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Few studies expressed the β-galactosidase encoding gene from L. plantarum in E. coli so far. In the present study, the recombinant β-galactosidase from L. plantarum FMNP01 was used as a catalyst in transgalactosylation to form tri-GOS and lactosucrose. In the presence of lactose and sucrose, six transfer products were formed in the transgalactosylation reaction with recombinant β-galactosidase L.pFMNP01Gal as a catalyst. Three transfer products were tri-galacto-oligosaccharides (tri-GOS), lactosucrose, and lactulose; the other three transfer products needed to be identified further. Based on a single factor test and response surface methodological approach, the optimal transgalactosylation conditions of the production of tri-GOS and lactosucrose were determined as initial sugar concentration of 50%, lactose: sucrose ratio of 1:2, enzyme concentration of 3 U/mL, and reaction time of 6 h at 50 °C resulting in a maximum tri-GOS concentration of 47.69 ± 1.36 g/L and a maximum lactosucrose concentration of 8.18 ± 0.97 g/L. [ABSTRACT FROM AUTHOR]

Hot deformation behavior of V–Ti microalloyed steel is carried out using Gleeble1500. The results show that the flow stress curve is mainly characterized by work hardening and high‐temperature deformation softening mechanisms. Herein, the combination of strain hardening rate–stress curve and stress–strain–temperature dynamic recrystallization 3D model can be used to determine the temperature and strain corresponding to the beginning and end of dynamic recrystallization. The recrystallization activation energy and hot deformation constitutive equation are calculated by austenite recrystallization kinetic regression. Comparing three constitutive equation models with different fitting accuracies, the hyperbolic sine equation with fitting accuracy of 0.99178 is obtained, and the thermal deformation activation energy is determined to be 286.897 kJ mol−1. It is close to the self‐diffusion activation energy of austenite 281 kJ mol−1, so the rate control mechanism under this deformation condition is the dislocation climbing of diffusion control. The combination of the 3D model of dynamic recrystallization and the constitutive equation can not only obtain the flow stress curve under a certain deformation condition, but also obtain the structure evolution information. The mutual verification of the two makes it possible to study the hot deformation behavior under different deformation conditions more comprehensively. [ABSTRACT FROM AUTHOR]

A simple and fast method for the simultaneous determination of two mouldy compounds, 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA), in cork by gas chromatography-mass spectrometry (GC-MS) was established. The analytes were extracted by ultrasonic extraction with methanol, and purified then by solid phase extraction using primary secondary amine (PSA) as solid phase. After concentrating, the sample was analyzed by GC-MS and quantified by the external standard method. The linear ranges were from 10 microg/L to 10 000 microg/L for TCA and TBA, the correlation coefficients (r2) of the calibration curves were above 0.99. The recoveries and the relative standard deviations (RSDs) of TCA and TBA in different kinds of corks were investigated. The recoveries ranged from 88.4% to 97.6% with the RSDs between 1.02% and 4.58% (n = 6). The limits of detection (LODs) were 12 microg/L for TCA and 18 microg/L for TBA, and the limits of quantification (LOQs) were 40 microg/L for TCA and 50 microg/L for TBA. The method is suitable to the determination of TCA and TBA in corks.