Study On Detection And Removal Of The Odor Of Tilapia

The paper studied on the odor and flavor of the Tilapia. The odors were detectedand analysised by SPME-GC-MS. The Electronic Nose was used to analysis theflavor of Tilapia. The influence of the LOX to the Tilapia flavor was also studied. TheGeosmin and2-methylisoborneol were measured. The usage of the O3on the odorremoving was also researched. Details of this paper were as follows:1. The SPME-GC-MS method was researched to detect the Tilapia flavors. Afterthe optimization of the experiment factors, PDMS/DVB was choose as the optimumSPME fiber. And the optimum experiment methods as follows: Extraction time:30min, armature speed:1050r/min, Extraction temperature:60℃. And the DB-5MSwas chosed as the optimum Capillary column. Hexanal, Heptanal, Octanal,2,3-octanedione,3-pentanone,1-Hexanol and1-penten-3-ol were detected andrecognized as the typical compounds of the fresh Tilapia. At the same time, differentparts of Tilapia and different cold storage time of Tilapia was detected and comparedby SPME-GC-MS.Cold tilapia of different frozen storage times was detected by an electronic nose (PEN3), and the paper analyzed the effect of frozen storage time on the flavor of tilapia.The data was analyzed by PCA method and LDA method. The result: electronic nosecould discriminate cold tilapia with different frozen storage time. PCA and LDAmethods both had nice ability to indentify old tilapia with different frozen storagetime. The sum of variances of the first main axis and the second main axis were91.69%with the method of PCA. The method of LDA had nice concentration andsingle tendency. In addition, sensors W5S, W1S, W2S and W1W in electronic nose(PEN3) were analyzed by Loarding method and were found that played an key role inthe detection. Therefore, the screen matrix arrangement of sensors of electronic noseshould be optimized according to different experiments.2. Geosmin(GEO) and2-Methylisoborneol(MIB) were off-flavor compounds,which created undesirable odors and taste in Aquatic product. We established a method of Microwave mediated distillation with solid-phase microextraction(SPME)and gas chromatography-mass spectrum(GC-MS)，and applied it to determine twosemi-volatile off-flavor compounds for-mentioned. Through the improvement for theparameters in microwave distillation, the optimum conditions were defined asfollows: the power of microwave was360W(40%of the rated power), the microwavetime was6min, and the argon flow was60mL/min. Under the optimum conditions,GEO and MIB could be determined best. The detection limits were calculated to be0.044μg/kg for GEO and0.095μg/kg for MIB. In the range of0.5~20μg/kg, therewere significant linear correlation for GEO and MIB, with r2at0.998and0.991respectively. The recovery calculated were42.7%for GEO and61.9%for MIB.With the determination method, the average content of GEO and MIB in Tilapiameat were4.97μg/kg,1.21μg/kg respectively.3. Tilapia LOX was purified by hydroxyapatite protein purification system.Enzyme activity and optimum substrate was researched, it was found that linolenicacid was the optimum substrate. Haemoglobin, LOX and FeCl3were used to oxidizethe model fish respectively. And the differences among flavors of the three oxidizeprocess.4. The0°C O3Water was used to remove the odors of Tilapia. Geosmin and2-Methylisoborneol were reduced by39.1%and30.4%respectively. Some typicalflavors like Hexanal, Heptanal, Octanal,2,3-Octanedione were reduced. However,the content of protein, fat, water and ash was not remarkable reduced. The researchshowed that0°C O3was a nice method for the odor removing of Tilapia.