Investigation Of Influencing Factors Of Dried Mud Carp Quality In Cooking And Tasting

Mud carp(Cirrhinus molitorella)is one of the important farmed freshwater fish in China,especially the South China,it is distributed mainly over Pearl River,Hainan Island and Taiwan.It owing to its enormous production,tender flesh,tasty taste and moderate price,mud carp is popular in fishery market and consumers.Currently,on the basis of fresh transportation and marketing,mud carp is also processed into fish balls,caned fried mud carp with salted black beans,and dried products.Salted-dried mud carp is popular not only for its special chewiness and flavor but also longer shelf life.The dried mud carp is a fashional dish among domestic and restaurant consumers.Especially with the rise of concepts such as central kitchen and prefabricated food,the consumer population of dired mud carp increased.However,the freshness of raw materials,processing technology and cooking methods of mud carp have important impacts on the overall cooking-tasting quality of dried mud carp.Herin,in this study,mud carp was used as raw material,a method for rapid detection of freshness of mud carp was developed.The effect of processing technology and cooking methods on the edible quality of dried mud carp were investigated systematically.The objective of the present study was to improve the overall cooking-tasting quality of dried aquatic products by ensuring the freshness of raw materials,optimizing processing technology and choosing appropriate cooking methods.The data provided the theory basis and technical reference of processing of dried mud carp.The details were listed as following:1)A new colorimetric indicator film by incorporating mulberry anthocyanin extracts(MAE)into gelatin/polyvinyl alcohol(GPVA)matrix was developed to detect the freshness of flesh.The interaction of anthocyanins and gelatin/polyvinyl alcohol is characterized by Fourier transform-infrared spectroscopy(FTIR)and isothermal titration calorimetry(ITC).The effect of different mulberry anthocyanins extract content on mechanical properties,microstructure,and color response efficiency of the developed colorimetric indicator films were investigated.Finally,the potential use of this colorimetric indicator film in monitoring fish spoilage was also examined.The results showed that the color of mulberry anthocyanin clearly changed in the pH range of 2.0-11.0.The color of MAE solutions changed from bright red to dark green with the pH value increasing from 2.0 to 11.0.MAE had a potential use as a sensitive dye with the color variations from bright red to dark green in a pH range of 2.0-11.0.The FT-IR and ITC analysis stated that the complex combination between MAE and gelatin/PVA was spontaneous and mainly driven by enthalpy(hydrogen binding and electrostatic interaction),which corresponding to the results of FT-IR.The excessive MAE might interact with GPVA matrix and improve the compatibility between gelatin and PVA,and the cross-section became more homogeneous.The extendability of of colorimetric indicator film were improved,resulting in the excellent mechanical behavior of the film.The colorimetric indicator film incorporated MAE could be sensitive to color variations as a result of pH changes,its color changes were clearly visible with naked eye.The color variation film could distinctly reflect the mud carp freshness and spoilage.Therefore,this colorimetric indicator film could be utilized as an effective method in monitoring fish spoilage.2)The effects of drying temperature and pre-salting methods on the quality and the formation of N-nitrosamines(NAs)of dried mud carp were investigated by evaluating appearance,color,texture properties,microstructure,microbia counts,total volatile basic nitrogen,thiobarbituric acid,and the formation of NAs among the samples.The result showed that the drying temperatures has a close relationship with the quality of dried mud carp and the formation of NAs.The samples dried at 35 ? and 25 ? showed obviously darker than these samples at 45 ? and 15 ?.It can be observed that the sample dried at 15 ? with 10%salt content had the lowest rehydration,high hardness and chewiness,and the myofibrils of mud carp dried at 15 ? arrayed closely.There were showed higher degree of the protein denatured in dried mud carp under 45 ? than that under 15 ?.On the other hand,the pre-salting methods has a close relationship with the quality of dried mud carp and the formation of NAs.With the increasing of salt content,the dried mud carp showed pure yellow appearance,lower b*value and rehydration,higher hardness and chewiness,more compact microstructure,more ordered array of myofibrils of mud carp,and lower TVB-N content,total aerobic count(TAC)and total Yeast and Mold count(TYM)levels.Interestingly,the levels of NAs in salted samples prepared from hot air drying at 45 ? increased with increased salt content.On the contrary,the levels of NAs decreased with increased salt,and those samples had the lower summation of NAs content(3.79-5.38?g/kg)in salted samples prepared from 15 ? drying.Using 15 ? drying,the dried mud carp with 4%(w/w)salt content shows an minimization of muscle decomposition and lower N-nitrosamines content(5.38?g/kg).The cold air drying could obtain better quality of dried fish.Moreover,during the cold-air drying(15 ?),less salt could be used in salting process during cold air drying,which is beneficial for the reduction of salt intake.3)The flavor(volatile compounds),taste(free amino acids),chewiness(texture),and microstructure properties of salted-dried fish cooked by microwave,air-frying,baking and steaming cooking were evaluated,and the sensory evaluation was also carried out to investigate the effect of cooking methods on the overall cooking-tasting quality of salted-dried mud carp.The results showed that microwave,air-frying,baking and steaming cooking could decrease the hardness and chewiness of dried fish sampled,and increase its springiness.Four cooking methods had no effect on the types of free amino acids in dried samples.13 free amino acids were detected in the samples and cooked samples.However,four cooking methods all affected the content of free amino acids.Microwave,air-frying,baking all reduced the total amount of free amino acids in dried fish,while the steaming cooking improved the total of free amino aids from 586.66 mg/100g to 631.45 mg/100g.The contents of aldehydes,ketones,olefins,esters,alkanes and alcohols in dried fish samples increased significantly after four cooking methods.The content of aldehydes and ketones in dried fish samples treated by air-frying cooking was the highest(relative content 37.07%).The contents of aldehydes,ketones and esters were significantly increased and the content of alkanes was declined in all cooked samples.The sample cooked by air-frying had the highest contents(37.07%)of aldehydes and ketones.The cooking treatment could result in serious shrink of muscle fiber of salted-dried fish,and the space among muscle fiber bundles was filled with cooking oil.The space among muscle fiber bundles was obvious relatively in the samples cooked by air-frying and baking.