UA82080C2 - Method for determination of fat in milk and milk products - Google Patents

Abstract

Method for determination of fat in milk and milk products that includes interaction of energy (optical, X-ray, acoustic, Etc.) with milk with following registration and analysis of output energy at given frequencies (wavelengths), at that one uses ratio of optical densities of sample that correspond to two characteristic for milk absorption wavelengths, in particular, that for one forms infrared radiation through heating filament, with modulation of infrared radiation with mechanical interrupter; one passes modulated infrared radiation through cuvette with milk sample and registers optical density of sampleD=ln(Inp/І),where Іnp – intensity of infrared radiation passed through sample,and І– intensity of infrared radiation that comes to sample at two wavelengths, one evaluated fat content of milk sample by value D

Description

Description of the invention

The invention relates to the field of agriculture, in particular animal husbandry and means of controlling the composition of 2 milk and dairy products.

A known method of determining the fat content of milk and dairy products is based on measuring the attenuation, transmission, reflection, refraction and scattering of ultrasonic (with a frequency exceeding 20 kHz) vibrations in milk; at the same time, they measure the speed of propagation of ultrasound, the attenuation coefficient, loss during reflection |Posudin Y.Y., Tymoshenko Yu.A., Modern method! determining the composition of milk. K.: Izd-vo 70. USHA, 1991, - 68 si.

Closest to the means to be ordered is a method of determining the fat content of milk and milk products based on the quantitative assessment of the absorption of milk in the infrared region of the spectrum, in which fat has characteristic absorption bands at 3.50 µm and 5.73 µm. The method involves recording the level of absorption (transmission) of infrared radiation at these analytical wavelengths (3.50 μm and 5.73 μm), thanks to which it is possible to determine the fat content in a milk sample. Absorption of infrared radiation by milk is determined by the presence of a number of structural groups in it (Vidz apa 5iaspia, 1987; Bygtap, 1987). Thus, a fat molecule can be considered as a glycerol "framework" with three fatty acid chains attached to it.

The main contribution to absorption is given by carbonyl groups (С-О) with double bonds. The excitation of such a bond between carbon and oxygen atoms leads to absorption in the region of 1745 cm"! (5.73 μm). Therefore, the fat content in milk can be related to the number of carbonyl bonds. In the absorption spectrum of milk, the most isolated and the one that can be quantified is the m-1745 cm! (5.73 μm) band. The half-width of this band is ma - M cm". When the concentration of fat in milk decreases, the half-width of this band increases (perhaps due to inhomogeneous expansion); in addition, there is a shift of the maximum of the band itself to the short-wave EM region (Fig. 1, a, b). This dependence of the half-width and the position of the absorption band at 1745 cm leads to a distortion of the absorption estimation results.

Thus, the disadvantage of the infrared spectrophotometry method is the non-linear dependence of the optical density 04745 on the concentration of fat in the milk sample, which affects the accuracy of determination of fat in milk.

The object of the proposed invention is to increase the accuracy of determination of milk and milk products. at

The task set by the invention is achieved by the fact that in the method of determining fat in milk and dairy products, which includes the interaction of energy (optical, X-ray, acoustic, etc.) with milk and subsequent registration and analysis of the output energy at certain frequencies (wavelengths), according to the invention, using o the ratio of the optical densities of the sample, which correspond to the two wavelengths characteristic for the absorption of milk, (namely 5-0473/ЮОу74д5 "for which they generate infrared radiation by heating the filament (ge) of the filament; modulate the infrared radiation with a mechanical interrupter; pass the modulated infrared radiation through a cuvette with a milk sample; the optical density of the sample is recorded

O-Ip(Ipro), " where Ipr is the intensity of infrared radiation transmitted by the sample, and Id is the intensity of infrared radiation falling on the sample at two wavelengths; evaluate eta) c by the value О the fat content of the milk sample. For the quantitative assessment of the fat content in milk, it is proposed to use the ratio of 5-О1473 0745 optical densities of the sample, which correspond to two characteristic wavelengths, namely y-1473 cm and y-1745 cm.

The method includes the following operations: oo 1. Infrared radiation is generated by heating the filament; 2. Modulate infrared radiation with a mechanical interrupter; ko 3. Pass modulated infrared radiation through a cuvette with a milk sample; o 4. Record the optical density of the sample O-Ip(Ipr/o), where Ipr is the intensity of infrared radiation transmitted by the sample, and Io is the intensity of infrared radiation falling on the sample at two wavelengths (ee); o 5. The fat content of the milk sample is estimated by the O value.

Figure 2 explains the principle of infrared spectrophotometry of milk and dairy products.

The radiation of the infrared source 1 is focused with the help of a spherical mirror 2 and through the diaphragm 5B, the modulator 4 and the lens 5 are directed to the cuvette 6 with the sample under study. Next, the radiation is passed through the interference filter 7, after which it enters the detector 8. The signal from the output

HF) of the detector is fed to the unit 9 of the converter, which controls the process of interrupting the infrared t radiation and amplifies the signal registered by the detector, converting it into a constant voltage that enters the digital voltmeter 10. Absorption bands of dairy products with different concentrations of fat 60 (milk, cream, sour cream and pure fat) are shown in Fig. 3-6.

The dependence of the B-Statz Ota ratio on the fat content in dairy products is linear (Fig. 7), which makes it possible to use it as a calibration graph for determining the fat content of milk and dairy products. b5

Claims (1)

The formula of the invention A method for determining fat in milk and milk products, which includes the interaction of energy (optical, X-ray, acoustic, etc.) with milk and the subsequent registration and analysis of the output energy at certain frequencies (wavelengths), which differs in that it uses the ratio of the optical densities of the sample, which correspond to two wavelengths characteristic for the absorption of milk, namely B-Suat3/Outd c for which they generate infrared radiation by heating the filament; modulate infrared radiation with a mechanical interrupter; modulated infrared radiation is passed through the /o0 cuvette with the milk sample; the optical density of the sample is recorded O-Iy(Ipro), where Ipr is the intensity of infrared radiation that passes through the sample, and Id is the intensity of infrared radiation that falls on the sample at two wavelengths, the fat content of the milk sample is estimated by the value of O. s 7 o o (ge) o s Zo so - and? so co o so c2 co 60 b5