Table of Content

25 November 2021, Volume 49 Issue 11

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2021, 49(11):  0. 

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Food Science & Technology

Flavor Compounds and Storage Property of Lactic Acid Bacteria Fermented Rice Cake



LIU Dongmei, KUANG Jiahua, HUANG Yanyan, et al

2021, 49(11):  1-8.  doi:10.12141/j.issn.1000-565X.200488

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The study aims to optimize the starter culture of Chinese traditional fermented rice cake.Lactobacillus plantarum DMDL9010 and L. delbrueckii subsp.bulgaricus DMDL-H1 at the ratio of 1：1 were deployed in the batter fermentation and co-fermented with Anqi yeast to ascertain the optimal addition of compound lactic acid bacteria.It turned out that the rice cake got high sensory score and the best texture when the optimal addition of compound lactic acid bacteria was 6%.Twenty two aroma compounds were detected in the co-fermented rice cake by headspace-solid-phase microextraction gas chromatography mass spectrometry （HP-SPME-GCMS）.Compared with the traditional one，compound lactic acid bacteria fermented rice cake was rich in esters.The investigation of sto-rage property of co-fermented rice cake in different storage temperature （4，28，37℃） and package methods （vacuum package，modified atmosphere packaging （50% of CO₂ + 50% of N₂），sealed package） showed that modified atmosphere packaging with 28℃ storage temperature can effectively maintain the sensory quality of co-fermented rice cake and significantly decrease the hardness and chewiness of it.

Preparation and Anticoagulant Activity of Sulfated Schizophyllan Polysaccharides



ZHENG Bisheng, WU Lei, ZHOU Lin, et al

2021, 49(11):  9-18.  doi:10.12141/j.issn.1000-565X.210122

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This paper mainly introduced the preparation and anticoagulant activity of sulfated Schizophyllan polysaccharides （S-SPG）.The single-factor and response surface method were used to optimize the preparation of polysaccharides-SPG with the sulfur trioxide-pyridine method.The anticoagulant activity was evaluated through APTT，TT，and PT assays.The results show that when the mass ratio of sulfur trioxide-pyridine complex to Schizophyllan polysaccharides （SPG） is 4，the reaction temperature is 70℃，and the reaction time is 3h，the degree of substitution of S-SPG was the highest （1.85）.The FT-IR and 13C NMR spectroscopy data proved that the sulfated group was successfully inserted into schizophyllan.Anticoagulant assays show that sulfated Schizophyllan polysaccharides exhibits strong anticoagulant activity and prolongs APTT and TT，but has no effect on PT.The anticoagulant acti-vity is positively correlated with the concentration and degree of substitution.S-SPG3 with the highest degree of substitution shows the strongest anticoagulant activity.When the mass concentration is 0.2g/L，the APTT values of S-SPG3 is 184.35s，which is 1.86 times of S-SPG2 and 2.49 times of S-SPG1 under the same concentration.Besides，the TT values of S-SPG3 was over 90 s at the mass concentration of 0.2g/L.

Genetic Diversity of Siderophores in a Multi-Drug Resistant Klebsiella pneumoniae ST37 of Swine Origin



YAN He LIANG Huixian

2021, 49(11):  19-26.  doi:10.12141/j.issn.1000-565X.210075

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Klebsiella pneumoniae is a opportunistic pathogen associated with acquired infections and is listed by the World Health Organization （WHO） as a drug-resistant pathogen that urgently needs to develop new antibiotics.Siderophores is an important virulence factor for K.pneumoniae to proliferate in host cells，mainly including enterobactin，yersiniabactin，aerobactin，and salmochelin.A multi-drug resistant K.pneumoniae ST37 KP200 was isolated from the liver of sick pigs.This study analyzed the evolutionary relationship and genetic diversity of si-derophores of KP200 and 160 K.pneumoniae ST37 strains from NCBI with bioinformatics software.The single-copy core genes analysis results show that KP200 and a Chinese K.pneumoniae of human origin locate in the same clade with similarity of 99.8%.Siderophores analysis shows that all ST37 strains carry enterobactin entABCEF and fepABC.KP200 and other 15 K.pneumoniae strains carry aerobactin transporter gene iutA.The nucleotide homo-logy of 16 iutA gene sequences is 73.49%～100%.Compared with the iutA nucleotide sequence carried by the hypervirulent K.pneumoniae NTUH-K2044，it finds that the iutA nucleotide carried by KP200 results in two amino acid substitutions due to two base mutations： Leu is replaced by Phe and Val is replaced by Leu.This study provides basis for studying the evolution and virulence of K.pneumoniae ST37.

