Method of determining level of toxicants in water, food products or body fluids and test system

FIELD: biotechnology.

SUBSTANCE: method of determining the level of toxicants in water, food products or body fluids by the test system of enzyme-linked immunosorbent assay held in the column, consists in that in the column of the test system a carrier is placed, which is used as an activated solid phase of physisorption - activated porous substrate with grafted covalently bonded molecules of toxicant, the carrier is treated with the blocking solution for closing on the carrier of free places of nonspecific binding, the test samples are added, which contain a certain amount of previously added antibodies specific to toxicants, at that the carrier is treated with conjugate-containing solution, which is used as the conjugate solution of antispecies antibodies chemically bound to luminescent quantum dots or with liposomes containing luminescent quantum dots, and the level of the toxicants is determined by lighting of the treated carrier by excitation radiation on the intensity of luminescence excited in the quantum dots. Test system for the method comprises a column in which a carrier in the form of an activated solid phase of physisorption is mounted - activated porous substrate with grafted covalently bound toxicant molecules, at that the column is provided with a device for measuring the level of luminescence, comprising a source of excitation radiation and a photodetector, at that in front of the photodetector a focusing optical system is additionally mounted, and the output of the photodetector is electrically connected through the signal amplifier and the analogue-digital converter to the control unit - a controller, which output is connected to the display unit and through the stabilisation unit to the excitation radiation source. The side walls of the column are made of material transparent for exciting and luminescent radiation.

EFFECT: invention improves the efficiency and accuracy of determining.

4 cl, 3 ex, 1 dwg

 

The invention relates to biotechnology and can be used to improve the efficiency and reliability of determining the level of toxicants in water, food or physiological liquids by conducting enzyme-linked immunosorbent assay.

The prior art discloses a method of enzyme-linked immunosorbent assay involving the adsorption of the antigens on the solid phase of physical sorption, incubation of the tested biological samples, incubation conjugational solution, spectrophotometric analysis of the reaction by the extinction of a solution of chromagen (EN 2014610 C1, G01N 33/53, 1994).

Also known a method of determining the level of toxicants in water, food or physiological liquids by held in the column of the test system enzyme-linked immunosorbent assay, including accommodation in the column carrier as a layer immunoaffinity gel with grafted antivirovym antibodies, fixed between two porous membranes, processing the media with blocking solution for closing on the media remaining free places nonspecific binding, immobilization on a carrier specific antibodies, making test samples, processing media conjugational solution and analysis of the processed media to the color change (EN 2374649 C1, G01N 33/53, 2009). Despite sufficient about�Tautou accuracy visually determining the level of toxicants in this way is not high enough.

Furthermore, the known test system for immunoassay determination of toxicants, including column, which has a carrier layer immunoaffinity gel grafted with specific antibodies, placed between two porous membranes (RU 2374649 C1, G01N 33/53, 2009). The disadvantage of this device is the lack of funds, ensuring the measurement of toxicants.

The technical result for which the invention is directed, is to increase the efficiency and reliability of the immunoassay to determine the level of toxicants in water, food or physiological liquids held in the column of the test system.

The solution of the problem with the achievement of the claimed technical result is achieved in that in the method of determining the level of toxicants in water, food or physiological liquids by held in the column of the test system enzyme-linked immunosorbent assay according to the invention in the column of the test system is placed in the carrier, which is used as the activated solid phase of physical adsorption - activated porous substrate grafted with a covalently bound molecules of toxicant, make processing the media with blocking solution for closing on the media remaining free places especificas�CSOs binding, make test samples containing a certain number of previously entered specific to the toxicant antibodies, thus make processing media conjugational solution, which is used as the conjugate solution antivitamin antibody, chemically linked to a fluorescent quantum dots or with liposomes containing fluorescent quantum dots, and the level of toxicants is determined by the illumination of the processed media exciting radiation intensity of luminescence excited in the quantum dots.

