Open Access

ARTICLE

Physicochemical Characterization and Antimicrobial Properties of Inulin Acetate Obtained by Microwave-Assisted Synthesis

by Nadezhda Petkova, Radka Arabadzhieva, Dragomir Vassilev, Gergana Gencheva, Yulian Tumbarski, Tsveteslava Ignatova-Ivanova, Sevginar Ibryamova, Mina Todorova, Milena Koleva, Panteley Denev

1 Department of Organic Chemistry and Inorganic Chemistry, University of Food Technologies, Plovdiv, 4002, Bulgaria
2 Department of Physics, Chemistry and Ecology, Technical University of Gabrovo, Gabrovo, 5300, Bulgaria
3 Department of Microbiology, University of Food Technologies, Plovdiv, 4002, Bulgaria
4 Department of Biology, Konstantin Preslavsky University of Shumen, Shumen, Bulgaria

* Corresponding Author: Nadezhda Petkova. Email:

(This article belongs to the Special Issue: The 10th Conference on Green Chemistry and Nanotechnologies in Polymeric Materials (GCNPM 2019))

Journal of Renewable Materials 2020, 8(4), 365-381. https://doi.org/10.32604/jrm.2020.09292

Received 29 November 2019; Accepted 13 January 2020; Issue published 24 April 2020

Abstract

Microwave-assisted irradiation was performed for esterification of chicory inulin with high degree of polymerization with acetic anhydride without a solvent only with a catalyst. The resulting esters were characterized by melting point, hydrophilic-lipophilic balance, thin-layer chromatography, ultraviolet spectroscopy, Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Inulin acetate demonstrated a high degree of acetylation (2.5–3.0) and presented a white, water-insoluble substance with bitter taste. The FTIR and NMR spectra confirmed esterification and demonstrated the incorporation of hydrophobic residue to the water soluble inulin backbone. Swelling capacity, water holding, oil-holding capacities, the foamability, foam stability and emulsifying properties were also evaluated. Inulin acetate showed promising foam stability 52% for 60 min and formed stable emulsions at concentration 0.2 g/ L with 50 and 80% oil phases. Its water holding capacity was lower than the oil holding capacity. In addition to this, for the first time, the antimicrobial potential of inulin acetate was tested against seventeen microorganisms (Gram-positive and Gram-negative bacteria, yeasts and fungi). Inulin acetate (10 mg/ml) inhibited the growth of Bacillus cereus, Escherichia coli ATCC 8739, Salmonella abony, Candida albicans and Penicillium sp. However, inulin acetate demonstrated antimicrobial activity at concentration 1 mg/ml against Listeria monocytogenes 863, Escherichia coli 3398, Candida albicans 8673, Fusarium oxysporum and Aspergillus niger. The current study demonstrated the applications of “green” synthesized inulin acetate as a foaming agent, oil-in-water emulsion stabilizer and antimicrobial substance in pharmaceutical, agricultural and cosmetic preparations.

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