular, processes for producing of extruded foods.

SUBSTANCE: method involves mixing basic products and extruding resultant mixture, with wheat and beans being used as basic products; grinding products to 0.32-0.63 mm sized particles; mixing in 3:2 proportion; wetting to 14-18% moisture content; processing in extruder with temperature of product in front of die making 420-435 K and pressure in extruder zone upstream of die making 6.5-7.0 MPa.

EFFECT: reduced production costs owing to utilization of widely known and cheap kinds of raw materials as basic components, provision for producing of foods having high biological and nutrient value.

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Description

The invention relates to food-concentrate industry, in particular to methods for the production of extruded products.

Closest to the proposed technical essence is a method of preparing extruded beans (Pat. No. 1738226, MKI ³ A23L 1/18, publ. 06/07/1992, BI No. 21), which consists in mixing pre-irrigated water beans with flavoring and extrusion at a temperature 150 ... 230 ° C and a pressure of 6 ... 12 MPa for 6 ... 12 s.

The disadvantages of this method are the low biological value of the resulting product and the imbalance of its composition, as well as the low quality of the finished product due to the use of whole beans.

The technical task of the invention is the production of combined extruded high quality food products balanced in composition, increasing their nutritional and biological value, expanding the range of extruded products using inexpensive and widespread raw materials.

The problem is achieved in that in the method of manufacturing an extruded product, including mixing the starting products and extruding the resulting mixture, it is new that wheat and beans are used as the starting products, the crops are crushed to a particle size of 0.32 to 0.63 mm, they are mixed in a proportion of 3: 2, moistened to 14 ... 18% and processed on a twin-screw extruder at a product temperature in front of the matrix of 420 ... 435 K and a pressure in the prematrix zone of the extruder of 6.5 ... 7.0 MPa.

The technical result of the invention is to obtain a high-quality extruded food product with high nutritional and biological value, subject to rational process parameters (temperature and pressure in front of the matrix, etc.).

Figure 1 shows a comparative characteristic of biological value (BC) and the coefficient of divergence of amino acid scores (KRAS): a) wheat; b) beans; c) wheat-bean mixture, figure 2 shows the ratio of components in the "ideal" product, justified by the Institute of Nutrition of the Academy of Medical Sciences of the Russian Federation, in comparison with the composition of the obtained extrudate. Figure 3 and figure 4 shows the obtained extruded products.

Obtaining extruded products is one of the promising areas of the integrated processing of grain raw materials.

Most of the extruded products currently being produced are not balanced in terms of amino acid composition, since their basis is most often made up of one component (wheat, rice, corn, etc.). Therefore, to increase their biological value and balance in amino acid composition, a scientific justification for the selection of new multicomponent mixtures is necessary.

When choosing the prescription composition of the grain mixture of wheat and beans, a number of factors were taken into account. Firstly, the need for maximum enrichment of the extruded product, mainly containing carbohydrates, with proteins and minerals in order to achieve their therapeutic, prophylactic or physiological dose. Secondly, the achievement of a pleasant taste and attractive structure characteristic of products of this class. It is worth noting that it is the appearance that is one of the main factors when choosing a foodstuff by a consumer. Therefore, along with the developed structure of extrudates, it is necessary to strive to obtain products balanced in nutritional and biological value.

The method is as follows. As the raw materials used: wheat (GOST 9353-90 Wheat. Requirements for harvesting and supply) and beans (GOST 7758-75 Beans). The feedstock is ground in a crusher and sieved through a No. 2 sieve in order to equalize the particle size distribution from 0.32 to 0.63 mm, then it is loaded into the mixer and thoroughly mixed in a 3: 2 ratio, moistened to 14 ... 18%. Next, the prepared mixture is processed on a twin-screw extruder at a product temperature in front of the matrix of 420 ... 435 K and a pressure in the prematrix zone of the extruder of 6.5 ... 7.0 MPa.

The processed material through the loading pipe enters the working chamber of the extruder, where it is moved by screws to the die.

As you move the product in the mixing zone is partially mixed, in the compression zone there is an abrupt increase in pressure and compaction of the product due to a sharp decrease in the size of the screw channel of the screws. In the plasticization zone, the product granules are partially converted to melt due to friction between product particles and screw turns.

