Non-destructive Evaluation Of Developmental And Fullness Of Eriocheir Sinensis And Detection Of Volatile Odor Components

Eriocheir Sinensis（E.Sinensis）is a very important commodity crab in China which is deeply loved by consumers.It has become an essential food because of its delicious flesh and unique flavor.Its competitiveness in the market is directly affected by its quality.Its quality is development and fullness,which was reflectd the development of hepatopancreas and gonads.The scent released after cooking is the aroma of the E.Sinensis which is an important sensory evaluation indicator.For development detection,the E.Sinensis from Sep.to Dec.was detected for low-field NMR transverse relaxation time（T₂）analysis.A regular model of hepatopancreas index（HSI）,gonadal index（GSI）and development of E.Sinensis was established in different months by T₂ relaxation for nondestructive detection,to make the mature or nearly mature E.Sinensis come on the market quickly for full market value and maximum benefits.The results showed that the fat content of E.sinensis in October was significantly different from that in other months（p<0.05）and the development of female crabs was always better than that of male crabs.The result of T₂ detection had the same rules as the change of HSI obtained from living anatomy.The gonads of E.sinensis were mature or nearly mature from Oct.to Dec..The flavor at this stage was the best,and the edible quality could be affected by fishing premature or late.The T₂detection could not only non-intrusive detection,but also could directly detect the living body,which could provide possibility for studying the change regulation of the lipid content of E.sinensis.The parameters of the T₂ relaxation time provided by the experiment could also be used as a standard to detect the development of E.sinensis in vivo,to achieve the purpose of quality evaluation and hierarchical management thereof.For fullness studies,low-field nuclear magnetic resonance imaging（LF-MRI）is used for nondestructive detection.3D model of lipid volume was established by MATLAB software,and 2D lipid area was quantified for better non-destructive evaluation of the fullness of E.sinensis from Sep.to Dec.The results showed a good linear relationship between the normalized lipid volume（3D model）and fat content.The male fitting curve was Y=-2E-06X²+0.0124X-0.7851,R²=0.9612,the fitting curve of female crab was Y=-3E-05X²+0.0865X-51.049,R²=0.9529,meaning that when studying changes in lipid content,Soxhlet extraction could be replaced completely by normalized lipid volume to quantify plumpness of E.sinensis.Compared with traditional detection methods,based on LF-1H MRI detection method was an environmentally friendly,direct and high sensitivity method.Based on the results of this experiment,LF-1H MRI could be considered as a preferred method for further study on the plumpness of E.sinensis.In this experiment,HS-SPME（headspace solid-phase microextraction）combined with GC×GC/TOFMS（two-dimensional gas chromatography-time of flight mass spectrometry）was used to detect the volatile aroma components of E.sinensis in Oct.after steaming to provides evidence for the creation of a volatile aroma material libraries of E.sinensis.The results showed that 315 and 335 species of male and female E.sinensis were analyzed.The ketones（60 and 57）,aldehydes（46 and 61）,S-containing compounds（14 and 16）,aromatic compounds（23 and 18）,and N-containing compounds（47 and 34）were the main contributors for the flavor of steamed female and male E.sinensis.In addition,the method established in the experiment was detected many substances because of the slower heating rate,which is helpful for comprehensive analysis.The volatile aroma compounds in the mixture of hepatopancreas and gonadal detected could be used as a follow-up study reference.