Property Characterization and Emulsion Stability of Solid Lipid Particles Prepared by Ultrasonic Treatment



ZHANG Xia, ZAN Shengjie, LI Bing, et al

2021, 49(11):  27-37.  doi:10.12141/j.issn.1000-565X.200767

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As a new type of food-grade Pickering particles，solid lipid particles （SLPs） draw wide attention due to their good bioavailability，safety，wide sources and high industrialization prospects.Controlling the size and morphology of SLPs is of great significance for the preparation of stable SLPs Pickering emulsion.This paper took high-melting-point solid fat-fully hydrogenated soybean oil （FHSO）as the research object and Tween 40 （T40） as emulsifier.SLPs with different particle size，crystal forms and morphologies were prepared with different ultrasonic power （300，350，400 and 450 W） and time （1，2，4，and 6 min）.The influence of SLPs on emulsion droplet size was studied.The results show that SLPs without T40 is wide stip-like with the average particle size（Z-average） of 1.6~2.9μm，and the crystal form is α-form；SLPs containing T40 is rod-like and with spherical shape，its Z-average is 259~480 nm，and the α-form and β-form crystals coexist.When the ultrasonic time is 4 min，Z-average of SLPs without T40 increase with the increase of ultrasonic power，with no obvious change in the crystal form and morphology，whereas Z-average of SLPs containing T40 increase gradually，and β-form and spherical crystals increased.When the ultrasonic power is 350 W，Z-average of SLPs without T40 decrease with the increase of ultrasonic time，with no obvious change in the crystal form and morphology，whereas Z-average of SLPs without T40 decrease significantly （from 480 nm to 261nm），but the morphology and crystal form does not change significantly.It can be concluded that the addition of T40 reduces the particle size of SLPs，changes the crystal form of SLPs，and promotes the transformation of the crystal morphology from plate-like to rod-like and spherical.For the emulsions prepared with the above SLPs，it is found that the emulsions containing SLPs without T40 are unstable and massive flocs appears on the upper layer；while stable white emulsions were obtained with the SLPs containing T40，and the emulsion particle size changes with the SLPs particle sizes，polymorphs and morphologies.

Two-Stage Temperature Control and Low-Dissolved-Oxygen Strategy for Efficient Eicosapentaenoic Acid Production by Schizochytrium



WANG Yonghua, MO Shuxin, XIAO Zheng, et al

2021, 49(11):  38-46,56.  doi:10.12141/j.issn.1000-565X.210116

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Eicosapentaenoic acid （EPA） is a kind of n3-polyunsaturated fatty acid with important physiological functions.It has broad commercial prospects in health food，medicine，feed and other industries.However，the deep-sea fish oil as the traditional source of EPA cannot meet the increasing market demand.In this paper，Schizochytrium was taken as the original strain，and a two-stage temperature and low-dissolved-oxygen（TST-LDO） strategy is proposed.The effect of fermentation temperature was optimized by single factor experiment at the shaking flask level，and the effects of two-stage temperature change time and dissolved oxygen on the fermentation performance of EPA production in Schizochytrium were studied in a 5L fermenter.The change of fatty acid components in the process of fermentation was studied.The results show that the highest EPA content （8.35%） is obtained at two-stage-temperature strategy （28℃（0~24h）→34℃（24~120h））.The optimal temperature change time is 24h，which is determined in a 5 L fermenter.The results of different dissolved oxygen studies show that the medium and high dissolved oxygen （10%DO and 25%DO） are more conducive to the growth and lipid accumulation of Schizochytrium，but the low dissolved oxygen （2%DO） is more conducive to the accumulation of EPA，and the content of EPA is 2.05 times and 4.98 times of the medium and high dissolved oxygen level，respectively.When fermentation reached 96 h under TST-LDO strategy，the biomass，lipid yield，EPA content in total fatty acid and EPA yield reached 56.60g/L，9.62g/L，12.50% and 1.14g/L，respectively.Compared with the pretreatment，EPA content and EPA yield increased by 14.5 times and 6.1 times，respectively.

