Preparation Of Mixed Smoke Liquid Based On Persimmon And Its Application In Grass Carp

Smoked products are popular among consumers in daily life.Traditional smoking is gradually replaced by liquid smoking because it is easy to cause the accumulation of harmful substances on food surface and environmental pollution.Liquid fumigation method is to use fumigation liquid instead of gas smoke,which can make food have almost the same flavor as traditional fumigation,and has higher safety.At present,only hawthorn kernel smoke liquid is approved in China,and the type of smoke liquid is still relatively single.Therefore,it is very important to select suitable smoke wood and develop new food smoke liquid through appropriate retorting process to enrich smoke liquid and improve wood added value.In this paper,persimmon,pomegranate,apricot,jujube and cypress were used as raw materials to prepare the smoke liquid respectively,and the similarities and differences between the five kinds of smoke liquid and the smoke liquid of red arrow and hawthorn kernel were compared and analyzed.Then,with persimmon as the main raw material,orange peel and sucrose as the auxiliary materials,the preparation process of persimmon mixed smoke liquid was optimized,and its quality characteristics were analyzed.Finally,it was applied to the production of smoked grass carp to explore the application of liquid fumigation technology in cured fish products.The results are as follows:(1)In this paper,the flavor characteristics of smoke liquid made from wood with broad prospects were analyzed.The flavor characteristics of seven kinds of smoke liquid were evaluated by sensory evaluation,Gas Chromatography-Mass Spectrometry(GC-MS),electronic nose analysis and physical and chemical index analysis.The results showed that the sensory score of persimmon smoke liquid was second only to red arrow and hawthorn kernel,A total of 90 volatile compounds,including phenols,aldehydes,ketones,alcohols,acids and esters,were identified from the seven f smoke liquid,and their contents were different.Phenols were the most volatile compounds,followed by aldehydes.The types and contents of the main volatile compounds(phenols and carbonyls)in persimmon,pomegranate and apricot smoke liquid are most similar to those in red arrow and hawthorn kernel smoke liquid,which has a certain application prospect in the preparation of smoke liquid.The results of odoractivityvalue and principal component analysis showed that guaiacol,furfural and 5methylfural had great contribution to the formation of flavor profile of the fumigation.The results of electronic nose showed that the odors of the seven fumigation liquids were similar but different,mainly in aromatic components,short-chain alkanes,alcohol-ether aldehydes and ketones.Among the seven smoke liquid,the content of total phenols in apricot smoke liquid was the highest(30.71 mg/mL),the content of carbonyl compounds in cypress smoke liquid was the highest(34.87 g/100mL),and the pH value of persimmon moke liquid was the highest(2.89).Through the above analysis,the persimmon with the best sensory evaluation and the prospect of preparing smoke liquid was selected to prepare the later mixed smoke liquid.(2)In order to explore the best preparation technology and quality characteristics of persimmon mixed smoke liquid,the preparation process of persimmon mixed smoke liquid was optimized by single factor and orthogonal test,and its safety and volatile flavor compounds were analyzed.The content of phenols and carbonyl compounds in the smoke liquid was taken as the index,with the temperature of distillation,the size of persimmon and the addition of sucrose as the single factors.The results showed that the best preparation process was as follows:temperature 450℃,persimmon size 0.6 cm,sucrose addition 8%,and the contents of phenolic and carbonyl compounds in smoke liquid were 15.68 mg/mL and 19.41 g/100mL respectively.Benzopyrene was not detected in the treated persimmon mixed smoke liquid.The results of GC-MS showed that 56 kinds of volatile compounds were detected in the mixed smoke liquid,including 18 ketones,8 esters,4 acids,3 aldehydes,14 phenols and 9 others.The relative content of phenolic compounds was 41.266%,followed by aldehydes(36.529%)and acids(0.421%).(3)Persimmon mixed smoke liquid was applied to grass carp to explore the effects of liquid technology on the quality of grass carp,the volatile components in grass carp before and after liquid smoke and the quality changes during cold storage.With the addition amount of smoke liquid,liquid time and drying time as factors,sensory score,texture and color difference as indexes,The results showed that the best liquid smoke process was as follows:the amount of liquid was 2%,the time of liquid smoke was 50 min,and the drying time was 60 min.The results of GC-MS showed that liquid fumigation increased the contents and species of phenols and ketones in grass carp.Then,texture,color difference,juice loss rate,pH value,malondialdehyde,volatile basic nitrogen content and sensory evaluation were used as indexes to explore the quality changes of liquid smoked grass carp during storage,and the blank grass carp without smoking liquid were used as control.With the prolongation of storage time,the quality of liquid smoked fish slices and blank fish slices gradually deteriorated.The liquid smoked fish fillets had higher sensory score,hardness and lower elasticity during the whole storage period.During storage,the a*value of blank fillets decreased gradually,while that of liquid smoked fillets increased gradually.The pH value of liquid smoked fillets was significantly lower than that of blank fillets(P<0.05).During storage,the juice loss rate of liquid smoked fillets was always higher than that of blank fillets,reaching 10.24%.However,the content of malondialdehyde and volatile base nitrogen of liquid smoked fillets was always lower than that of blank fillets.To sum up,persimmon has a good prospect for the preparation of smoke liquid.The volatile flavor compounds in the mixed smoke liquid of persimmon are rich and do not contain benzopyrene.The liquid smoked grass carp made from the mixed smoke liquid has good sensory quality.