Quality Monitoring And Correlation Studies Of Turbot Flesh During Different Cooking Methods And Freezing-thawing Process

Turbot(Scophthalmus maximus L.)is one of the main representative marine fish species.Its flesh is popular in consumers because it has a white and tender taste with little bone with small visceral mass and a high dressing percentage,etc.Currently,turbot is mainly sold as live fish and frozen flesh on the market.Thus,it is particularly important to study the quality change of turbot flesh in different processing and thawing methods,as well as freezing and thawing processes.But the traditional methods of quality analysis were complex and time-consuming,which can not achieve real-time monitoring.In this study,low field NMR technology combined with traditional quality testing methods were used to study the feasibility of identification and prediction in turbot processing using the principal component analysis and linear correlation analysis technology.The main conclusions are as follows:The mobility and content of immobile water showed significant reduce trend during the different heating processes.While the mobility and content of bound water changed a little,and the trend of free water changed by different methods.Frying and baking processes exhibited significant influence in water content of turbot flesh,the boiling and stewing processes showed moderate influence,and steaming and microwave displayed little influence.The turbot flesh treated with different heating methods could be identified by principal component analysis method.Good correlation was found between NMR parameters and the weightloss rate,color and texture parameters.The mobility and content of bound water changed little in turbot flesh during room temperature,water and microwave thawing processes.The change of the immobile water was significant and showed a decreasing trend during all the thawing methods.Free water varied a little.The flesh underwent different thawing prosesses could be well identified by principal component analysis method.Quality parameters including color,tenderness,water hoiding capacity,pH value and microstructure were affected during different thawing methods.The fat oxidation and protein denaturation degree was also different.In conclusion,water thawing method is the probably the suitable method for short-term thawing of turbot flesh.Both mobility and content of immobile water reduced dramatically when the turbot flesh was undergone freezing and thawing cycles for 30 times.While the bound water and free water changed little.Different freezing and thawing times could be well identified by principal component analysis method.Each quality parameter suffered irreversible damage.In the process of actual production and processing,the repeated freezing and thawing should be avoided.In a word,the cycles of freezing and thawing should be controlled less than 10 times.