When this activated porous substrate is prepared by ultrasonic treatment made of pure polypropylene porous substrate is a Frit placed in ethanol 96% ethyl alcohol, followed by clean - sequential passing through the porous membrane of 50% ethyl alcohol.

The solution of this problem is provided by the fact that in the test system for the method of determining the level of toxicants in water, food or physiological liquids, comprising a column with a carrier according to the invention the carrier is made in the form of an activated solid phase of physical adsorption - activated porous substrate grafted with a covalently bound molecules of toxicant, wherein the column is provided with a device� for measuring the level of luminescence, including a source of exciting radiation, and a photodetector, and the photodetector is further established by the focusing optical system, and the output of the photodetector is electrically connected through a signal amplifier and an analog-to-digital Converter to the control unit controller, the output of which is connected to the display unit through the block and stabilize a source of exciting radiation, wherein the side wall of the column is made of transparent for the exciting and fluorescent radiation of the material.

In addition, between the photodetector and a focusing optical system of the device for measuring the level of luminescence can be placed filter.

Due to the presence in solution of the conjugate fluorescent quantum dots (or liposomes containing fluorescent quantum dots), chemically related antivirovym antibodies (rabbit intimissimi antibodies), which have the ability to contact specific to the toxicant antibodies and in the coverage of the exciting radiation lumines cent, in the claimed invention that implements indirect competitive enzyme-linked immunoassay, is provided by an increase in the intensity of the useful signal of the luminescence is inversely proportional to the concentration of toxins, which increases the sensitivity of the method for determining the�owna toxicants in water, food or physiological liquids. Furthermore, the presence in the claimed test system is a device for measuring the level of luminescence including a source of exciting radiation, and a photodetector, which is connected to the control unit controller, allows you to automatically simply and reliably determine the level of toxicants in terms of the intensity of luminescence excited in the quantum dots.

The drawing schematically shows a General view of the test system.

The stated test system for determining the level of toxicants in water, food or physiological liquids, includes a column 1 with side walls made from transparent to excitation and fluorescent radiation material with a carrier in the form of an activated solid phase of physical adsorption - activated porous substrate (Frit) 2 grafted - covalently bound molecules of toxicant-antigen, and a device for measuring the level of luminescence including a source 3 of the exciting radiation, made of, for example, in the form of a set of LEDs with a maximum output wavelength in the range of 395÷500 nm, and the photodetector 4 (photodiode), the spectral sensitivity range which lies in the range of 420÷675 nm, and the photodetector 4 is further installed focusing op�the algebraic system 5 (e.g., the converging lens (F=5÷30 mm), and between the photodetector 4, and a focusing optical system 5 can be placed the filter and the filter 6, the transmission spectrum corresponding to the spectrum of luminescence. The output of the photodetector 5 is electrically connected through an amplifier 7 signal and analog-to-digital Converter 8 to the control unit 9 to the controller, the output of which is connected to the display unit 10 and through the block 11 of the stabilization source 3 of the exciting radiation.

The inventive method of determining the level of toxicants is implemented as follows.

The activated solid phase of physical sorption is prepared by processing (activation) for 15 minutes, made of a polypropylene porous substrate 2 ultrasonically in ethanol and 96% ethanol, followed by clean - sequential passing through the porous substrate 2 passing 500 μl of water-alcohol solution of 50% ethyl alcohol, 500 ml of water and 700 µl of carbonate buffer (0.1 M sodium bicarbonate, 0.1 M sodium chloride, pH 8.3). Then added 150 μl of a solution of toxicant-antigen with a concentration of 2.5 g/l and 450 µl of carbonate buffer (pH 8.3) containing 0.1 M sodium bicarbonate and 0.1 M sodium chloride and incubated for 2 hours at room temperature. The residue unbound toxicant-antigen is removed by washing the porous padlock� 5 ml of carbonate buffer (pH 8.3), containing 0.1 M sodium bicarbonate and 0.1 M sodium chloride. To close the remaining free places nonspecific binding porous substrate treated with a blocking solution, which is used as a 0.2 M solution of glycine in carbonate buffer (pH 8.3) containing 0.1 M sodium bicarbonate and 0.1 M sodium chloride, and stirred for 2 hours at room temperature. After the procedure of blocking the porous substrate was washed successively with 5 ml of acetate buffer (0.1 M sodium acetate, 0.5 mol of sodium chloride, pH=4.0) and 10 ml of phosphate buffer (pH=7.4÷7.6).

