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The effects of adding different amounts (0.1%–0.5%) of arabic gum (AG) or guar gum (GG), natural polysaccharides with similar molecular mass but different viscosity, on the emulsifying properties of myofibrillar protein (MP) were investigated. The results showed that both AG and GG could significantly improve the emulsifying properties of MP, and AG was more effective in improving the emulsifying activity, while GG was more conducive to the emulsion stability. Both emulsifying activity index (EAI) and emulsion stability index (ESI) initially increased and then decreased with increasing the amount of added polysaccharides, reaching maximum values when 0.3% AG or 0.2% GG was added. Both polysaccharides, especially GG, resulted in a marked reduction of the interfacial protein content. The droplet size of emulsions gradually decreased with increasing the amount of added polysaccharides, and the droplet size distribution became more uniform. When more than 0.3% GG was added, slight flocculation occurred in the emulsions. At the same concentration, GG reduced the droplet size of the emulsions compared to AG. Rheological analysis confirmed that all emulsions were pseudoplastic fluids, exhibiting weak gel properties. AG at low levels (≤ 0.3%) caused a decrease in the viscosity of the emulsions while remarkably increasing the storage modulus. In contrast, the addition of GG significantly increased the apparent viscosity and storage modulus of the emulsions. Compared with AG, the emulsion prepared with GG, with higher viscosity, exhibited greater apparent viscosity and storage modulus, which was more favorable to the emulsion stability.

The large molecular weight and high viscosity of natural konjac glucomannan (KGM) limit its industrial application. Microbial degradation of low-molecular-weight KGM has health benefits and various biological functions; however, the available KGM strains used in the industry have microbial contamination and low degradation efficiencies. Therefore, exploring novelly adaptable strains is critical for industrial processes. Here, the Bacillus licheniformis Z7-1 strain isolated from decaying konjac showed high efficiency for KGM degradation. The monosaccharide composition of the degradation products had a reduced molar ratio of mannose to glucose, indicating that Z7-1 preferentially degraded glucose in KGM. The degraded component was further characterized by ESI-MS, Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM), and it also exhibited good antibacterial activity against various food-spoilage bacteria. Genome sequencing and zymolytic analysis revealed that abundant carbohydrate-active enzymes exist in the Z7-1 genome, with at least five types of extracellular enzymes responsible for KGM degradation, manifesting multi-enzyme synergetic action. The extracellular enzymes had significant thermal stability, indicating their potential application in industry. This study provides an alternative method for obtaining low-molecular-weight KGM with antibacterial functions and supports foundational knowledge for its development as a biocatalyst for the direct conversion of biomass polysaccharides into functional components. [ABSTRACT FROM AUTHOR]

The transport properties of two different [Si.sub.2]Li clusters adsorption structures (bridge-site type and apex-site type) between two semi-infinite Au(100)-3 x 3 electrodes have been studied using first principles based on density functional theory and non-equilibrium Green's function in this paper. The I-V curves of both systems are linear and demonstrate the properties of metal resistance. The bridge-site type displays better electron transport capacity due to more transferring charge between the cluster and electrodes. The conductance change of the two systems becomes completely different due to the drift of the energy level under bias, which is no longer dependent on the transfer of charge. Key words: first-principles, electronic transport, charge distribution, conductance, energy level. Nous fondant sur des principes premiers bases sur la theorie de la fonctionnelle de densite et la fonction de Green hors d'equilibre, nous etudions les proprietes de transport de deux differentes structures d'adsorption en agregats [Si.sub.2]Li (de type pont et de type sommet) entre deux electrodes semi-infinies Au(100)-3 x 3. Les courbes I-V des deux systemes sont lineaires et ont les proprietes d'une resistance metallique. Le type pont montre un meilleur transport electronique, a cause du plus grand transfert de charges entre l'agregat et les electrodes. La variation de conductance des deux systemes est completement differente a cause de la derive du niveau d'energie sous tension de polarisation (0.5 V-1.5 V), qui ne depend plus du transfert de charge. [Traduit par la Redaction] Mots-cles : principes premiers, transport electronique, distribution de charge, conductance, niveau d'energie., 1. Introduction In the past few decades, silicon clusters and metal-doped silicon clusters have been studied both theoretically and experimentally in depth, partly because of their potential applications in optical [...]