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[en] Starches isolated from amaranth and buckwheat were analysed for thermal characteristics, crystallinity, gel textural properties and light transmittance. Buckwheat starch gels were harder with higher chewiness and springiness than amaranth starch gels. Starch from common buckwheat produced the hardest gel and amaranth starch from VL-44 cultivar produced the softest gel. Gelatinisation temperatures of amaranth and buckwheat starches differed significantly and tartary buckwheat starch showed the highest values for TP and TC. Buckwheat starches showed lower enthalpy change values than amaranth starches of both the cultivars. X-ray diffractometry confirmed ‘A’ type crystalline pattern for all tested starch samples and higher relative crystallinity was noticed in amaranth starches than buckwheat starches. Tartary buckwheat exhibited the lowest value of relative crystallinity and amaranth starch of Durga cultivars showed the highest value of relative crystallinity. FTIR spectrums showed band at similar wavenumbers (cm−1) with varying intensities. A declining order of paste clarity during storage at refrigeration temperature was observed for all starches.
[en] Highlights: • Successful synthesis of LaAlO3 using starch. • LaAlO3 nucleation was identified within a mixed lanthanum-aluminum precursor at 700 °C. • Residual OH groups and anions stabilize the nanocomposite structure of perovskite. • Perovskite with a La rich surface with distortions partly persistent upto 1300 °C.
[en] The particleboards were fabricated using Rhizophora spp. wood particles with particles size less than 74 micrometre . The corn starch was used as a bio-adhesive in the fabrication of Rhizophora spp. particleboards. The corn starch bonded particleboards were fabricated at 5% and 10% corn starch based on dry mass of Rhizophora spp. wood particles. The measurement of mass attenuation coefficients of the particleboards were made at low and intermediate photon energies. The mass attenuation coefficient at low photon energy was measured using X-ray fluorescent (XRF) configuration based on attenuation of K_α_1 X-ray energies between 16.59 and 25.26 keV given by niobium, molybdenum, palladium and tin metal plates. The calculated mass attenuation coefficients of samples were compared to the theoretical values mass attenuation coefficients of water calculated using the photon cross-section database (XCOM). The results showed that mass attenuation coefficients of 10 % corn starch added Rhizophora spp. particleboards were in good agreement of water within 7.96 and 4.94 % for 5 % and 10 % corn starch Rhizophora spp. Particleboards, respectively compared to 14.57 and 16.16 % in binderless Rhizophora spp. particleboards and raw Rhizophora spp. wood, respectively. (author)
[en] A stopped-flow method for the determination of 2-mercaptopyrimidine and its 14 derivatives by the iodine-azide has been elaborated. Spectrophotometric detection was applied and the decrease in the absorbance of the iodine-starch complex was monitored at 595 nm within 5 s. The effect of the concentration of the reagents on the rate of the reaction was investigated and a kinetic method for determination of compounds is proposed. 2-Mercaptopyrimidines can be determined at 10-6 to 10-5 mol L-1 level and the relative standard deviation is below 1%. The elaborated method has been applied to the determination of 6-methyl- and 6-propyl-2-thiouracil in drugs
[en] Radiation modification on liquid retention properties of native cassava starch, gelatinized at 850C, by graft copolymerization with acrylonitrile was carried out by mutual irradiation to γ-rays. A thin aluminium foil was used to cover the inner wall of the reaction vessel so that the extent of homo polymer could be reduced to be less than 1.6% with a distilled water retention value of 665 g/g of the dry weight of the saponified grafted product. Confirmations of graft copolymerization and saponification reactions were made by the infrared spectrophotometric technique. The combined effect of radiation parameters in terms of an irradiation time and a dose rate to the same total dose on the extent of grafting reaction expressed in terms of grafting parameters which directly influenced liquid retention values was evaluated in conjunction with statistical analysis
[en] Irradiation is one of the most effective methods able to change starch structure and its functional properties. Effects of irradiation are largely related to particular structure and molecular organisation of starch from various botanical sources. In this research, the effect of gamma irradiation (3, 5, 10, 20, 35 and 50kGy) on the rheological, structural, and morphological properties of three starch varieties (potato, tapioca and wheat) was studied. Rheological analyses show that all the starches develop different behaviours during gelatinization. Potato starch yielded the high swelling power (SP) and exhibited a maximum value of consistency during pasting, followed by that of tapioca one. The lower values of SP and maximum consistency were observed in the case of wheat starch. For all starch varieties, the pic consistency during pasting decrease with increasing irradiation dose. An increase in the SP was observed for all the studied starches irradiated with lower dose (until 20kGy). This parameter decreases at higher doses. On the other hand, irradiation improves the water solubility index (WSI) of all the studied starch. In addition, spectra of Fourier transformed infrared spectroscopy (FTIR) showed that the irradiated starch displayed a significant decrease in the intensity of the OH stretch (3000; 3600 cm-1), C H stretch (between 2800 and 3000 cm-1), bending mode of water (between 1600 and 1800 cm-1) and in the bending mode of glycosidic linkage (between 900 and 950cm-1). Structural analysis using electron spins resonance (ESR) illustrates the presence of three signals in 3490, 3500 and 3510 G, respectively. These signals confirm the presence of free radicals in the tapioca and wheat starches through radiation treatment. The X-ray diffraction (XRD) spectra showed that potato starch has B type morphology while tapioca and wheat starches have a crystalline A type morphology. In the same analysis, it was shown that irradiation treatment has no major changes in the polymorphic structure of all starch granules. Microphotographs of scanning electrons microscopy (SEM) showed that up to 50 kGy irradiation did not present any modification on the morphological state of the tapioca starch granules.
