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关键词： Dimethoxy-N '-(phenylsulfonyl)-benzenesulfonohydrazide   Calcium ion   Sensitivity   Limit of detection   Limit of quantification   Natural sample  

摘要： Two new molecules (2,5-dimethoxy-N'-(phenylsulfonyl)-benzenesulfonohydrazide, DMPSBSH and 2,5-dimethoxy-N'-(phenylsulfonyl)-4-methylbenzenesulfonohydrazide, DMPSMBSH) were synthesized by using a simple condensation method from 2,5-dimethoxy-benzene-1-sulfonyl chloride (DMBSC) and benzenesulphonylhydrazine (BSH) and 4-methyl-benzenesulfonylhydrazine (4-MBSH) respectively in a good yield which were crystallized in MeOH and then re-crystallized from acetone and EtOAc (50:50). Synthesized molecules were characterized by means of spectroscopic techniques for example H-1 NMR, C-13 NMR, FTIR, and UVeVis. A probe was furnished by deposition of little layer of DMPSBSH and DMPSMBSH onto a flat GCE with conducting polymer matrix, Nafion (Nf). This furnished probe was used for the impending detection of calcium ion (Ca2+) by using a dependable current-voltage technique. Analytical parameters (Sensitivity, LOD, and LOQ) of the proposed probe (DMPSMBSH/GCE/Nf) towards Ca2+ were calculated from the calibration curve as 2531.65 pA mu M(-1)cm(-2), approximate to 98.25 pM, and 327.5 mM respectively. This imminent DMPSMBSH/GCE/Nf probe applied to the selective determination of Ca2+ in spiked natural samples and found good results. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Lotus seed starch nanoparticles   Enzymatic hydrolysis   Physicochemical properties  

摘要： Lotus seed starch (IS) was enzymatically hydrolyzed by pullulanase, beta-amylase and alpha-amylase to obtain three types of starch nanopartides (SNPs): P-SNPs, beta-SNPs and alpha-SNPs, respectively. The structure and physicochemical properties of lotus seed starch nanoparticles (LS-SNPs) were systematically studied by Laser particle size analysis, Scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectrometry, Nuclear magnetic resonance (NMR) and Gel permeation chromatography (GPC). The results showed that compared to LS (10,466.7 +/- 230.9 nm), the D [3,2] of P-SNPs were (334.7 +/- 16.2), which indicated that LS was decomposed into LS-SNPs with low degree of polymerization. P-SNPs showed the highest efficiency, with 81.74% of samples reaching the nanoscale. The particle size order was LS > beta-SNPs (alpha-SNPs) > P-SNPs. XRD results showed P-SNPs had the highest crystallinity 65.07%. During preparation of LS-SNPs, crystal region was destroyed, and double helix structure became stronger, but no new functional groups were introduced. P-SNPs had the smallest amorphous area and also showed a minimal molecular weight and the broadest molecular weight distribution. P-SNPs had the smallest particle size and the highest crystallinity, so P-SNPs were the best of all LS-SNPs. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Surface morphology  

摘要： In this study, in order to evaluate influences of different drying methods on the structural characteristics, physicochemical properties and antioxidant activities of exopolysaccharides (EPS) from Lactobacillus helveticus MB2-1, three drying methods, including spray-drying (SD), freeze-drying (FD) and spray freeze-drying (SFD), were applied to dry EPS. Results showed that different drying procedures had no significant influence on the primary structure and constituent monosaccharides of EPSs. However, the surface morphology of the three dried EPSs varied greatly in size and shape due to different drying processes. Among three dried EPSs, the particle size distribution of spray freeze-dried EPS (SF-EPS) was relatively narrower and uniform. Additionally. SF-EPS behaved better apparent viscosity and emulsifying property than spray-dried EPS (S-EPS) and freeze-dried EPS (F-EPS). SF-EPS exhibited stronger antioxidant activities when compared with S-EPS and F-EPS, according to the results of scavenging activities on different radicals and chelating activity on ferrous ion. Overall, SFD was the appropriate method for industrial production of EPS from Lactobacillus helveticus MB2-1 with better physicochemical properties and antioxidant activities. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Pea starch   Maltogenic amylase   Pullulanase   Branch density   Crystalline complex   Amorphous complex  

