2021 Vol. 36, No. 3
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The extraction conditions of headspace solid phase microextraction (HS-SPME) of volatile flavor compounds from gluten-free potato steamed bread were optimized by response surface methodology based on the selection of extraction fibers.Meanwhile,composition of volatile components during the gluten free steamed bread processing was analyzed by HS-SPME and gas chromatography-mass spectrometry (GC-MS).Results showed that the extraction fiber of DVB/CAR/PDMS was suitable for the extraction of volatile flavor compounds from gluten-free potato steamed bread.The optimal SPME parameters were sample weight 2.42 g,extraction time 60 min,and extraction temperature 50℃,the peak number and peak area/weight under the optimal conditions were 38 and 7.75×107,respectively.In the process of making gluten-free potato steamed bread,a total of 69 volatile flavor compounds were detected,and the number increased significantly with the fermentation time increasing,especially the content of alcohols,acids and esters.Moreover,pyrazines content increased significantly during steaming process.
With mango and kiwi as the main raw materials,the effect of the ratio of mango to kiwi fruit,the amount of sugar,the amount of citric acid and the amount of xanthan gum on sensory quality and physicochemical properties of mango kiwi compound jam were studied by single factor experiment.Then orthogonal experiment was used to optimize the technical formula of the compound jam.When the ratio of mango and kiwi was 52.5:7.5,10.00% white sugar,0.15% citric acid,it was the best technological condition for making mango kiwi fruit compound jam.The jam prepared on this condition was clear in color,uniform in texture,sweet and sour in taste,nutritious and healthy.
Natural yellow pigments were used instead of synthetic pigments to color salt-baked chicken,and the natural antioxidant was used to protect the color.The ratio of compound color fixatives was optimized through single factor test and orthogonal test,and the effect of compound color fixatives on the light stability,thermal stability and color stability of the colored salt-baked chicken nuggets was analyzed.The result showed that the addition of 0.015% gardenia yellow had a good coloring effect on salt-baked chicken,and GY60 with an addition amount of 0.025% also had a good coloring effect,but its light stability was not as good as that of gardenia yellow,monascus yellow and AY152 were not suitable for salt-baked chicken because of their poor color and stability.The compound color preserving agent made up of 0.010% sodium erythorbate,0.015% tea polyphenol and 0.010% sodium phytate had a good color preserving effect on salt-baked chicken.The residual absorbance rate of the soup after boiling was 89.8%,and the residual absorbance rate after 4 days of sunlight exposure was 71.6%,both higher than the blank group.The color fade of the chicken nuggets under natural light indoors was also slower than that of the blank group,and they still had a better color after 4 days.
High Fisher ratio oligopeptides had a variety of physiological activities due to their unique amino acid composition.This article reviewed the related literature on functional properties and active mechanism of high Fisher ratio oligopeptides due to the unique amino acid composition.It pointed out that high Fisher ratio oligopeptides have good anti-fatigue and alcohol relieving functions,and it could be used as biologically active peptides in the development and application of anti-fatigue beverages,alcohol relieving soups and other functional products;high Fisher ratio oligopeptides could assist in the treatment of liver disease and promote the return of the Fisher ratio of the normal range,but the mechanism of the effect on liver disease is still unclear and need further research and verification;high Fisher ratio oligopeptides could regulate the metabolism of phenylalanine in the body,high Fisher ratio oligopeptides medicine and food would become one of the development directions of phenylketonuria (PKU) diet therapy.In the future,in-depth research could be carried out on the digestive properties and applicability of high Fisher ratio oligopeptides in medical foods,probiotic functional properties,interaction with other food components during processing,and the impact on food quality characteristics,to further promote application of high Fisher ratio oligopeptides in medical food industry.
The medium of Stenotrophomonas sp.H3-1 was optimized by one single factor experiment.The strain was prepared into bacteria-preparation and preliminarily used in tobacco fermentation,and the quality changes of tobacco leaves before and after fermentation were compared.It showed that the optimized culture medium was 2.0 g/L of maltose asthe carbon source and the nitrogen source is ammonium sulfate of 2.0 g/L,initial pH value 8,temperature 40℃.After tobacco fermentation,the mass concentrations of five flavor substances changed obviously,the mass concentrations of solanone and 9-hydroxy-4,7-megadiene-3-one,which had greater effect on aroma composition,all increased to different degrees.The evaluation results showed that the aroma quality,aroma quantity and aroma concentration of tobacco leaves were improved after fermented with bacterial preparations.
Using GC-MS technology to analyze the composition of the aroma components in the ceramic membrane separation components of Yunyan essential oil, the ROAV value was calculated to determine the key aroma components, and perform sensory analysis, and the partial least square method (PLSR) was used to establish the separation of the components of the Yunyan essential oil ceramic membrane PLSR model of key aroma components and sensory indicators to explore the correlation between key aroma components and sensory attributes. The research results showed that in the 50 nm Yunyan essential oil ceramic membrane retentate, there were 31 different volatile aroma substances, of which 3-hydroxy-β-damascenone and nonanal were the key aroma components, sweet fragrance had a strong correlation with 3-hydroxy-β-Damascone,and flower fragrance had a strong correlation with nonanal. In the 50 nm Yunyan essential oil ceramic membrane permeate, there were 23 different volatile substances, among which 3-hydroxy-β-damascenone and megastigmatrienone were the key aroma components, spices had a strong correlation with megastigmatrienone,and the sweet fragrance had a strong correlation with 3-hydroxy-β-damascone.
