2009_Book_FoodChemistry

460 8 Food Additives
saponification number of the emulsifier, AV =
acid value of the separated acid):
(
HLB = 20 1 − SV )
(8.40)
AV
On the basis of experimental group numbers (Table
8.21), the HLB value can be calculated using
the formula:
HLB = ∑(hydrophilic group number)−
∑(hydrophobic group number)+7 (8.41)
Some examples listed in Table 8.22 show very
good correspondence between calculated and experimentally
found HLB values.
Table 8.21. Group number N H and N L for HLB calculation
Hydrophilic group N H Lipophilic group N L
0.15
OSO − 3 ,Na+ 38.7 CH 0.475
SO 3 −,Na + 37.4 CH 2 0.475
COO − ,Na + 21.1 CH 3 0.475
COO − ,K + 19.1 CH 0.475
Sorbitan ring 6.8 CH CH 2 O
Ester 2.4 CH 3
COOH 2.1
OH (free) 1.9 Benzene ring 1.662
O 1.3
(CH 2 CH 2 -O) 0.33
Table 8.22. Hydrophilic lipophilic balance (HLB) values
of some surfactants
HLB-value
Compound Found Calculated
Oleic acid 1.0
Sorbitol tristearate 2.1 2.1
Stearyl monoglyceride 3.4 3.8
Sorbitol monostearate 4.7 4.7
Sorbitol monolaurate 8.6
Gelatin 9.8
Polyoxyethylene sorbitol 10.5 10
tristearate
Methylcellulose 10.5
Polyoxyethylene sorbitol 14.9
monostearate
Polyoxyethylene sorbitol 15.0 15
monooleate
Sodium oleate 18.0
Potassium oleate 20.0
Table 8.23. HLB-values related to their industrial application
HLB-range
Application
3–6 w/o-Emulsifiers
7–9 Humectants
8–18 o/w-Emulsifiers
15–18 Turbidity stabilization
The HLB values indicated the first industrial applications
(Table 8.23). For a detailed characterization,
however, comprehensive knowledge of
possible interactions of the emulsifier with the
many components of a food emulsion is still lacking.
Hence, emulsifiers are mainly used in accordance
with empirical considerations.
It has been observed with neutral emulsifiers that
the degree of hydration of the polar groups decreases
with a rise in temperature and the influence
of the lipophilic groups increases. Phase inversion
occurs o/w → w/o. The temperature at
which inversion occurs is called the phase conversion
temperature.
8.15.3 Synthetic Emulsifiers
Today, 150,000–200,000 t of emulsifiers are produced
worldwide. Of this amount, mono-and diacylglycerides
and their derivatives account for the
largest part, i. e. about 75%. Synthetic emulsifiers
include a series of nonionic compounds. Unlike
the ionic compounds, the nonionic emulsifiers are
not in danger of decreasing in interfacial activity
through salt formation with food constituents.
The utilization of emulsifiers is legislated and often
differently regulated in some countries. The
synthetic emulsifiers described below are used
worldwide.
8.15.3.1 Mono-, Diacylglycerides
and Derivatives
Mono- and diacylglycerides, which are mostly
used as mixtures, are produced as described
in 3.3.2. Other emulsifiers with special activities
are obtained by derivatization (cf. Table 8.24).
As a result of the diverse reaction possibilities