RU2477469C1 - Honey quality control method - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: method involves quantitative determination of content of the chemical indicator i.e. hydrogen peroxide in honey; the hydrogen peroxide quantitative content is determined by iodometric reaction with potassium iodide; the quantity of iodide released in the form of complex anion I₃ ^- is registered by the electronic absorption spectroscopy method; the hydrogen peroxide content in honey is calculated in mg per kg which allows to distinguish natural honey from artificial honey because hydrogen peroxide content in natural honey is equal to no less than 4 mg/kg while hydrogen peroxide content in artificial honey is absent.

EFFECT: determination simplification and high sensitivity.

3 cl, 4 tbl

Description

The invention relates to methods for the analysis of food products, and in particular to methods for assessing the quality of honey, and can be used in the food industry to recognize a natural and falsified product, as well as in the practice of research work in the study of the biological properties of honey.

Bee honey is a highly nutritious food product with unique healing and bactericidal properties (Aganin A.V. Honey and his research. Saratov, Publishing House of Saratov University, 1985, 152 pp.). An in-depth interest in the properties of honey and attempts to explain their uniqueness have a long history.

However, there are big problems with the quality of bee honey consumed by the population in all countries. Information about the falsifications of honey first appeared back in 1855 (Amos Ruth in his Encyclopedia of Beekeeping (1876) cites Gassel's book “The Detection of Falsifications”, 1855). Over the past years, methods of falsification have been improved, and counterfeit honey has become difficult to distinguish from natural honey not only organoleptically, but also in laboratory tests, therefore, the problem of conducting a comprehensive examination of the quality of bee honey is currently becoming more acute.

There are a large number of methods for determining the quality of honey, but most of them are purely high-quality and uninformative (Chepurnoy IP. Examination of the quality of honey. Educational-methodical manual. M: publishing house "Dashkov and Co.", 2002).

Closest to the proposed method for controlling the quality of honey is a method for the quantitative determination of the content of oxymethylfurfural (OMF) in honey in accordance with GOST 19792-2001 (Interstate standard. Natural honey. Technical conditions - prototype). The method is based on colorimetric analysis of OMF in the presence of barbituric acid and para-toluidine. The method is as follows: prepare a 0.5% aqueous solution of barbituric acid (barbituric acid is pre-dried at 105 ° C for one hour), a 10% solution of para-toluidine in a 10% solution of acetic acid in isopropanol and 20 % aqueous solution of honey. In two clean, dry tubes, 2 cm ³ of honey solution and 5 cm ³ of para-toluidine solution are poured. 1 cm ^{3 of} distilled water is added to one tube, mixed and poured into a control cell. In another test tube add 1 cm ³ solution of barbituric acid, mix and fill the second cuvette. The extinction of the solution is measured and the OMF content in the honey sample is calculated. The content of OMF in 1 kg of honey should not exceed 25 mg.

The prototype method allows one to reliably recognize natural honey and evaluate its quality, since the content of OMF is the main criterion for determining the shelf life of bee honey and for detecting its falsifications (for example, the introduction of starch or beet molasses in bee honey leads to a sharp increase in the content of OMF) . The disadvantages of the prototype method are the complexity and duration, the need to use toxic and expensive reagents and high complexity.

The task of the invention is to develop a no less reliable way to control the quality of honey, but much less complex and time-consuming and characterized by high sensitivity.

регистрируют методом электронной абсорбционной спектроскопии и рассчитывают содержание пероксида водорода в меде в мг на кг, что позволяет отличать натуральный мед от искусственного, так как в натуральных медах содержание пероксида водорода составляет не менее 4 мг/кг, а в искусственном меде пероксид водорода отсутствует.The solution to this problem is achieved by the proposed method for controlling the quality of honey, including the quantitative determination of the chemical indicator in honey, in which hydrogen peroxide is used as a chemical indicator, the quantitative content of which in honey is determined by iodometric reaction with potassium iodide, and the amount of iodine released in the form of a complex anion

register by electronic absorption spectroscopy and calculate the hydrogen peroxide content in honey in mg per kg, which makes it possible to distinguish natural honey from artificial honey, since in natural honey, the content of hydrogen peroxide is at least 4 mg / kg, and there is no hydrogen peroxide in artificial honey.

The proposed method allows us to distinguish honey by botanical origin, since different botanical types of honey contain different amounts of hydrogen peroxide, namely: the content of hydrogen peroxide in linden honey is 9-14 mg / kg, in buckwheat honey - 8-10 mg / kg, forbs honey - 7-13 mg / kg, in clover honey - 5-6 mg / kg, in sunflower honey - 4-5 mg / kg.