Preparation，Structure Characterization and in vitro Antioxidant Activity of Rice Oligopeptides



LIU Wenying, FENG Xiaowen, CHENG Qingli, et al

2021, 49(11):  47-56.  doi:10.12141/j.issn.1000-565X.210001

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Rice oligopeptides were prepared from rice protein powder by two-step enzymatic hydrolysis.Based on the analysis of their basic physical and chemical components，the structure of rice oligopeptides was characterized by amino acid composition，relative molecular weight distribution，scanning electron microscopy，ultraviolet spectrum  and circular dichroism.The in vitro antioxidant activity of rice oligopeptides was investigated by four index of in vitro antioxidant evaluation system including hydroxyl radical scavenging ability，ferric ion reducing antioxidant power （FRAP），oxygen radical absorbance capacity （ORAC） and reduction capacity.The results show that： the protein and peptide contents in rice oligopeptides are 95.75%±0.53% and 89.11%±0.94%；rice oligopeptides are rich in antioxidant amino acids such as leucine，alanine and valine，and the components with relative molecular weight less than 1000 accounted for 91.84%；rice oligopeptides are obvious spherical granules，and have irregular folds and pores on the surface；the maximum absorption peak appears at 270 nm wavelength；the contents of α-helix，parallel β-fold，antiparallel β-fold，β-turn and random coil are 6.0%±0.3%，3.3%±0.2%，40.2%±1.9%，19.5%±1.0%，and 32.1%±2.5%，respectively.The IC50 value of rice oligopeptides to hydroxyl free radical is about 11.1g/L，and ORAC value is （498.88±18.29） μmol/g （with Trolox as the standard）；the FRAP value of rice oligopeptides at 15.0g/L is equivalent to that of 0.04g/L positive control Vc，and the redu-cing ability of rice oligopeptides at 15.0g/L is equivalent to that of 0.05g/L Vc. 

Environmental Science & Technology

Microbial Diversity Analysis of Biotrickling Filter and Screening of VOC Degrading Bacteria



LI Li, CHEN Cai, JIN Zekun, et al

2021, 49(11):  57-68.  doi:10.12141/j.issn.1000-565X.210033

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The biological activity of a biotrickling filter determines the capability of a biological treatment plant in treating organic waste gas，and the most important factor affecting the bioactivity of activated sludge is the microbial community.In order to understand the microbial community structure，diversity and abundance in a biotrickling filter，metagenomic technology was used to analyze the microbial diversity of filler solids in the biofilter of volatile organic compound treatment system.The results show that the relative abundance of bacteria，eukaryotes，archaea，viruses in biotrickling filter are 89.34%，1.99%，1.06% and 0.03% respectively，and the microbes are assigned to 75 phylums，195 classes，395 orders，752 families and 1798 genera.Bacteria in activated sludge are mainly Proteobacteria，Actinobacteria，Bacteroidetes，Firmicutes and Chloroflexi.In addition，18 toluene degrading bacteria strains，21 xylene degrading bacteria strains and 15 butyl acetate degrading bacteria strains were screened from the activated sludge using the only carbon source medium，which were mainly identified as Acinetobacter sp.and Pseudomonas sp..The degradation rates of 100 mg/L toluene，p-xylene and m-xylene are 99.98%，99.89% and 88.34% within 48h by the degrading strain CX20.The butyl acetate degrading strain CBA12 can completely degrade 100mg/L of butyl acetate within 48h.The isolated strains show good VOC degradation ability and have a wide application prospect in the field of waste gas treatment.

On Optimized Removal of Nitrogen and Carbon with Anaerobic Ammonium Oxidation Based on Matching Multiple Factors #br# and Response Surface Method



CHEN Yongzhi, YUAN Zhongling, ZHANG Min'an, et al

2021, 49(11):  69-79.  doi:10.12141/j.issn.1000-565X.200581

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The partial nitrificated domestic sewage treated in the autors laboratory was added into the anaerobic ammoxation ASBR reactor as raw wastewater，and NaNO₂ or CH₃COONa was added quantitatively when the temperature was（24±0.5）℃and pH was 8.0~8.2.The effects of NO₂^--N/NH₄⁺-N ratio，hydraulic retention time (HRT) and C/N ratio (COD/NH₄⁺-N) on anammox coupled denitrification and decarbonization were investigated respectively.The interaction among the three factors was explored by response surface analysis method.The results show that，when the NO₂^--N/NH₄⁺-N ratio was 1.4~1.6，HRT was 33 h，and C/N ratio was 3~5，the system's anammox coupled denitrification and carbon removal efficiency were the highest.Analysis of variance (ANOVA) results show that the degree of influence of each factor on the total nitrogen removal rate (TNR) was：C/N ratio>HRT>NO-2-N/NH+4-N ratio.The optimal matching scheme is C/N ratio：4.28，HRT：33.48h，and NO₂^--N/NH₄⁺-N ratio：1.46，and the average TNR verified by parallel experiments was 90.12% .

