Research progress in authenticity identification and detection technology of honey
Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 649-658.
As a kind of natural, nutrient-rich food and health care product, honey is favored by consumers around the world. However, it is a highly adulterated food. Therefore, the research on the authenticity identification and detection technology of honey has been long deeply concerned. Here, domestic and international researches on the honey quality were summarized, and a vision about the identification techniques and authenticity analysis of honey in recent 20 years was introduced. According to the comprehensive analysis, the authenticity of honey could be identified to some extent effectively by modern detection technology which is conducive to the quality control of honey. However, there existed defects such as requiring expensive instruments, complex operation, long testing time, professional background and fixed operating location, etc. Moreover, it is difficult to eliminate honey adulteration completely as the development and application of the existing honey detection technology have fallen behind the adulteration technology. It is necessary to develop specific identification technology mainly focusing on the endogenous honey components, not on the exogenous substances. In recent years, the research and application of biomarkers based on genomics and proteomics are very common in related fields. However, there are no reports on identification of honey authenticity and nectar based on these technologies. It is expected that developing a new fast test technique based on honey characteristic markers—immuno-colloidal gold chromatographic test strips or kits will be the main development direction of honey quality control and authenticity identification technology in the future.
Simultaneous detection of
Listeria monocytogenes and pathogenic Vibrio by dual peptide nucleic acid fluorescence in situ hybridization Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 659-666.
Listeria monocytogenes and pathogenic Vibrio are common and harmful foodborne pathogens in daily life. Besides the culture-based, biochemical, immunological and molecular methods for applications in clinical diagnostics and food microbiology, fluorescence in situ hybridization (FISH) using labeled peptide nucleic acid (PNA) probes as an alternative methodology for detection of L. monocytogenes and Vibrio were developed. To improve the efficiency, multi-probe PNA-FISH assay was established for simultaneous detection of multiple microorganisms. Based on the singlet PNA probe for detection of L. monocytogenes and Vibrio, respectively, by labeling different fluorescent dyes to the specific PNA probes, the PNA-FISH procedure for simultaneous detection of L. monocytogenes and Vibrio was optimized. By the usage of a Leica DM 6000B fluorescence microscope, four kinds of fluorescence filter cubes I3, L5, N21 and Y3 were compared after labeled with FAM and Cy3 fluorescences. As a result, for dual fluorescence detection, the combination of L5 and Y3 was suggested to observe the green fluorescence and red fluorescence, respectively. Comparing the effect of the volume ratio of the two strain solution on the test results, when the ratio decreased from 1∶1 to 1∶9, both strains could be detected; when the ratio decreased to 1∶19, the less was difficult to observe. It is indicated that, after labeled with FAM and Cy3 fluorescences, green and red fluorescences released by PNA probes can be observed through filter cubes L5 and Y3, respectively, within the usage of Leica DM 6000B fluorescence microscope, suggesting that the PNA-FISH synchronously detecting dual-species bacteria can be achieved by ordinary fluorescence microscope, if choosing suitable fluorescent dyes and fluorescence filter cubes.
Effects of brackish water irrigation on tomato yield and fruit sucrose metabolism in sunlight greenhouse
Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 667-677.
Based on the first crop experiment (spring), we carried out the second crop experiment in the autumn and winter of 2016, with the“Jingfan 301”tomato cultivar as the experimental material, by a single-factor completely randomized block design, and studied the effects of different brackish water irrigation patterns on the tomato composition and yield, and the activities of glucose metabolism related enzymes during the white mature, color turning and mature stages of tomato fruits. The results showed as follows: 1) The content of soluble sugar in tomato fruits under the direct brackish water irrigation was higher than that under other irrigations, and starch content under the direct fresh water irrigation was higher than under the brackish water irrigation with significant difference. 2) Brackish water irrigation improved the activities of invertase and sucrose synthase in tomato fruits, and the invertase activity was the highest under the direct brackish water irrigation, followed by brackish water and fresh water irrigation in sequence, and the lowest under the direct fresh water irrigation. 3) The tomato yield was the highest under the direct fresh water irrigation, then followed by the brackish water and fresh water irrigation in sequence, and the yield under the direct brackish water irrigation and brackish water∶fresh water=1∶1 irrigation was lower. 4) Different irrigation patterns of brackish water could lead to the accumulation of soil salinity. Among them, soil salt accumulation was the most serious under the direct brackish water irrigation, followed by the brackish water and fresh water irrigation according to the tomato growth period, but the least serious was under the brackish water∶fresh water=1∶1 irrigation. Combined with tomato yield, soil salinity and nutrient accumulation, it is considered that the brackish water and fresh water irrigation in sequence is the best irrigation pattern.
