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关键词： Squid   Microstructure   Myofibrillar proteins (MPs)   Proteome  

摘要： Neon flying squid (OB) and jumbo squid (DG) mantles were evaluated to reveal the similarities and differences in their physicochemical features and protein abundances. Microstructural results indicated that the OB mantle exhibited numerous myofibril fragments and disordered microstructures after frozen storage compared with DG tissues. Chemical analysis suggested that freezing resulted in a rapid decrease in myofibrillar protein (MP) content, Ca2+-ATPase activity, and total sulfhydryl content, and promoted the increase in carbonyl content of MPs in both OB and DG. While, DG presented better MP stability than OB muscle after 120 days of frozen storage. Label-free proteomic analysis detected 24 down- and 33 up-regulated differentially abundant proteins (DAPs) in OB and DG mantles. Identified DAPs including isocitrate dehydrogenase and malic enzyme initiated a rapid decrease in the MP properties in OB samples. Moreover, DAPs were related to cytoskeleton function, including paramyosin, tropomyosin, and troponin C, which improved the stability of DG in response to freezing-induced changes.

关键词： 大气单颗粒   颗粒形貌   数量贡献   质量贡献   工业排放源  

摘要： 城市地区大气气溶胶颗粒的物理化学特性复杂,理清单颗粒精细的化学成分和混合状态对于大气污染溯源和精细治理具有重要意义。本研究利用被动式气溶胶采样器分别在山东省日照市城区和钢铁园区两个区域进行了定点采样,并利用智能扫描电镜环境颗粒物分析系统(IntelliSEM EPAS)对采集的大气单颗粒物样品进行分析。结果表明,日照市大气颗粒物主要由不规则碳质颗粒(C-rich)、含硫颗粒(Ca-S、Na-S-Ca)与矿物颗粒组成。其中,城区样品中C-rich颗粒数量贡献为53.5%,是钢铁园区样品的2.5倍,大于1μm的颗粒物数量为9.0%,是钢铁园区样品的1.7倍,城区居民活动和工业过程是城市中大气颗粒物特别是二次细颗粒的主要来源。钢铁园区样品中含硫颗粒物数量贡献为72.9%,含硫颗粒物质量贡献为30.9%,富铁颗粒物质量贡献为5.3%,分别是城区样品的1.8倍、3.6倍和2.9倍,表明钢铁园区大气颗粒物的主要来源包括钢铁企业排放的一次污染物及其转化生成的二次细颗粒物。

关键词： Myofibrillar proteins   AAPH   Protein oxidation   Structure   Gel properties  

摘要： Protein oxidation of fish products during storage and processing is of interest recently. In this study, the effect of peroxyl radicals generated from 2,2 '-azobis (2-amidinopropane) dihydrochloride (AAPH) on the physicochemical and gel properties of myofibrillar protein (MP) from grass carp was investigated. After incubation with AAPH (0.04, 0.2, 1, 5, 25 mM), the carbonyl and dityrosine content, and surface hydrophobicity index of MP were higher than that of the non-oxidation control. Conversely, this treatment decreased the free ammonia, total and free sulfhydryl content of MP progressively. The transformation from alpha-helix to beta-sheet and beta-turn in MP treated with AAPH was found. The fluorescence quenching of tryptophan occurred in the 5 and 25 mM AAPH groups. When the AAPH concentration reached to 25 mM, the protein solubility decreased to 58%, compared to the control group. Meanwhile, this AAPH treatment damaged the elastic feature of MP and also decreased the water holding capacity, gel strength and texture of gel, which were closely depended on the oxidation degree. The poor and rough microstructure provided solid and visible evidence for the loss of gel properties in oxidation treatment groups. In short, these results gave a deeper understanding for the changes of physicochemical and gel properties of fish MP subjected to oxidation environment.

