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关键词： Proteins  

摘要： In this paper, a selected starter culture of Staphylococcus xylosus, Pediococcus acidilactici, and Debaryomyces hansenii was used to produce fermented beef jerky. The influence of inoculating compound starter on the basic nutrition composition, physical and chemical properties, and texture characteristics of jerkies were investigated. The study results demonstrated that the addition of compound starter quickly reduced the beef pH (from 6.46 to 4.42) and increased the total free amino acids and free fatty acids contents. The nitrite residues and histamine content in the fermentation group were significantly lower than that in the control group. The gel electrophoresis pattern showed that part of the macromolecular protein in inoculated samples was gradually degraded into small molecule protein, and some bands disappeared. It can be seen that inoculation of starter can improve the quality, safety, and texture characteristics of fermented beef jerky. Practical applications Microbial fermentation is a unique and long-standing way of meat processing and preservation. This study found that the inoculation of compound starters can increase the nutritional value and improve texture, flavor, safety of beef jerky. These results suggest that Staphylococcus xylosus, Pediococcus acidilactici, and Debaryomyces hansenii could be considered as mixed bacterial starters in fermented beef jerky to improve product quality and safety, which provides a theoretical basis for the strain screening and processing of fermented beef products.

关键词： Karst soil   Microbial community   Tropical forest   MiSeq sequencing  

摘要： Shallow karst soils can support productive forests, but their microbiota has been poorly studied in tropical areas where they accomplish relevant biogeochemical functions. Therefore, we studied the bacterial, archaeal, and fungal communities of Rendzic Leptosols from a tropical sub-humid area in the Peninsula of Yucatan (Mexico), aiming to know these microorganisms and the physicochemical characteristics that shape their communities. The soils were moderately alkaline (pH similar to 8.4), with a high content of organic-C (17-29%) and a clay fraction >43%. The microbial component was estimated at 2.8 x 10(7) 16S rDNA gene copies/g (Bacteria/Archaea) and 9.3 x 10(4) ITS copies/g (Fungi). The microbial communities were divergent among subsites, possibly due to soil microheterogeneity, and less than 1.5% of the phylotypes were observed in at least 65% of the samples. These shared microorganisms were affiliated to phyla often found in forest soils such as Acidobacteria, Actinobacteria, Rokubacteria, and Mortierellomycota, which are reported as effective organic matter transformers. N-fixing bacteria (Bradyrhizobium) and nitrifiers (Thaumarchaeota and Nitrospira) were also detected. pH was the main factor associated with the bacterial and archaeal community structure. The functional prediction suggests that soil microorganisms have a high potential for carbon metabolism and the biosynthesis of antibiotics, besides polymer and pollutant degradation, such as phenolic substances and PAHs. Consequently, these shallow black soils harbor a diverse biosphere that can readily transform litter material and fix-N to increase the C- and N-soil pools, supporting thus a productive low forest.

关键词： Fermented tilapia sausage   Pediococcus pentosaceus   Microbial community   Biogenic amines   Free amino acids   Correlation  

摘要： Amine-negative lactic acid bacteria can prevent excess biogenic amines from accumulating in sausage. In this study, the amine-negative Pediococcus pentosaceus 30-7 and 30-15 with good fermentation properties and biogenic amine removal ability were isolated for tilapia sausage production. P. pentosaceus 30-7 improved the physical characteristics such as gel strength and hardness in tilapia sausage, while P. pentosaceus 30-15 significantly enhanced the contents of umami and sweet free amino acids. The microbial metabolic network revealed that the dominant microbial community in the fermentation process including Pediococcus and Lactococcus contributed to the physicochemical formation of sausage. The significant decrease of biogenic amine contents after addition of P. pentosaceus strains mainly resulted from their ability to remove biogenic amines and to inhibit the growth of amine-producing Enterobacter, Citrobacter, and Streptococcus. This study provides an effective method for directionally improving the physicochemical properties and safety in fermented tilapia sausage.

