Mamta Bhardwaj has obtained her Bachelor’s degree in Biotechnology, Masters in Food Engineering & Technology and is presently a Doctoral student and an INSPIRE Fellow at Sant Longowal Institute of Engineering & Technology, India. Her current research interests include starch and its nanoparticles and rheology of food materials, particularly the dynamic mechanical analysis.


Starch is one of the most abundant biopolymer extracted from plants in the form of micro-granules. Due to fascinating properties of being non-toxic, non-irritant, low-cost, ease of modification and versatile use, etc., makes starch a promising candidate to prepare nanoparticles. Starch nanoparticles already attract great interest because of their wide application in food, cosmetics, medicines as well as various composites. Various botanical sources are available for extraction of starch nanoparticles facilitating nanoparticles with a range of amylose content, shape, viscosity in suspension and thermal resistance. Starch nanoparticles can be synthesized by both physical and chemical methods. In the present study, starch nanoparticles were synthesized from two varieties of Pearl millet (HHB67 and ProAgro 9444) by acid hydrolysis and acid hydrolysis coupled with ultrasonication. Acid hydrolysis at 3.2 M H2SO4 and 40 oC for 5 days resulted in starch nanoparticles in the range of 40-60 nm whereas acid hydrolysis for 2 days coupled with ultrasonication resulted in 20-30 nm particle size. Among the two varieties HHB67 gave nanoparticles with smaller size than ProAgro 9444 due to more amylopectin content viz., 85% amylopectin in HHB67 and 79% in ProAgro 9444. Morphological and crystalline structure was analyzed by scanning electron microscopy and XRD respectively. The results revealed that nanoparticles possess A-type granular structure as obtained for the crystalline structure of original starch varieties. Besides the nanometric size, methods and varieties showed significant difference in solubility, hygroscopicity and paste clarity. Dynamic mechanical analysis was studied to obtain temperature and amplitude sweep data. Nanoparticles obtained by acid hydrolysis and acid hydrolysis coupled with ultrasonication can be used in bio-nanocomposites.