摘要： An enzymatic method was investigated to initiate a strategy of increasing the branch density of pea starch, thus facilitating the formation of a starch -lipid complex after debranching. When the starch was modified by exposure to maltogenic amylase (MAL) and pullulanase (PUL), lower molecular weight values and higher amylose content resulted compared to the untreated sample. High-performance anion -exchange chromatography results sug- gested that the average chain length decreased and the branch density increased after the starch received MAL treatment. The diffraction intensities and the total melting enthalpies of the dual -enzyme treated complex were greater than those for other samples when the level of MAL between 4-12 U/g. Fourier transform infrared spectroscopy revealed that more ordered structure was formed in MAL (4/8/12)-PUL-starch-lauric acid (Lau) complexes. Digestive performance analysis indicated that the enzyme resistance of the starch -Lau complex was reinforced by applying the MAL-PUL modification to the starch.

关键词： Carbanion   Ionic liquids   Physicochemical properties   Viscosity, basicity  

摘要： Densities, viscosities, refractive indices and conductivities of four carbanion-functionalized ionic liquids (ILs) were measured in the temperature range of 2982-348.2 K. The effect of temperature on these physicochemical properties were also studied. The results showed that the values of density and refractive index decreased linearly but the conductivity increased exponentially with the increase of temperature, while the viscosity decreased exponentially with the temperature increased. Moreover, the conductivities of phosphonium carbanion-functionalized ILs were much lower than common phosphonium amino add ILs because of high ionic association and poor ion mobility of carbanion. In addition, the characterization of FT-IR and H-1 NMR by using pyrrole as a probe molecule showed that [P-4448][Dib] exhibited the strongest basicity among these four carbanion-functionalized ILs. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Atlantic mackerel (Scomber scombrus)   Fillets   Sodium erythorbate   Polyphosphate   Lipid oxidation  

摘要： This study aimed to evaluate the shelf-life of mechanically filleted well-fed Atlantic mackerel during frozen storage at - 25 degrees C and effect of treatment with antioxidants (sodium erythorbate and a polyphosphate mixture) and different antioxidant application methods (dipping, spraying and glazing). Both physicochemical measurements and sensory analysis were applied. Antioxidant treatments prolonged shelf-life of mackerel. Sensory analysis indicated that untreated fillets had a shelf-life of less than 2.5 months, while all antioxidant treated fillets exceeded that. The most effective treatment, dipping fillets into a sodium erythorbate solution, yielding a shelf-life of 15 months. Physicochemical methods used to evaluate degradation of lipids in the fillets were free fatty acids (FFA), lipid hydroperoxides (PV) and thiobarbituric acid reactive substances (TBARS). They did not correlate with sensory results and might therefore be a questionable choice for evaluation of oxidation and development of rancid flavour and odour in complex matrixes such as Atlantic mackerel.

关键词： Salmon   Alcalase   beta-Cyclodextrin   2-Butanol   Hydrophobic amino acids   Debittering  

摘要： Impacts of 2-butanol and beta-cyclodextrin (beta-CD) at various ratios and treatment times on bitterness, physicochemical and functional properties of Alcalase salmon frame protein hydrolysate (ASF) were investigated. ASF treated with 2-butanol at a ratio of 1:4 (w/v) for 20 min (ASFB) or with beta-CD at a ratio of 1:1 (w/w) for 30 min (ASF-C-1) had lower bitterness score than ASF (p < 0.05). Bitterness score of ASF (8.45) was reduced to the lowest score (1.32) when ASFB was subsequently treated with beta-CD at a 1:1 ratio (w/w) for 30 min (ASFB-C-1). Surface hydrophobicity of all debittered samples was lower than that of ASF sample (p < 0.05). The level of aromatic amino acids-containing peptides was reduced in ASFB-C-1 as shown by gel permeation chromatography. ASFB-C-1 sample had higher overall-likeness score but lower antioxidant properties than ASF (p < 0.05). The desired antioxidant activity could be achieved via increasing the amount of protein hydrolysate without imparting undesirable taste.

