JPH0814559B2 - Simple method for measuring carbonyl value - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for measuring a carbonyl value derived from a carbonyl group of fats and oils, for example, a simple method for measuring a carbonyl value of animal / vegetable fats and oils, mineral oils and the like.

(Prior art and its problems) Various methods have been proposed as a method for evaluating deterioration of fats and oils (eg, animal oil, vegetable oil, fat, fatty substance, etc.) and mineral oil, but typical ones have been proposed. And as a reliable method, there is a measurement of a carbonyl value mainly derived from a carbonyl group. As a quantification method, there is a method by absorption of ultraviolet rays and infrared rays caused by = CO, but this method is difficult to measure when the ratio of carbonyl groups is small.

The carbonyl value of fats and oils has an important meaning as an index of oxidative deterioration of fats and oils. For example, triacylglycerol, which is a kind of neutral fats and oils, is an ester bond of one molecule of glycerol with three molecules of fatty acid, and this fatty acid is oxidized by oxygen in the air to form hydroperoxide as a primary product. . This is further decomposed into hydrocarbons,
Produces organic acids and carbonyl compounds. Among them, carbonyl compounds increase with time and have been used for a long time as a standard for oxidation.

Therefore, by measuring the carbonyl value, the quality of foods, especially the quality of fats and oils, is evaluated. As a method for measuring such a carbonyl value, the method of Henick et al. (J. Amer. Oil Chemi
sts'Soc., 31 , 88 (1954)), Kumazawa et al.'s method (oil chemistry, 1
4 , 167 (1965)), and those that are included in the standard method for analyzing fats and oils (edited by Japan Oil Chemistry Association) are typical. This method is based on the reaction of carbonyls with 2,4-dinitrophenylhydrazine to form a hydrazone, and the fact that the hydrazone is basic and becomes a quinoid ion to cause coloration, and the absorbance at a wavelength of 440 mμ is measured. Measured and done. However, this method has problems that it takes time and labor to perform a chemical reaction, destroys the sample, and requires a two-step process including chemical treatment, measurement of absorbance, and the like.

As described above, the conventional carbonyl number measurement method is complicated and requires skill, and further, the fact that the safety of the organic solvent is demanded nowadays is estranged.

However, in the "Hental Code for Bento and Sozai" (Environmental Food No. 161, June 1979), the carbonyl number was adopted as the management standard for frying oil for the reasons described above, but its measurement Due to the difficulty of the law, it is the current situation that it is not generally adopted.

On the other hand, attempts have been made to replace these classical / analytical methods with modern science, especially electrical ones. However, electrical conductivity, capacitance,
There are reports on the dielectric constant, etc., but very few from the viewpoint of the deterioration of fats and oils. An example of using the dielectric constant to determine the deterioration of fats and oils is a cooking oil sensor manufactured by Northern Instruments, Inc. in the United States, but it has been used only as a measure of deterioration.

In addition, mineral oils such as transformer oils and motor oils also have a problem of deterioration due to oxidation, but the evaluation method is recorded in JIS for each application and item.
The physical characteristic number is the main, and the chemical characteristic number is few because it has not been officially enacted, so there is little description, and in reality, the analytical test method for fats and oils is used and applied.

The present inventors have conducted extensive studies as to whether electrical special values cannot be used for the method for determining the deterioration of edible oils, transformer oils, motor oils, etc., and as a result, found that the dielectric constant here correlates with the carbonyl value. .

(Means for Solving Problems) The present invention is a simple method for measuring a carbonyl value, which is characterized in that the carbonyl value of fats and oils is quantitatively obtained by measuring the dielectric constant.

