Study On The Pre-mixed Bread Flour With A High Content Of Oat Flour

Bread is one of the most important staple foods in the world.However,bread made from refined wheat cannot satisfy people’s daily nutrition intake,which lacks dietary fiber,mineral and bioactive substances.With more attention being attached to the healthy diet nowsdays,oats are widely used in bread production due to their high nutritional value.However,oats lack glutenin and gliadin which are necessary for the formation of gluten.In addition,the high water absorption and high viscosity of oat brans have an adverse effect on the structure of gluten.Both limit the amount of oat flour in bread.At present,the proportion of oat flour in most oat bread at home is less than 30%of the total grain flour.In order to improve the quality of oat bread with a high oat flour content,we selected oat flour as the research object and the content of oat flour in oat bread flour was 50%based on the grain flour,and develop the pre-mixed oat bread flour with stable performance during storage,The main research contents were as follows:First,used as a raw material,the oat flour was treated with roasting,atmospheric steaming,high-pressure steaming and microwave to improve the processing adaptability and storage stability of the oat flour.it was found that treated with atmospheric steaming,high-pressure steaming and microwave,the lipase inactivation rate of oat flour was over 80%.The gelatinization degree,water holding capacity,solubility and swelling power increased significantly.The crystallize decreased significantly.The pasting properties were changed significantly.The oat bread made with atmospheric steamed oat flour had the best quality.Compared with the control,the specific volume of the bread was decreased by 12.9%and the hardness was decreased by 57.6%.High-pressure steaming and microwave treatment increase the water holding capacity of the oat flour to 1.08 g/g and 1.14 g/g which increased by 83.1%and 93.2%respectively compared to the control.When the content of oat flour in oat bread flour was 50%based on the grain flour,it made the dough water absorption over 100%and the bread collapsed rapidly within 10 minutes after baking.Secondly,In order to weaken the adverse effects ofβ-glucan on the bread quality and gluten structure due to its high water absorption and high viscosity,the effect ofβ-glucanase on properties of dough,gluten proteins and bread was investigated.Results showed thatβ-glucanase had great potential to be an effective improver.Compared to the control,the addition ofβ-glucanase developed dough’s processing adaptability because of significantly reduction in water absorption,storage modulus（G’）and loss modulus（G’’）.The specific volume of oat bread increased from 4.04 m L/g to 4.85 m L/g and the hardness of the bread crumb decreased from 261 g to 159 g.The cell density and porosity of breadcrumb increased significantly.Moreover,after the hydrolysis ofβ-glucan byβ-glucanase,the average molecular weight ofβ-glucan in oat dough decreased from 350 k Da to 62 k Da.The non-covalent interaction between gluten proteins was strengthened and the degree of hydration and aggregation of gluten increase in the presence ofβ-glucanase,which was associated with increased content of SDS-extractable protein,increased proportion ofβ-sheets accompanied by the decreased proportion of random coils andβ-turns in the secondary structure and reduced surface hydrophobicity.Finally,the Plackett-Burman design and fractional factorial design were used to screen and optimize the bread improvers includingβ-glucanase,sodium stearoyl lactylate（SSL）,diacetyl tartaric acid ester of mono（di）glycerides（DATEM）,glucose oxidase（GOX）,ascorbic acid（AH₂）,monoglycerides and guar gum to improve the quality of pre-mixed oat bread flour.Results showed that the use ofβ-glucanase with SSL or guar gum could significantly increase the specific volume and softness of bread.The combination of SSL andβ-glucanase could make the bread crumb fine and shiny.The combination ofβ-glucanase,SSL and guar gum could make the oat bread crust smooth and significantly delay the aging speed of oat bread during storage.After being optimized,the composite improver addition level were SSL 0.25%,β-glucanase 6 U/g and guar gum 0.25%.