Example 1

To determine the level of toxicant, such as zearalenone concentration in the analyzed environment (natural water) pre-prepare - synthesize the conjugate solution antivitamin antibody, chemically linked to a fluorescent quantum dots - semiconductor nanoparticles CdSe/ZnS, as follows.

Previously 20 µl of a solution antivitamin antibodies in carbonate buffer (0.1 M sodium bicarbonate, 0.1 M sodium chloride, pH 8.3) merge with 800 μl of a solution of quantum dots CdSe/ZnS (1/10 dilution in carbonate buffer (0.1 M sodium bicarbonate, 0.1 M sodium chloride, pH 8.3), the number of quantum dots CdSe/ZnS equal to 3.2×10-4 mol), and stirred for 12 hours at 4°C.

Then a previously prepared porous substrate 2 with �revitali - covalently bound molecules of toxicant-antigen is placed in an empty column 1 type Bond Elut (V=1 ml), pre-washed by phosphate buffer (pH=7.4÷7.6) and stored at 4°C.

To 1 ml of the analyzed medium is added 25 μl of a solution specific to the toxicant-zeralenone monoclonal mouse antibodies, stirred for 5 minutes and passed through a prepared in the above form column 1, and then washed with column 1 phosphate buffer (pH=7.4÷7.6) containing 0.05% Tween 20.

Then, in column 1 was added 100 ál of the previously prepared solution of conjugate antivitamin antibody, chemically linked to a fluorescent quantum dots - semiconductor nanoparticles CdSe/ZnS (1/30 dilution in phosphate buffer (pH=7.4÷7.6) containing 0.05% Tween 20 and 0.2% bovine serum albumin), and incubated for 6 minutes. The excess conjugate is removed by washing the column 1 phosphate buffer (pH=7.4÷7.6) and carry out the lighting of the carrier 2 containing luminescent semiconductor quantum dots (semiconductor nanoparticles, a luminous flux coming from the source 3 of the exciting radiation, and record resulting from the exciting radiation, the level of luminescence, the value of which is proportional to the concentration of toxicant-zearalenone in the analyzed environment.

Thus, if in the analyzed environment �oncentrate of toxicant-zearalenone higher than the concentration of specific antibodies, added to the sample, which corresponds, for example, maximum allowable toxicant concentration, the binding of specific antibodies to the molecules of toxicant-zearalenone, and while passing through the carrier 2 conjugate solution antivitamin antibodies with fluorescent labels, luminescent quantum dots due to the lack of specific antibodies associated with molecules zearalenone, adsorbed on the carrier 2 contained in the conjugate antitypical antibodies remain unbound (free) and removed after leaching from the column 1 together with luminescent quantum dots - semiconductor nanoparticles CdSe/ZnS. As a result, when the irradiation of the carrier - layer 2 source 3 of the exciting radiation, the luminescence does not occur.

In that case, if in the analyzed environment, the concentration of toxicant-zearalenone does not exceed the concentration of specific antibodies added to the sample, which corresponds, for example, the maximum allowable concentration of toxicant or toxicant-zeralenone in the analyzed environment is missing, then the excess binding of specific antibodies to the molecules of toxicant-zearalenone, adsorbed on the carrier 2 and while passing through the carrier 2 conjugate solution antivitamin antibodies with fluorescent labels - �uminescence quantum dots is the binding of specific antibodies, bound with molecules of zearalenone, adsorbed on the carrier 2, with the conjugate antivirovym antibodies containing luminescent semiconductor quantum dots (semiconductor nanoparticles CdSe/ZnS. As a result, when the irradiation of the carrier 2, the source 4 of the exciting radiation luminescence occurs, the level of which is inversely proportional to the concentration of toxicant-zearalenone in the analyzed environment.

