SU1099281A1 - Device for milk analysis - Google Patents

Abstract

A DEVICE FOR ANALYSIS OF MILK, containing milk and solvent dispensers, connected through a sequentially placed mixing unit, a homogenizer and a cuvette for measuring protein content, a stabilized radiation source, a light filter located in the optical channel of the cuvette, a radiation receiver, a gain and conversion unit for the radiation receiver signal and showing a device, characterized in that, in order to increase accuracy, it is equipped with a cuvette for measuring the content of the lyre and a filter located in the optical the channel of the latter, the cuvette for measuring the fat content is connected in series with the cuvette for measuring the protein content, and the ratio of the optical lengths of the cuvette is (L in the range of 6-10.

Description

The invention relates to the analysis of the composition of food products, namely to the analysis of the composition of milk, and can be used in the dairy industry, as well as during work on the selection of livestock. A device for analyzing a milk containing a light source, a cuvette, a light filter, photodetectors of a transmitted and scattered light fluxes, and a lens for focusing scattered light lj is known. However, the accuracy of the analysis is not typical for this device. It is also known a device for milk analysis, containing milk and solvent dispensers, connected through a sequentially placed mixing bottle, a homogenizer, and a cuvette for measuring protein content signal of the receiver of the radiation and showing the device 2J, However, the known device is characterized by an insufficiently high accuracy of determining the protein content and the impossibility of simultaneously Fat determination. The aim of the invention is to improve the accuracy of determination. The post goal is achieved by the fact that a device containing milk and solvent dispensers connected through successive dimensions. a mixed mixing unit, a homogenizer and a cell for measuring protein content, a stabilized radiation source, a light filter located in the optical channel of the cell, a radiation receiver, a amplification and signal conversion unit, a radiation receiver and indicating device, are additionally equipped with a cell for measuring the fat content and light 4 the fiber located in the optical channel of the latter, the cuvette for measuring the fat content is connected in series with the cuvette for measuring the protein content, and the ratio of the optical their cuvette lengths are within 6-10. FIG. 1 shows a diagram of the proposed device; in fig. 2 and 3 are graphs of the dependences D and K on the wavelength. The device consists of containers 1 and 2, respectively, for the analyzed sample of milk and solvent, dispensers 3 and 4, respectively, milk and solvent, mixing unit 5, homogenizer 6, cuvette 7 and 8 for measuring fat and protein, respectively, stabilized radiation source 9, light filters 10 and 11 located respectively in the optical channels of the cuvette 7 and 8 of the receivers 12 and 13 of the radiation, respectively, located in the optical channels of the cuvette 7 and 8, the block 14 of amplification and conversion of the signals of the radiation receivers and pok 15. The spectral range of the stabilized radiation source 9 is 200–430 nm, the transmission band of the light filter is 10,400–430 nm, and the light filter is 11– 200–210 nm. Optical lina cuvet 7-300 microns, cuvet 8-40 microns. An aqueous solution of sodium lauryl sulfate with a concentration of 10 g / l is used as the solvent. The device works as follows. Milk dispenser 3 takes 1.4 ml of milk from tank 1 and delivers it to mixing block 5. At the same time, solvent dispenser 4 takes 13.5 ml of solvent from tank 2 and feeds it to mixing block 5. When mixing milk with solvent, casein micelles are destroyed on sublitselly, and the transparency of milk increases dramatically. The homogenizer 6 selects the mixture of milk and solvent from the mixing unit 5, homogenizes it at a pressure of at least 14 MPa, chops the fat balls, and delivers the homogenized mixture to the cuvettes 7 and 8, displacing the previous sample being analyzed. The radiation from the source 9 passes through the light filters 10 and 11, the cuvet 7 and 8 and goes to the radiation receivers 12 and 13. In this case, in the cuvette 7, the radiation is scattered by the fat particles, and in the cuvette 8, the radiation is absorbed by the protein and scattered by the fat particles. In this connection, the signal from radiation receiver 12 is proportional to the fat content of the milk sample being examined. The signal from radiation receiver 13 is a function of the fat and protein content of the milk sample being examined. Both signals arrive at block 14 for amplifying and converting signals where they are amplified and converted into specific information about the content of fat and protein in milk displayed on the indicating device. 15. Photometry of a homogenized mixture is carried out in the spectral ranges 200-210 and 400-430 nm in layers of different thickness, and the ratio of the thickness of the photometric layer for the spectral range 200-210 nm to the thickness of the photometric layer for the spectral range at 400-430 nm should be in the range of 0.1-0.15, and the dilution degree is chosen so that the ratio of the thickness of the photometric layer for the spectral range nm to the degree of dilution is within 0.000250,0005cm. The content of protein and fat in milk, measured in two spectral ranges of the optical density, determines the system of equations D, 2i (K, C, +) + (1) Dj + Kg,. (2) where D. is the optical density, measured in the spectral range of 200–210 nm, DJ — optical density, measured in the spectral range of 400–430 nm; C ;, is the percentage concentration of iron in milk; JCc is the percentage concentration of protein in milk; KJ-KC-calibration factors. In the wavelength range of about 200, milk proteins have a very strong absorption due to the presence of peptides. The presence of polypeptide chains is a characteristic feature of all protein substances. Therefore, the specific absorption ratios of different protein fractions differ slightly. FIG. Figure 2 shows the experimental dependences of the relative specific absorption ratios of sodium caseinate solutions (curve 1), whey proteins (curve 2), total milk protein (curve 3), and the relative specific attenuation coefficient of the homogenized fat emulsion of milk (curve 4) on the wavelength ( per unit of the value of the specific absorption coefficient of the total protein solution at a wavelength (190 nm). Changes in the ratio between different milk protein fractions within 10% result in extremely low It is impractical to use shorter wavelengths (200 nm) for measuring the total protein content during Lotometry in the 200-210 nm wavelength range, since the absorption of milk salts, as well as the absorption of water and air, starts to affect the measurement results. The use of longer wavelengths (210 nm) for photometry is also impractical, since it increases the relative contribution to the optical density of the attenuation of radiation on the fat particles (Fig. 2, curves 3 and 4) and, accordingly, the accuracy of the determination of the protein content decreases. The use for photometry of a rather narrow spectral interval (200-210 nm) is also advisable because, despite the sharp drop in the dependence of the attenuation coefficient of the homogenized mixture on the wavelength, the linear dependence of D f (C, C2) is provided, which simplifies signal processing and increases measurement accuracy. In this case, the thickness of the photometric layer for the wavelength range of 200-210 nm and the dilution degree are chosen so that the ratio of the thickness of the photometric layer to the dilution rate is within 0.00025-0,0005 cm. For example, with a dilution degree of 10 (1 volume milk plus 9 volumes of solvent) the thickness of the photometric layer should be selected within 0.0025-0.005 cm, and for dilution rates of 20 (1 volume of milk plus 19 volumes of solvent) the thickness of the photometric layer should be chosen within 0.005-0.01 cm At the same time providing a maximum accuracy of measurements, because the photometry of the known theory that the minimum error determining the concentration of light absorbing agent is observed at a value of optical density D 0,434, B5 and at 0, 3 measurements carried out with twice the minimum error.