The proposed method allows to distinguish honey by shelf life, since the content of hydrogen peroxide in natural honey decreases during storage at an average rate of 4.0 · 10 ^-4 to 7.0 · 10 ^-4 mg / kg · day, depending on the botanical origin.

Hydrogen peroxide (PV) is one of the main factors determining the bactericidal effect of honey. PV is formed in honey under the influence of glucooxidase, an enzyme produced by the pharyngeal glands of bees. The glucose oxidation catalyzed by glucose oxidase results in the formation of gluconic acid and PV (Aganin A.V. Honey and his research. Publishing House of Saratov University, 1985, p. 53; White JW, Subers MH Studies on Honey Inhibine. 2. A Chemical Assay. Journal of Apicultural Research, 2 (2), 1963, p. 93-100).

Known data on the content of PV in honey were obtained by a complex and laborious method requiring the use of expensive reagents: peroxidase enzyme and 3,3'-dimethoxybenzidine (White JW, Subers MH Studies on Honey Inhibine. 2. A Chemical Assay. Journal of Apicultural Research, 2 (2), 1963, p. 93-100). This method was used in scientific research in the study of the biological properties of honey, but it is unsuitable for expert assessment of honey.

.In the proposed method for controlling the quality of honey for the quantitative determination of the content of PV, the iodometric method was chosen. During the interaction of potassium iodide with PV in an acidic medium, molecular iodine is released, which forms an complex anion with an excess of iodide anion

.

In high-quality iodometric methods for the determination of oxidizing agents, including PV, the released iodine is fixed by the appearance of a blue color with a starch solution (see, for example, GOST 24067-80 Interstate Standard. Milk. Method for the determination of hydrogen peroxide). In quantitative methods, the released iodine is titrated with sodium thiosulfate solution, but starch is also used as an indicator, which leads to great difficulties in determining the equivalence point, since in this case it is titrated not until the color appears (as is usually the case), but until the color disappears, but the resulting compound of iodine with starch reacts very slowly with sodium thiosulfate and the analyzed solution can be easily titrated (S.K. Piskareva, K.M. Barashkov, K.M. Olshanova. Analytical chemistry. Textbook for secondary special education Institutions, 2nd ed. revised and extended - M .: Higher school, 1994, 384 pp.).

In the claimed method for controlling the quality of honey, the formed I ₃ ^- anion ^is detected by electronic absorption spectroscopy (registration wavelength λ _max = 351 nm, the molar extinction coefficient of solutions ε (I ₃ ^- ) = 26400 l · mol ^-1 · cm ^-1 ), which allowed to achieve high sensitivity of determination of PV - up to 0.1 mg PV per 1 kg of honey, which corresponds to 10 ^-5 % PV.

The proposed method is as follows.

). Затем с использованием типового спектрофотометра, настроенного на диапазон длин волн 300-800 нм, записывают электронные спектры каждого из образцов и проводят определение оптической плотности аналитических растворов (D) при значении длины волны 351 нм. Из найденного значения D необходимо вычесть собственное поглощение раствора соответствующего образца меда (D_м), аналогичным образом разбавленного дистиллированной водой, в том же спектральном диапазоне (либо использовать такой раствор в качестве сравнительной кюветы). (Измерение D позволяет определять концентрацию ПВ (С_ПВ) в аналитическом растворе в моль/л: С_ПВ=(D-D_м)/ε·l). В качестве «холостого опыта» для анализа вместо 1 мл раствора меда берут 1 мл дистиллированной воды и далее аналогично описанному подкисляют, обескислороживают, добавляют раствор иодида калия и выдерживают в темноте (в сравнительную кювету наливают дистиллированную воду).By rigging honey sample weighing 1 g (m _nav) was added distilled water to a volume of 2 ml (for rapid dissolution is possible to further use the mixing device). To 1 ml of the obtained honey solution (the remaining second 1 ml of this solution is used for parallel determination), 1 ml of a solution of sulfuric acid (0.2 mol / l) is added, purged with carbon dioxide or other heavy inert gas to displace oxygen and mixed with 2 ml of also deoxygenated 5% (mass.) Aqueous solution of potassium iodide, followed by repeated blowing with carbon dioxide. The resulting analytical solution (4 ml, containing 1/2 m _nav ) is left at a temperature of 20-22 ° C in the dark for a day (to ensure complete completion of the reaction of the released iodine with an excess of iodide anion to form a complex anion

) Then, using a typical spectrophotometer tuned to a wavelength range of 300-800 nm, the electronic spectra of each of the samples are recorded and the optical density of the analytical solutions (D) is determined at a wavelength of 351 nm. From the found value of D, it is necessary to subtract the intrinsic absorption of the solution of the corresponding honey sample (D _m ), similarly diluted with distilled water, in the same spectral range (or use such a solution as a comparative cell). (The measurement of D makes it possible to determine the concentration of PV (C _PV ) in the analytical solution in mol / L: C _PV = (DD _m ) / ε · l). As a “blank experiment” for analysis, instead of 1 ml of honey solution, 1 ml of distilled water is taken and then acidified, deoxygenated as described, potassium iodide solution is added and kept in the dark (distilled water is poured into a comparative cuvette).