This coming from the carrier 2, the total light-front consisting of a useful signal of luminescence and the parasitic signal of the exciting radiation is focused by the optical system 5, passes through the optical filter 6, which attenuates spurious signals, and the filtered total light wavefront with selected useful signal is supplied to the photodetector 4 (photodiode). Produced at the output of the photodetector 4, the electric signal (voltage value which corresponds to the level of luminescence) is amplified by a signal amplifier 7, is digitized by an analog-to-digital Converter 8 and the digital representation is transmitted to register to the input of block 9 of the control of the controller for registration of luminescence, where it is processed by comparing with pre-stored calibration constants, and the quantitative value of the level of luminescence, proportional�diesel toxicant concentration-zearalenone, and/or the corresponding value of the level (concentration) of a toxicant is introduced into the memory of the control unit 9 of the controller and displayed in the display unit 10.

In addition, the control unit 9 of the controller in accordance with the software algorithm in the automatic mode provides programmable control of the led source 3 of the exciting radiation, by normalizing unit 11 to the stabilization of the voltage source 3 of the exciting radiation, and ensures the preservation of the memory parameters of calibration constants (calibration curve), the values of which are determined in a preliminary calibration measurements using standard sources of exciting radiation and preliminary calibration of the column 1 by means of the analyzed medium containing toxicants, such as zearalenon known concentration.

Example 2

To determine the level of toxicant, such as zearalenone concentration in the analyzed environment (natural water) pre-prepare a solution in stages conjugate antivitamin antibodies with liposomes containing water-soluble luminescent semiconductor quantum dots (semiconductor nanoparticles CdSe/ZnS, as follows.

In the first phase by the method of hydration of thin films prepared liposomes containing water-soluble �luminescence quantum dots semiconductor nanoparticles CdSe/ZnS. For this, 70 mg (94 mmol) of phospholipids (Lipoid S75) was dissolved in 1 ml of chloroform in a round bottom flask (V=10 ml). Then the chloroform was evaporated using a rotary evaporator to form a film of phospholipid on the walls of the flask. The resulting film of phospholipids is treated with 6 ml of water containing 5 μmol of quantum dots CdSe/ZnS and stirred for 30 minutes at a temperature of 45°C. the solution was Then treated with ultrasound for 5 minutes to achieve an acceptable particle size of liposomes (100 nm). The resulting solution containing liposomes with water soluble quantum dots CdSe/ZnS stored at a temperature of 45°C.

In the second stage synthesize the conjugate solution antivitamin antibodies with liposomes containing quantum dots.

To 0.4 ml of a solution containing liposomes with incorporated quantum dots - semiconductor nanoparticles CdSe/ZnS drip with constant stirring, add 0.5 ml of 2.5% solution of glutaraldehyde in water, after which the resulting solution is stirred for 4 hours at room temperature. The excess glutaraldehyde is removed by dialysis for 2 days at 4°C. Then drip with constant stirring for 2 hours at room temperature, add 20 ál of the solution antivitamin of antitel phosphate buffer (pH=7.4-7.6). Then add 60 ál of 3M glycine in sodium hydroxide solution (pH=7,2) to block the remaining free aldehyde groups of glutaraldehyde on the surface of liposomes. The resulting mixture was kept at 4°C with constant stirring. The excess unreacted components are removed by dialysis for 3 hours. The resulting conjugates are stored at 4°C.

To 1 ml of the analyzed medium is added 25 μl of a solution specific to the toxicant-zeralenone monoclonal mouse antibodies, stirred for 5 minutes and passed through prepared analogously to example 1 column 1, then column was washed with 1 phosphate buffer (pH=7.4÷7.6) containing 0.05% Tween 20.

