2009_Book_FoodChemistry

14 Edible Fats * and Oils
14.1 Foreword
Most fats and oils consist of triacylglycerides (recently
also denoted as triacylglycerols; cf. 3.3.1)
which differ in their fatty acid compositions to
a certain extent. Other constituents which make
up less than 3% of fats and oils are the unsaponifiable
fraction (cf. 3.8) and a number of acyl lipids;
e. g., traces of free fatty acids, mono- and diacylglycerols.
The term “fat” generally designates a solid at
room temperature and “oil” a liquid. The designations
are rather imprecise, since the degree
of firmness is dependent on climate and, moreover,
many fats are neither solid nor liquid, but
are semi-solid. Nevertheless, in this chapter, unless
specifically emphasized, these terms based
on consistency will be retained.
14.2 Data on Production
and Consumption
Data on the production of oilseeds and other crops
are summarized in Table 14.0. The world production
of vegetable fats has multiplied since the time
before the Second World War (Table 14.1). There
has been a significant rise in production since
1964 of soybean, palm and sunflower oils, as well
as rapeseed oil. Soybean oil, butter and edible
beef fat and lard are most commonly produced
in FR Germany (Table 14.1). The per capita consumption
of plant oils in Germany has increased
in the past years (Table 14.2).
14.3 Origin of Individual Fats
and Oils
14.3.1 Animal Fats
14.3.1.1 Land Animal Fats
The depot fats and organ fats of domestic animals,
such as cattle and hogs, and milk fat, which was
covered in Chapter 10, are important animal raw
materials for fat production. The role of sheep
fat, however, is not significant. The major fatty
acids of these three sources are oleic, stearic and
palmitic (Table 14.3).
It should be noted that the fatty acid composition
of individual fat samples may vary greatly. The
fat composition of land animals is affected by the
kind and breed of animal and by the feed. The
composition of plant fats depends on the cultivar
and growth environment, i. e. climate and geographical
location of the oilseed or fruit plant (cf.
Fig. 3.3.1.5). Therefore only average values are
given in the following tables dealing with fatty
acid composition.
In contrast to oil from plant tissue, the recovery
of animal fat is not restricted by rigid cell walls
or sclerenchyma supporting tissue. Only heating
is needed to release fat from adipose tissue (dry
or wet rendering with hot water or steam). The
fat expands when heated, tearing the adipose tissue
cell membrane and flowing freely. Further fat
separation is simple and does not pose a technical
problem (Fig. 14.1).
* Butter is dealt with in Chapter 10.2.3.
Fig. 14.1. Steps involved in wet rendering
H.-D. Belitz · W. Grosch · P. Schieberle, Food Chemistry 640
© Springer 2009