just say that it is x percent saturated, y percent monounsaturated, and z percent polyunsaturated, without adding the object (fatty acid) that these adjectives in truth modify.
Instead of saying, as I have seen many times, “a saturated (or unsaturated) fat,” which is meaningless, we should say “a fat high in saturates (or high in unsaturates)” or “a highly saturated (or highly unsaturated) fat.” Those are shorthand ways of saying “high in saturated (or unsaturated) fatty acids.”
In general, the less often the term fatty acid is used the better, because people already understand the term fat (or think they do), and that word is less intimidating. But if individual fatty acids must be discussed, the term should be defined the first time it is used as something like “the building blocks of fats.”
WHEN GOOD FATS GO BAD
What makes fats turn rancid?
F ree fatty acids. That is, fatty acid molecules that have been broken off from their fat molecules. Most fatty acids are foul-smelling and bad-tasting chemicals, and it doesn’t take much of them to give a fatty food an off flavor.
There are two main ways in which the fatty acids can become disconnected: the fat’s reaction with water (hydrolysis) and its reaction with oxygen (oxidation).
You might think that fats and oils won’t react with water because they are so loathe to mix. But given time, enzymes that are naturally present in many fatty foods can make the reaction happen. (Tech-speak: They catalyze the hydrolysis.) So foods like butter and nuts can turn rancid by hydrolysis simply by being stored for a long time. Butter is particularly vulnerable because it contains short-chain fatty acids, and these smaller molecules can fly off into the air more easily (Techspeak: They are more volatile) and produce a bad smell. In rancid butter, butyric acid is the main culprit.
High temperatures also speed up the rancidity of an oil by hydrolysis, such as when wet foods are deep-fried in it. That’s one reason why deep-frying oil begins to smell bad when overused.
The second major cause of rancidity, oxidation, happens most readily in fats containing unsaturated fatty acids, with polyunsaturates being oxidized more readily than monounsaturates. The oxidation is speeded up (catalyzed) by heat, light, and trace amounts of metals, which may be present from the machinery that processed the food. Preservatives such as ethylenediaminetetraacetic acid, mercifully nicknamed EDTA, prevent metal-catalyzed oxidation by imprisoning (sequestering) the metal atoms.
Moral: Because rancidity reactions are catalyzed by heat and light, cooking oils and other fatty foods should be kept in a cool, dark place. Now you know why the labels always tell you that.
ENOUGH IS ENOUGH
On food labels I often see “partially hydrogenated” vegetable oil. What is hydrogenation, and if it’s so good why don’t they go all the way with it?
O ils are hydrogenated, that is, hydrogen atoms are forced into their molecules under pressure to make them more saturated, because saturated fats are thicker—more solid and less liquid—than unsaturated fats. The hydrogen atoms fill in hydrogen-poor gaps (Techspeak: double bonds, which are more rigid than single bonds) in the oil molecules, and that makes them more flexible. They can then pack together more closely and stick to each other more tightly, so they won’t flow as easily. Result: The fat becomes thicker, less liquid and more solid.
If the oils in your margarine hadn’t been partially hydrogenated, you’d be pouring it instead of spreading it. But partial hydrogenation may fill in only about 20 percent of the missing hydrogen atoms in the molecules. If your margarine were 100 percent hydrogenated, it would be like trying to spread candle wax on your toast.
Unfortunately, saturated fats are less healthful than unsaturated fats. Food manufacturers therefore walk a tightrope between minimum hydrogenation for health and
Instead of saying, as I have seen many times, “a saturated (or unsaturated) fat,” which is meaningless, we should say “a fat high in saturates (or high in unsaturates)” or “a highly saturated (or highly unsaturated) fat.” Those are shorthand ways of saying “high in saturated (or unsaturated) fatty acids.”
In general, the less often the term fatty acid is used the better, because people already understand the term fat (or think they do), and that word is less intimidating. But if individual fatty acids must be discussed, the term should be defined the first time it is used as something like “the building blocks of fats.”
WHEN GOOD FATS GO BAD
What makes fats turn rancid?
F ree fatty acids. That is, fatty acid molecules that have been broken off from their fat molecules. Most fatty acids are foul-smelling and bad-tasting chemicals, and it doesn’t take much of them to give a fatty food an off flavor.
There are two main ways in which the fatty acids can become disconnected: the fat’s reaction with water (hydrolysis) and its reaction with oxygen (oxidation).
You might think that fats and oils won’t react with water because they are so loathe to mix. But given time, enzymes that are naturally present in many fatty foods can make the reaction happen. (Tech-speak: They catalyze the hydrolysis.) So foods like butter and nuts can turn rancid by hydrolysis simply by being stored for a long time. Butter is particularly vulnerable because it contains short-chain fatty acids, and these smaller molecules can fly off into the air more easily (Techspeak: They are more volatile) and produce a bad smell. In rancid butter, butyric acid is the main culprit.
High temperatures also speed up the rancidity of an oil by hydrolysis, such as when wet foods are deep-fried in it. That’s one reason why deep-frying oil begins to smell bad when overused.
The second major cause of rancidity, oxidation, happens most readily in fats containing unsaturated fatty acids, with polyunsaturates being oxidized more readily than monounsaturates. The oxidation is speeded up (catalyzed) by heat, light, and trace amounts of metals, which may be present from the machinery that processed the food. Preservatives such as ethylenediaminetetraacetic acid, mercifully nicknamed EDTA, prevent metal-catalyzed oxidation by imprisoning (sequestering) the metal atoms.
Moral: Because rancidity reactions are catalyzed by heat and light, cooking oils and other fatty foods should be kept in a cool, dark place. Now you know why the labels always tell you that.
ENOUGH IS ENOUGH
On food labels I often see “partially hydrogenated” vegetable oil. What is hydrogenation, and if it’s so good why don’t they go all the way with it?
O ils are hydrogenated, that is, hydrogen atoms are forced into their molecules under pressure to make them more saturated, because saturated fats are thicker—more solid and less liquid—than unsaturated fats. The hydrogen atoms fill in hydrogen-poor gaps (Techspeak: double bonds, which are more rigid than single bonds) in the oil molecules, and that makes them more flexible. They can then pack together more closely and stick to each other more tightly, so they won’t flow as easily. Result: The fat becomes thicker, less liquid and more solid.
If the oils in your margarine hadn’t been partially hydrogenated, you’d be pouring it instead of spreading it. But partial hydrogenation may fill in only about 20 percent of the missing hydrogen atoms in the molecules. If your margarine were 100 percent hydrogenated, it would be like trying to spread candle wax on your toast.
Unfortunately, saturated fats are less healthful than unsaturated fats. Food manufacturers therefore walk a tightrope between minimum hydrogenation for health and
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