SU1275289A1 - Method of determining content of aluminium in meat foodstuffs - Google Patents

Abstract

The invention relates to methods for controlling the quality of food products: and can be used in the food industry for the sanitary assessment of canned meat products in aluminum containers. Improving the accuracy of determining the aluminum content in meat products is achieved by mineralizing the product sample by calcining (dry method), dissolving the mineral part in dilute hydrochloric acid, and correcting the pH of the solution using a bromocresol green-methyl red mixed indicator. After the complexing agent has been introduced, the mixture is kept at room temperature for 15–20 minutes, chloroform of the formed complexes of interfering metals is extracted by chloroform, injected into a solution of 8-hydroxy (L n line and extracted with hydroxyquinolate from aluminum. The amount of aluminum is determined by photometric measurement extract with the use of a pure extractant (chloroform) as a comparison solution. SP II 2 tab., 1 ill. to cx

Description

The invention relates to methods of foam-enhancing heating to carbonization of food quality control and can be used in the food industry for the sanitary-chemical evaluation of canned meat products in aluminum containers.

The purpose of the invention is improving the accuracy of determination.

The essence of the proposed method for determining the aluminum content in meat food products is that the mineralization of the product sample is carried out by calcination (dry method), then the mineral part is dissolved in dilute hydrochloric acid, the pH of the solution is adjusted using a mixed indicator of bromocresol green - methyl red. After the introduction of the complexing agent, the mixture is kept at room temperature for 15 to 20 minutes, stage-by-stage chloroform extraction of the resulting interfering metal complexes is carried out, 8 ~ hydroxyquinoline is introduced into the solution, and aluminum hydroxyquinolate is extracted.

The determination of the amount of aluminum is carried out by photometry of the obtained extract using pure extractant (chloroform) as a comparison solution

The use of a mixed indicator allows for maximum accuracy in the correction of pH, (there is a clear transition of color), which increases the accuracy of determining the aluminum content in products,

The exposure of the mixture after the introduction of the complexing agent at room temperature for 15-20 minutes allows you to completely complete the complexation reaction and in the future to ensure the completeness of separation of interfering metals during the shorter extraction time.

Mineralization of the sample by the dry method (instead of wet by the known method) allows, along with increasing the accuracy of the analysis, to reduce environmental pollution by toxic waste and reduce the complexity of the method.

Example I. A sample of .25 g, taken from an average sample of canned meat with an accuracy of 0.01 g, is placed in a quartz cup (crucible) and heated on an electric stove, stening the product and stopping smoke emission. Then, the cup was placed in a muffle furnace at 250 ° C, increase tempera5 round oven at 50 ^Q C every 7 'min to 450 ° C and continue heating the product to form a gray ash, the cups are removed from the oven, cooled in air to room temperature, the wetted ash with a few drops of concentrated nitric acid, and then heated on an electric stove until it stops, acid vapor is released. ”The cup is transferred back to the oven at 250 ° C, the oven temperature is brought to 450 ° C and the ash is calcined for 1 hour. If necessary, treatment with nitric acid and n okalivanie repeated to obtain without loi or colored ash containing no carbon particle. The ash cup is cooled, 5 cm ³ of hydrochloric acid solution (1 + 1) is added, and the acid is evaporated on a tile until wet salts are obtained. Then the ash is dissolved in 0.1 And hydrochloric acid, the ash solution is transferred to a 50 cm ³ volumetric flask and the solution volume is adjusted to the mark using the same acid.

