Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 1, pp. 127−131.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © T.V. Shevchenko, E.A. Kondratov, E.V. Ul’rikh, A.M. Popov, V.S. Lobanova, I.O. Tokmakova, 2013, published in Zhurnal Prikladnoi
Khimii, 2013, Vol. 86, No. 1, pp. 138−142.
On the Variation of Physicochemical Properties
of Starch Samples Treated by Microwave Radiation
T. V. Shevchenko, E. A. Kondratov, E. V. Ul’rikh, A. M. Popov,
V. S. Lobanova, and I. O. Tokmakova
Kemerovo Technological Institute of Food Industry, Kemerovo, Russia
Received May 12, 2012
Abstract—Acid-base properties of potato starch suspensions, unirradiated and exposed to microwave radiation,
and also comparative structural and mechanical properties of their cooked gels were studied by the methods of
electronic photography of starch grains, direct potentiometry, and potentiometric titration.
Starch is important food and engineering product
widely applied in various branches of food industry
(milk, meat, canning, baking, and confectionery), and
also in nonfood technologies: textile, pharmaceutical,
polygraphic, etc. . It is a permanently restored food
object of the vegetable origin and belongs to natural
polymers. In cells of plants starch is in the form of dense
formations (starch grains), which range in size from 15
up to 100 μm .
Starch is basically a mixture of two polymers, linear
(amyloses) and branched (amylopectin). Amylopectin
branching is formed due to side groups. The molecular
weight of amylopectin reaches several millions and that of
amylose does not exceed hundreds thousand . In water
ﬂ exible macromolecules of amylose combine in coils.
Apart from the enumerated organic components,
starch contains residuals of the inorganic compound,
phosphoric acid, which are connected with several
glucose residuals through ether bonds according to the
general formula [R = СН
]. The content of
these phosphoric acid residuals in amylose is negligible
(0.03%), and in amylopectin it is higher (0.20–0.22%)
[1, 2]. Individual links of amylopectin molecules are
negatively charged, and the molecules have a rigid con-
formation. The structure of the main starch components
is presented in Fig. 1 .
Physicochemical properties of native starch depend on
the nature of a starch-containing raw material, which not
always meet necessary demands of customers. Therefore
presently the major attention is given to the development
of effective methods of a purposeful change of starch
natural properties, i.e. modiﬁ cation of its properties.
Modiﬁ cation methods can be chemical, physical, or mixed
in nature. Of the greatest interest are physical modiﬁ cation
methods: mechanical and microwave radiation (MWR)
methods, which, unlike chemical methods, make it pos-
sible to change main technological properties of starch
without reagents [3–6].
At present the microwave chemistry, chemical trans-
formations under the MWR action, successfully develops.
It is known that MWR is the radiation in the microwave
frequency range of 0.03–30 GHz, which pulsates perma-
nently 2–100 times per second depending on frequency,
setting in motion molecules of polar substances. In the
home microwave ovens adjusted on water molecules, the
frequency of water molecules of 2.45 GHz (25 vibrations
per second) is chosen. Thus water molecules intensively
absorb the ﬁ eld energy, which converts to various types of
energy: vibrational, rotational, and the energy of possible
radical decomposition of water molecules according to