(1) Fatty acid composition

In terms of intrinsic quality, the higher the content of unsaturated fatty acids, especially oleic acid, the better. The content of unsaturated fatty acids increases with latitude, but in my country's camellia oleifera cultivation areas, this difference is only 2 to 3 percentage points. For camellia oil with a total unsaturated fatty acid content of more than 90%, the impact on the quality very small.

(2) Trace active ingredient content

Tea oil contains trace ingredients such as vitamin E, phytosterols, squalene, and polyphenols. Although it accounts for a very low proportion in oil and fat, it has strong health care functions and is an important component of the nutritional quality of camellia oil. Generally speaking, the fresher the raw materials and the shorter the storage time, the higher the content of these components in the oil; the lower the refining intensity, the higher the content.

(3) Quality requirements

The quality requirements for camellia oil in national standards include characteristic indicators, general quality indicators and mandatory health indicators, which are the key to preventing adulteration and ensuring quality and quality safety.

Characteristic indicators include refractive index, relative density, iodine value, saponification value, unsaponifiable matter and fatty acid composition. The characteristic indicators of qualified camellia oil products must be within the specified numerical range.

Hygiene indicators are mandatory indicators, including acid value, peroxide value, solvent residue, benzo(a)pyrene, aflatoxin, heavy metal content, etc., which must be lower than the corresponding grade of camellia seed oil national standards and edible oil hygiene standards . The lower the values ​​of these indicators, the higher the safety quality of the oil.

Other indicators, such as color, transparency, water and volatile matter, 280°C heating test, and insoluble impurity requirements for pressed oil, in addition to soap content, smoke point, freezing test and other requirements for leached oil. Generally speaking, the higher the transparency and smoke point of the same product, the better, and the lower the other indicators, the better.

(1) Smell

Tea oil has an inherent smell. Whether the smell of oil is normal or not can indicate the quality of the oil, the oil's processing technology and storage conditions. Although different processing techniques and processing intensity will result in different odor concentrations, any tea oil product should not have burnt, rancid or other off-flavors. The national oil quality standards require that the cooking oil inspection method is to heat the cooking oil to 50°C and smell the volatile odor with your nose to determine the quality of the cooking oil.

(2) Taste

It refers to the taste that can be tasted through the mouth. Unrefined camellia oil has a unique fragrance, while refined oil has no taste. If the taste is strange, it means the oil quality, processing method, packaging and storage conditions are poor. Edible oil with poor freshness may have varying degrees of rancidity.

(3) Color

Due to different processing methods, the color of oil can be dark or light. For example, oil produced by steaming, frying or hot pressing is often darker in color than oil produced by cold pressing, while refined oil is very light in color. It is worth mentioning that within the specified range, the color and luster of oil have no direct relationship with quality.

(4) Transparency

Good quality should be transparent. If the oil is turbid and has low transparency, it means there is a lot of water, mucin and phospholipids in the oil, and the degree of processing and refining is poor. Generally, high-quality edible oil is clear to the naked eye under sunlight and lighting, without fog, suspended solids, impurities, or turbidity, and has good transparency.

(5) Sediment

The material that can sink when edible vegetable oil is below 20°C and left to stand for 20 hours is called sediment. The higher the quality of tea oil, the less sediment. Less sediment indicates a high level of oil processing technology and good packaging quality.