A steroid-estrogen-degrading strain ye22 with Estone(E1)as substrate was screened out from tobacco industry wastewater treatment plant sludge.It was identified as Acinetobacter junii by 16S rRNA sequencing.The results showed that the growth characteristics and degradation kinetics of the strain were studied.After 9 days fermentation,the degradation rate of E1 could reach 41.88%.The concentration of E1 in tobaccoindustrial wastewater and tobacco concentrate was higher,reaching 1.41×10-4 g/L and 9.01×10-5 g/L, respectively.The ye22 strain cultured to logarithmic phrase could degrade 32.07% of E1 in tobacco industry wastewater and 27.23% of E1 in tobacco concentrate within 9 days.
The latest research progress in the application of texture analyzer to the determination of tobacco leaf mechanical properties (softness,adhesion,penetration,pull,shear force, texture and brittleness) was reviewed.It pointed out that the texture analyzer to determine the mechanical properties of tobacco leaves was objective and sensitive,which can more comprehensively reflect the stress conditions of tobacco leaves during storage,transportation,and industrial processing,and the test results were closely related to the quality of tobacco leaves.However,the texture analyzer detection technology in the determination of mechanical properties of tobacco leaves also had shortcomings such as high requirements for samples consistency,no standardized test parameters,methods and the necessity to improve detection accuracy and other deficiencies.The research should focus on adjusting and optimizing the test parameters of the texture analyzer,establishing normalized and standardized tobacco sample pretreatment methods and testing procedures;and establishing standard testing methods for tobacco stem return rate,tobacco softness,so as to further promote the application of texture analyzer in tobacco research area.
The problems of dynamic modeling and simulation of compliant mechanisms with large deformation were investigated based on the geometrically exact beam theory (GEBT).Using the assumption of Euler-Bernoulli beam,the deformation field of the large deformation beam element was constructed,which could guarantee the perpendicularity between beam cross section and center line.The generalized element force,mass matrix and external force of the geometrically exact Euler-Bernoulli beam element were derived,and the accurately dynamic models of two typical compliant mechanisms including the compliant four-bar mechanism and spatial arc-guide compliant mechanism were established and simulated.The comparison of numerical results obtained by the proposed method,commercial software ADAMS and the absolute nodal coordinate formulation (ANCF) beam element model showed that using geometrically exact Euler-Bernoulli beam element for dynamic simulation analysis of compliant mechanism had advantages both in calculation efficiency and accuracy.
Aiming at the problems that the rolling bearing of rotating machinery is liable to be damaged in bad working environment,and the fault diagnosis at present relies too much on manual feature extraction,a rolling bearing fault diagnosis method based on wavelet packet decomposition and convolutional neural network (WPDEC-CNN) was proposed.This method used wavelet packet decomposition to process the vibration time-domain signal to obtain wavelet coefficients that characterized the signal similarly, and then preprocessed them and input them into CNN for classification and recognition.The experimental results showed that the loss rate of WPDEC-CNN was 0.108 9, which was lower than that of the BP neural network and the CNN.The fault classification accuracy of WPDEC-CNN reached 97.3%, higher than that of the BP neural network and the CNN, which verified the effectiveness of the proposed fault diagnosis method.
Based on the principle of geometric phase,the relevant research of generating vortex beam by metasurfaces (the plasmonic metasurfaces,the all-dielectric metasurfaces,the Gap-plasmon metasurfaces and the multi-function metasurfaces) was reviewed in recent years.It was pointed out that the metasurfaces based on the geometric phase had the characteristics of simple design and dispersion-free of vortex beam.In the near-infrared band,the plasmonic metasurfaces had the characteristics of easy fabrication and broadband,the all-dielectric metasurfaces had the characteristic of high transmittance.In the mid-infrared band,the Gap plasmon metasurfaces had the characteristics of high reflectance and aberration-free.The multi-function metasurfaces were capable of generating vector and scalar vortex beams simultaneously.With the maturity of nanofabrication technology,in the future,metasurfaces will develop in the direction of low loss,broadband,adjustability,multi-function and so on,and the advanced nano-fabrication technology will enable metasurfaces available for integrated optical system.
Based on the concept of normal matrix,conjugate transpose matrix,characteristic value of matrix and so on,using theory and method of singular value decomposition,some properties of a class of matrix A which meet A*=kA3(0≠k∈R) were explored.It was found that matrix A could be diagonalized,especially the singular value decomposition form of matrix A was obtained,and the result of the series convergence of correlation matrix was researched under certain conditions,and the convergence property of function sequence of correlation matrix was discussed,so the basic theoretical reserve of diagonalizable matrix was expanded.
By utilizing the concepts and theories of singular value,tensor product,tensor sum and the connection of eigenvalue with determinant of matrices,another proof on theorem 2 in literature[1] was given,the singular value and spectral decomposition and the determinant of the matrix suited to A*=A2 were investigated,the conclusions were also obtained:(A⊗B)*=(A⊗B)2 on tensor product about two matrices A and B which satisfied the above condition,the relationship of eigenvalues of A* with A,the relationship between eigenvectors,and spectral decomposition formular of the matrice A.
Founded in 1986, bimonthly
Administered by:The Education Department Henan Province
Sponsored by:Zhengzhou University of Light Industry
Editor-in-chief:Wei Shizhong
Executive Editor-in-Chief:Zou Lin
Deputy Editor-in-Chief:Qu Shuanghong
Edited & published by:Editorial Department of Journal of Light Industry
CN 41-1437/TS
ISSN 2096-1553
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