Physical Chemistry of Foods

Pure Triglycerides. To understand something of natural fat
crystallization, we need to know some properties of pure triglycerides.
Some data are given in Table 15.2.
We will start withuniform triglycerides, in which the molecules contain
only one species of fatty acid residue. The table gives melting points of the
constituent fatty acids as well as of the triglycerides. Notice that there is a
fair correlation between the two, although the range is markedly wider for
the triglycerides (about 150 K). There is also a fair correlation between
melting point and heat of fusion. The latter values vary more widely if the
molar heat of fusion is taken. The variation in melting properties then
follows from the variation in the fatty acid molecules. The most important
variables are

TABLE15.2 Some Properties of Fatty Acids and Triglyceridesa

Fatty
acid Code Notation Tm 8 C Triglyceride Tm(a), 8 C

Tm,

8 C

DHf,

J?g
^1

Butyric B C 4:0
8 BBB
75
Caproic Co C 6:0
4 CoCoCo
25
Caprylic Cy C 8:0 16 CyCyCy
54 8 148
Capric C C10:0 32 CCC
10 32 170
Lauric L C12:0 44 LLL 14 46 186
Myristic M C14:0 54 MMM 31 58 197
Palmitic P C16:0 63 PPP 46 66 205
Stearic S C18:0 70 SSS 55 73 212
Elaidic E C18:1,t 44 EEE 16 42 150
Oleic O C18:1 16 OOO
32 5 113
Linoleic Li C18:2
6 LiLiLi
13 85
Linolenic Ln C18:3
13 LnLnLn
24

PPB 21 44 155

PSP 47 67 195

POP 18 37 190

PPO 18 34

SOS 23 43 194

SOO 1 23

aIn the ‘‘notation’’ the first number is that of carbon atoms in the molecule; after the colon is the

number of double bonds, followed bytif it concerns a double bond in the trans configuration
(cis is far more common). Melting pointsTmand heats of fusionDHfare given in the most
stable polymorph (generallyb).Tm(a) refers to theapolymorph.