Fats

脂肪

Fats, oils, waxes, and sterols are collectively known as lipids. The broad class of substances known as fats don't have a common structure, but can be generally classified as esters of fatty acids and glycerol. There can be one to three ester linkages of fatty acid chains to the glycerol, leading to the classification as monoglycerides, diglycerides and triglycerides. Sometimes the use of the word "fat" is limited to the triglycerides. The term fatty acid is a substructure of the lipids, and should not be used as a synonym for "fat".

脂肪、油、蜡和甾醇 collectively 被称为脂类。虽然被称为脂肪的广泛物质没有共同的结构，但通常可以被分类为脂肪酸和甘油的酯。脂肪酸链可以与甘油形成一个到三个酯键，从而被分类为单甘油酯、双甘油酯和三甘油酯。有时“脂肪”一词被限制用于三甘油酯。脂肪酸是脂类的一个子结构，不应被用作“脂肪”的同义词。

Naturally occurring fatty acids nearly always have an even number of carbon atoms.

天然存在的脂肪酸几乎总是具有偶数个碳原子。

Saturated Fats

饱和脂肪

A fully saturated fat has no double bonds between the carbons in its fatty acid chains. Generally speaking, animal fats are more highly saturated than vegetable fats. Highly saturated fats are usually solid at room temperature.

完全饱和的脂肪酸链中碳原子之间没有双键。通常来说，动物脂肪比植物脂肪更饱和。高度饱和的脂肪通常在室温下呈固态。

Unsaturated Fats

不饱和脂肪酸

A fully saturated fat has no double bonds between the carbons in its fatty acid chains. If there are many double bonds in the fatty acids, then usually the fat will be liquid and will be called an oil. Most oils are of vegetable origin. The term "polyunsaturated fat" will also be used to describe such fats.

完全饱和的脂肪酸其碳链中没有双键。如果脂肪酸中存在许多双键，通常该脂肪会呈液态，被称为油。大多数油来源于植物。术语'多不饱和脂肪'也将用于描述此类脂肪。

Trans fat is the common name for a type of unsaturated fat with trans-isomer fatty acids. Most trans fats consumed today are created industrially in partial hydrogenation of plant oils - a process developed in the early 1900s and first commercialized as Crisco in 1911. The goal of partial hydrogenation is to add hydrogen atoms to cis-unsaturated fats, making them more saturated. These saturated fats have a higher melting point, which makes them attractive for baking and extends their shelf-life. Trans fats are not essential in the diet and have been linked with rises in levels of "bad" LDL cholesterol and lowering levels of "good" HDL cholesterol.

反式脂肪是不饱和脂肪的俗称，其主要成分是反式异构脂肪酸。目前大多数摄入的反式脂肪是在植物油部分氢化过程中工业制造的——这种工艺在20世纪初被开发，并于1911年首次商业化生产，名为Crisco。部分氢化的目的是向顺式不饱和脂肪添加氢原子，使其更加饱和。这些饱和脂肪具有更高的熔点，因此适合用于烘焙，并能延长其保质期。反式脂肪并非饮食中必需的成分，与低密度脂蛋白（“坏”胆固醇）水平升高和高密度脂蛋白（“好”胆固醇）水平降低有关。