Page 8 - Physicochemical properties of Indian plant gums- IINRG, Ranchi

The chemical composition and microbial standards of gums obtained from different acacia
tree species have been comparedand sho'*rr to be appropriate for use in food.

Table I Chemical composition of gums obtained fromlcacia nilotica and Acacia senegal

Heary metals (ppm)
Moisture (%)

Table 2 Microbiological testing of gums obtained from I cacia nilotica and, Acacia senegal

Aerobic plate counVg
Yeast and Molds/g
E.Coli/12.5g

Wscosity: The viscosity of 30 percent of A. nilotica and, A. senegal gums at shear rate
of 9.6 Sec-rwas found to be 120 cps and 95 cps respectively. Viscosity ofboth the gums
decreases as the shear rate increases. Therefore, both the gums can be termed as pseudo-
plastic material. Studies on viscosity and temperature have shown that drop in viscosity of
these gums are significant when heated from 300 to 900C. Viscosity ofl. nilotica drops fuom
120 cps to 46 cps andl. senegal drops flom 95 cps to 33 cps. Viscosity of 50lo solution of
these gums showed synergistic increase when 0.5olo and 1% xanthan gum was added and in
both the gums synergistic viscosities were lower than the viscosity of0.5% and 10lo xanthan
gum alone. Synergistic increase in the viscosity ofa mixed solution decreases on addition
ofurea (4.0, 6.0 and 8.0 M), thereby showing that increase in viscosity is due to hydrogen
bonding. A comparison of the physico-chemical properties of A. nilotica gum solution
with those of A. senegal gtm solutions suggests that there are important differences in the
molecular architecture ofthe two gums in addition to fine structure variations, which are
predictable fiom knowledge ofthe difference in chemical composition of the two gums.

Electrical conductitiv i Grm arabica obtained from acacia tree has been found to be an
ionic conductor It has been found to show high value of ionic conductivity after swelling
which may be due to release of ions during swelling. The overall conduction mechanism
has been suggested to be protonic in natue rather than electronic one.