Edible fats and oils can be divided into two categories: [animal] and [plant] oils. Vegetable oils include rapeseed oil, peanut oil, corn oil, soybean oil, palm oil, canola oil, and sunflower oil. Commonly used terms in daily life such as "cholesterol", "unsaturated fatty acids", "aflatoxin", "erucic acid", etc., what is the relationship with edible oil? The following is explained separately for everyone:
★cholesterol
The high level of cholesterol in the blood has been confirmed to have a great relationship with cardiovascular diseases. Scientists believe that the higher the risk of getting drunk, the greater the chance of suffering from heart disease, and the high cholesterol in the blood will cause atherosclerosis in the body's blood vessels. Arterial blood vessels precipitate fat, cholesterol and other substances, resulting in narrow blood vessels, ducts, and damaged blood vessel walls. Severe blood circulation may also cause poor blood circulation or cause blood vessels to harden and block. General vegetable fats are cholesterol-free.
★unsaturated fatty acids
The cholesterol in the body is transferred from two different density fat proteins to the designated tissue, called low density and high density fat protein.
Low-density lipoprotein + cholesterol → most likely to condense in the blood vessel wall, resulting in blood vessel hardening and siltation in the future.
High-density lipoprotein + cholesterol → can clear the blockage of the accumulation of blood vessel walls, but also has the potential to dissolve low-density lipoproteins.
Therefore, the function of high-density lipoprotein can help reduce the formation of vascular diseases. Saturated fatty acids can be converted into cholesterol in the body and increase the level in the body. If the food intake is large, it will increase the combination of low-density lipoprotein cholesterol and build up blood vessels. Vascular occlusion opportunities in the future.
From previous experiments, it was proved that polyunsaturated fat can reduce the level of low-density lipoproteins and reduce the chance of developing vascular diseases. Therefore, foods containing polyunsaturated fats are considered to be better than those rich in saturated fatty acids.
Aflatoxin
Aflatoxin belongs to the group of the endostatin toxin, also known as flavomycin or luteolin. Aflatoxin strains are more resilient than other strains, and even if they can grow in cleaner environments, peanuts can be aflatoxin-producing bacteria that are not properly stored. It has also been found from animal experiments that these toxins are carcinogenic.
Erucic acid
Erucic acid is the main fatty acid in rapeseed oil and plant seeds. It was found in animal experiments that high erucic acid-containing rapeseed oil caused accumulation of fat particles in the heart and muscle damage caused by cell damage. At present, many countries have implemented food accountant control, and the United Nations World Health Organization (FAO/WHO) has also established an accountant standard.
Cooking oil refining process
Soil-squeezed and unrefined edible oils and fats can only be called crude oil. Many of them will contain impurities such as water, free fatty acids, pigments, resins, etc. In addition to health factors, crude oil is not resistant to long-term storage because its impurities cause hydrolysis. Sex rancidity, refined oil can reduce these ills.
The refining process of edible oil mainly has the following:
refining
If the crude oil contains water, the impurities suspended in it will form a gum. In order to remove these gums, the hydrolysis method is commonly used so that the phospholipids are not dissolved in the oil after hydrolysis, and the free fatty acids in the oil cannot be removed during the peeling process. And other impurities, chemical refining method is to use sodium hydroxide to neutralize the free fatty acids in the oil. When the free fatty acids are neutralized and produce soap, the resulting soap can not be dissolved in grease, and because the density of the two is different, so Centrifugation The separation method removes the neutralized fat. Neutralization oil is washed with water to remove the remaining soap, and then the water is vacuum-dried.
Decolorization
The commonly used oils in crude oils are darker and have lower clarity. For example, chlorophyll of soybean oil, carotenoids of palm oil, etc. can be absorbed with bleaching earth or activated carbon to absorb the pigments in the oil. The decolorization process is usually carried out under vacuum to support the oxidation of the oils and fats; the grease and bleaching earth or activated carbon are decolorized and separated from the grease by a filter, and impurities remaining in the grease such as soap and metal can be further removed during the filtration process. And some of the original grease odor and other scavenging, filtered oil should be lighter and more clear.
Deodorization
Artificial butter and white cream are needed to produce odorless oils, but both vegetable oils and marine animals contain special flavors that must be removed prior to application. Grease contains highly volatile odorous substances such as aldehydes or ketones, which are more volatile than glycerides, so the use of high-temperature steam, it is removed by distillation; due to high temperature and moisture, the oil is easily oxidized or hydrolyzed, so The deodorization must be carried out at a relatively low temperature and under vacuum. When the quality of the oil is deodorized, it is completely different from the crude oil, and the peroxide content is successively reduced. The use of grease is more stable and the color is clearer. Since free fatty acids are easily carried out in the deodorization process, free fatty acids and highly volatile odorous substances are distilled off under the proper vacuum and high temperatures.