Faculty Publications
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Item Microscopic and spectroscopic characterization of rice and corn starch(Wiley-Liss Inc., 2020) Govindaraju, I.; Pallen, S.; Umashankar, S.; Mal, S.S.; Kaniyala Melanthota, S.; Mahato, D.R.; Zhuo, G.-Y.; Mahato, K.K.; Mazumder, N.Starch granules from rice and corn were isolated, and their molecular mechanism on interaction with ?-amylase was characterized through biochemical test, microscopic imaging, and spectroscopic measurements. The micro-scale structure of starch granules were observed under an optical microscope and their average size was in the range 1–100 ?m. The surface topological structures of starch with micro-holes due to the effect of ?- amylase were also visualized under scanning electron microscope. The crystallinity was confirmed by X-ray diffraction patterns as well as second-harmonic generation microscopy. The change in chemical bonds before and after hydrolysis of the starch granules by ?- amylase was determined by Fourier transform infrared spectroscopy. Combination of microscopy and spectroscopy techniques relates structural and chemical features that explain starch enzymatic hydrolysis which will provide a valid basis for future studies in food science and insights into the energy transformation dynamics. © 2020 Wiley Periodicals, Inc.Item Investigation of structural and physico-chemical properties of rice starch with varied amylose content: A combined microscopy, spectroscopy, and thermal study(Elsevier B.V., 2022) Govindaraju, I.; Zhuo, G.-Y.; Chakraborty, I.; Melanthota, S.K.; Mal, S.; Sarmah, B.; Baruah, V.J.; Mahato, K.K.; Mazumder, N.Starch from a given botanical source can vary considerably in terms of physicochemical properties in its native and hydrolyzed forms. The current study investigated the structural and functional characteristics of starch from ten indigenous rice varieties endemic to Northeast India. In vitro enzymatic hydrolysis was used to reveal the dextrose equivalent profile of each type of starch. Gezep Sali and Betguti Sali respectively exhibited the highest and lowest starch hydrolysis. Among the ten rice varieties, amylose content varied between 7.50 and 28.58%. Optical and scanning electron microscopy (SEM) revealed the polyhedral shape of the native starch granules and deformation of the shape upon enzymatic hydrolysis. Second harmonic generation (SHG) microscopy and X-ray diffraction (XRD) analysis confirmed the presence of and variations in starch crystallinity. XRD revealed spectral peaks characteristic of A-type starch crystals in the native form. The elevated intensity of XRD peaks in hydrolyzed starch granules confirmed the occurrence of amylose hydrolysis rather than hydrolysis in amylopectin regions. Fourier transform infrared (FTIR) spectra revealed the common stretching and bending of bonds in all native starches; however, changes were observed in the fingerprint region (1080, 1000, 926 cm−1) of hydrolyzed starch granules, which indicates the amylolysis of the amylose region and disturbances in the ordered arrangement in the crystalline part. Differential scanning calorimeter (DSC) endotherms revealed the highest and lowest gelatinization peak temperatures in Harfoni (78 °C) and Tulosi Sali (41 °C) rice cultivars, respectively. The findings in this study can help to optimize the usage of rice starch in food and non-food industries. Furthermore, understanding the control points of starch digestion and genetically tailoring rice grains with different digestibility could be beneficial for nutraceutical applications. © 2021 Elsevier LtdItem Enhancement of dysprosium oxide doped zinc alumino borosilicate glasses in thermal, optical and luminescence domain for solid state lighting application(Elsevier B.V., 2022) Monisha, M.; Mazumder, N.; Melanthota, S.K.; Padasale, B.; Almuqrin, A.H.; Sayyed, M.I.; Karunakara, N.; Kamath, S.D.Zinc alumino borosilicate (ZABS) glasses incorporated with Dy3+ ions are prepared through melt-quenching technique. Non-crystallinity behaviour of the glasses are confirmed through XRD studies. The presence of functional and vibrational groups in the glass network are witnessed through FTIR studies. From the differential thermal analysis (DTA), the thermal stability of the glasses are found to be greater than 90 °C. UV–Visible–NIR spectra of glasses showed strong absorptions of Dy3+ ions in the NIR region (∼1267 nm). The highest bandgap value is obtained for ZABSDy0.5 (4.27 eV) glass that has the lowest amount of non-bridging oxygens. The ionic nature of dysprosium ions in the glass vicinity is thereby known through bonding parameter calculation. Judd-Ofelt (J-O) intensity parameters showed the trend Ω2 > Ω6 > Ω4, maintained same for all synthesized glasses. The luminescence spectra showed three emission peaks of Dy3+ ions at 482 (6H15/2), 575 (6H13/2) and 663 (6H11/2) nm. The hypersensitive transition observed at 4F9/2 → 6H13/2 exhibits a greater emission cross-section and radiative transition for all the glasses. Through the decay measurements, the lifetime of the Dy3+ ions are calculated. The estimated CIE coordinates for the glasses showed their location in white light region. The correlated colour temperature (CCT) values are obtained between 4200 and 4500 K suggesting the importance of glasses to use for white-LEDs application. © 2022 Elsevier B.V.Item Evaluation of physicochemical properties of citric acid crosslinked starch elastomers reinforced with silicon dioxide(Royal Society of Chemistry, 2024) Pooja, N.; Chakraborty, I.; Mal, S.S.; Bharath Prasad, A.S.; Mahato, K.K.; Mazumder, N.Thermoplastic starch (TPS), derived from renewable resources, offers advantages such as biodegradability and lower production costs compared to petroleum-based plastics. However, its limited mechanical properties pose a challenge for broader applications. This research aims to explore the potential of enhancing the mechanical and barrier properties of TPS films through the incorporation of silicon dioxide as a reinforcement filler and citric acid as a crosslinking agent. By introducing silicon dioxide as a reinforcement filler, the mechanical strength of the TPS films is expected to be improved. Additionally, the incorporation of citric acid as a crosslinking agent is anticipated to enhance the barrier properties of the films. The combination of these additives holds promise for creating TPS films with improved performance, contributing to the development of sustainable and environmentally friendly materials in various industries. The results reveal that SiO2 improves the stiffness of the films at lower concentrations but causes brittleness at higher concentrations. In contrast, citric acid crosslinked films exhibit improved flexibility and density. Scanning electron microscopy demonstrates the morphological changes in the films, with SiO2 affecting surface roughness and aggregate formation. SiO2 reduces film thickness and transparency, while citric acid enhances water resistance and barrier properties. X-ray diffraction analysis shows a reduction in crystallinity due to the plasticization process. Fourier-transform infrared spectroscopy highlights chemical changes and antimicrobial activity is observed with citric acid against specific bacteria. The soil burial test reveals that citric acid crosslinked films exhibit slower degradation due to antimicrobial properties. The combination of SiO2 reinforcement and citric acid crosslinking enhances the overall performance of the films, promising sustainable and environmentally friendly materials for various applications. © 2024 The Royal Society of Chemistry.