RU2341793C1 - Method of measuring humidity of stock cubes, dry bouillons and soup bases - Google Patents

Abstract

FIELD: analytical chemistry.

SUBSTANCE: method includes using static "electronic nose", whose matrix is formed from 2 weight-sensitive piezo-sensors, whose electrodes are modified by even application of film of acetone solutions of polyethylene glycol PEG-2000 and polyvinylpyrrolidone, and subjected to drying. Modified weight-sensitive piezo-sensors are fixed in holders on cover and put in bode of static "electronic nose". Completeness of removal of free solvents from films is controlled by constancy of fluctuations of weight-sensitive piezo-sensors, then sample of stock cube, dry bouillon or soup base is taken, heated, crushed thoroughly and mixed, placed into weighing bottle with polyurethane membrane on cover. Sample is kept in weighing bottle during 10-15 minutes. After saturation of gas phase with water vapours through polyurethane membrane sample of equilibrium gas phase is taken with 3-5 cm³ syringe, which is quickly injected into body of static "electronic nose". Frequency of fluctuations of weight-sensitive piezo-sensors is fixed, total analytic signal is formed in form of kinetic "visual print" and is compared with standards. Area of figure S_"в.а" is calculated and humidity of sample ω % is determined using calibrating diagram drawn in coordinates S_"в.а"=f (ω, wt %).

EFFECT: high expressiveness, reliability, accuracy, objectivity and simplicity of determining.

3 dwg

Description

The invention relates to analytical chemistry of food products and can be used to determine the moisture content of bouillon cubes, dry broths and soup bases using a static "electronic nose".

An object of the invention is to develop a method for determining the moisture content of bouillon cubes, dry broths and soup bases using a static "electronic nose", which provides high reliability, accuracy, objectivity, simplicity and expressiveness of determination.

The technical problem is achieved in that a method for determining the moisture content of broth cubes, dry broths and soup bases, characterized in that it involves the use of a static "electronic nose", the matrix of which is formed from two mass-sensitive piezosensors, the electrodes of which are modified by uniformly applying a film of acetone solutions of polyethylene glycol PEG-2000 and polyvinylpyrrolidone are dried at a temperature of 40-45 ° C for 15-20 minutes, and the mass of the dried film should be 10-15 μg, mod The fixed mass-sensitive piezosensors are fixed in the holders on the lid and placed in the body of a static "electronic nose", the completeness of removal of free solvents from the films is controlled by the constant frequency of oscillations of the mass-sensitive piezosensors, then a sample of the bouillon cube, dry broth or soup base weighing 2- is taken. 3 g, heat it up to 20 ± 2 ° С, thoroughly grind and mix, place it in a bottle with a volume of 20 ± 5 cm ³ with a polyurethane membrane on the lid, hold the sample in a bottle for 10-15 minutes, after saturation the gas phase of water vapor through a polyurethane membrane is taken with a syringe 3-5 cm ^{3 of the} equilibrium gas phase, it is quickly injected into the body of a static "electronic nose", the oscillation frequency of the mass-sensitive piezosensors is fixed for 3-4 minutes, the total analytical signal is formed in the form of a kinetic “Visual imprint” and compare it with the standards, calculate the area of the figure S _in.a. and determine the moisture content of the sample ω% using a calibration graph constructed in the coordinates S _v.a = f (ω, wt.%).

The technical result consists in the development of a method for determining the moisture content of bouillon cubes, dry broths and soup bases using a static "electronic nose", consisting of mass-sensitive piezosensors, which can reduce the time taken to determine (analysis time does not exceed 25 minutes); to increase the accuracy, objectivity of measurement and the reliability of the determination of even small amounts of moisture; provide easy processing of results and decision making.

Figure 1 - kinetic "visual imprints" of standard samples:

standard 1 - Maggi dry chicken cube;

standard 2 - chicken bouillon cube “Galina Blanca” dry;

standard 3 - chicken bouillon cube "Maggi" permissible humidity;

standard 4 - chicken bouillon cube "Galina Blanca" permissible humidity.

Figure 2 - kinetic "visual imprints" of the analyzed samples of chicken broth cubes (example):

Sample 1, Sample 3 - Maggi chicken broth cubes;

Sample 2, sample 4 - Galina Blanca bouillon cubes.

