Study On Fermented Soy Sauce With Extruding Peanut Meal As Pretreatment Of Raw Materials

Extrusion technology was applied pretreatment method in soy sauce fermentation with peanut meal as the main raw material,which facilitated the volume of mixture expansion and the loose structure.Consequently,this pretreatment method contributes to the flavour and total nitrogen utilization of final product by facilitating microbial growth during koji-making and fermentation.The main purpose of this study is to optimize the extrusion parameters of peanut meal for brewing soy sauce,the corresponding koji-making parameters and fermentation parameters and analyze the volatile flavor compounds and amino acids in peanut meal soy sauce,which will provide further technical support for application of extrusion technology in soy sauce.The following conclusions are obtained through experiments:(1)Optimize the extrusion parameters of peanut meal.An experimental rotational central composite design was used to optimize the extrusion parameters of peanut meal with protein digestibility as the main research indicator and water-soluble protein content,starch gelatinization rate and extrusion rate as the reference indecators.The effects of barrel temperature,screw speed,flour content and water content on each indicator during extrusion were evaluated using the response surface methodology.Under optimal conditions(96.0 °C barrel temperature,200.0 r/min screw speed,19.0% flour content and 22.0% water content),the protein digestibility reached 87.13%,which was 20.66% higher than that of the traditional cooking process,and the water-soluble protein content reached 13.47%,the starch gelatinization rate reached 87.38% and the extrusion rate reached 267%.(2)Optimize the koji-making parameters of expanded peanut meal.An experimental rotational central composite design was used to optimize the koji-making parameters of koji with protease activity as the main research indicator and amylase activity and glucoamylase activity as the reference indecators.The effects of koji-making temperature,bran content,water content and Koji time on each indicator during koji-making were evaluated using the response surface methodology.Under optimal conditions(33.0 °C koji-making temperature,30.0% bran content,105.0% water content and 42.0 h Koji time),theprotease activity reached 2327 U/g,and the amylase activity was 547 U/g and glucoamylase activity was 395U/g.(3)Optimize the fermentation parameters of expanded peanut meal.An experimental rotational central composite design was used to optimize the fermentation parameters of soy sauce with total nitrogen utilization as the main research indicator and amino acid nitrogencontent,nitrogen content,acid content,soluble salt-free solid content and red index as the reference indecators.The effects of brine content,fermentation temperature and fermentation time on each indicator during fermentation were evaluated using the response surface methodology.Under optimal conditions(85.0% brine content,45.0 °C fermentation temperature and 14.0 d fermentation time),the total nitrogen utilization reached 89.87%,the amino acid nitrogen content reached 1.03 g/100 m L,the nitrogen content was 1.63 g/100 m L,the acid content 1.44 g/m L,the soluble salt-free solid content was 16.16 g/100 m and the red index was 2.59.(4)Analysis of flavor components and amino acid in peanut meal soy sauce.HS-SPME and GC-MS were used to investigate the volatile compounds of extruded peanut meal soy sauce(EPS)and cooked contrast soy sauce(CCS).Amino acid analyser(L-8900 System)equipped with a visible detector used to analysis the amino acid of the two kinds of soy sauce.The results showed that 57 types of volatile compounds were identified in EPS and 35 types were identified in CCS.There were three types of pyrazines and six types of alcohols detected in EPS were greater than those found in CCS.17 kinds of amino acids were detected in the two kinds of soy sauce,the total content of amino acids in EPS was 4659 mg/100 m L and the total content of amino acids in CCS was 3718 mg/100 m L.The total content amino acids and 12 types of amino acids in soy sauce made from EPS were significantly higher than found in CCS.