Senin, 29 Juni 2015
[Casimir C. Akoh, David B. Min] Food Lipids Chemi
[Casimir C. Akoh, David B. Min] Food Lipids Chemi
DEFINITIONS OF LIPIDS
No exact definition of lipids exists. Christie [1] defines lipids as ‘‘a wide variety of natural products including fatty acids and their derivatives, steroids, terpenes, carotenoids, and bile acids, which have in common a ready solubility in organic solvents such as diethyl ether, hexane, benzene, chloroform, or methanol.’’Kates [2] says that lipids are ‘‘those substances which are (a) insoluble in water; (b) soluble in organic solvents such as chloroform, ether or benzene; (c) contain long-chain hydrocarbon groups in their molecules; and (d) are present in or derived from living organisms.’’ Gurr and James [3] point out that the standard definition includes ‘‘a chemically heterogeneous group of substances, having in common the property of insolubility in water, but solubility in nonpolar solvents such as chloroform, hydrocarbons or alcohols.’’ Despite common usage, definitions based on solubility have obvious problems. Some compounds that are considered lipids, such as C1–C4 very short-chain fatty acids (VSCFAs), are completely miscible with water and insoluble in nonpolar solvents. Some researchers have accepted this solubility definition strictly and exclude C1–C3 fatty acids in a definition of lipids, keeping C4 (butyric acid) only because of its presence in dairy fats. Additionally, some compounds that are considered lipids, such as some trans fatty acids (those not derived from bacterial hydrogenation), are not derived directly from living organisms. The development of synthetic acaloric and reduced calorie lipids complicates the issue because they may fit into solubility-based definitions but are not derived from living organisms, may be acaloric, and may contain esters of VSCFAs
No exact definition of lipids exists. Christie [1] defines lipids as ‘‘a wide variety of natural products including fatty acids and their derivatives, steroids, terpenes, carotenoids, and bile acids, which have in common a ready solubility in organic solvents such as diethyl ether, hexane, benzene, chloroform, or methanol.’’Kates [2] says that lipids are ‘‘those substances which are (a) insoluble in water; (b) soluble in organic solvents such as chloroform, ether or benzene; (c) contain long-chain hydrocarbon groups in their molecules; and (d) are present in or derived from living organisms.’’ Gurr and James [3] point out that the standard definition includes ‘‘a chemically heterogeneous group of substances, having in common the property of insolubility in water, but solubility in nonpolar solvents such as chloroform, hydrocarbons or alcohols.’’ Despite common usage, definitions based on solubility have obvious problems. Some compounds that are considered lipids, such as C1–C4 very short-chain fatty acids (VSCFAs), are completely miscible with water and insoluble in nonpolar solvents. Some researchers have accepted this solubility definition strictly and exclude C1–C3 fatty acids in a definition of lipids, keeping C4 (butyric acid) only because of its presence in dairy fats. Additionally, some compounds that are considered lipids, such as some trans fatty acids (those not derived from bacterial hydrogenation), are not derived directly from living organisms. The development of synthetic acaloric and reduced calorie lipids complicates the issue because they may fit into solubility-based definitions but are not derived from living organisms, may be acaloric, and may contain esters of VSCFAs
if you are interested in reading this book please download at the link below..
.Thanks and Enjoy..
Langganan:
Posting Komentar
(
Atom
)
Tidak ada komentar :
Posting Komentar