The PV content in honey in mg per kg (ω) is calculated by the formula:

ω = [(DD _m ) / ε · l] · M / m _nav · V · 1000,

Where

D is the spectrophotometer reading for the analytical solution of honey at a wavelength of 351 nm;

D _m - spectrophotometer reading at a wavelength of 351 nm for a control solution of honey (without adding reagents);

, ε=26400 л·моль^-1·см^-1);ε is the molar repayment ratio

, ε = 26400 l · mol ^-1 · cm ^-1 );

l is the width of the cell, cm;

M is the molar mass of PV, g / mol (34 g / mol);

m _nav - a hinge of honey, g;

V is the volume of the solution containing a hinge of honey m _nav , ml (V = 8 ml);

1000 is a coefficient for converting the PV content in honey in mg per kg.

The proposed method was developed as a result of the study of a large number of samples of natural bee honey of various botanical and territorial origin, as well as samples of artificially prepared honey. The objects of study were natural honey samples from the laboratory of veterinary sanitation in beekeeping GNU VNIIVSGE, selected for examination and certification for further implementation at the Moscow Spring Fair 2011, and artificial honey samples prepared in this laboratory. Honey samples were taken according to GOST 19792-2001 “Natural honey. Technical conditions. " The quantitative content of PV was determined at the IHP RAS. A total of 92 honey samples were examined.

Table 1 shows the results of a quantitative determination of PV in honey samples of various botanical and territorial origin, as well as artificial honey.

Table 1 The content of PV (mg / kg) in various honey. No. p / p Test samples of honey The amount of PV, mg / kg one Donnikovy (Saratov Region) 5.68 2 Buckwheat (Kursk region) 8.54 3 Donnikovy (Volgograd region) 5.70 four Lipovy (Saratov Region) 10.85 5 Linden (Krasnodar Territory) 10.97 6 Buckwheat (Kursk region) 9.85 7 Sunflower (Rostov Region) 5.30 8 Sunflower (Krasnodar Territory) 4.30 9 Sunflower (Krasnodar Territory) 4.86 10 Sunflower (Krasnodar Territory) 4.50 eleven Buckwheat (Voronezh region) 8.03 12 Buckwheat (Kursk region) 8.70 13 Linden (Mari El Republic) 9.40 fourteen Linden (Vyatka) 9.04 fifteen Lipovy (Saratov Region) 14.25 16 Forest Forbs 7.20 17 Taiga forbs 7.00 eighteen Meadow grass 13.50 19 Artificial honey №1 0.10 twenty Artificial honey №2 0 21 Artificial honey №3 0 22 Artificial honey №4 0.09 23 Artificial honey №5 0

As can be seen from table 1, the maximum amount of PV determined in samples of artificial honey does not exceed 0.1 mg / kg (usually the measurement result did not differ from the control sample containing no honey), which is within the sensitivity of the method, while the amount of PV in the samples natural honey ranged from 14.25 to 4.30 mg / kg, that is, the proposed method allows you to reliably distinguish between natural and artificial honey, which is an extremely important criterion for expert evaluation of honey.

From the presented data it is seen that honey of various botanical origin contains a different amount of PV. The largest amount of PV is found in linden and meadow honey, the smallest - in sunflower. It is significant that the amount of PV in samples from different territories, but of the same botanical origin, is similar in quantitative values, that is, the proposed method allows us to distinguish honey by botanical origin.

It is known that during storage or when heated, the bactericidal effect of honey weakens (Aganin A.V. Honey and his research. Publishing House of Saratov University, 1985, p. 54). We have studied the effect of shelf life, heating and exposure to daylight on the content of PV in various honeys.

Measurements were taken after 1, 5, 6, 7, 8, and 9 months from the date of pumping (see table 2). At the same time, the kinetics of the decrease in PV in the samples was studied and the rate of decrease in the concentration of PV in the honey of different botanical origin was calculated.