Then there is further compression of the product. Further, in the homogenization zone, the transformation of the softened granules into a homogeneous melt occurs due to an increase in pressure. The melt pressure of the product in the dosing zone reaches the required value, the final melting of small inclusions is ensured, and a melt is formed, uniform in structure and temperature. This allows for the normal operation of the extruder to have a predetermined, uniform cross-section temperature of the melt of the product.

In the stabilization zone, pressure and temperature fields of the product melt are equalized. Then it enters the pre-area and is forced through the outlet in the matrix.

After the product leaves the matrix as a result of a sharp change in temperature and pressure, moisture evaporates instantly, the energy accumulated by the product is released at a rate approximately equal to the rate of explosion, which leads to the formation of a porous structure and an increase in the volume of extrudate (expansion), which leaves the matrix in the form of a bundle . Moreover, as a result of the "explosion" of the product (or "decompression shock"), deep transformations of its structure take place: rupture of the cell walls, destruction, hydrolysis [Thermoplastic extrusion: scientific foundations, technology, equipment / Under. ed. A.N. Bogatyreva, V.P. Yuryev. - M.: Step, 1994, - 200 p.).

In this case, extruded products of good quality are obtained, the degree of expansion of which is about 300% with a diameter of the matrix of 6 · 10 ^-3 m (the degree of expansion is defined as the ratio of the cross-sectional area of the extrudate to the area of the outlet of the matrix of the extruder). At the exit of the extruder, a rotating knife is installed, which, depending on the speed of rotation, cuts the extruded bundle emerging from the matrix into sticks of various lengths (Fig. 3) or granules (Fig. 4).

The method is illustrated by the following example.

Example. Wheat and beans are crushed to a particle size of 0.32 to 0.63 mm, thoroughly mixed in a 3: 2 ratio, moistened to 14 ... 18% and processed on a twin-screw extruder at a product temperature in front of a matrix of 420 ... 435 K and pressure in the prematrix zone of the extruder 6.5 ... 7.0 MPa. Moreover, the degree of expansion of extruded products is 300%.

The use of crushed raw materials with a particle size of up to 0.32 mm led to an unstable extrusion process, clogging of the outlet with the product. As a result of the extrusion of raw materials with a particle size of more than 0.63 mm, the product swelling is uneven, the product had porousity uneven over the cross section. In the cross section of the product, it was possible to distinguish the inclusion of a small number of particles, which can be explained by the incomplete transition of the mixture particles into the melt.

The need to moisten the mixture (up to 14 ... 18%) is due to the following considerations. It is proved that the expansion of the product at the exit from the holes of the matrix is directly a consequence of the physical properties of water [Thermoplastic extrusion: scientific foundations, technology, equipment / Under. ed. A.N. Bogatyreva, V.P. Yuryev. - M .: Step, 1994, - 200 p.]. Under such thermal conditions (the temperature in the extruder can vary from 130 to 200 ° C) and under very high pressure, water exists only in a liquid state. When the plasticized material leaves the matrix and reaches atmospheric pressure, water from a state of superheated liquid instantly turns into steam, releasing a significant amount of energy. Under the influence of vapor pressure, pores are formed in the product, and the remaining whole starch grains break. If the moisture in the mixture was less than 14%, then it was not enough and the product did not swell at the exit of the extruder. Conversely, if the moisture in the product was more than 18%, this also led to a decrease in the degree of expansion, since this forms a more dense product structure with a rough consistency. The reason for these changes is that with increasing humidity increases the plasticity of the mass, and this leads to a decrease in mechanical stresses in the extrudate. Consequently, the amount of heat released as a result of the work of viscous friction forces was not enough to obtain an expanded structure.

The extruder should operate at a product pressure in the pre-matrix zone that does not exceed the optimum value. This is necessary, since the pressure value uniquely determines the temperature of the product processing, on which the quality of the finished product, in turn, depends. Established [Thermoplastic extrusion: scientific foundations, technology, equipment / Under. ed. A.N. Bogatyreva, V.P. Yuryev. - M .: Step, 1994, - 200 p.], That the main components (carbohydrates, proteins, fats, vitamins, etc.) of food products have different optimal temperatures necessary for complete and qualitative physico-chemical changes during extrusion.

For an efficient and high-quality extrusion process, it is necessary to select the nature of the temperature change at which the main components of the products are subjected, on the one hand, to a complete hydrothermal treatment, and on the other, they have a “soft” (sparing) temperature effect that prevents their thermal decomposition.