An aliquot of the ash solution, containing approximately 5–20 μg of aluminum, is placed in a short-nose separatory funnel, 1 cm ^{3 of a} 1M solution of acetic acid and two drops of an indicator prepared by mixing 0.1% alcohol solution of bromocresol green and 0 , 2% alcohol solution of metipa red (3 + 1). Then, an aqueous solution of ammonia (1 + 1) is added dropwise to the funnel until the color of the indicator changes from pink to green, 10 cm ^{3 of} ammonium acetate buffer pH 5.2, prepared by interfering in the cold for 36 vol. distilled water, 25 vol.h. concentrated aqueous ammonia and 40 vol.h. glacial acetic acid and bring distilled water to a mixture volume of 50 cm ³ . After that, 2 cm ^{3 of a} freshly prepared 3% aqueous solution of sodium diethyldithiocarbamate are added to the funnel, stirred, left to stand for 15 minutes, and then complexes of interfering metals are extracted with chloroform. To do this, add 10 cm ^{3 of} chloroform to the funnel, shake vigorously for 0.5-1 min, and after separating the layers, the lower layer is drained and discarded. The extraction is carried out three times, then the funnel is shaken slightly and the aqueous layer is left for 10 15 minutes to completely separate the organic phase, after which the settled drops of chloroform are drained. The funnel 10 make see ^e 1% solution of 8-hydroxyquinoline in chloroform, the mixture was shaken for 5 minutes and after separating the layers, Yu bottom layer is drained through a cotton filter, embedded in the spout of the funnel, a photometric cuvette. The optical density of the extract is measured against chloroform on a 15 ^P P spectrophotometer ^and a wavelength of 385 nm or on a photoelectrocolorimeter with a blue filter (1 _max = 400 ± + 5 nm).

To calculate the amount of aluminum, 20 use a calibration graph obtained by the above test method on standard solutions with an aluminum content of 20 μg in the sample. 25

The drawing shows a calibration graph for the determination of aluminum with 8-hydroxyquinoline, state 1 - measurement using a blind sample as a comparison solution; Zo 2 - measurement using a pure solvent (chloroform) as a comparison solution.

In the table. 1 shows the dependence of the turbidity of the reaction mixture after making sodium diethyldithiocarbamate on the exposure time at room temperature.

The turbidity in this case is caused by the formation of a suspension of interfering metal insoluble diethyl dithiocarbamates in water (iron, zinc, copper, etc.). Measurements are taken on a photoelectrocolorimeter, model USh (GDR). 45

In the table. 2 shows the results of determining the amount of aluminum in canned meat from Butuz chickens after adding standard aluminum solution.

The sensitivity of the method is 5 μg of aluminum in urobe or 0.5 μg / kg. The average discrepancy between the two parallel definitions is 6%.

The proposed method makes it possible to control the transition of metal into a product during the development and storage of canned meat products in aluminum containers (the maximum allowable aluminum content in meat products is 10 mg / kg).

The application of the proposed method improves the safety of meat food products from the sanitary-chemical point of view, and also reduces environmental pollution by toxic waste.

Claims (1)