Effects of nitrogen supply level on nutrient absorption, distribution and yield of cucumber grown in substrate bag culture system
Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 678-686.
The experiment was conducted to study the effects of different nitrogen supply levels on nutrient uptake, distribution and yield of cucumber grown in substrate bag culture system. The different supply nitrogen treatments were as follows: the control (CK, 0 kg N per plant), low nitrogen (N
1, 0.016 kg N per plant), medium nitrogen (N 2, 0.023 kg N per plant) and high nitrogen (N 3, 0.030 kg N per plant). Results showed that the accumulation of nitrogen, phosphorus and potassium in cucumber increased at first and then decreased with the increase of nitrogen supply, indicating that reasonable nitrogen level was beneficial for cucumber to improve the absorption of nitrogen, phosphorus and potassium, especially significantly enhanced the absorption of nitrogen, phosphorus and potassium in fruiting period of cucumber. In the whole growth period, cucumbers had the highest absorption rate of potassium, followed by nitrogen, and then phosphorus. The yield was the highest with the medium nitrogen treatment. The utilization rates of nitrogen in cucumber were between 21.3% and 27.8% with different treatments, which increased in early stage and then decreased later with the increase of nitrogen. Using the path analysis of leaf area, stem diameter, dry matter quality and yield of cucumber, the results illustrated that yield could be used as the first index of nitrogen uptake. In the whole, the medium nitrogen treatment (0.023 kg N per plant) is relatively appropriate nitrogen supply level for cucumber substrate bag culture.
Identification of pathogens causing fruit spot disease on
Citrus grandis. Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 687-694.
Recently, a fruit spot disease was found on pummelo [
Citrus grandis Osbeck, Syn. C. maxima (Burm) Merr.] fruits during our investigation of diseases in pummelo orchards as well as in packing houses in Guangdong, Guangxi, and Fujian provinces and municipality. Symptoms of irregular or rounded small spots on the fruit surface firstly appeared, similar as the size of sesame, which were red brown and sunk. The center of spots gradually turned gray. The occurrence of spots was only limited to the flavedo and never extended into the sac of pummelo fruits, which significantly reduced the marketable quality of fruits, although did not decrease inner quality. Twenty fungal pure isolates were obtained using the tissue-isolation method, and the identification of these fungi was carried out based on morphology and molecular phylogenetic analysis which was performed with sequencing of internal transcribed spacer (ITS) rDNA, transcriptional elongation factor (TEF) and filamentous actin (ACT) genes. The results of morphological and phylogenetic studies demonstrated that the 20 isolates were identified as Cladosporium genus. These Cladosporium isolates were classified into two species, in which eighteen isolates were grouped into C . tenuissimum and two isolates belonged to C . xantochromaticum. It implied that, C. tenuissimum was the predominant species, and C . xantochromaticum was a new record fungus in China isolated from Citrus genus plant for the first time. A pathogenicity test was performed by inoculating a piece of fungal colony on the surface of healthy pummelo fruits. The result showed that the same symptoms appeared after 7 days of inoculation, confirming that the isolates were the pathogens of pummelo fruit spot disease. This research lays a foundation for further study on the way of disease occurrence and prevention.
Preparation and performance evaluation of cyclodextrin bifunctional monomer molecularly imprinted polymers
Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 695-703.
The preparation and performance evaluation of the cyclodextrin bifunctional monomer molecularly imprinted polymer were studied. A series of di (2-ethylhexyl) phthalate (DEHP) imprinted polymers were prepared using allyl-
β-cyclodextrin (allyl- β-CD) either alone or in conjunction with methacrylic acid (MAA), methyl methacrylate (MMA), acrylonitrile (AN), and acrylamide (AA) as the binary functional monomers. According to values of the binding specificity experiment, the binary functional monomers (M-MAA, M-MMA, and M-AN) were superior to a single functional monomer (M- β-CD); the average value of bound substrates from binary functional monomers was 110 μmol/g, whereas a single was 90 μmol/g.When M-MAA, M-MMAand M-AN were chosen as the stationary phase for molecularly imprinted solid-phase extraction (MISPE) and used to analyze the spiked infant formula, the recovery rate of DEHP ranged from 89.06% to 97.98% with relative standard deviations (RSD)≤6.47%. In addition,computational simulation results showed that MAAand AN had the strongest binding capacity with template molecules. All in all, the productions of binary functional monomer-synthesized molecularly imprinted polymer (MIPs) have yielded higher binding ability than that of single ones and are efficient separation of hydrophobic molecules.