Analysis of theoretical and experimental data [Ostrikov A.N. Extrusion in food technology / A.N. Ostrikov, O.V. Abramov, A.S. Rudometkin. - S-Pb .: GIORD - 2004, - 288 p.] Showed that for high-quality extrusion processing it is necessary to gradually increase the temperature of the product with subsequent stabilization. It was experimentally established that for this product, the temperature in front of the matrix T = 420 ... 435 K makes it possible to achieve a pressure in the prematrix zone of the extruder P = 6.5 ... 7.0 MPa. It is in this temperature range that the mixture undergoes full and deep physico-chemical changes in proteins, carbohydrates and other components, giving them the properties most suitable for complete assimilation by the human body.

The extruded products obtained with rational process parameters were investigated by a set of indicators characterizing the consumer properties, nutritional and energy value of the finished product. They were crushed, sieved through a metal mesh No. 025 (GOST 4601-73) and subjected to analysis. Extruded products were analyzed according to organoleptic characteristics according to GOST 15113.3-77, humidity according to GOST 15113.4-77, acidity according to GOST 15113.5-77.

Organoleptic characteristics: the product was obtained in the form of straight, curved sticks of rounded cross section or in the form of granules with a rough surface and developed porosity. In terms of color (creamy with a yellowish tint), taste and aroma (corresponding to the initial type of raw material), the extrudate has satisfactory consumer data characteristic of such a group of food products as “breakfast cereals”.

To assess the quality characteristics of extruded products, the following physicochemical properties were studied: swelling (water absorption capacity), solubility, and water retention capacity (table). These important indicators, demonstrating the ability of the extrudate to bind water and dissolve in it, characterize its carbohydrate composition, as well as consumer properties and partially digestibility of the product. It has been established that these indicators of extruded products correspond to those typical of traditional breakfast cereals.

Other physicochemical characteristics also met the standards for this category of products (table). The energy value of the resulting product is 1221 kJ / 100 g.

Table Physico-chemical characteristics of the extrudate The name of indicators Dimension Extrudate Swelling g / g 3.30 Solubility % 41.40 Water retention capacity g / g 4.20 Humidity % 6.50 Acidity hail 7.10 Mass fraction of total sugar, in terms of SV % 4.29 Mass fraction of fat, in terms of SV % 2,30

Determination of the biological value of extrudates. Assessment of amino acid balance and biological value of products was carried out according to the following indicators: the difference coefficient of amino acid scores (KRAS) and the biological value (BC) of food protein. For comparison, we present in parallel the data on BC and KRAS of wheat and beans (Fig. 1).

The amount of amino acids in the extrudate exceeds their content in wheat, this is due to a decrease in the final moisture content of the extrudate and partially its enrichment with protein substances of beans, which confirms the high biological value of the product and the advisability of processing the mixture of wheat and beans by extrusion.

Nutritional analysis of developed extruded products. One of the main requirements for food products in addition to high consumer properties is the balance of their composition.

The ratio of components in the "ideal" product, justified by the Institute of Nutrition of the Academy of Medical Sciences of the Russian Federation, in comparison with the composition of the obtained extrudates is presented in figure 2.

As can be seen from figure 2, due to the consumption of 100 g of extruded products, you can satisfy the daily need for protein at 16.8%, carbohydrates - 9.3% and minerals - 19.5%.

As can be seen from the example and the above in the method of producing extruded grain sticks, the most effective is that wheat and beans are used as products, crops are crushed to a particle size of 0.32 to 0.63 mm, mixed in a 3: 2 ratio, moistened up to 14 ... 18% and carry out processing on an extruder at a product temperature in front of the matrix 420 ... 435 K and a pressure in the prematrix zone of the extruder 6.5 ... 7.0 MPa.

Thus, the use of the invention will allow:

- receive extruded cereal products with good consumer properties and a sufficiently high biological and nutritional value; they are more balanced in the composition of essential amino acids, and are also optimized according to the criterion “coefficient of difference of amino acid scores” (KRAS);

- use widespread and inexpensive types of raw materials as initial components of the mixture;

- expand the range of products.

Claims (1)

A method of manufacturing an extruded product, including mixing the starting products and extruding the resulting mixture, characterized in that wheat and beans are used as the starting products, the cultures are crushed to a particle size of 0.32 to 0.63 mm, mixed in a 3: 2 ratio, moistened up to 14 ... 18% and carry out the processing on a twin-screw extruder at a product temperature in front of the matrix 420 ... 435 K and a pressure in the prematrix zone of the extruder 6.5 ... 7.0 MPa.

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