Chemical and Functional Properties of Food Saccharides

Fresh
water
© 2004 by CRC Press LLC
Clean beet
Beet slicing
Cossettes
Countercurrent
extraction
Pulp pressing
FIGURE 4.2 Beet extraction process.
(4.1)
where ds is the weight of sugar diffusing through the area A in time dτ; dc/dx the
concentration gradient of the solute; and D f the diffusion coefficient, which
depends on temperature according to the Einstein and Smoluchowski correlation
(Equation 4.2):
(4.2)
where k is the constant for the dissolved substance, T the absolute temperature, and
η the viscosity of the solution.
The juice after extraction has a considerable quantity of colloidal matter and a
large number of fine pulp particles. They must be eliminated prior to juice purification.
4 The nonsucrose content of the raw juice is determined by beet quality,
conditions under which sugar is extracted, quality of cossettes, draft, pH value,
temperature, time, and bacterial control.
4.2.3 JUICE PURIFICATION
ds D A dc
dx d = f τ
kT
Df
= η
Raw juice
to purification
Press water
Figure 4.3 shows the fundamental options of raw juice purification. Juice purification
in the lime/carbonic acid treatment can be considered as a sequence of the following
operations: (1) precipitation and flocculation of colloidal components such as pectins
and proteins; (2) precipitation of phosphates, citrates, oxalates, and other insoluble
salts; (3) alkaline degradation of invert sugar and amides into organic acids, providing
thermostability of the juice on evaporation; (4) reduction of the calcium salt