关键词： Stingless bee honey   Raw honey   Dehumidified honey   Geographical origins   Physicochemical properties   ATR-FTIR   Chemometrics  

摘要： Stingless bee honey has been well recognized and consumed due to its nutritional and therapeutic values. This study investigated the physicochemical properties and chemical profiles of Malaysian stingless bee honey from different species, dehumidification process, and geographical origins using chemometric techniques. In total, 122 samples were collected from different species across different states in Malaysia. The range for each of the physicochemical properties in the studied samples was as stipulated by the Malaysian standard. However, a significantly different (p < 0.05) in the value of free acidity (FA), pH, and ash content (AC) was observed between honeys obtained from the species of Heterotrigona itama and Geniotrigona thoracica. The attenuated total reflection Fourier-transform infrared (ATR-FTIR) chemometrics showed that the wavenumbers at 2934, 1400, 1040, and 1256 cm-1 were more prominent in H. itama and G. thoracica, whereas the predominant wavenumbers at 600 - 900 cm-1 were observed in Tetrigona apicalis. The chemometric analyzes showed the reliability of physicochemical properties and ATR-FTIR to differentiate the stingless bee honey on the basis of the dehumidification process and geographical origins but not by species. The findings indicate the potential use of the ATR-FTIR-based chemometric approach in the classification and quality control of Malaysian stingless bee honey besides the existing physicochemical analysis.

关键词： Water   Cellophane   Cellulose   Mirror symmetry   Interfacial water   Nafion  

摘要： We present experimental data on water repetitively brought in contact with cellophane. Although this hydrophilic polymer is insoluble in water, repetitively immersing it in water changes the liquid's properties. We compare the physicochemical properties of the water left over after removing the cellophane to those of previously published data on water repetitively brought in contact with other in water insoluble polymers (cotton wool or Nafion). Some of the properties are similar. All the properties considerably differ from those of the Milli-Q(R)water used. On lyophilizing these waters, solid residues remain. The residues are soluble in water. The chemical nature of the residues differs from that of the perturbing polymers.

关键词： Water-in-oil-in-water (W/O/W) emulsion   Multiple emulsion   Resveratrol   Bioavailability  

摘要： Evaluations have been made about the physicochemical stability in water-in-oil-in-water (W/O/W) emulsion loaded with resveratrol under different pH, NaCl concentration, temperature, and storage time. The in vitro digestion and Caco-2 cell transport were also investigated. Results showed W/O/W emulsion remained stable at pH 2-8, temperatures of 25-70 degrees C and could be stable storage for 77 days. With an increase in NaCl concentration from 1 to 500 mM, the zeta potential changed from-40 mV to-10 mV, but the droplets size didn't show any significant change. The in vitro digestion showed W/O/W emulsion could maintain the structure until small intestine which could give higher protecting for resveratrol. Meanwhile, W/O/W emulsion could reduce the efflux rate of resveratrol across the Caco-2 cell monolayers and special complex of W/O/W emulsion could delay resveratrol release. Results indicated that W/O/W emulsion was suitable vehicle for resveratrol and could improve its bioavailability considering those complicated influence factors.

关键词： DPP-IV inhibitory peptides   Physicochemical properties   Dynamic time warping   Orthogonal minimum spanning tree   Support vector machine  

摘要： Dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides play a crucial role in drug development and the treatment of diabetes. Thus, it is an urgent task to fast and precise distinguishing DPP-IV inhibitory peptides from non-DPP-IV inhibitory peptides. This study developed a support vector machine (SVM) based model to accurately identify DPP-IV inhibitory peptides. Specifically, the peptide sequences were firstly encoded by fifty kinds of physicochemical properties, and dynamic time warping algorithm was introduced to capture the correlation information of distinct physicochemical properties of amino acids. To further remove the effect of noise, orthogonal minimum spanning tree algorithm was proposed. Finally, the features were inputted into SVM to discriminate DPP-IV from non-DPP-IV inhibitory peptides. In the jackknife test, our proposed method achieved 86.28% and 87.97% classification accuracies on benchmark and independent datasets, respectively. The experimental results showed that the proposed method achieved significant improvement in classification performance, as compared with the existing method. The datasets and code are publicly available at https://***/articles/online_resource/iDPPIV/14769174.