Influence of Atomization and Evaporation of Desulfurization Wastewater on Cement Furnace Pollutants



LIU Dingping SHEN Kang

2021, 49(11):  80-86.  doi:10.12141/j.issn.1000-565X.200598

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In view of the increasingly serious pollution problem of cement industry and the increasingly strict requirements for desulfurization wastewater discharge，this study proposed to use the waste heat of clinker of grate cooler to evaporate the desulfurization wastewater of cement furnace.This method realized zero discharge.The effects of atomization and evaporation of desulfurization wastewater at the grate cooler on flue gas temperature，NOx concentration，ammonia escape concentration and flue gas dust mass concentration were studied by experiments on a cement furnace production line with a clinker output of 6000t/d and mixed with dry sludge.The experiment results show that NH3 produced after the evaporation of desulfurization wastewater enters the decomposition furnace with the tertiary air and reacts with NOx in the furnace，and this process is conducive to reducing the ammonia injection of SNCR (selective non catalytic reduction) system.Under the full load of the furnace and maintaining the stable working condition of SNCR system and dry sludge mixing，the NOx emission concentration gradually decreases with the increase of desulfurization wastewater injection.When the injection amount of wastewater is 5.5m3/h，the NOx concentration reaches the lowest value.The evaporation of desulfurization wastewater at the high temperature section of grate cooler will reduce the temperature of tertiary air and secondary air，and inhibit the generation of thermal NOx in decomposition furnace.The evaporation of desulfurization wastewater in high temperature environment will produce HCl and SO2 gas，which has a certain impact on the efficiency of wet desulfurization.

Electronics, Communication & Automation Technology

Speech Bandwidth Extension Based on Flatten-CNN



YANG Junmei LEI Yang CHEN Xikun

2021, 49(11):  87-94.  doi:10.12141/j.issn.1000-565X.210173

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The existing deep learning-based speech bandwidth extension algorithms have many disadvantages：the time domain algorithms speech  feature extraction  is not accurate enough and its training data is too large；the frequency domain algorithm pays little attention to the information association between frames in log power spectrum feature extraction and the number of frequency axes is odd number which is inconvenient for deepening the network depth.In addition，it ignores time domain information；the time-frequency two-domain algorithm model is relatively complicated.To solve these problems，this paper proposed a speech bandwidth extension algorithm based on Flatten-CNN.Firstly，in order to make full use of speech features and reduce the amount of data，the algorithm was operated on frequency domain.Secondly，an improved encoder was proposed  to make use of the logarithmic power spectrum time axis information.The log power spectrum feature extraction of two-axis was realized by introducing tile layers.Thirdly，in order to deepen the network depth，the last point was removed during the frequency axis data processing and a zero was added when restoring，so  to ensure that the frequency axis number is an even number.Finally，in order to utilize the voice signal time domain information，time domain loss was introduced into the loss function.The effectiveness of the algorithm  was verified with the TIMIT data set and the VCTK data set.The experimental results show that，compared with the current mainstream algorithms，the new algorithm can improve the high-bandwidth speech quality，showing better hearing effect.

5G Frequency Selection Surface Shape Optimization Method Based on Genetic Algorithm



JIN Gang HE Zhihao WANG Yingjun

2021, 49(11):  95-105.  doi:10.12141/j.issn.1000-565X.210022

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The development of 5G has promoted the miniaturization and integration of communication equipment，but it also leads to new electromagnetic compatibility problems.Introducing Frequency Selective Surface (FSS) into devices can effectively reduce the interference between devices.In order to overcome the weaknesses of traditional design methods，such as low efficiency，poor quality and dependence on experience，a new FSS shape optimization method was proposed herein.The proposed method presented a strategy to define the shape optimization parameters in the polar coordinate system according to the non-self-intersecting characteristics of FSS.Furthermore，based on the genetic algorithm，the method realized the intelligent search of parameters optimized by FSS and realized the intelligent optimazition of FSS unit shape in terms of the operating frequency and electromagnetic shielding performance.Three numerical examples including solid，ring and slot units have been used to verify the proposed method.The results show that the optimized FSS resonant frequency moves to 28GHz and its electromagnetic shielding performance is improved.The FSS obtained by the proposed method is stable and suitable for 5G environment.