Then, in column 1 was added 100 ál of the previously prepared solution of conjugate antivitamin antibody, chemically linked to a liposome containing a water-soluble luminescent semiconductor quantum dots (semiconductor nanoparticles CdSe/ZnS (1/30 dilution in phosphate buffer (pH=7.4÷7.6), and incubated for 6 minutes. The excess conjugate is removed by washing the column 1 phosphate buffer (pH=7.4÷7.6), after which a luminous flux coming from the source 3 of the exciting radiation, exercise light medium 2 containing luminescent semiconductor quantum dots (semiconductor nanoparticles, and register arisen as a result�e of the exciting radiation, the level of luminescence, the value of which is proportional to the concentration of toxicant-zearalenone in the analyzed environment.

Example 3. To determine the level of toxicant, such as zearalenone concentration in the analyzed environment (natural water) pre-prepare a solution in stages conjugate zearalenone with liposomes containing hydrophobic luminescent semiconductor quantum dots (semiconductor nanoparticles CdSe/ZnS, as follows.

In the first stage, 70 mg (94 mmol) of phospholipids (Lipoid S75), and 30 pmol of hydrophobic quantum dots (λem=577 nm) in toluene (52 ml) dissolved in 1 ml of chloroform in a round bottom flask (V=10 ml) when exposed to ultrasound at 4°C.

Then the resulting solution was added 3 ml of water and the chloroform was evaporated using a rotary evaporator. Thereafter, a further 3 ml of water and within 60 minutes mix the solution with the formed liposomes at 4°C.

The solution was then treated with ultrasound for 5 minutes to achieve an acceptable particle size of liposomes (100 nm). The resulting solution containing liposomes with hydrophobic quantum dots CdSe/ZnS, store at 4°C.

In the second stage, carry out the synthesis of conjugate antivitamin antibodies with liposomes containing hydrophobic quantum dots.

To 0.4 ml of a solution containing liposomes with incorporated�bubbled quantum dots - semiconductor nanoparticles CdSe/ZnS drip with constant stirring, add 0.5 ml of 2.5% solution of glutaraldehyde in water, after which the resulting solution is stirred for 3 hours at room temperature. The excess glutaraldehyde is removed by dialysis for 2 days at 4°C. Then drip with constant stirring for 2 hours at room temperature, add 20 ál of the solution antivitamin antibodies in phosphate buffer (pH=7.4-7.6). Then add 60 ál of 3M glycine in sodium hydroxide solution (pH=7,2) to block the remaining free aldehyde groups of glutaraldehyde on the surface of liposomes. The resulting mixture was kept at 4°C with constant stirring. The excess unreacted components are removed by dialysis for 3 hours. The resulting conjugates are stored at 4°C.

To 1 ml of the analyzed medium is added 25 μl of a solution specific to the toxicant-zeralenone monoclonal mouse antibodies, stirred for 5 minutes and passed through prepared analogously to example 1 column 1, then column was washed with 1 phosphate buffer (pH=7.4÷7.6) containing 0.05% Tween 20.

Then, in column 1 was added 100 ál of the previously prepared solution of conjugate antivitamin antibody, chemically linked to a liposome containing a hydrophobic fluorescent quantum dots - semiconductor nanoparticles CdSe/ZnS (1/30 dilution in phosphate buffer (pH=7.4÷7.6), and incubated for 10 minutes. The excess conjugate is removed by washing the column 1 phosphate buffer (pH=7.4÷7.6), followed by the lighting of the carrier 2 containing luminescent semiconductor quantum dots (semiconductor nanoparticles, a luminous flux coming from the source 3 of the exciting radiation, and record resulting from the exciting radiation, the level of luminescence, the value of which is proportional to the concentration of toxicant-zearalenone in the analyzed environment.

The claimed invention provides the possibility of determining the level of toxicants in water, food or physiological liquids by held in the column of the test system is a direct competitive enzyme-linked immunosorbent assay levels of toxicant with a limit of detection (sensitivity) 1÷3 ng/ml.

