| Procambarus clarkii alias crayfish,is rich in protein,lipids,amino acids,astaxanthin and other nutrients.It originated in the central and eastern United States,in the 1830 s into our country.In 2017,the total economic output value of crayfish in our country increased by 83.15% compared with that in 2016,and now it has become an important resource of freshwater products in China.It has various functions such as lowering blood pressure,lowering blood lipids and enhancing immune system.At present,Procambarus clarkii is mainly used in the preparation of cooked products,flavorings and other products,as well as extraction of active ingredients such as astaxanthin and chitin.In the study of the preparation of flavorings from Procambarus clarkii,there exist some processing problems,such as low utilization of raw materials,serious waste of resources and so on.In this paper,based the enterprise requirment according to the development trend of green and healthy aquatic seasonings,we applied ultrasonic assisted technology to enzymatic hydrolize crayfish.The flavor is optimized in Maillard reaction,the crayfish seasoning powder was prepared by spray drying method,providing a basis for the deep processing of aquatic products and the development of new products in the seasoning market.1.In order to obtain optimic enzymatic hydrolysis conditions of Procambarus clarkii,acid protease,neutral protease,alkaline protease,bovine trypsin and papain were used to enzymatically hydrolyze Procambarus clarkii respectively.Taking hydrolysis degree,amino acid conversion rate and protein utilization rate as indexes,the hydrolysis efficiency of alkaline protease was the best,followed by bovine trypsin and papain.On the basis of single enzymatic hydrolysis,double enzymatic hydrolysis was carried out to further improve of the enzymatic hydrolysis effect.The optimumconditions for double enzymatic hydrolysis of crayfish were as follows: first,alkaline protease was added to the hydrolysate of crayfish at the solid-liquid ratio of 1:2(g/mL),enzyme addition of 2500U/g,an enzymatic hydrolysis temperature of 60?,pH of 8.0,and the time of 3h,which was followed by the addition of papain at the enzyme volume was 2000U/g,pH 7.0,enzymatic hydrolysis time 2h,the degree of enzymatic hydrolysis of crayfish reached(23.48±0.60)%,the conversion rate of amino acid reached(31.53±0.40)%,and the utilization rate of protein reached(83.89±0.53)%.2.Ultrasonic-Assisted enzymatic hydrolysis was used to improve the degree of enzymatic hydrolysis of crayfish.The optimum conditions of ultrasonic-assisted enzymatic hydrolysis of crayfish were determined by response surface optimization design.The experimental results showed that optimal conditions of enzymatic hydrolysis were: ultrasonic time of 34.11 min,ultrasonic power of 367.14 W,and enzymatic hydrolysis time of “3+2”h.Under this condition,the hydrolysis degree of crayfish reached(31.33±0.20)% and increased by 7.85% compared with that without ultrasound treatment.At the same time,fourier transform infrared spectroscopy and fluorescence spectroscopy were used to scan the hydrolysate before and after ultrasound treatment.The results showed that the protein structure of the hydrolysate could be further broken by ultrasound treatment.3.In order to optimize the flavor of the enzymatic hydrolysate of crayfish,the Maillard reaction was carried out by designing single factor test and orthogonal test.Sensory evaluation(including indicators of smell,umami,color,etc.),level of low molecular weight aroma intermediates and concentration of melanoid polymer were taken as indexes,the order of factors affecting Maillard reaction was determined as follows: reaction time > reaction temperature > reaction pH > ratio of reducing sugar > amount of reducing sugar added.According to sensory score and range analysis,the reaction conditions of Maillard reaction were reaction time 90 minutes,reaction temperature 100 ?,reaction pH value 9.0,ratio of reducing sugar 1:2,addition of reducing sugar 4%,The sensory score of Maillard reaction of crayfish enzymatic hydrolysate was the highest.4.Amino acid automatic analyzer was used to analyze 16 free amino acids in raw material freeze-dried powder,enzymatic hydrolysate and Maillard reaction solution of Procambarus clarkii.The total free amino acids were 13.08mg/mL,297.81mg/mL and 57.80mg/mL,respectively.The results showed that free amino acids were released after enzymatic hydrolysis.After Maillard reaction,the content of free amino acids in the product was reduced by 240.01mg/mL,and the utilization rate of free amino acids was 80.59%.This indicated that free amino acids in enzymatic hydrolysate were fully utilized by Maillard reaction.5.Headspace solid-phase microextraction combined with gas chromatography-mass spectrometry(HS-SPME-GC-MS)was used to detect the volatile components in the raw material freeze-dried powder,enzymatic hydrolysate and Maillard reaction solution of crayfish.76,77 and 52 species volatile components were detected respectively.Through the analysis of volatile components of three samples,it was determined that the most important component contributing to the flavor of Maillard reaction solution was aldehydes,and the characteristic flavor substance was benzaldehyde.6.In order to obtain seasoning powder of crayfish,the effects of spray drying conditions on the spray drying of crayfish seasonings were investigated by collecting rate,dispersing time,wettability and sensory evaluation.The conditions for spray drying were determined as follows: maltodextrin was selected as the drying aid,he inlet air temperature was 180?,the feed flow rate was 20mL/min,and the amount of the maltodextrin was 20%.Compared with the vacuum freeze dried seasoning powder,the results showed that all the indexes of seasoning powder processed by vacuum freeze-drying was better than that of spray dried seasoning powder,but the cost was higher.Considering the actual economic benefits,spray drying technology was selected as the preparation method of Procambarus clarkii flavorings. |
PDF Full Text Request