Effects of rapid ageing technology on the aroma quality of white tea using gas chromatographymass spectrometry/mass spectrometry combined with chemometrics
Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 704-710.
To investigate the effects of rapid ageing technology on the aroma quality of white tea, the Yinghong No. 9 white tea of the same batch stored in a natural environment was used as a control group (CK), and that one stored in a rapid ageing environment was used as a treatment group. The aroma components of the white tea samples in the two different storage conditions were extracted by a headspace solid-phase micro-extraction (HS-SPME) technique and were analyzed by gas chromatography-mass spectrometry (GC-MS) combined with chemometric software Mass Profiler Professional (MPP). Moreover, sensory analysis was performed to evaluate their aroma quality. Results showed that there were significant differences on the aroma type, composition and content of aromas between these two kinds of white tea. The CK had a sweet and green aroma, while the rapid ageing white tea (the treatment group) was featured with stronger sweet aroma than the CK. All entities extracted from raw data through deconvolution were subjected to principal component filter with MPP, including coefficient of variation (CV＜25%), fold change (FC≥2), significance analysis (P＜0.01). By matching mass spectrum and retention index (RI), 25 differential entities were identified finally. The result from principal component analysis (PCA) showed that the 25 entities explained 99.79% of total variance on PC 1 and well reflected the difference between the CK and treatment group. Among these 25 components, esters, ketones, hydrocarbons were the major chemical classes. Ten components existed just in the treatment group, including n -hexanoic acid, 2-decanone, 3- nonen-2-one, 3-penten-2-one-4-methyl, and so on. Six esters existed only in the CK, including hexadecanoic acid methyl ester, octanoic acid methyl ester, acetic acid 2-phenylethyl ester, nonanoic acid methyl ester, heptanoic acid methyl ester, hexanoic acid 3-hexenyl ester. Nine components existed in both the CK and the treatment group, with the contents of toluene and 1-methyl-4-(1-methylethenyl)-benzene rising in the treatment group, while the contents of α -ionone, β -ionone, hexanoic acid methyl ester, 2-pentadecanone, 6,10,14- trimethyl, butylated hydroxytoluene, tridecane 3-methyl, and 6-isocedrol declining in the treatment group. In conclusion, rapid ageing technology can accelerate transformation of volatile compounds in white tea to some extent, thus to promote the aroma quality of white tea.
Effects of 5- azacytidine-2’- deoxycytidine on the proliferation, cell cycle, and apoptosis of fetal bovine fibroblast cells
Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 727-734.
Fetal bovine fibroblast cells (FBFCs) are widely used in cellular reprogramming and methylation. In this study, the effects of 5- azacytidine-2’- deoxycytidines (5-Aza-CdR), a DNA methylation inhibitor on the physiological characteristics of FBFCs were investigated. The FBFCs derived from a bovine fetus were treated with 5-Aza-CdR at different concentrations for 24, 48 and 72 h, respectively, to determine the changes of cell proliferation, viability, cell cycle distribution and apoptosis rates. The results demonstrated that 5- Aza- CdR treatment in the FBFCs resulted in a decrease of cell proliferation, cell viability, and an increase of total cell apoptosis in a dose-dependent manner. The best treatment strategy for 5-Aza-CdR was less than 0.1 μmol/L for 24 h, which showed minimal adverse effects on FBFCs. The above results indicate that the low dose DNA demethylation inhibitor treatment in FBFCs is beneficial for cell reprogramming.
Early development of the vertebral column and appendicular skeleton in Sebastiscus marmoratus larvae
Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 735-742.