1. Method of determining the level of toxicants in water, food or physiological liquids by held in the column of the test system enzyme-linked immunosorbent assay, characterized by the fact that in the column of the test system is placed in the carrier, which is used as the activated solid phase of physical adsorption - activated porous substrate grafted with a covalently bound molecules of toxicant, production�DYT media processing with blocking solution for closing on the media remaining free places nonspecific binding, make test samples containing a certain number of previously entered specific to the toxicant antibodies, thus make processing media conjugational solution, which is used as the conjugate solution antivitamin antibody, chemically linked to a fluorescent quantum dots or with liposomes containing fluorescent quantum dots, and the level of toxicants is determined by the illumination of the processed media exciting radiation intensity of luminescence excited in the quantum dots.

2. A method according to claim 1, characterized in that the activated porous substrate is prepared by ultrasonic treatment made of pure polypropylene porous substrate placed in ethanol 96% ethyl alcohol, followed by clean - sequential passing through the porous membrane of 50% ethyl alcohol.

3. The test system for the method of determining the level of toxicants in water, food or physiological liquids according to claim 1, comprising a column with a carrier, characterized in that the carrier is made in the form of an activated solid phase of physical adsorption - activated porous substrate grafted with a covalently bound molecules of toxicant, wherein the column is provided with a device for level measurement LUMIN�sancii, including a source of exciting radiation, and a photodetector, and the photodetector is further established by the focusing optical system, and the output of the photodetector is electrically connected through a signal amplifier and an analog-to-digital Converter to the control unit controller, the output of which is connected to the display unit through the block and stabilize a source of exciting radiation, wherein the side wall of the column is made of transparent for the exciting and fluorescent radiation of the material.

4. Test system according to claim 3, characterized in that between the sensor and the focusing optical system of the device for measuring the level of luminescence can be placed filter.



 

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13 cl, 8 dwg

FIELD: food industry.

SUBSTANCE: determination method envisages weighing of a 2.0-5.0 g sample of marshmallow. One places the sample in a 1,000 ml measuring flask, adds 100-200 cm3 of 10 mmol/l solution of benzoic acid with temperature equal to 60-70°C. Then the mass is thoroughly stirred in a 75-85°C water bath during 10-20 min until complete dissolution of the sample. The solution is filtered through a paper filter and diluted to the marked volume with benzoic acid solution having concentration equal to 10 mmol/l and centrifuged during 10-15 min at a rate of 2500-3000 rpm. Then clear solution if transferred into a vessel for performance of organic acids composition study by capillary electrophoresis method with indirect detecting using a buffer solution. The buffer solution consists of 8-12 mmol/l of benzoic acid, 8-10 mmol/l of diethylamine, 0.45-0.55 mmol/l of cetyl trimethyl ammonium bromide, 0.05-0.10 mmol/l of ethylenediaminotetraacetic acid. The solution pH is 5.0-5.7. The capillar length is 50-97 cm with the capillary effective length being 43-90 cm while the capillary external diameter is 50-75 mcm. The sample is introduced within the range of values of pressure multiplied by introduction time 200-1000 mbar×s. Detecting is performed by means of a diode matrix detector with the thermostat temperature equal to 21-28°C and voltage equal to 15-30 kV. Calculation of the malic acid and tartaric acid peaks height is performed at wave length amounting to 230 nm. Then the apple puree weight fraction is determined from a certain mathematical formula.

EFFECT: invention allows to determine weight fraction of apple puree in marshmallow and reduce the study performance time.