The fats and oils to be measured according to the present invention have a problem of deterioration due to changes with time due to use, and are mainly responsible for the formation of carbonyl groups such as animal oils, vegetable oils, fats, fatty substances, mineral oils. And the like, and the origin of the oil and fat is triacylglycerol, and the origin is all animals, plants and microorganisms, and similarly its structure is mainly hydrocarbon-based trans oil, motor oil. Mineral oils such as

The measuring apparatus and measuring method of the dielectric constant used in the present invention,
The one used for the measurement of the dielectric constant in the general electrochemical field is sufficient. Further, the display of the value of the dielectric constant in the measuring device may be performed by itself, the value of the relative dielectric constant, or the value converted into the carbonyl value.

(Effect of the Invention) According to the present invention, since the carbonyl value is determined by measuring the dielectric constant, the measurement of the carbonyl value can be simplified.
In addition, since it does not require harmful organic solvents or complicated sample preparation, it is possible to perform simple measurements without worrying about the effect on the human body, and its industrial utility is immeasurable. is there.

(Example) Example 1 1000 g of fresh white squeezing oil was poured into two stainless steel cylindrical pots each having a diameter of 18 cm, and each was heated with an electric heater at 180 ° C.
The temperature was adjusted to 210 ° C. After heating for 6 hours a day, 30 g of frying oil was sampled at the end of heating for 1 day, and this operation was continued for 6 days (total 36 hours).

The carbonyl value (and acid value) of each sample was determined based on the standard oil and fat analysis method (edited by Japan Oil Chemistry Association). The relative permittivity of the same sample was measured and the correlation was examined. The results are shown in Table 1, FIG. 1 and FIG.

From the table and the drawings, when viewed at each heating temperature, a high correlation is observed between the carbonyl value and the acid value and the relative dielectric constant. However, looking at the correlations in all plots, the carbonyl value shows a high correlation with the relative permittivity, but the acid value shows a considerably poor correlation with the relative permittivity. Therefore, it was proved that there is a very high correlation between the carbonyl value and the dielectric constant.

Example 2 As in Example 1, heating was performed at 180 ° C. and 210 ° C., and heating was performed for 6 hours a day. However, in this example, 50 g of water was added to 25 g of cornstarch every hour, and the mixture was fried for 3 minutes.
The oil was deteriorated by bringing it closer to the actual frying conditions.

At the end of the day's work, 30 g of frying oil was sampled and continued for a total of 6 days (4 days at 210 ° C).

For each sample, the carbonyl value and the relative dielectric constant were measured as in Example 1. Table 2 shows the results.

As described above, there was a high correlation between the carbonyl value and the relative dielectric constant even when the frying oil deteriorated in the water system. Therefore, it was proved that there is a high correlation between the carbonyl value and the dielectric constant.

[Brief description of drawings]

FIG. 1 shows that soybean white squeezing oil in Example 1 was used at 180 ° C. and 2
210 when heated to 10 ° C and under the frying conditions of Example 2
It is a graph which shows the correlation of a carbonyl value and relative dielectric constant at the time of heating at ° C. In the figure, ○ indicates × when heated to 210 ° C. in Example 1.
Indicates the case of heating to 180 ° C. in Example 1, and Δ indicates the case of heating to 210 ° C. in Example 2. FIG. 2 shows that soybean white squeezing oil was added at 180 ° C. and 2 in Example 1.
210 when heated to 10 ° C and under the frying conditions of Example 2
It is a graph which shows the correlation of an acid value and relative dielectric constant at the time of heating at ° C. In the figure, ○ indicates × when heated to 210 ° C. in Example 1.
Indicates the case of heating to 180 ° C. in Example 1, and Δ indicates the case of heating to 210 ° C. in Example 2.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiko Tomita 2 Higashimachi, Kichijoin Miya, Minami-ku, Kyoto-shi, Kyoto Prefecture Horiba Seisakusho Co., Ltd. (56) References JP-A-55-146033 (JP, A)

Claims (1)

[Claims] 1. A simple method for measuring a carbonyl value, which comprises quantitatively obtaining the carbonyl value of fats and oils by measuring the dielectric constant.