Analysis of commonly used solvents for food flavors and fragrances

Objective to analyze the content of commonly used solvents in flavors and fragrances. Methods the contents of flavors and fragrances were preliminarily determined by the determination of flavor density and refractive index, and the common solvents in flavors and fragrances were qualitatively and quantitatively analyzed by capillary gas chromatography. Results the method is simple, accurate and effective. Conclusion it provides a reference for flavor and fragrance company to develop, control product quality and imitate fragrance.

[Key words]

Gas chromatography; Essence

Chinese Library Classification No.: r155 5

Document identification code: a

Article No.: 1003-6245 (2008) 10-0796-02

With the rapid development of social economy, the status of flavors and fragrances in the fine chemical industry is becoming more and more significant. Therefore, it is particularly important to control its quality. Perfume is the general term of aroma substances extracted from aromatic substances or obtained by artificial synthesis. Flavor is a fragrance mixture [1] with a certain flavor, which is made by mixing a variety of spices according to a certain proportion and technology. The most important ingredient in food flavors and fragrances is a variety of solvents. Understanding the composition of solvents is an important part of developing flavor and fragrance products, and solvent composition is one of the important signs of the stability and suitability of flavors and fragrances. Therefore, the detection of solvents in flavors and fragrances is of great significance.

1 measurement of flavor content

In the inspection of flavors and fragrances, we usually measure the content of flavors and fragrances by measuring the density and refractive index of flavors and fragrances. When flavors contain other impurities or the content of alcohol in flavor changes, their density and refractive index will change compared with pure substances, so density and refractive index are two very important indicators.

1.1 instrument

De series densitometer and re series refractometer (Mettler Toledo company)

1.2 method

The DE density meter adopts the U tube oscillation principle and measures the density value by measuring the resonance frequency of the fragrance and fragrance. The flavor sample (not bubbles) can be injected into the U tube of the densitometer with a syringe. After about 30 seconds, the density data of the sample can be stabilized. The refractive index can also accurately measure the refractive index coefficient of the flavor and fragrance, and there is no significant difference between the [2] and the national standard method (t<0.05) (Table 1).

Qualitative analysis of the main solvents in 2 flavors

The components in flavors and fragrances can be roughly divided into two categories (1): volatile components (such as alcohols, esters, hydrocarbons, olefins) and non-volatile components (such as coumarin, flavonoids, flavanones, etc.) according to their boiling point. For volatile components in flavors and fragrances, gas chromatography (GC) is still the most commonly used method of separation at present, [2].

2.1 instrument and chromatographic conditions

PE gas chromatograph, peg2m capillary column 0.32 × zero point five zero × The column temperature was 70 ℃ (1 min) - 240 ℃ (30 min); Heating rate: 15 ℃ / min; Injection temperature: 250 ℃; Detector temperature: 280 ℃; Carrier gas: high purity nitrogen, 60ml / min; Injection volume: 0.5 μ L; Detector: FID

2.2 standard solution preparation mixed standard storage solution configuration: use anhydrous ethanol (superior alcohol) to fix the volume to the scale, shake and mix well. Mixed standard solution configuration: according to the needs of the experiment, dilute with anhydrous ethanol at different times.

2.3 test method: firstly, the retention time of each solvent was determined. First, add glyceryl triacetate 0.52g to 5ml anhydrous ethanol (superior alcohol) into a 50ml dry and clean volumetric flask (ground mouth, with plug), fix the volume to the scale, shake and mix well, take 0.5 G μ Then add 0.51g isopropyl myristate into the standard solution, shake and mix well, and take 0.5g μ Then weigh 4.97g of benzyl alcohol, 5.05g of diethyl phthalate, 5.13g of propylene glycol, 5.01g of benzyl benzoate and 5.00g of tri citrate in the volumetric flask, and determine the retention time of all solvents in turn (attached table).

Quantitative analysis of the main solvents in 3 flavors

Accurately weigh 5.0746g of glyceryl triacetate in a 50ml dry and clean volumetric flask (ground mouth, with plug), use anhydrous ethanol (superior alcohol) to fix the volume to the scale, shake and mix well. Then dilute the standard solution with absolute ethanol to 0.2596g/ml, 0.5190g/ml and 0.7788g/ml. 50 respectively μ The linear regression equation was y = 1.092 × 104x+9 679 × 104,r=0.9989。 This method can be used for quantitative analysis of other solvents.

4 discussion:

4.1 the determination of the density and refractive index of flavors and fragrances can be used for the inspection of raw materials.

Essence has natural flavor and synthetic essence. For their raw materials, because of different origin and quality, the quality is also uneven, so we should measure density and refractive index, control its content. In addition, since the essence of the product is usually made up of a variety of flavors, the change in the content of each component will result in the change of the density and refractive index of the mixed flavor in the dispensing process of the essence. Therefore, the accurate determination of the density and refractive index of the essence will play a significant role in controlling the flavour preparation.

4.2 ion of chromatographic conditions

In the 421 column ion, gas chromatography was first used to separate aroma components with packed columns, but the column efficiency of packed columns was not high enough to meet the requirements of complex flavor samples. Capillary gas chromatography is an analytical method developed in recent years, it has high sensitivity and ivity, can quickly and effectively determine the accurate content of a variety of substances, and has a variety of different specifications of capillary columns to choose from [3]. Peg2m capillary column was used × zero point five zero × 60 mm, the separation effect is better, but the peak of soybean oil and octadecanoic acid glyceride ODO does not appear.

422 the choice of column temperature is due to the complexity of flavors and fragrances. The range of column temperature was 70 ℃ (1min) - 240 ℃ (30min). During the experiment, it was found that the separation effect was good if the heating rate was 5 ℃ / min, and the baseline was stable, but the peak was slow, and it took 1 h to finish all the peaks. If the heating rate was 25 ℃ / min, the baseline floated, the peak shape was not good, and the separation effect was not good. So the heating rate is 15 ℃ / min.

4.2.3 the carrier gas flow rate is ed through the spectrum under different flow rates and the number of trays. When the number of trays is high and the separation effect is good, the corresponding carrier gas flow rate is the experimental carrier gas flow. The flow rate of carrier gas was 60 ml / min. Each substance can be separated, and the peak shape is good, the reproducibility is good, the separation effect is ideal.

4.3 the method is simple, accurate and effective

It also provides a reference for flavor and fragrance companies to develop and control the quality of products. In addition, it can help the perfumer to judge the smell free solvents and facilitate the perfumery work of fragrance workers.