Figure 3 is a calibration graph for determining the humidity of the bouillon cubes (for example).

The method for determining the humidity of bouillon cubes, dry broths and soup stems is implemented as follows.

The static "electronic nose" matrix is formed from two mass-sensitive piezosensors, the electrodes of which are modified by uniformly applying a film of acetone solutions of PEG-2000 polyethylene glycol and polyvinylpyrrolidone (standard stationary phases for gas chromatography), and they are dried at a temperature of 40-45 ° С for 15 -20 minutes, the mass of the dried film should be 10-15 μg, the modified mass-sensitive piezosensors are fixed in the holders on the lid and placed in the body of a static "electronic nose", the removal of free solvents from the films is controlled by the constant frequency of oscillations of mass-sensitive piezosensors, then a sample of the bouillon cube, dry broth or soup base weighing 2-3 g is taken, heated to 20 ± 2 ° C, thoroughly crushed and mixed, placed in a box volume 20 ± 5 cm ³ with a polyurethane membrane on the lid, the sample is kept in a bottle for 10-15 minutes, after saturation of the gas phase with water vapor through a polyurethane membrane, a 3-5 cm ³ equilibrium gas phase is taken with a syringe, which is quickly injected into the body static "electronic nose", fix the oscillation frequency of mass-sensitive piezosensors for 3-4 minutes, the total analytical signal is formed in the form of a kinetic "visual imprint" and compared with standards, figure square S _{v.a is calculated.} and determine the moisture content of the sample ω% using a calibration graph constructed in the coordinates of S _century.a = f (ω, wt.%).

The regeneration of the sorbents and the detection cell is carried out with dried laboratory air supplied to the cell using a compressor for 10-20 s.

The method is illustrated by the following example.

Example. We demonstrate the feasibility of the method by the example of analysis of chicken broth cubes "Maggi" and "Galina Blanca".

The matrix of a static “electronic nose” is formed from two mass-sensitive piezosensors with a natural oscillation frequency of 10.5 MHz, the electrodes of the piezosensors are modified with acetone solutions (PEG-2000 polyethylene glycol and polyvinylpyrrolidone) so that after drying at 40 ° C for 15 minutes the mass of the films was 15 μg. Modified mass-sensitive piezosensors are fixed in holders on the lid and placed in the body of a static “electronic nose”. The completeness of removal of free solvents from the films is controlled by the constancy of the oscillation frequency of the mass-sensitive piezosensors (drift of not more than 5 Hz / min).

Selected as an example to demonstrate the capabilities of the proposed method, samples of bouillon cubes of various humidity are placed in glasses, heated to 20 ± 2 ° C, thoroughly knead, stirred with a glass rod and 2 g of each sample is taken. A sample of each sample is placed in a 20 cm ³ bottle with a polyurethane membrane on the lid. The sample in the bottle is kept for 10 minutes, after saturation of the gas phase with water vapor through a polyurethane membrane, a 3 cm ³ equilibrium gas phase is taken with a syringe.

The equilibrium gas phase of the sample of the standard standard bouillon cube of various humidity is introduced into the casing of the static “electronic nose” with a syringe. To build a calibration graph (figure 3), the humidity is determined gravimetrically.

The responses of mass-sensitive piezosensors are recorded with a frequency meter for 3 minutes. The total analytical signal is formed in the form of kinetic "visual imprints" - standards (figure 1).

The regeneration of sorbents and detection cells after each sample is carried out by purging with dried laboratory air for 10 s.

Equally analyze the equilibrium gas phases of the bouillon cubes selected for testing. The kinetic “visual prints” obtained for them (Fig. 2) are compared with the standards; if necessary, the humidity is found according to the calibration curve (Fig. 3).

The results of the analysis of the bouillon cubes "Maggi" and "Galina Blanca" no the claimed method are presented in the table.

Table The results of the analysis of samples of bouillon cubes by the present method Sample Name Compliance Moisture content, % "Maggi" (storage conditions were observed) corresponds to one "Maggi" (storage conditions not observed) does not match 5.2 "Galina Blanca" (storage conditions were observed) corresponds to 1,2 Galina Blanca (storage conditions not observed) does not match 4.7

The analysis time, taking into account sample preparation, is 25 minutes, the measurement time is 3 minutes, the number of measurements without updating the films on the sensor electrodes is 100. The duration of the film deposition step on the electrodes of mass-sensitive piezosensors does not exceed 45 minutes.

