1.1 Comparison of sea buckthorn seed oil and common vegetable oils
The physical and chemical indexes of sea buckthorn seed oil and common vegetable oils show that sea buckthorn seed oil and common vegetable oils are at the same level in refractive index, specific gravity and saponification value. The specific gravity of sea buckthorn seed oil is 0.9175-0.9270 (common vegetable oils 0.9100-0.9200); refractive index 1.4722-1.4791(common vegetable oils 1.4600-1.4800), saponification value 185.9-208.2(common vegetable oils 180-200). The iodine value of sea buckthorn seed oil is 30.7-149.7, which similar to sunflower oil, and
ordinary seed oils.

The carotenoids level of sea buckthorn seed oil is 2-23mg/l00g, while vitamin E content is 115.1-239.7mg/l00g, which is much higher than common vegetable oils. The fatty acid composition of sea buckthorn seed oil consists of palmitic acid, oleic acid, linoleic acid and linolenic acid.

In addition to the low content of palmitic acid (8.7-11.0%), the other three are at the same level, oleic acid 18.69-26.0%, linoleic acid 35.84-40.0% and linolenic acid 23.8-32.72%. The four fatthy acids account for 98% of the total fatty acids, 87.76-89.17% of the total unsaturated components.

1.2 Identification of seabuckthorn seed oil
1.2.1 Identification by odor
Sea buckthorn seed oil has a characteristic odor from sea buckthorn fruits, whcih can be used to identify the quality.

1.2.2 Identification by beta-carotene and alpha-tocopherol analysis
Sea buckthorn seed oil contains a lot of tocopherols, which can be confirmed by feature analysis. Although the content of carotenoids is low, but the features of beta-carotene test are still obvious enough to identify sea buckthorn seed oil.

1.2.3 Fatty acids identification
The fatty acicds of sea buckthorn seed oil are mainly palmitic acid, oleic acid, linoleic acid and linolenic acid. The content of each component is in a relatively narrow range, the fatty acid composition can be used to identify it. 1.3 Identification of sea buckthorn seed oil mixed with other vegetable oils

1.3.1 Identification of sea buckthorn seed oil mixed with lauric acid oils
Sea buckthorn seed oil contains no lauric acid, if the analysis result shows lauric acid in sea buckthorn seed oil fatty acids, which proves that it is mixed with lauric acid oils.

1.3.2 Identification of sea buckthorn seed oil mixed with palmitic acid oils
Sea buckthorn seed oil contains approximately 10% palmitic acid, when it’s mixed with palmitic acid oils, the content of palmitic acid will rise while the total unsaturated components decrease. Therefore, if the content of palmitic acid in sea buckthorn seed oil is more than 11%,the total unsaturated components less than 87%, it is possible sea buckthorn seed oil is mixed with palmitic acid oils.

1.3.3 Identification of sea buckthorn seed oil mixed with oleic acid-linoleic acid oils
There are three types of oleic acid-linoleic acid oils according to their concentration: the first type is higher oleic acid oils; the second is oils with oleic acid and linoleic acid at the same level; the third is oils with higher linoleic acid and linolenic acid.

When sea buckthorn seed oil is mixed with the first type of oils, its oleic acid content is high, palmitic acid, linoleic acid and linolenic acid content will decrease. and linolenic acid decreases the most, the total unsaturated components is more than 90%, therefore, if the test result shows the above changes, it is possible sea buckthorn seed oil is mixed with the first type of oils.

When sea buckthorn seed oil is mixed with the second type of oils, the fatty acid composition will change as following: oleic acid and linoleic acid increase, palmitic acid and linolenic acid decrease, the unsaturated components reach more than 90%.

Therefore, if the test result of sea buckthorn seed oil shows oleic acid more than 26%, linoleic acid more than 40%, the total unsaturated components over 90%, it is possible that sea buckthorn seed oil is mixed with the second type of oils. When the sea buckthorn seed oil is mixed with the third type of oils, it increases linolenic acid and linoleic acid, meanwhile palmitic acid and oleic acid decrease, the total unsaturated components reach more than 90%. So when the analysis of sea buckthorn seed oil fatty acids shows more than 40% linoleic acid, more than 23% linolenic acid, the unsaturated components up to 90%, it is possible that sea buckthorn seed oil is mixed with the third type of oils.

1.3.3 Identification of sea buckthorn seed oil mixed with castor oil and rapeseed oil
Castor oil is rich in ricinoleic acid, rapeseed oil is rich in erucic acid. When sea buckthorn seed oil is mixed with castor oil or rapeseed oil, the fatty acid profile will definitely show ricinoleic acid or erucic acid. If analysis shows that ricinoleic acid, it is castor oil, and erucic acid is rapeseed oil.

1.3.5 Identification of sea buckthorn seed oil mixed with sea buckthorn fruit oil
The main fatty acids of sea buckthorn fruit oil inlcude palmitic acid, palmitoleic acid and oleic acid. Sea buckthorn seed oil include palmitic acid , oleic acid, linoleic acid and linolenic acid. When the two oils are mixed together, palmitic acid and oleic acid will remain unchanged, linoleic acid and linolenic acid change greatly. If palmitoleic acid is high, there is more sea buckthorn fruit oil than sea buckthorn seed oil in the oil; with high linolenic acid, there is more sea buckthorn seed oil than sea buckthorn fruit oil in the oil.

Conclusion
Sea buckthorn oil identification methods include odor identification, alfa-tocopherol and beta-carotene test methods, but the fatty acid composition test is the most reliable method.