Brewing And Quality Analysis Of White Soy Sauce Based On Extrusion Technology

White soy sauce is highly popular with people in Jiangsu and Zhejiang as the characteristic seasoning in northern Jiangsu due to the sweet,palatable,mellow and soft taste,the prominent auce and ester fragrance,clarified and lustrous colour.The production processes of traditional white soy sauce exist in some problems,such as uneven heating,easy caking and higher labor intensity,which severely limits the deep development and utilization of white soy sauce.The soy sauce brewing materials treated by extrusion technology can make starch quickly gelatinization,protein moderate degeneration,nutrition factors passivation,which improve the utilization rate of raw materials,shorten the fermentation cycle,save costs,realize automation and continuous production and so on.Based on above,in present study white soy sauce is used as the research object,aiming at developing and improving the brewing technology of traditional white soy sauce and further analyzing its edible quality by extrusion technology.Specifically speaking,the optimum processing conditions of extruded wheat flour were studied and the effects of different treatment methods?extrusion and traditional cooking?on physicochemical properties of raw materials were discussed.After that the fermentation conditions of white soy sauce were investigated.On this basis,the edible quality of white soy sauce was further analyzed.The extrusion process parameters were optimized by the single factor experiment and the response surface methodology?RSM?using the extruded wheat flour as the materials and enzyme activity of koji as the index.The test results by comprehensive analysis determined that the optimum extrusion parameters were materials with 40%-45%moisture content,screw speed at 100 r/min,feeding speed at 10 kg/h and barrel temperature at 80-100?.Under these conditions,the optimal glucoamylase activity,neutral protease activity and alkaline protease activity were 1293.49 U/g,516.32 U/g and 148.56 U/g,respectively.Wheat flour was treated by extrusion and traditional cooking,and compared the differences of two processed materials in physical and chemical properties,including basic composition,water absorption,solubility,volume density,reducing sugar content,gelatinization degree and microstructure,and then the change rules of starch and protein after extrusion and traditional cooking were analyzed.The results showed that the content of protein,starch,fat and total amino acid of extruded materials obviously decreased,the content of reducing sugar and starch gelatinization significantly increased,and the volume density obviously decreased.The water absorption and water solubility of the materials obtained by the two treatment methods were improved,but the water-soluble of extruded materials improved82.32%than traditional cooking materials.Scanning Electron Microscope?SEM?was used to observe the microstructure of extruded materials and traditional cooking materials.It could be seen from SEM that the microstructure surface of extruded materials was loose,rough and irregular with voids,which was suitable for the adhesion of microorganism and increased the action area of the enzyme.But the microstructure surface of traditional cooking materials was dense smooth.The results of X-ray diffraction?XRD?showed that the crystal structure of extruded starch transformed from A-type to V-type.The relative crystallinity of the extruded starch was 11.51%.The chain length distribution of the extruded wheat starch showed that the A chain was significantly increased,but the B₂ and B₃ chain remarkably decreased,which indicated that the starch had been obviously degraded.The results of laser confocal microscope showed that the protein structure of wheat flour by extrusion and traditional cooking was destroyed and the appearance of protein aggregated.The wheat flour used for white soy sauce was treated by the optimum extrusion conditions,and the effects of fermentation temperature,fermentation time and salt addition on fermentation were studied.The content of reducing sugar and amino acid nitrogen were regarded as the indexes.The optimum fermentation conditions were optimized by the single factor experiment and the response surface methodology?RSM?.The optimum fermentation conditions were 40%salt addition,fermentation for 30 days and fermentation temperature at 45?.Under these conditions,the reducing sugar content and amino acid nitrogen of white soy sauce could up to281.35 mg/mL and 0.65 g/100 m L,respectively.Based on the above research,the edible quality of white soy sauce was further analyzed.The results showed that the content of amino acid nitrogen,reducing sugar,total sugar,total nitrogen,soluble salt-free intangible substance in white soy sauce fermented by extruded wheat flour was higher than that of traditional cooking wheat flour.The free amino acids in white soy sauce were investigated,and the results showed that compared with white soy sauce fermented by traditional cooking wheat flour,the total amino acid content of white soy sauce fermented by extruded wheat flour was up to 3278.99 mg/100m L.The content of umami taste amino acid and sweet taste amino acid significantly improved,and these taste amino acids endowed white soy sauce good flavor.Moreover,the content of bitter taste amino acid decreased obviously.The whole taste and fragrance of two kinds of white soy sauce were analyzed using Electronic Tongue and Electronic Nose,and the results showed that the whole taste and fragrance of white soy sauce obtained by two treatments were similar.Headspace solid-phase microextraction and GC-MS were used to analyze volatile flavor compounds in white soy sauce.It was concluded that alcohols,esters,acids and aldehydes were the main compounds of white soy sauce.83kinds of compounds were detected in white soy sauce fermented by extruded wheat flour,including 15 kinds of alcohols,18 kinds of aldehyde,11 kinds of ketone,5 kinds of acids,and20 kinds of esters,2 Kinds of phenol,7 kinds of pyrazole,5 kinds of furan.While 68 kinds of compounds were detected in white soy sauce fermented by traditional cooking wheat flour,including 14 kinds of alcohols,16 kinds of aldehyde,9 kinds of ketone,6 kinds of acid,15kinds of esters,1 kind of phenol,4 kinds of pyrazole,and 3 kinds of furan.These flavor compounds could be divided into 14 categories according to their aroma characteristics,among of which the fruity,green,charred,floral and malt aroma constituted were the main body of white soy sauce.Although the volatile compounds of these two kinds of white soy sauce were different in type and content,the flavor components of the main body were similar.