关键词： Porous anodic alumina   Pulse anodization   Aluminum oxide nanotubes   Current density   Post-treatment  

摘要： A study on advanced structural engineering of anodic alumina nanotubes (AANTs) manufactured by pulse anodization is presented. In-depth analysis of the electrochemical parameters of pulse anodization was carried out, distinctive sections of the anodization were defined. Evolution of the profiles has been quantified and described with regards to different current density applied and pulse duration during hard anodization. A smart combination of different anodization conditions enables precise control over the nanotubes' geometric features and physiochemical properties. Nanotubes are produced with varying pulse period, current density level and various post-anodization treatments (different sonication time, temperature and thermal annealing of anodic alumina film before fragmentation) under galvanostatic mode in sulfuric acid electrolyte modified with 10% (v) ethanol. The average length of nanotubes is tailor-engineered from 424 +/- 92 to 1010 +/- 118 nm, with an average inner diameter that ranges from 37 to 48 nm. It is also demonstrated that the level of current density input during pulse anodization has a direct effect on the zeta-potential of nanotubes, which can be tuned between 25 and 8.5 mV. Additionally, it is possible to produce nanotubes with a negative zeta-potential of -6.3 mV upon post-annealing treatment. Separation of nanotubes from the original template is improved by sonication at low temperature, providing a new means of increasing the production yield of these nanostructures. Furthermore, nanotubes are found to increasingly degrade with the bath temperature during separation. To better understand the impact of the fabrication parameters over the physical and chemical properties of nanotubes is a key step to design and tailor-engineer these model 1D nanostructures for specific applications. AANTs provide many attractive features that could find broad applicability in disciplines such as catalysis, drug delivery, nanofabrication and sensing.

关键词： Chitosan-based macroparticles   Eggshell membrane   Macroporous structure   Protease immobilization   Substrate diffusion  

摘要： Chitosan-based macroparticle is a common carrier for enzyme immobilization applied in food industry. Driven by the requirement of large carrier pores for the biomacromolecular substrates such as protein, the eggshell membrane powder (ESMP) was employed as multifunctional porogen to improve the physicochemical structure of chitosan-based macroparticles. The prepared macroparticles were characterized by SEM, XRD, FTIR, Raman spectroscopy, nitrogen adsorption -desorption isotherms, and thermogravimetric analysis. The results showed that an increase of ESMP percentage could improve the porosity of macro holes in macroparticles, and it also enlarged the size of mesopores. Moreover, the ESMP significantly increased (P < 0.05) the amount of papain immobilization, whereas the specific activity of immobilized papain achieved a maximum value of 871.95 U/mg at CSESM2 and then declined with the increase of ESMP. Therefore, the inclusion of 20 % ESMP in chitosan-based macroparticles gave the highest activity of its immobilized protease.

关键词： Lotus seed starch   Morphology   Pasting   Thermal  

摘要： Native and gamma (gamma) irradiated lotus seed starches were studied for their physicochemical, thermal, pasting and morphological properties. Upon gamma irradiation of 5, 10, 15 and 20 kGy, amylose content of starches was decreased as the dose of irradiation was increased. Lotus seeds starch granules had bimodal size distribution varying in size from small to large. Observation under scanning electron microscope (SEM) showed that at low dose of irradiation (5, 10kGy), no significant changes were observed in shape and size. However, minor alterations were notice during treatment of 15kGy and 20 kGy, which included roughness. Irradiation significantly decreased the pasting properties (peak, trough, final and setback viscosities) of the starch. For native starch, T-o, T-p, and T-c of 137.44 degrees C, 13829 degrees C and 143.21 degrees C and 169.51 degrees C, 169.72 degrees C, and 177.73 degrees C respectively was observed for first and second peak. Upon irradiation, the gelatinization temperatures were decreased. The irradiated starch showed no change in diffraction pattern compared to native lotus seed starch but a dose-dependent decrease in relative crystallinity was observed. (C) 2020 Elsevier B.V. All rights reserved.