What is the difference between traditional sesame oil grinding and mechanical sesame oil pressing?

The difference between ground sesame oil and machine pressed sesame oil

(a) the implementation of different standards.

Although the standard GB/T 8233- 1987 is the same as that of ground sesame oil, the manufacturers of machine-pressed sesame oil also said so when explaining it to consumers, which caused some misunderstandings to ordinary consumers and thought that the quality of ground sesame oil was the same as that of machine-pressed sesame oil. But in fact, in the national standards, there are still some different requirements for the two:

1, color: small ground sesame oil requires red ≤ 1 1, while machine-pressed sesame oil requires red ≤ 12, so the machine-pressed sesame oil is dark red in color and brown in appearance.

2.280℃ heating test: Small ground sesame oil requires no precipitation, while machine-pressed sesame oil allows precipitation, so the appearance of machine-pressed sesame oil is dark and turbid compared with small ground sesame oil.

(2) Different pretreatment processes

1. The production process of small sesame oil is to select sesame seeds, wash them with clear water, remove impurities and some substances harmful to human body with clear water, and then drain them for 2 hours. During the two-hour drainage process, sesame seeds were in a state of germination and growth because they absorbed enough water. After biological respiration, many organic substances beneficial to human body are activated, which is an important index to evaluate the functional nutritional components of sesame oil.

2. The process of mechanical pressing is only through simple screening, namely baking and frying. Because of the lack of soaking and germination process in the early stage, sesame seeds can not form active substances beneficial to human body, which makes some special functions of sesame oil, such as protecting blood vessels and delaying aging, unable to play.

(c) The process of oil separation is different

1, the process is different:

(1) Small ground sesame oil is produced by water substitution method. This method mainly uses the affinity difference of non-oil components in oil to oil and water, and uses the different specific gravity of oil and water to separate oil from other substances. Heavy metal compounds harmful to human health are precipitated into the sauce residue because of their large proportion, thus avoiding the harm of heavy metals to human body.

(2) Mechanical oil pressing only uses physical pressing to press out the oil pressure, so the heavy metal compounds in sesame seeds are mixed into the oil, forming a potential hidden danger.

(3) Due to the incomplete extraction of some mechanically squeezed oil (the residual oil still contains about 10%), the factory uses chemical solvent leaching method to extract the residual oil, and the chemical solvent cannot be completely removed, resulting in the residual chemical solvent. It is harmful to human health after eating, but in the national standard, the machine-made sesame oil is not allowed to detect solvent residues. Generally speaking, in order to retain the fragrance of sesame oil, these extracted oils will not be desolventized and refined. However, these manufacturers are well aware of the negative impact of leaching process on the flavor of sesame oil, so they adopted a flexible method when they went on the market: blending sesame oil with machine-pressed sesame oil to reduce the harm of oil pressing and improve the flavor of machine-pressed sesame oil. After being put on the market, it has become a "small sesame oil" that is difficult for ordinary consumers to distinguish, and it is actually a consumer.

The solvent used in the leaching process in China is mainly composed of hexaalkane, which is a mixture of various alkanes with a boiling point of 62-85℃. This petroleum fraction is usually called No.6 solvent, in which alkanes account for 80.2%, naphthenes account for 18%, olefins account for 1.6%, and aromatics account for 0.7%. WHO/Fao (18%) is called commercial hexane in the market, which is a kind of "hexane" mainly composed of hexaalkanes. It is a mixture. Solvent light gasoline often contains toxic impurities such as benzene and polycyclic aromatic hydrocarbons because of its insufficient purity. ) pyrene is a carcinogen. Because sesame oil is a perennial food, if it is polluted, it will do great harm to human health. According to the hygienic standard of edible oil in China, the residual solvent in extracted oil should not exceed 50ppm, which is a conclusion from the comprehensive consideration of toxicology and production technology.

Because of the particularity of sesame oil, it is poured directly into vegetables without cooking (that is, sesame oil is a raw edible oil), and if it is mixed with pressed oil with solvent residue, it will affect the health of consumers.

2. Temperature difference:

The separation process of (1) small mill process oil is only 75 ~ 82℃. At this temperature, the main aromatic substances and functional nutrients in sesame oil are almost not lost, and the content of vitamin E is retained to the greatest extent.

(2) When oil is extracted by mechanical pressing technology, the temperature is as high as 245℃. At such a high temperature, aromatic substances and functional nutrients are almost completely volatilized and destroyed, which makes sesame oil unable to play its role in promoting blood and metabolism and treating arteriosclerosis and asthma in the elderly. At high temperature, monosaccharides in sesame react with amino acids to produce black compounds harmful to human body, and these compounds have a burnt taste, which is the reason why pressed oil has a burnt taste.

(4) Differences in filtration process

1. The ground sesame oil is filtered by natural plant fibers, and the strong aroma components in the sesame oil are retained to the greatest extent. At the same time, wax and phosphorus that affect the appearance of sesame oil adhere to plant fibers because they have affinity for plant fibers. Therefore, the small sesame oil treated by this process has a crystal clear appearance, does not precipitate for a long time, and can maintain its color, fragrance and taste for a long time.

2. Because the press oil contains a lot of wax and phospholipids, the viscosity is too high, so it can only be filtered by a screen, and wax and phosphorus have no affinity for the screen, so they are dissolved in the oil one by one, which makes the press oil look turbid.

Edit this paragraph how to distinguish between small ground sesame oil and machine-made sesame oil

look

The temperature of ground sesame oil is low during processing, so the color of ground sesame oil is generally brownish red, while the temperature of machine-made sesame oil is as high as 245℃ during processing, so the color is dark and purple red.

Wen'er

Small ground sesame oil has a strong and mellow pure fragrance of sesame oil. Machine-made sesame oil has a strong burning smell.

Three essentials

Take a bottle of sesame oil and shake it vigorously for about 1 min. Stand the bottle upright and observe the upper surface of the oil: there will be a layer of foam bubbles on the surface of sesame oil, but they will disappear immediately; There are many yellow bubbles on the surface of machine-made sesame oil, which can't disappear for a long time.

Edible

If cooked with rice, it is called "Xianjia cuisine" by the people. According to scientific analysis, the main components of sesame oil are unsaturated fatty acids, accounting for 85% ~ 90%, oleic acid and linoleic acid accounting for 50% respectively. It is characterized by strong stability and easy storage, because sesame oil contains a natural antioxidant-sesame acid. Sesame oil also contains minerals such as protein, sesamin, vitamin E, lecithin, sucrose, calcium, phosphorus and iron. It is an edible oil with extremely rich nutrition.