Quality Monitoring Analysis Of Sea Cucumber During Drying Process By Low Field Nuclear Magnetic Resonance And Imaging Technology

Sea cucumber is deeply loved by consumers for high nutritional value and unique taste.However traditional methods were complex,time-consuming and cannot achieve real-time monitoring,etc.Low field nuclear magnetic resonance(LF-NMR)technology can monitor hydrogen dynamic changes and provide visualized image information rapidly and non-intrusively.In this paper,LF-NMR was used to discriminate different sea cucumber subjected to different drying methods,determine the water status and distribution and investigate the relationships between the NMR parameters and dehydration rate,texture of dried sea cucumber during dehydration process and the effect of temperatures on drying characteristics of sea cucumber was also studied.Prediction models of water contents were established during drying process.Four main conclusions were listed below:(1)CPMG(Carr-Purcell-Meiboom-Gill)peak signals were collected using LF-NMR,combined with principle component analysis(PCA)to process the echo data of sea cucumbers dried with different methods.The results showed that the first principal component(PC1)can explain 97%of the total variance and the second principal component(PC2)3%.It was satisfactory to distinguish sea cucumbers dried with different methods.(2)Relaxation profile and T1-T2 weighted images were obtained by LF-NMR and MRI to correlate transverse relaxation times with Texture Profile Analysis(TPA)parameters.The results of liner regression showed significant correlation between NMR parameters and hardness,chewiness along with rate of water loss.The best drying time was 12 h based on drying curves or MRI images.(3)Five models(Wang and Singh,Newton,Page,Logaritmic,Two-term)were chosen to simulate the drying dynamic characteristics.Two-term model was the best one to describe the drying dynamics of sea cucumber with R2=0.998 and RMSE= 0.011 compared with the other four models.(4)Three different temperatures(45?60?75 ?)were set to detect the trait of water changes upon heating via LF-NMR in situ.The results revealed that the transverse relaxation times under different temperatures were significantly different,the best drying temperature was 60 ? and the effect of temperatures on drying characteristics can be reflected to a certain extent by LF-NMR technology.This research can provide theoretical basis for seafood processing.