关键词： 2   3   5   6-tetrachloro-p-benzoquinone (TCBQ)   NBO   NLO   HOMO-LUMO   ADME   MEP   CADD  

摘要： Vibrational, NLO, NBO, FMO, NMR substance move, and an auxiliary investigation of 2,3,5,6-tetrachloro-p-benzoquinone, utilizing quantum computational figuring, are performed. Atomic geometry, Mulliken charges, and vibrational wavenumbers are resolved by Hartree-Fock (HF) and DFT calculations in the B3LYP framework with the 6-311++G(d,p) premise set and confirmed by the experimental information. The potential energy distribution (PED) generates the assignments of vibrational wavenumbers. An analysis of the electronic properties is carried out using the time-autonomous DFT technique, providing HOMO and LUMO energies. Molecular electrostatic potential (MEP), natural bond orbitals (NBO), and nonlinear optical (NLO) properties are also reported. C-13 and H-1 NMR synthetic movements are distinguished by the GIAO procedure and diverged from the test substance move. The TED commitment as a blended mode with different vibrations is around 75%. Physicochemical descriptors, ADME boundaries, pharmacokinetics, pH significance, medicative and restorative nature are processed for the title compound. These properties are computed utilizing a computer aided drug design to encourage the sedate disclosure.

关键词： Apple pomace   degree of esterification   optimisation   pectin extraction   yield  

摘要： This study explored the valorisation of apple pomace by extracting pectin with both high and low degrees of esterification (DM). Two types of pectin were extracted with a DM of 43.29% being low methoxyl (LM) pectic polysaccharide and high methoxyl (HM) pectin with a DM of 65.88%. HM pectin was characterised by a WHC and OHC of 1.3 g g(-1) and 0.4 g g(-1), respectively, compared to 0.32 g g(-1) and 0.14 g g(-1), respectively, for LM pectic polysaccharide. HM pectin possessed greater purity indicated by 69.18% GalA, whereas LM pectic polysaccharide possessed 41.26% GalA. HM pectin revealed better functionality in terms of high emulsifying activity which was concentration-dependent, and emulsion stability than LM pectic polysaccharide. The solubility of HM pectin was 90.8%, which is preferable for various industrial applications. LM pectic polysaccharide was characterised by a higher % radical-scavenging activity in a concentration-dependent manner. XRD analysis revealed LM pectic polysaccharide to possess higher crystallinity (53%) and SEM analysis revealed its surface to be rough and coarse.

关键词： Honey   Authenticity   Quality   FTIR spectroscopy   Physicochemical parameters  

摘要： Samples of raspberry, mint, rape, sunflower, thyme, acacia and tilia honey were subjected to authentication using destructive (melissopalinological analysis and physicochemical parameters determination) and nondestructive (Fourier transform infrared spectroscopy - FTIR) methods. The melissopalinological analysis confirmed that all types of honey samples were authentic monofloral honey. To correlate the FTIR spectral information with the physicochemical parameters and therefore assess the usefulness of FTIR in the analysis of honey quality and authenticity, the spectral information was coupled with principal component analysis (PCA), linear discriminant analysis (LDA) and partial least square regression (PLS-R). PCA showed a clear separation can be observed for 5 groups of honey, namely: mint, rape, acacia, tilia and sunflower honeys, while thyme and raspberry honeys are mixing some samples. Moreover, the PLS-R model was found successful in predicting the physicochemical parameters of honey based on FTIR spectra. These results show that FTIR spectroscopy can be simultaneously used to confirm the authenticity of honey and also its quality and freshness.

关键词： Rare earth elements  

摘要： A series of M-AlOx mixed oxides (M = Cu, Co, Ni) with the addition of high loadings of rare earth elements (REE, R = Ce, Nd, Pr;R0.5M0.8Al0.2, molar ratio) were investigated in N2O decomposition. The precursors were prepared by coprecipitation and subsequent calcination at 600 degrees C. The obtained mixed metal oxides were characterized by X-ray diffraction with Rietveld analysis, N-2 sorption, and H-2 temperature-programmed reduction. Depending on the nature of REE and the initial M-Al system, R cations could be separately segregated in oxide form or coordinated with the transition metal cations and form mixed structures. The addition of Ce3+ consistently led to nanocrystalline CeO2 mixed with the divalent oxides, whereas the addition of Nd3+ or Pr3+ resulted in the formation of their respective oxide phases as well as perovskites/Ruddlesden-Popper phases. The presence of REE modified the textural and redox properties of the calcined materials. The rare earth element-induced formation of low-temperature reducible MOx species that systematically improved the N2O decomposition on the modified catalysts compared to the pristine M-Al materials by the order of Co > Ni > Cu. The Ce0.5Co0.8Al0.2 catalyst revealed the highest activity and remained stable (approximately 90% of N2O conversion) for 50 h during time-on-stream in 1000 ppm N2O, 200 ppm NO, 20 000 ppm O-2, 2500 ppm H2O/N-2 balance at WHSV = 16 L g(-1) h(-1).

