Buy large jugs of cooking oil, as the price is more favorable than in small bottles, and many people believe that cooking oil has a long shelf life and doesn't spoil easily. Therefore, many families prefer to buy 5kg jugs and even purchase several during promotions to store at home. Is this practice advisable?
The Enemies of Oil: Air and Sunlight
For families that don't cook often, a 5L jug of cooking oil, once opened, might sit for three to four months before being used up. Even if you cook every day, a jug will last for over a month. It may not seem to have exceeded the expiration date on the label, but if stored improperly, it can actually go bad in just one week.
So, what's the problem? Liang Qianfang, a nutritionist at the First People's Hospital of Guangzhou, explains that opened oil is particularly unstable because it is easily oxidized. Once oxidized, the fatty acids in the oil become rancid, causing it to taste sour and affecting the flavor of your dishes. More seriously, the nutritional value of the oil decreases; it destroys unsaturated fatty acids (the "good" fats), and long-term consumption can promote aging in the body due to the large amount of free radicals produced, and even increase the risk of chronic diseases.
How fast does this oxidation occur? Let's look at the results of researchers' experiments: after opening the lid, oxygen from the air enters the oil jug. Even if the cap is screwed back on, it is no longer airtight. After three months of storage, its peroxide value will exceed the national standard. If the oil is poured into an open container, this only takes a week. Furthermore, if you store the oil where light can reach it, the rate of spoilage will increase by 20 to 30 times.
Safe Storage of Cooking Oil
× It turns out that exposure to air and light are the enemies of cooking oil and fried foods. A sour taste is a sign that they have gone bad. What improper actions in your storage process are causing your oil to expire prematurely? Correct your storage methods.
√ Placing the oil bottle next to the stove or by the window will accelerate oxidation as the temperature rises.
√ Try not to mix new oil with old oil, because oxidation can be "contagious".
√ Try to buy fresh oil. Oil also oxidizes slowly during storage, but the process is much slower if it remains unopened.
√ Store the oil in a dark, cool place away from high temperatures.
√ Use a lidded oil bottle and pour out about a week's worth of oil from the large jug. Seal the rest of the jug tightly.
√ Put the sealed jug away. Avoid pouring oil directly from the main container each time, as this increases the chance of oxidation.
√ Opened oil should be used up within three months. If you rarely cook and can't finish a large bottle, opt for smaller bottles.