1 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: method of determining fat-soluble vitamins A, D2, E and β-carotene which are present at the same time includes separating the fat-soluble vitamins from a substance by extraction with 96% ethanol, separating the alcohol extract of vitamins using a separating funnel, successive chromatography using Sorbfil PTSKH-P-A silica gel plates on a polymer substrate using two eluents with a different range, time of saturating the chamber with eluent vapour of 20 minutes and elution time of 55 min; drying the plates at temperature not lower than 80°C in a temperature-controlled chamber for 3-5 min, treating the plates with a developer - 5% alcohol solution of phosphatomolybdic acid; according to the invention, the eluents used are hexane:chloroform (19:1) and hexane:chloroform (3:1), and detection of the chromatographic zone of β-carotene is carried out before treating the plates with a developer in day light.

EFFECT: simpler and faster process of determining fat-soluble vitamins.

10 dwg, 3 ex

FIELD: chemistry.

SUBSTANCE: filler used is chromogenic ion-exchange dispersed silica with covalently grafted hydrazones or formazans.

EFFECT: high sensitivity and selectivity of detecting metals.

3 tbl, 4 dwg, 14 ex

FIELD: chemistry.

SUBSTANCE: method involves extracting polyphenols from a crushed tea sample; determining concentration of polyphenols in the extract by a colorimetric method using Folin-Ciocalteu reagent, wherein the extract is obtained using a crushed tea sample weighing 1.0-1.5 g and 50-75 cm3 water at 95-100°C; steeping for 5 minutes at room temperature and filtering; diluting the obtained extract with water 25 times, collecting 0.5-0.6 cm3 of the diluted extract; adding 3.0 cm3 of a 0.5 M Na2CO3 solution and 0.3 cm3 of Folin-Ciocalteu reagent and measuring optical density of the solution at wavelength 765 nm after 2-3 min; determining concentration of polyphenols in the diluted extract from a calibration curve of optical density of tannin solution versus weigh concentration of tannin in the solution; the amount of polyphenols in tea transferred into the aqueous extract is expressed through its weight fraction in the analysed tea sample X, % per dry substance, which is calculated using a formula.

EFFECT: faster analysis, reducing the number of simple operations and low consumption of reagents.

2 tbl, 2 ex

FIELD: food industry.

SUBSTANCE: method includes bread baking and sampling crumb of freshly baked bread and bread incubated at 37°C during 16-20 h. One prepares water extracts of alpha amylase of the collected bread crumb samples with further filtration of the extracts. Then one determines their fluidifying capacity (FC) by the rate of starch fluidification by alpha amylase using a device for determination of the falling number value. FC value is determined from the formula FC=FNkFNiFNk60s100% where FC - fluidifying capacity, %; FNk - starch falling number value with bread immediately after baling, sec; FNi - starch falling number value with bread having been stored, sec.

EFFECT: method enables precise diagnostics of potato disease 8-12 hours prior to appearance of its first organoleptic manifestations in bread.

1 dwg, 1 tbl, 1 ex

FIELD: food industry.

SUBSTANCE: method envisages the sample acid hydrolysis, the hydrolysate filtration and chromatographic separation with subsequent automatic identification and quantitative evaluation of amino acids content using an automatic analyser. The invention allows to determine amino acids in the food product proteins composition with amino acids content equal to nearly 0.1-3.5 g/100 g of the product (1.5-17 g/100 g of protein) with application of sequential elution of amino acids with a buffer solutions mixture and simultaneous detection of the components at two wave lengths being 440 and 570 nm.

EFFECT: acceleration of the process of amino acids isolation from the food product and determination accuracy enhancement due to losses decrease and highly sensitive material application.

2 tbl

FIELD: analytical methods in food industry.

SUBSTANCE: method comprises providing food sample, adding it to separating funnel with filter, adding extractant, stirring resulting mixture, separating miscella by aspiration from separating funnel, distilling extractant therefrom, removing non-lipid substances from extract lipids, and weighing lipids. Distinguishing feature of invention is that stirring of extract mixture is accomplished via throwing off pressure in separating funnel until pressure provides boiling of extractant, whereupon pressure is returned to its initial value.

EFFECT: increased productivity of examination due to accelerated recovery of lipids and significantly prolonged service time of filter.

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