关键词： walnut protein   peroxyl radicals   structural   emulsifying properties  

摘要： In this paper, the effects of peroxyl radical oxidation on the physicochemical and functional properties of walnut protein were investigated. Walnut protein isolate (WPI) containing 2,2 '-azobis(2-amidinopropane) dihydrochloride (AAPH) was oxidatively stressed under aerobic conditions in peroxyl radical-generating media. Incubation of walnut protein with increasing concentration of AAPH resulted in gradual carbonyl generation and free sulfhydryl group degradation. The results of surface hydrophobicity implied that oxidation leads to protein aggregation thus decreasing protein solubility in an AAPH concentration-dependent manner (P < 0.05). Emulsifying properties exhibited a significant increase (P < 0.05) at AAPH concentrations up to 0.2 mM and higher AAPH concentrations reduced the emulsifying capacity of WPI. These results indicate that appropriate oxidation is helpful to improve the emulsifying properties of protein, and with an increase of oxidation degree, emulsifying functional will damage.

关键词： Natural forest conversion   Soil fertility   Soil properties   Meta-analysis  

摘要： The conversion of natural forest to artificial vegetation may deplete nutrients and thus affect the soil quality. However, little is known about synergetic changes of microbial and physicochemical dynamics in soils after natural forest conversion and their implications. In the current study, we synthesized the responses of soil microbial and physicochemical properties in the uppermost soil layer (<20 cm) following natural forest conversion, as reported in 51 published studies (127 sites). Our results showed that the response ratios of soil moisture, soil microbial carbon and nitrogen, bacteria, fungi, enzymatic activities, soil organic carbon, total carbon, total nitrogen, NO3-, total phosphorus, available phosphorus, cations (K+, Mg2+ and Ca2+), and cation exchange capacity (CEC) overall declined following natural forest replacement. In contrast, natural forest conversion caused significant increases in soil bulk density, soil pH and NH4+. Reductions of microbial carbon, organic carbon and total nitrogen in soil were independent of revegetation type, but variations in soil pH, available phosphorus and fungi were correlated to land use. Soil CEC reduction increased soil pH, allowing soils to retain NH4+, which promoted fungal growth. Moreover, natural forest replacement led to the loss of soil cations in regions of higher precipitation. Revegetation practices led to greater consumption of soil microbial and chemical nutrients and produced "harder" soils (increased soil compaction and decreased moisture content) in warmer regions. Stand age influenced ratios of soil carbon to nitrogen and ratios of bacteria to fungi following natural forest conversion. Altogether, our study suggests that natural forest conversion results in decreased soil microbial and chemical fertility, and desirable soil properties are more likely to be lost in warmer regions and over time as global climate warming exacerbates, which in turn may potentially damage ecosystem sustainability.

关键词： CaCl2   dulce de leche   milk jam   rheology   sodium bicarbonate  

摘要： Rheological properties of sixteen milk jam treatments produced from commercial full-fat (3 g/100 g) and skimmed (0.15 g/100 g) cow milk by the addition of sucrose, sodium bicarbonate and CaCl2 were examined. pH, titratable acidity, total solids and ash contents in the milk jam samples ranged from 6.2 to 6.8, 1.3 to 3.3 g/100 g, 56.7 to 70.5 g/100 g and 1.7 to 3 g/100 g, respectively, with a significant variability (P 0.05). The flow behaviour and consistency indices ranged from 0.7 to 0.9 and 2.7 to 208 ***, respectively. Rheological measurements showed that the maximal G' x 10(2) value showed considerable variation (5-932 Pa). As sucrose content increased, pH and total solid content increased, whereas ash content and the L value decreased. Also, a negative correlation between pH and L* (lightness) was found (P < 0.05). Dynamic rheology showed that the jam from skimmed milk with full sucrose and without sodium bicarbonate exhibited more solid-like behaviour than the ones prepared with full sucrose and with sodium bicarbonate. In conclusion, the increase in milk fat caused a decrease in resistance of the mixture subjected to the deformation, which is very important for production of quality milk jam.