[en] Owing to the simultaneous occurrence of nucleation and nuclei aggregation in nanoprecipitation approach, the preparation of monodisperse nanospheres from polysaccharide remains a great challenge. Herein a two-step approach is presented for size controlled preparation of monodisperse polysaccharide-based nanospheres with PDI of 0.05 from starch acetate (SA). First, the starch acetate nanospheres (SANs) with average size in the range from 100 to 160 nm were produced by a moderate and constant hydrophobic interaction (MCHI) process. Second, based on principle of Ostwald ripening, a facile hydrothermal method was employed to modulate the size of the SANs obtained from the first step, yielding monodisperse nanospheres ranging from 200 to 1400 nm. This two-step method was also successfully applied to the preparation of ethyl cellulose nanospheres, which provided a facile strategy to prepare nanospheres from polysaccharides. Finally, SANs (744 nm) and ECNs (802 nm) were used to fabricate 2D photonic crystals by self-assembly, further verifying high monodispersity of obtained polysaccharide-based nanospheres. (paper)
[en] It has been already shown that degradation resulting from gamma irradiation induces a decrease in order of starch granules and influences gelatinisation taking place during heating of starch and flour suspensions. In presented paper, DSC (differential scanning calorimetry) studies were carried out for wheat starch, non-irradiated and irradiated using doses in the range from 5 to 30 kGy. The influence of the conditions applied during DSC measurements on the possibility to observe differences between the amylose-lipid complex transition and retrogradation taking place in the non-irradiated and particularly irradiated starch samples was checked. The better differentiation between the amylose-lipid complex transition taking place in particular samples accompanied by the better reproducity were obtained in the case of dense suspensions as compared to the watery suspensions as well as during the first analysis performed for the recrystallised gels
[en] Radiation processing can be used to modify the properties of biopolymers in order to widen its commercial application. Effect of irradiation (0, 5, 10 and 20 kGy) on the properties of Sago starch was studied. Apparent percentage carboxyl content increased with radiation dose while pH and bulk density of starch decreased as the dose of radiation increased. A dose dependent increase in solubility and light transmittance was observed while there was decrease in swelling capacity. Radiation processing of starch reduced syneresis at all the time points studied. XRD of starch revealed that there was no change in the pattern on radiation processing of starch. Sago starch is an inexpensive biopolymer that can be used to develop packaging films. However due to certain limitations such as low solubility, starch is modified/blended with other polymers for preparing films. Irradiated starch was blended with gelatin and lime juice to improve the functional property of the films. Films prepared with 2:1 starch/gelatin blend had the highest tensile and puncture strength and radiation processing of starch improved its mechanical properties. Addition of lime juice (LJ) resulted in the films having antioxidant and antibacterial properties. The practical application of using these films in food packaging was demonstrated in shelf life extension of minced chicken meat. Minced chicken meat packed in starch/gelatin films without LJ spoiled within 3 days while that packed in LJ containing films had a shelf life of 12 days during chilled storage. Lipid peroxidation of minced chicken packed in composite films containing LJ was also less. Hence, use of functional food packaging films with irradiated Sago starch-gelatin and LJ to enhance shelf life of food products is an environmentally and economically viable option for the food industry. (author)