Four points to prevent expiration of edible oil
Release Time:2016-01-29
Many people think that oil, unlike milk and vegetables, is a store-resistant food, but this is not the case. Oil does not breed bacteria, but it is very easy to oxidize. Oil oxidation is a free radical reaction, which not only reduces the nutritional value of oil, destroys unsaturated fatty acids, but also promotes the aging of human body by producing a large number of free radicals. People are keen to eat various antioxidant foods and health care products, the main purpose is to eliminate free radicals and avoid human aging. Long-term consumption of stale oils runs counter to this goal and may even increase the risk of chronic diseases.
Sealing grease is not easy to oxidize
For all kinds of oils and fats sold on the market, the state has clear standards, which require the oxidation degree to be controlled within a certain range. Therefore, the quality of oils and fats sold in supermarkets can be assured.
When choosing and purchasing, we should look at the date of leaving the factory and try to choose fresh oil, because the oil will oxidize slowly during storage. However, as long as the oil is in a closed state, its oxidation rate can be neglected. However, once the oil is brought home, the cap is opened and the seal is lost, the oxidation rate of the oil will be greatly increased.
Storage after opening should not exceed three months
When buying cooking oil in supermarkets, many people like to buy 5 kilograms of barrels. They think the price is more reasonable. For families who don't cook very often, it takes three or four months to finish the oil after it is opened. Even in families that often cook, a barrel of oil often takes more than a month to run out.
According to the test, after opening the lid of the oil drum, only screwing the lid can not completely isolate oxygen. In this case, after three months of storage, the peroxide value of the oil will exceed the national standard. If the oil is placed in an oil kettle that can freely contact with the outside air, or in some open containers, the oxidation degree will exceed the national standard in only one week.
However, this is still the case when grease is out of the sun. Oil oxidation reaction likes light very much. If oil is exposed to light, its oxidation reaction rate will increase 20-30 times, that is to say, the rate of overdue deterioration will be greatly accelerated. In fact, many families put oil kettles and barrels in the kitchen and near the windowsill, which is very unwise. At the same time, like all chemical reactions, the oxidation of oil will accelerate with the increase of temperature, that is to say, the higher the temperature, the shorter the storage time of oil. It's summer now, and the oxidation rate is the fastest season of the year.
An interesting phenomenon was also found in the experiment: the higher the grade of cooking oil, the faster the oxidation rate after encountering oxygen. This is because high-grade oils and fats are highly refined, and natural antioxidants such as vitamin E and polyphenols in seeds will be removed by most of the refining process, so that their oxidation "resistance" will naturally decline. At present, urban people mainly eat first-class cooking oil, which is also the most easily oxidized oil.
4 points to prevent oil expiration
In order to avoid premature expiration of fried vegetable oil and free radicals causing aging, we should do the following four things in our daily life:
1. After buying the barrels of cooking oil, pour them into the kettle, then tighten the lid and put it back in. Never pour oil in a barrel every time you cook, which means fresh oxygen enters the barrel every day.
2. The amount of oil stored in the kettle should be the amount that can be eaten in a week. It's best to buy an oil kettle that can screw the lid on. Never put the oil in an open container.
3. Whether oil drums or oil kettles, they must be kept in a dark and shady place. Never put them on the balcony or on the side of the stove. Don't let them be affected by sunshine and heat.
4. New and old oils should not be mixed together as far as possible, because the oxidation of oils and fats will be "contagious".