The study on the development of the vertebral column, pelvic and anal fins of
Sebastiscus marmoratus larvae [1-50 days age after hatching (d.a.h)] was conducted by the clearing and staining technique of cartilage and bone. The results showed that the notochord was not segmented, which seemed a cone at 1-7 d.a.h. The vertebral column development started from haemal arches and neural arches at 13 d.a.h. The haemal and neural arches extended to haemal and neural spines at 18 d.a.h, respectively. Segmental bone rings appeared at 29 d.a.h. Vertebral column was ossified from front to back, and then was completely ossified at 36 d.a.h. The trunk and caudal vertebra were formed 9-10 and 14-15 cervical vertebra segments, respectively. The development sequence of appendicular skeletons was from the pectoral fins, caudal fins, dorsal fins, anal fins to ventral fins. The development of the caudal fin started from the appearance of the hypural at 8 d.a.h, then one piece of urostyle, two pieces of epural, and five pieces of hypural were formed at 13 d.a.h. The second and third hypurals were combined together at 15 d.a.h, the same as the fourth and fifth hypurals. The caudal fin was ossified at 40 d.a.h. The development of the pectoral fins started with appearance of coracoid at 1 d.a.h. Cartilages of appendicular pectoral fins were formed at 16 d.a.h, and cleithrum and pectoral girdle were ossified at 39 d.a.h. Eight hyaloidin pterygiophores appeared at 13 d.a.h. Cartilages of appendicular dorsal fins were formed at 16 d.a.h, and the frontal fin rays of dorsal fins were transformed 11-12 dorsal spines. Five hyaloidin pterygiophores appeared at 15 d.a.h. Cartilages of appendicular anal fins were formed at 19 d.a.h, and the frontal fin rays of anal fins were transformed three anal spines at 20 d.a.h. Ossification of pelvic and anal fins were first started at 31 d.a.h. Therefore, the study on the early development of the vertebral column and the appendicular skeleton in S. marmoratus is important for classification, and promotes comprehending of environmental preferences and functional morphology during the whole ontogenetic stage.
Geometrical parameter calculation of excised wheat leaves based on image analysis
Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 748-754.
Aiming at some deficiency of geometrical parameter calculation in plant leaves at present, we proposed a computational method suitable for measuring area, length, width and perimeter of excised wheat leaves. Wheat image was segmented under a certain background by histogram algorithm. Leaf area was calculated by statistical image number method, and leaf perimeter was calculated on the distance between adjacent pixels of the blade edge. Leaf length and width were measured by improved minimum enclosing rectangle. Then the calculated results were compared with the measured values, and statistical analysis was carried out. The results showed the calculated results were close to the measured values. The root mean square error (RMSE) values for area, length and width of wheat leaves were 0.49 cm
2, 0.57 cm and 0.04 cm, respectively. The coefficient of determination ( R 2) for area, length and width of wheat leaves were 0.99, 0.97 and 0.96, respectively. The differences in RMSE values were close to 0 and R 2 values were close to 1, and the calculated results and the measured values were insignificant, indicating that the improved algorithms for measuring area, length, width and perimeter of wheat leaves are not influenced by wheat leaf shapes, suitable for different conditions, reliable and practicable.
Feeding precision experiment of projective feeding machine
Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 755-764.
In recent years, China’s aquaculture has developed rapidly, so it is a necessary trend that the use of feeding machine will replace the artificial feeding. In order to determine the factors that affect the precision of the feeding machine and their influence degree, we took the QC-TR-15 feeding machine as the experimental object, and 29 sets of tests were designed by using Box-Behnken response surface design method, and in accordance with the order of experimental numbers to start the test, the effects of wind speed, feeding time interval, feeding amount and cylinder capacity on the feeding accuracy were studied. Then the Design Expert 8.0.6 software was used for data analysis, and a quadratic regression model for the feeding accuracy was obtained. The results of variance analysis showed that the wind speed had extremely significant effect on the feeding accuracy (
P＜0.000 1) in the four factors, and other factors had no significant effect. The results of the single factor analysis and interaction analysis showed that the influence degree of each factor on the feeding accuracy was as follows: wind speed＞feed amount＞feeding time interval＞cylinder capacity. The above results can provide a reference for optimization and application of the type of feeding machine.
Rice cropping information extraction mapping based on sample knowledge mining using high resolution remote sensing images
Journal of Zhejiang University (Agriculture and Life Sciences), 2018, 44(6): 765-774.
The rice fields in high resolution remote sensing images present mixed information constituted by distinct ground objects such as rice, soil, water, weed, duckweed and so on. Thus a novel approach for mapping of rice cropping areas based on sample knowledge mining was brought up according to spatial autocorrelation theory, which took advantage of the spectra combinational regularity. The accompanying mapping strategy was formulated based on this method. First, we segmented the high resolution remote sensing image into spectrally homogeneous base-units that represented distinct mixture information of several ground objects by grouping adjacent pixels with similar spectra. Second, we constructed a set of rice base-unit types through analysis of the base-unit types that contain rice field samples, and combine all the base-unit whose type belonged to this set to form initial rice cropping region. Finally, we vectorized the initial rice cropping region to initial rice cropping polygons, and then removed the polygons incompatible with spectra combinational regularity of rice fields through similarity analysis of combined feature of base-units between the rice cropping polygons and the rice field sample polygons. The overall accuracy of experimental rice cropping areas mapping results was over 96%. The successful application of this novel approach proves its efficiency and indicates its great potential for further utilization.