March vegetables bloom,
Rapeseed is ripe in June,
Seed oil pressed in August.
After four seasons of sowing in autumn, storing in winter, growing in spring and harvesting in summer, a grain of rapeseed has matured, and through the processes of removing impurities, frying seeds, squeezing, filtering and settling, clear, transparent and mellow rapeseed has entered thousands of households.
Everyone has appreciated the beauty of rape blossoms and tasted the fragrance brought by rapeseed oil, so how much do you know about rapeseed oil? Today, small farmers invited Hu Qiong, a researcher from the Institute of Oilseed Crops, Chinese Academy of Agricultural Sciences, to listen to experts talk about rapeseed oil!
The name of rape
At the end of the Eastern Han Dynasty, Fu Qian wrote "Popular Wen", which recorded that "Brassica is called Hu Cai", and "Brassica" was the ancient rape in China, which was often used as a vegetable at that time.
Later, people gradually discovered that rape seeds can produce oil, so they bred Chinese cabbage rape which can extract oil through breeding and domestication. Rapeseed is also named after "oil".
How rapeseed becomes vegetable oil
Generally speaking, rapeseed oil extraction technology can be divided into "pressing" and "extraction".
"Squeezing" is the physical and mechanical squeezing of rapeseed by using squeezing equipment to produce oil, which can be divided into cold pressing and hot pressing, among which hot pressing is more commonly used.
"Hot pressing" means that rapeseed is heated by frying, steaming, etc., and then mechanically pressed to produce oil; "Cold pressing" means that rapeseed is pressed without baking or slightly heating, and the "crude oil" squeezed by cold pressing needs heating and dehydration before it can be filtered out into clear vegetable oil.
In contrast, hot pickled mustard tuber oil is rich in flavor because of the influence of high temperature; Cold mustard tuber oil is clear and beautiful in color, but light in fragrance.
"Extraction" is to soak or spray rapeseed with an organic solvent that can dissolve oil, so that the oil in the oil can be extracted.
In addition, it is popular to extract vegetable oil by "microwave pressing" on the market at present. This method uses microwave to heat rapeseed, which can better control the temperature and make the color of oil clear. At the same time, it is also conducive to the efficient release and dissolution of nutrients and oils in rapeseed, and plays a certain role in enhancing fragrance.
N reasons for choosing vegetable oil
In general, three kinds of rapeseed, Chinese cabbage rape, cabbage rape and mustard rape, can be used for oil extraction. However, because of the strong disease resistance and good quality of Brassica napus, most of them belong to double-low varieties (low erucic acid and glucosinolate content) and high oil yield, so they are mostly selected for oil extraction.
rap oil
Fatty acid composition balance: the fatty acid composition in rapeseed oil is relatively balanced, and the saturated fatty acid content in vegetable oil is the lowest, about 7%.
High oleic acid content: It is pointed out in the Dietary Guide for China Residents that oleic acid can reduce bad cholesterol and increase good cholesterol. In the eyes of experts, oleic acid is also an important indicator to measure whether an edible oil is more conducive to health. At present, the oleic acid content of most vegetable oils sold in the market can reach 60%, and the oleic acid content of rapeseed oil with high content can even reach more than 70%, which can well meet the public’s demand for oleic acid.
Reasonable ratio of linoleic acid to linolenic acid: According to the Standard for Healthy Edible Oil issued by FAO, the ratio of linoleic acid to linolenic acid in essential fatty acids should be less than or equal to 4:1. Linoleic acid and linolenic acid are one kind of unsaturated fatty acids, which cannot be synthesized by human body. The proportion of rapeseed oil is reasonable.
Rich in nutrients: Rapeseed oil also contains major trace elements needed by human body, such as iron, copper and zinc, and the proportion of vitamin E in rapeseed oil is relatively appropriate.
Rapeseed oil is currently recognized as "the healthiest edible vegetable oil for the public".
What is unique about "low erucic acid vegetable oil"
"Low erucic acid rapeseed oil" refers to rapeseed oil with erucic acid content not exceeding 3%. It is made by squeezing low erucic acid rapeseed, and the erucic acid content is much lower than that of traditional rapeseed oil.
At present, the United Nations Food and Agriculture Organization (FAO) and WHO have put forward a limited standard for erucic acid in edible oil, requiring that the erucic acid content in edible oil should be less than 5%. The standard of erucic acid content in edible oil in some countries requires that it should not exceed 2% of total fatty acids.
In the chemical molecular composition of oleic acid and linolenic acid, the carbon chain is short, while erucic acid is a long-chain unsaturated fatty acid, which consists of 22 carbon chains. The long carbon chain is difficult to digest and has poor absorption and utilization rate, which will reduce the nutritional value of vegetable oil. And high doses of erucic acid can also induce myocardial fat accumulation, congestive heart failure and other diseases.
Now, the vegetable oil brands advertised as "low erucic acid rapeseed oil" in Shangchao and grain and oil stores are generally up to standard in erucic acid content, so you can buy them with confidence.
Tips for eating vegetable oil
No.1: which onesPeople are not fit to eat vegetable oil?
Rapeseed oil is suitable for all ages. Under normal circumstances, as long as there is no allergic reaction to the ingredients of rapeseed oil, most people are suitable for eating rapeseed oil.
However, in view of acute gastroenteritis, diarrhea and other diseases, it is suggested to control the dosage of vegetable oil. Although there is an old saying that "too much oil will not spoil vegetables", it is important to remember that too much oil will spoil people, so it is not advisable to drink too much cooking oil every day, just in moderation.
No.2: how to preserve the vegetable oil after opening?
It is recommended to keep it away from light and heat. Rapeseed oil after daily opening can be stored in a glass bottle for sealing, away from the stove, and placed in a dark cabinet, so as to avoid the emission of effective components in the rapeseed oil and not affect the fragrance and taste of the oil.
No.3: what is the best way to eat vegetable oil?
The content of unstable fatty acids in rapeseed oil is less, so it will not form too many trans fatty acids harmful to human body after heating, and high-temperature cooking can release the fragrance of rapeseed oil well and enrich the taste of vegetables.
Rapeseed oil is listed as the first choice for making Chili oil because of its strong fragrance, bright oil and high temperature resistance. Stir-frying rapeseed oil and pepper at high temperature can effectively blend their unique flavors and increase the overall flavor of Chili oil.
If it is high oleic rapeseed oil, its stability is better. Compared with other types of vegetable oil, it can withstand high temperature heating and repeated frying. Suitable for making fried food, such as fried dough sticks, French fries and other foods.
In addition, the fragrance of normal temperature rapeseed oil itself is not as rich as sesame oil, and if it is used to mix cold dishes without heating, it may not taste particularly good. Therefore, if the heated vegetable oil is used to mix cold dishes, the oil fragrance will be more obvious.
Food is the most important thing for the people.
Smelling the original vegetable oil fragrance,
Are you full of appetite at every meal?
What other tricks are there to eat vegetable oil?
Welcome to discuss with small farmers,
Be a little expert in using oil!