Starch Nanocomposite and Nanoparticles: Biomedical Applications - Modern Trends in Chemistry and Chemical Engineering - page 59

Starch Nanocrystals
Starch nanocrystals can be obtained by an acid hydrolysis on starch native granules.
They consist of crystalline nanoplatelets about 6-8 nm thick with a length of 20-40
nm and a width of 15-30 nm. These starch nanocrystals displayed interesting reinforc-
ing properties when dispersed in different mediums. Interesting reinforcing capability
was also obtained for nanocrystals of reinforced starch plasticized by glycerol. Graft-
ing of larger chains on the surfaces of starch nanocrystals enhance the nonpolar nature
of original nanoparticles and dispersion in organic media. The mechanical proper-
ties of nanocomposite materials processed from the modified nanocrystals and natural
rubber were found to be lower than those for unmodified nanoparticles, because the
length of the grafted chains is high enough, entanglements are expected to occur with
the polymeric matrix.
Njavara Rice Starch
Njavara is a rice variety widespread to Kerala, mainly seen in the northern parts (Fig.
3.2). The cultivation of this rice variety is recorded from 2500 years back. Njavara is
a unique grain plant in the Oryza group and widely used in the Ayurvedic system of
medicine, especially in Panchakarma treatment. Njavara as a special cereal, have the
properties to rectify the basic ills affecting our circulatory, respiratory, and the diges-
tive systems. This variety is highly resistant to drought conditions and is generally
resistant to diseases. Dehusked Njavara rice has 73% carbohydrates, 9.5% protein,
2.5% fat, 1.4% ash, and 1628 kJ per 100 g of energy. Higher amounts of thiamine
(27-32%), riboflavin (4-25%), and niacin (2-36%) and the total dietary fiber content
in Njavara was found to be 34-44% higher than compared to the other rice varieties.
Significantly higher phosphorus, potassium, magnesium, sodium, and calcium levels
were found in Njavara rice. Two types of Njavara are recognized, the black and golden
yellow glumed. In the case of black glumed variety, the seed color is red.
Figure 3.2. Njavara rice.
Applications of Starch
Starch is a versatile and economical, and has many uses as thickener, water binder,
emulsion stabilizer, and gelling agent. Starch is often used as an inherent natural in-
gredient but it is also added for its functionality. Mixing with hydrocolloids and low
molecular weight sugars can also reduce retrogradation. At high concentrations, starch