Study On The Preparation Technology Of Flavor Base Material From Wheat

Wheat is the second largest food crop in China,and it is also an important raw material for the production of condiments/flavoring by fermentation.Gluten owns a high content of glutamic acid,and it is rich in flavor peptide sequence.So it is an excellent ingredient for making seasonings and flavoring bases.And using wheat flour and gluten as raw materials to develop wheat-source flavor base materials,can provide high-grade flavor base materials for food industry,and improve the quality of product and technical level of related industries.In this study,wheat flour and gluten were used as raw materials to study the technology of Solid state koji making-liquid enzymatic hydrolysis.The results showed that among three pretreatment methods of roasting,extrusion and extrusion,extrusion had the best effect on the preparation of yeast,the activity of protease and amylase were 634.47 U/g and 75.89 U/g,respectively.And the reducing sugar conversion,hydrolysis degree and protein recovery rate reached 58.35%,52.75%and 79.46%,respectively.Among the effects of enzymatic hydrolysis of various exogenous enzymes on wheat koji,glutaminase played the most prominent role,and the optimal adding amount of the enzyme was 0.3%.The quality of enzymatic hydrolysate was the best after enzymatic hydrolysis for 48 h at natural p H value and solid-liquid ratio 1:3.At this time,the reducing sugar conversion rate,degree of hydrolysis,protein recovery rate and glutamate content of enzymatic hydrolysate were63.73%,56.99%,80.22%and 1.925 g/100m L,respectively.Meanwhile,the content of glutamate was increased by 51.22%compared with direct hydrolysis.And the ratio of fresh and sweet amino acids reached 57.08%.The general flask shaking process for glutamic acid production by Corynebacterium glutamicum fermentation was optimized.The results showed that when the seed culture medium was cultured for 11 h with 6%inoculation amount,5%glucose,0.1%Na₂HPO₄,0.1%KCl,0.04%Mg SO₄,and 2 ppm ferrous ion and manganese ion,the yield of glutamate was the highest which reached 2%,and the conversion rate of sugar and acid was 40%.The above indexes in the enzymatic hydrolysate of wheat koji were close to the nutrient requirements of the medium,but the content of biotin was 23.18?g/L,which was too high to meet the requirement of glutamate fermentation.The effects of different dosage of wheat koji hydrolysate on the seed culture and acid production of Corynebacterium glutamate were studied.The results showed that the OD value of the seed liquid added with 25%and 50%hydrolysate was 0.58 and 0.63,respectively,and the glucose consumption was 1.83 g/100m L and 2.25 g/100m L,respectively,which were close to those of the seed liquid cultured using corn pulp.Comparing with corn pulp,the 50%hydrolysate was better for seed culture.When the adding amount of enzymatic hydrolysate of wheat koji was 0-5%,the OD value of fermentation liquid/broth increased with the adding amount.When the adding amount was 1%,the content of glutamate in the fermentation broth reached 2%,while the adding amount was more than 1%,the content of glutamate in the fermentation broth decreased rapidly.The effect of Corynebacterium glutamate fermentation on the flavor of wheat koji hydrolysate was studied.The results showed that the fermentation of Corynebacterium glutamate could significantly improve the sensory quality of wheat koji hydrolysate,and the fermentation broth owned unique flavor,fresh and thick taste.The optimal sensory quality was obtained when the inoculation amount was 6%and the fermentation temperature was32?for 3 days.At this moment,the contents of succinate and glutamic acid in the fermentation broth were increased by 133.2%and 15.0%,respectively.The content of peptide with molecular weight less than 300 Da accounted for 86.86%.GC-MS analysis showed that the contents of tetramethylpyrazine,phenylethanol and 3-hydroxy-2-butanone with good flavor increased from 5.209?g/L,5.716?g/L and 10.164?g/L to 1539.286?g/L,556.298?g/L and 290.925?g/L,respectively,increasing by 295,97 and 28 times,respectively.And they accounted for 70.3%of the total aroma components,which indicated that the fermentation broth had good applications of natural flavor base materials.