The invention relates to methods for controlling the quality of food products and can be used in the food industry for sanitary and chemical evaluation of canned meat products in aluminum containers. The purpose of the invention is to improve the accuracy of determination. The essence of the proposed method for determining the content of AP 01-1I1 in meat food products is that the mineralization of the product sample is carried out by the calcination method (dry method). Then the mineral part is dissolved in dilute hydrochloric acid; pH of the solution was adjusted using a bromcresol green methyl red red mixing indicator. After the introduction of the co-complexing agent, the mixture is kept at room temperature for 15-20 minutes, chloroform of the complexes formed from the complexes are carried out with chloroform, their metals are injected into a solution of 8-hydroxy iiiioline and extracted with hydroxyquinolate alumi ni. The determination of the amount of aluminum is carried out by photometry of a scoop extract with the use of pure extractant (chloroform) as a comparison solution. The use of a mixed indicator ensures maximum accuracy with respect to pH correction, (there is a clear color change). om i-p-5 in products, After the mixture was injected into a microcompactor at room temperature for 15--20 min, the mixture was completely reassured for complexation and further chit completeness of separation of interfering-p .gih metals for time-ekstraksch 5i "mineralization process samples (instead of the known wet method) allows bunks with ds povpieniem analysis accuracy lower nennost okrrkayuschey contaminated by toxic waste and reduce the complexity of the method. Example I, A weighed portion of 25 grams, 3 h of carcasses from an average sample of canned food with an accuracy of 0.01 g, is placed in a quartz cup (crucible) and heated on a hotplate, gradually increasing the heat until charring of the product and cessation of excretion / smoke. The cup is then placed in a muffle furnace. The oven temperature is increased by 50 ° C every 30 minutes to 450 ° C and the product is heated until the formation of sulfur ash. The cup is removed from the oven, cooled in air to room temperature, the ash is moistened with several drops and concentrated nitric acid, and then heated on a hotplate; until the release of acid vapors stops. The cup is transferred back to the oven at 250 ° C, the oven temperature is adjusted to 450 ° C and the ash is calcined for 1 hour. If necessary, treatment with nitric acid and calcination is repeated until white or colored ash containing no coal particles is obtained. The ash cup is cooled, 5 cm hydrochloric acid solution (1 + 1) is added and the acid is evaporated on a hotplate to form wet salts. The ash is then dissolved in 0.1 M hydrochloric acid, the ash solution is transferred to a 50 cm volumetric flask and the volume of the solution is adjusted to the mark with the same acid. An aliquot of the ash solution, presumably containing 5–20 µg of aluminum, is placed in a separating funnel with a short spit, 1 cm of 1 M acetic acid solution is added, and two drops of the indicator prepared by mixing a 0.1% alcoholic solution of broth-tetrasol green and methyl alcohol red (3 + 1). Then, a solution of ammonia (1 + 1) is added dropwise to the funnel until the indicator turns from pink to green, 10 cm of ammonium acetate buffer, pH 5.2j, prepared by mixing in the cold 36 parts by hour. distilled WATER 25 ob.h. concentrated aqueous ammonia and 40 vol / h, glacial acetic acid; the acids were not brought distilled water to a mixture of 50 cm. After that, 2 sc are introduced into the funnel: freshly prepared 3% aqueous solution of sodium diethyl dithiocarbamate solution, stirred, settled for 15 min, and then complexes of interfering metals are extracted with chloroform. To do this, add 10 cm of chloroform to the funnel, vigorously shake 0.5-1 i-mb and, after separating the layers, the lower layer is drained. And discarded. The extraction is carried out three times, the funnel is then shaken gently and the aqueous layer is left for 10-15 minutes to completely separate the organic phase, and then the precipitated chloroform droplets are drained. Shake the mixture vigorously with 10 cm of a 1% solution of 8-hydroxyquinoline in chloroform, shake the mixture for 5 minutes and, after separating the layers, drain the bottom layer through a cotton filter inserted into the new funnel into the cell for photometry. The optical density of the extract is measured against chloroform on a spectrophotometer at a wavelength of 385 nm or on a photoelectric spectrometer with a blue filter (i "ax + 5 nm). To calculate the amount of aluminum, use the calibration schedule obtained by the above test method on standard solutions with an aluminum content of 20 µg in the sample. The drawing shows the calibration. a graph for the determination of aluminum with 8-hydroxyquinoline, state 1 — measurement using a blind test as a comparison solution; 2 - measurement using a pure solvent (chloroform) as a comparison solution. In tab. Figure 1 shows the dependence of the turbidity of the reaction mixture after the outside of sodium diethyldithiocarbamate on exposure time at room temperature. Turbidity in this case is due to the formation of a suspension of water-insoluble diethyldithiocarbamate interfering metals (iron, zinc, copper, etc.). Measurements are carried out on a photoelectric colorimeter, model USh (GDR). In tab. Figure 2 shows the results of determining the amount of aluminum in canned food from Butter 894 after adding additives to the standard aluminum solution. The sensitivity of the method is 5 µg aluminum in tipo6e or 0.5 µg / kg. The mean difference between parallel determinations is 6%. The proposed method makes it possible to control the transition of the metal into the product during the production and storage of canned meat in aluminum containers (the maximum permissible content of aluminum in meat products is 10 mg / kg). The application of the proposed method improves the safety of meat products from a sanitary-chemical point of view, as well as reduces environmental pollution by toxic waste. The invention The method of determining the aluminum content in meat products, including sampling, its mineralization, dissolving the mineral part, correcting the pH of the solution using an indicator, introducing the complexing agent, multistage chloroform extraction of the formed metal complexes that interfere with the determination of aluminum, introducing 8-hydroxyquinoline in the solution, extraction obtained aluminum hydroxyquinol and determination of the amount of aluminum by photometry of the obtained extract, characterized in that to increase the accuracy of determination, the sample is mineralized by calcining, the mineral part is dissolved with dilute hydrochloric acid, at J3TOH, a mixed indicator of bromocresol green - methyl red is used for pH correction, and after introducing the complexing agent, the mixture is additionally kept at room temperature for 15–20 minutes . I About I 0.5 I 12 Time, Ftn Turbidity, units, scale absorbs 4552 55 13 Table 1 25 20 Table 2 I 3 I 5 I 10 15 57.5 60 64 6869 69