As a result of the studies, it was found that the rate of decrease in PV in all tested botanical types of honey, except linden (initially containing the largest amount of PV), increases markedly during storage, as can be seen from a comparison of the decrease in PV content in the first 6 months of storage and the average speed for 9 months of storage (see table 2). As can be seen from table 2, after 9 months of storage, the PV content in various types of honey decreased by at least 50%, which allows us to use the proposed method for estimating the shelf life of honey.

Table 3 shows the results of a study of the effect of heating (in a water bath at 95 ° C for 4 hours) on the PV content in honey samples.

From the data of table 3 it is seen that after heating the honey samples, the PV content sharply decreases, since under the influence of high temperatures there is a rapid decomposition of the existing PV.

table 2 The PV content (mg / kg) in various honey depending on the duration of storage. The rate of decrease in PV content (mg / kg · day). No. p / p Test samples of honey The amount of PV (mg / kg) depending on the shelf life (month) The rate of decrease in the content of PV, mg / kg · day one 5 6 7 8 9 Average for the first 6 months. Average for 9 months. one Buckwheat (Kursk region) 8.5 7.0 6.7 6.6 4.9 4.5 12 · 10 ^-4 15 · 10 ^-4 2 Lipovy (Saratov Region) 10.8 8.4 7.0 6.1 4.8 4.0 23 · 10 ^-4 21 · 10 ^-4 3 Donnikovy (Volgograd region) 6.0 5.7 3.7 2.8 2.1 2.0 14 · 10 ^-4 15 · 10 ^-4 four Sunflower (Rostov Region) 5.3 4.5 3.9 3.6 3.2 2.9 6.2 · 10 ^-4 9.8 · 10 ^-4 5 Forbs (forest) 7.0 7.0 5.3 4.0 2.1 2.1 11 · 10 ^-4 24 · 10 ^-4

Table 3 The effect of heating honey on the content of PV. No. p / p Test samples of honey The amount of PV before heating, mg / kg The amount of PV after heating, mg / kg one Linden (Krasnodar Territory) 11.0 1.9 2 Sunflower (Rostov Region) 4.9 0.2 3 Sunflower (Krasnodar Territory) 4.3 0.2 four Sunflower (Krasnodar Territory) 4.9 1.4 5 Buckwheat (Kursk region) 8.7 2.4 6 Linden (Vyatka) 9.0 1.5

Table 4 shows the results of a study of the effect of daylight irradiation on the PV content in honey samples: honey samples of various botanical origin were stored at room temperature for 4 months in the dark and in the light (illumination close to domestic conditions).

Table 4 The effect of daylight on the content of PV in honey samples. No. p / p The botanical origin of honey The amount of PV when stored in the dark, mg / kg The amount of PV when stored in the light, mg / kg one Lugovoi 13.3 4.9 2 Linden 14.3 9.9 3 Sage 5.1 2.9 four Donnik 6.0 5.1

From the data of table 4 it can be seen that after irradiation of honey samples with daylight in all the studied cases, but not as sharply as during heating or long-term storage, the PV content decreases.

Thus, the proposed method for controlling the quality of honey makes it possible to reliably distinguish between natural and artificial honey, makes it possible to distinguish honey by botanical origin, and makes it possible to evaluate the degree of preservation by honey of its natural healing properties, since it makes it possible to identify a product that has undergone prolonged storage or lighting, or even a single heating. The method is highly sensitive - 10 ^-5 % PV - and at the same time it is simpler, less time consuming and does not require the use of toxic and expensive reagents.

Claims (3)

1. A method for controlling the quality of honey, including quantifying the content of a chemical indicator in honey, characterized in that hydrogen peroxide is used as a chemical indicator, the quantitative content of which in honey is determined by iodometric reaction with potassium iodide, while the amount of iodine released is in the form of a complex anion

register by electronic absorption spectroscopy and calculate the hydrogen peroxide content in honey in mg per kg, which makes it possible to distinguish natural honey from artificial honey, since in natural honey, the content of hydrogen peroxide is at least 4 mg / kg, and there is no hydrogen peroxide in artificial honey. 2. The method according to claim 1, characterized in that it allows you to distinguish honey by botanical origin, since different botanical types of honey contain different amounts of hydrogen peroxide, namely: the content of hydrogen peroxide in linden honey is 9-14 mg / kg, buckwheat honey - 8-10 mg / kg, for herbal honey - 7-13 mg / kg, in clover honey - 5-6 mg / kg, in sunflower honey - 4-5 mg / kg. 3. The method according to claim 1, characterized in that it allows you to distinguish honey by shelf life, since the content of hydrogen peroxide in natural honey during storage decreases with an average speed of 4.0 · 10 ^-4 to 7.0 · 10 ^{- 4} mg / kg · day, depending on the botanical origin.