Enzymatic production of 5'-inosinic acid by AMP deaminase from a newly isolated Aspergillus oryzae.

5'-adenylic acid deaminase (AMP deaminase), an important enzyme for the food industry, can catalyze the irreversible hydrolysis of adenosine monophosphate (AMP) to inosine monophosphate (IMP) and ammonia. In this study, a new strain was screened that efficiently produces 3191.6U/g of AMP deaminase at 32°C. After purification, the optimal temperature and pH of the AMP deaminase were found to be 40°C and 6.0, respectively, but it was partially inhibited by Fe(3+), Cu(2+), Al(3+), and Zn(2+). With amplification of the AMP deaminase production system, 6mL of crude enzyme could produce 2.00mg/g of IMP from 2.04mg/g of dried yeast with an 84.8% molar yield after 40min. These results provide a new insight into AMP deaminase production and offer a potential platform for producing 5'-IMP.

[The Discrimination of Chinese Strong Aroma Type Liquors with Three-Dimensional Fluorescence Spectroscopy Combined with Principal Component Analysis and Support Vector Machine].

In this paper, a method for discrimination of different bands liquor with strong aroma type based on three-dimensional fluorescence spectrum technology was developed. Firstly, the three-dimensional fluorescence spectra of seven different brands liquor were measured by the FLS920 fluorescence spectrometer which produced by Edinburgh in England. The spectral show that different bands liquors have similar fluorescence characteristics and it's difficult to distinguish them only with Fluorescent characteristic parameters. Because of this, the first-order and second-order partial derivatives respect to fluorescence emission wavelength on each of the excitation wavelength were carried out in this paper. Daubechies7 (db7) orthonormal wavelet with compact support was used to compress the spectral data. The forth approximate coefficients were finally chosen as the new data matrix. Then the new data matrix was analyzed by principal component analysis (PCA) and the principal components were extracted to be used as the inputs of support vector machine (SVM). The K-fold cross validation was applied to optimize the parameters c and y and the prediction model was constructed in the end. Fourteen samples were selected randomly from each brand that in total of ninety-eight samples were selected as the training set, and the rest forty-two samples were collected as the prediction set. The effect of three different spectral data after processing on the model is compared, original data, the first-order and second-order partial derivatives on the spectral data. The results show that the three-dimensional fluorescence spectra with the pretreatment of second-order partial derivatives coupled with PCA and SVM can make a good performance on the brands identification of strong aroma type liquors, the accuracy of the established model and prediction accuracy were 98.98% and 100%, respectively. This method has the advantage of easy operation, high speed, low cost and provides a good help in the detection and identification of Chinese liquor.

[Comparative Study on the Molecular Structures and Spectral Properties of Ponceau 4R and Amaranth].

The Edinburgh FLS920P steady-instantaneous fluorescence spectrometer was applied on the detection of the absorption and the emission spectra of ponceau 4R and amaranth, which are isomers to each other. After that, the spectral parameters of them were compared. Then, the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used on the optimization of ponceau 4R and amaranth under the ground and excited state, respectively, in order to compare the differences in configurations of them under different states. On the base of the results above, the absorption and emission spectra of the two isomers were calculated with TD-DFT, and the polarized continuum model (PCM) was applied on the base of 6-311++G (d, p). The fluorescence mechanism, the relationships between the properties of fluorescence spectra and the molecular geometry were all analyzed. The results shows that, the structures of the two molecules are non-planar, these two naphthalene rings are not co-planar, respectively, and there's hydrogen bond in amaranth. When the two isomers were on the ground state, the planarity of the naphthalene ring which exists the hydrogen bond mentioned above in amaranth is better than the corresponding part of ponceau 4R. The two isomers are nearly co-planar when they're on the excited state. The molecular structures of ponceau 4R and amaranth optimized above are basically reasonable, for the quantum chemistry calculation spectral results are agree with the experiments. The planarity of the naphthalene rings on the right side in ponceau 4R is worse than that in amaranth, the ponceau 4R molecule experienced more vibration and rotation from the excited to the ground state, lost more energy, which lead to the reduction of energy for emitting fluorescent photons. So ponceau 4R has longer fluorescence emission wave- length than amaranth. In this paper, the molecular structure information of ponceau 4R and amaranth were obtained, and the differences of the spectral characteristics between them were found out. The results can provide references for the study of the relationship between the spectral properties and the configuration of isomers.

[Commercial orange juice beverages detection by fluorescence spectroscopy combined with PCA-ED and PLSR methods].

In order to classify the orange juiice beverages effectively, the fluorescence character differences of two kinds of orange juice beverages including 100% orange juice and orange drink were analyzed and compared, principal component analysis combined with Euclidean distance was adopted to classify two kinds of orange juice beverages, and ideal classification results were obtained. Meanwhile, the orange juice content estimation model was established by using fluorescence spectroscopy combined with partial least squares regression method, and the correlation coefficient R, root mean square error of calibration RMSEC and root mean square error of prediction RMSEP were 0.997, 0.87% and 2.05%, respectively. The experimental results indicate that the calibration model offers comparatively accurate content estimation, which reflect the actual orange juice content in the commercial orange juice beverages. The exploration to classify orange juice beverages was carried out from two aspects of qualitative and quantitative analysis by employing fluorescence spectroscopy combined with chemometrics method, which can provide a new idea for the classification and adulteration detection of commercial orange juice beverages, and also can give certain reference basis for the quality control of orange juice raw material.

[Determination of carmine in carbonated beverages using 3-D fluorescence spectra coupled with second-order calibration algorithm].

Three-dimensional fluorescence spectra combined with second-order calibration algorithm based on alternate a weighted residual (ANWE) was applied to the direct concentration determination of carmine in carbonated beverages. Firstly, 3-D fluorescence spectra of carmine and sunset yellow mixed solutions with different concentrations were obtained by employing spectrometer, and analyzed by using ANWE, the correlation coefficient between calibration concentration and the actual concentration was 0.9917, and the average recovery was 100.92%±2.71%. The results show that the ANWE algorithm is reliable. Then, the commercial carbonated soft drinks in 8, 9, 12 and 13 times diluted concentration were detected by using ANWE algorithm, the correlation coefficient between relative concentration and the actual concentration were 0.9930, 0.9930, 0.9932 and 0.7932, respectively, and the contents of carmine in beverage were 38.88, 37.71, 37.68 and 39.65 µg · mL(-1), respectively. The average concentration was (38.48±0.96) µg · mL(-1). Finally, the standard addition method was applied to estimate the prediction accuracy between calibration concentration and the actual concentration was 0.9935, and the average recovery was 102.99%±2.15%. The results can provide a new idea for the rapid content determination of food pigments in commercial beverages.