The method is feasible. It is possible to determine the humidity of bouillon cubes, dry broths and soup bases in a wide range of humidity.

As follows from the example, FIGS. 1, 2, 3 and tables, the proposed method allows the use of a static “electronic nose” to measure the humidity of the bouillon cubes, dry broths and soup bases, the matrix of which is formed from two mass-sensitive piezosensors, the electrodes of which are modified uniformly by applying a film of acetone solutions of PEG-2000 polyethylene glycol and polyvinylpyrrolidone, they are dried at a temperature of 40-45 ° C for 15-20 minutes, the mass of the dried film should be 10-15 μg, modified mass-sensitive Piezosensors are fixed in the holders on the lid and placed in a static “electronic nose” case, the completeness of removal of free solvents from the films is controlled by the frequency of oscillations of the mass-sensitive piezosensors, then a sample of the bouillon cube, dry broth or soup base weighing 2-3 g is taken it is heated to 20 ± 2 ° C, thoroughly crushed and mixed, placed in a bottle with a volume of 20 ± 5 cm ³ with a polyurethane membrane on the lid, the sample is kept in the bottle for 10-15 minutes, after the gas phase is saturated with water vapor through the polyurethane membrane is taken with a syringe of 3-5 cm ^{3 of the} equilibrium gas phase, which is quickly injected into the body of the static "electronic nose", the oscillation frequency of the mass-sensitive piezosensors is fixed for 3-4 minutes, the total analytical signal is formed in the form of a kinetic "visual imprint" and compare it with the standards, calculate the area of the figure S _v.a. and determine the moisture content of the sample ω% using a calibration graph constructed in the coordinates of S _century.a = f (ω, wt.%).

A change in the mass of films on the electrodes of mass-sensitive piezosensors, the nature of sorbents, algorithms for processing the responses of piezosensors leads to an increase in the analysis error, a small difference in the “visual prints” of the standards and the analyzed samples, worsens the metrological characteristics of the method.

The proposed method for measuring the humidity of bouillon cubes, dry broths and soup bases allows you to:

- use the statistical "electronic nose" to determine moisture;

- increase the rapidity of determination (analysis time does not exceed 15 minutes);

- increase the accuracy, objectivity of measurement;

- increase the reliability of the determination of even small amounts of moisture and a slight change in its content in the sample;

- simplify the processing of results and decision making.

No analogues found.

Claims (1)

A method for determining the humidity of bouillon cubes, dry broths and soup bases, characterized in that it involves the use of a static "electronic nose", the matrix of which is formed from 2 mass-sensitive piezosensors, the electrodes of which are modified by uniformly applying a film of PEG-2000 polyethylene glycol acetone solutions and polyvinylpyrrolidone, is dried at a temperature of 40-45 ° C for 15-20 minutes, and the mass of the dried film should be 10-15 μg, modified mass-sensitive piezosens The rods are fixed in the holders on the lid and placed in the case of a static “electronic nose”, the completeness of the removal of free solvents from the films is controlled by the constancy of the oscillation frequency of the mass-sensitive piezosensors, then a sample of the bouillon cube, dry broth or soup base weighing 2-3 g is taken, heated it is up to 20 ± 2 ° С, thoroughly crushed and mixed, placed in a bottle with a volume of 20 ± 5 cm ³ with a polyurethane membrane on the lid, the sample is kept in the bottle for 10-15 minutes, after the gas phase is saturated with water vapor through a polyurethane meme the brane is taken with a syringe 3-5 cm ^{3 of the} equilibrium gas phase, which is quickly injected into the body of the static "electronic nose", the oscillation frequency of the mass-sensitive piezosensors is fixed for 3-4 minutes, the total analytical signal is formed in the form of a kinetic "visual imprint" and compared him with the standards, calculate the area of the figure S _v.a and determine the moisture content of the sample ω% using a calibration graph constructed in the coordinates S _v.a = f (ω, wt.%).

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