Music Source Separation Method Based on Unet Combining SE and BiSRU



ZHANG Ruifeng, BAI Jintong, GUAN Xin, et al

2021, 49(11):  106-115,134.  doi:10.12141/j.issn.1000-565X.200593

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Music source separation is one of the most important research topics in the field of music information retrieval.Traditional music source separation methods have shortcomings，such as hypothesis dependence，limited model complexity，and poor representation ability.To resolve these problems，it takes a long time to train the time-domain end-to-end deep learning network model，and the separation performance still needs to be improved.Therefore，in order to further optimize the representation ability and computational efficiency of the time domain end-to-end separation model，the study proposed an end-to-end network Unet-SE-BiSRU based on the Demucs model which has the best performance in time domain separation at present.Attention mechanism was introduced into the generalized coding layer and decoding layer，and the squeezing-excitation block(SE) was used to extract features selectively according to the type of audio to be separated.To deal with gradient explosion or disappearance that may occur in the learning process，a group normalization was added after one-dimensional con-volution.The bidirectional long short-term memory network was refined to a bidirectional simple recurrent unit(BiSRU)，which improves the parallelism of learning and reduces the amount of model parameters.The experimental results show that the signal-noise ratio of the improved network model is improved by 0.34dB，which is the best one among the time-domain end-to end methods to the best of our knowledge，and the training time is reduced by 3/5.

Research Progress of Tactile Sensors Based on Nano-ZnO



LIU Yurong CHEN Ming

2021, 49(11):  116-126.  doi:10.12141/j.issn.1000-565X.210104

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Tactile sensors have received extensive attention and research because they can imitate human skin to perceive external information.Among varies kinds of tactile sensor，Nano-ZnO-based tactile sensor has broad application prospects in the fields of bionic robots，human-computer interaction，biomedicine devices and wearable electronic systems due to its advantages of high sensitivity，high mechanical strength，strong flexibility，easy integration，good biocompatibility，and low-cost technology.This paper firstly introduced the piezoelectric mechanism and the manufacturing of Nano-ZnO-based tactile sensor.Next，it summarized the study progress of Nano-ZnO piezoelectric tactile sensor from the four aspects of piezoelectric performance improvement，multi-function，integration，and array fabrication，and listed the latest achievements in related technical fields and research directions.Then it summarized the application research of Nano-ZnO piezoelectric tactile sensor in pressure imaging，human action detection and physiological health monitoring in detail，and analyzed the shortcomings and the research trend of Nano-ZnO piezoelectric tactile sensor.

Steganalysis Method with Feature Enhanced by Embedding Probability of Motion Vector



LIU Shuowei, LIU Beibei, HU Yongjian, et al

2021, 49(11):  127-134.  doi:10.12141/j.issn.1000-565X.200664

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Based on the fact that most steganography approaches follow the rules of minimum distortion or maximum entropy，this paper proposed to employ the distribution of optimal embedding probability as the prior knowledge for video steganalysis.To better characterize the embedding priority of motion vectors，it defined a measurement of the embedding distortion of motion vectors using features from three aspects，namely motion feature，texture feature and local optimality under coding framework，and the embedding probabilities of motion vectors were estimated with Gibbs distribution.Thus this study proposed a way of quantitatively enhancing the steganalytic features with the embedding probabilities and the mechanism of the enhancement was explained from the perspective of relative entropy.Experimental results show that the detection accuracy of three classical steganalytic methods have been unanimously improved and show robustness against different bitrates after the enhancement with the proposed method.The effectiveness of the new method is also verified by the comparison with the latest deep neural network VSRNet detection method.

Salient Object Detection Based on Feature Enhancement in Complex Scene



LI Bo RAO Haobo

2021, 49(11):  135-144.  doi:10.12141/j.issn.1000-565X.210125

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The performance of salient object detection is greatly improved by the superior feature extraction ability of Fully Convolutional Neural Networks(FCN).However，the simple fusion strategies (feature addition or concatenation) cannot effectively enhance features，resulting in algorithms object misdetection and missed detection in complex scenes.The paper proposed a specifically feature enhancement method to improve the performance of salient object detection.Firstly，object misdetection mostly occurs in a scene where the background is cluttered or the object and the background are intertwined，so it greatly alleviate the object misdetection problem from the perspective of global enhancement and structural enhancement，respectively.Secondly，the missed detection of the object generally occurs in the interior and edge of the object，so the study introduce residual learning to learn the information of the missed region and refine the loss of the object interior and edge.Finally，comparison results between the proposed method with other 13 kinds of advanced methods over 5 benchmark datasets indicate that the proposed model is superior to other 13 methods，and the problems of object misdetection and missed detection in complex scenes were successfully solved.