Soybean oil — also marketed as vegetable oil — is an inexpensive and widely available cooking oil, ideal for a quick stir-fry or for brushing onto vegetables before roasting them in the oven. Shopping for soybean oil can be confusing. The average supermarket will usually have several different brands on the shelves. Not to worry. You can identify the best soybean oil by its light color, by its clarity, by its low viscosity and by its ingredients.
The best soybean oil has a light amber color, about the color of dried pine sap or lemonade. A darker color indicates that the oil has either been sitting around on the shelf too long or has been improperly processed. Refiners use heat and pressure to separate the oil from soybeans, but using too much heat will burn the oil. That gives it a muddy or brown color and an unpleasant taste. By contrast, oil that is too light may have been adulterated with less-expensive oil.
Good-quality vegetable oil can also be identified by its clarity. Soybean oil should be jewel-clear, not cloudy, smoky or have any visible grittiness. The presence of particulate matter or opaque color can mean the oil is old, has been burned during processing, has been mixed with other oils or ingredients or even that the oil has somehow been contaminated. Judge clarity by holding the bottle between your eyes and a price tag. You should be able to read the tag through the oil.
The best soybean oil can also be identified by its low viscosity. Soybean oil, as a cooking oil, adds flavor but also helps prevent foods from sticking to the pot or pan. Thus, the oil itself should flow easily and not be sticky. To judge this, tilt the bottle and see if it coats the sides of the container. If it does, it is probably too old, as most oils increase in stickiness as they age.
Finally, the best vegetable oil should include nothing but the oil from soybeans. Some manufacturers mix soybean oil with other oils in order to make the oil seem more desirable and boost their profit margins, but regional laws usually require these to be listed on the ingredient label. Read the ingredient list and check for any added oils like canola oil or olive oil. These often taste good but may reduce the oil's smoke point, making it more likely to burn.
