饱和脂肪酸对于文科背景的学生来说可能一脸懵逼。但是PTE听力就是考到了。下面文波PTE的小编就给大家总结下饱和脂肪酸的中英文背景知识：
维基百科中说：
A saturated fat is a type of fat in which the fatty acid chains have all or predominantly single bonds. A fat is made of two kinds of smaller molecules: glycerol and fatty acids.
Fats are made of long chains of carbon (C) atoms. Some carbon atoms are linked by single bonds (-C-C-) and others are linked by double bonds (-C=C-). Double bonds can react with hydrogen to form single bonds. They are called saturated, because the second bond is broken up and each half of the bond is attached to (saturated with) a hydrogen atom. Most animal fats are saturated. The fats of plants and fish are generally unsaturated.
Saturated fats tend to have higher melting points than their corresponding unsaturated fats, leading to the popular understanding that saturated fats tend to be solids at room temperatures, while unsaturated fats tend to be liquid at room temperature with varying degrees of viscosity (meaning both saturated and unsaturated fats are found to be liquid at body temperature).
科学网说：
我们在日常生活中所说的“油水”，指的是脂肪。脂肪由脂肪酸和甘油结合而成。脂肪酸的样子像一条长长的链条，它是由一个个碳原子串起来的，碳原子上面还有氢原子与之相连。
根据链条的结构，把脂肪酸分成三大类：链条上每个碳原子都尽可能多地与氢原子结合，达到“饱和状态”的，就是“饱和脂肪酸”。有的脂肪酸的链条中间，还有可以和氢原子结合的位置空着，处于“不饱和状态”，就是“不饱和脂肪酸”，少了一对氢原子，称为“单不饱和脂肪酸”，少了多对氢原子，就叫做“多不饱和脂肪酸”。
根据氢原子的缺失位置，多不饱和脂肪酸又分成欧米伽－3和欧米伽－6两类。根据碳链上氢原子的位置，不饱和脂肪酸又可以分成两种，如果氢原子都位于同一侧，叫做“顺式脂肪酸”，链的形状曲折；如果氢原子位于两侧，叫做“反式脂肪酸”，是直链。反式脂肪酸的性质类似于饱和脂肪酸。
脂肪是体内储存能量的物质，脂肪酸还参与了许多重要的生理活动。体内的脂肪酸有的是饱和的，有的是不饱和的，我们是不是都必须从食物中补充它们呢？一般人，甚至包括一些医生，会这么想，以为人体内有什么物质，就必须补什么物质。这种想法太简单化了，没有考虑到食物的消化、吸收和代谢。