关键词： Acidification  

摘要： Acid-rennet skim milk gels were formed by simultaneous bacterial fermentation and renneting at three different temperatures at constant inoculum level. Temperatures >24 degrees C accelerated milk acidification and resulted in firmer and more cohesive gels. It was possible to shorten the acidification process from similar to 795 min (28 degrees C) to similar to 600 min (32 degrees C) without affecting curd quality;there was no significant difference in texture properties between curds formed at 28 or 32 degrees C. Internal structure of curds, observed using scanning electron microscopy, was substantially affected by acidification rate. More crosslinking and thicker bonds were formed when milk was coagulated at 32 degrees C compared with 24 or 28 degrees C. Faster network formation at 32 degrees C resulted in bigger pores, favouring whey leakage. Increasing temperature significantly increased syneresis, due to intensified intra-network rearrangements. Milk incubation temperature can therefore be used as a process variable to increase syneresis and alter acid-rennet gel texture. (C) 2021 The Authors. Published by Elsevier Ltd.

关键词： Fat mimetic   Wholefood fat replacer   Descriptive sensory evaluation   Reduced-fat cookie  

摘要： Fat is an essential component for cookies structure and sensory attributes, but there is a necessity to replace or mimic fat in order to prevent lifestyle diseases. Hence, this study investigated the effect of industrial by-product, i.e., Partially defatted tomato seed flour (PDTSF) as a fat replacer on physicochemical and sensory characteristics of millet-based cookies at 10, 20, 30, and 40% (w/w) fat replacement levels. The physicochemical and functional properties of PDTSF were analyzed. PDTSF exhibited excellent nutritional profile and functional properties. PDTSF supplemented cookies showed a significant increase (p <= 0.05) in hardness, protein, ash, and carbohydrate content and the significant decrease in spread ratio, fat, and energy value with an increment of PDTSF. Descriptive sensory evaluation of millet-based cookies at all fat replacement levels showed good acceptability. Storage analysis for 30 days revealed as acceptance of cookies is not affected due to moisture intake and hardness. Hence, the results confirmed the positive effect on PDTSF as a whole food fat replacer to produce Reduced- fat millet cookies at 10 and 20% fat replacement levels. [GRAPHICS]

关键词： Corn cob   Geospatial investigation   Physicochemical properties   Power generation   Pyrolysis   Thermodynamic parameters  

摘要： Biomass represents vast under-explored feedstock for energy generation across the globe. Among other factors, the location from where the feedstock is harvested may affect the overall properties and the efficiency of bioreactors used in the conversion process. Herein is reported some physicochemical properties, the kinetic study and thermodynamic analysis of corn cob sourced from two major economies in sub-Sahara African region. Brunauer Emmett and Teller (BET) analysis was performed to investigate the surface characteristics of corn cob while Fourier transform infrared (FTIR) spectroscopy revealed the corresponding functional group present in the selected biomass residue. The proximate and CHNSO analyses were performed using the standard equipment and following the standard procedures, then the result is reported and compared based on the geographical locations under consideration. Also, the thermal decomposition study was carried out at different heating rates (10, 15, 30 degrees C min(-1)) in inert atmosphere while the kinetic parameters were evaluated based on Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. The analysis of variance (ANOVA) showed that there is a statistically significant difference between ultimate constituents, the fixed carbon, and volatile matter obtained from the two countries at 95% confidence level. FTIR spectroscopy showed different spectra peak in both samples which means there are varying quantity of structural elements in each feedstock. The pore surface area (1.375 m(2)/g) obtained for corn cob from South Africa (SC25) was greater than the value (1.074 m(2)/g) obtained for Nigeria (NC25). From the result, the highest value of activation energy (E-a = 190.1 kJ mol(-1) and 189.9 kJ mol(-1)) was estimated for SC25 based on KAS and FWO methods, respectively. The result showed that the geographical location may somewhat affect some energetic properties of biomass and further provides useful information about thermodynami