In order to take into account the effect of radiation attenuation by fat particles on the optical density D (in the spectral range of 200210 nm) and to simultaneously determine the content of fat (fluorescence (1) and (2) in this method, a homogenized mixture is measured in the spectral range 400 -430 nm, which is chosen based on the fact that in the spectral range at Ti 400 nm, the optical density of the homogenized mixture is significantly affected by protein absorption, and the choice of this spectral range at A «: 400 leads to a complication of ur vneny (2) and, respectively, to the complication of the processing of experimental data and lower accuracy of determining the fat and protein content.

In the spectral range of i 400 nm, neither protein nor fat is absorbed by radiation, TortbKo is attenuated by radiation scattering on fat particles. The homogenization of the milk mixture with the solvent provides a rationed

the distribution of fat particles in size, thereby eliminating the influence of individual properties of milk, which is expressed in the variation of the distribution of fat particles in size.

FIG. Figure 3 shows the experimental dependence of the optical density of the homogenized mixture of milk and solvent on the wavelength (the fat content in the initial milk is 3.2%, the dilution is 1:10, the optical length of the cell is 2 0.3 mm). The width of the spectral range of 400–430 nm is chosen to provide linear

the nature of the dependence of the coefficient of fat loss from dpiny waves.

To ensure maximum measurement accuracy at selected dilution rates and thickness of the photometric layer, it is necessary that the ratio of the optical lengths of the cuvette, respectively, for measuring the content of fat and protein is in the range of 6-10, which will provide a measurement

data components of milk samples in the optimal range of optical densities for the spectral ranges of 200-210 and 400-430 nm. "

As a result of the use of this device for the analysis of milk for the content of protein and fat only at breeding stations, the economic effect will be 16.4078 million rubles.

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Claims (1)

DEVICE FOR MILK ANALYSIS containing milk and solvent dispensers connected through a sequentially placed mixing unit, a homogenizer, and a cuvette for measuring protein content, a stabilized radiation source, a light filter located in the optical channel of the cuvette, a radiation receiver, and an amplifier for signal conversion and conversion of the radiation receiver and showing an instrument, characterized in that, in order to increase accuracy, it is equipped with a cuvette for measuring fat content and a light filter located in the optical channel le latter, wherein the cuvette for measurements of fat content of rhenium in series with the cuvette of the protein content, and the lengths of optical cuvette within 6-10. IC connected for mixing ς © N3 □ o> 1 1099281