Effect Of Wheat Flour Yield And Polished-graded Ratio On The Quality And Flavor Of Wheat Steamed Bread

High flour yield or polished-graded milling wheat flour contain more cortex and wheat germ, enrich nutrients. High flour yield and polished-graded milling wheat flour have characteristics of their own components, which contain more fat and soluble sugar. Steamed bread made by this flour have important influence on its quality and flavor. Therefore it has important signification to deeply understand the effect of wheat flour yield and polished-graded ratio on the quality and flavor of wheat steamed bread. This paper systematic studies the effect of wheat flour yield and polished-graded ratio on the wheat flour physical and chemical indexes, dough rheological properties, steamed bread quality and flavor, providing theoretical basis for quality control. The results were as follow:1. With raising the flour yield, wheat flour water absorption and development time and softness increased, stability time and farinograph quality number decreased., paste property decreased. High yield wheat flour had normal gas deliverability, higher gas permeability, limited fermentation ability. With raising the wheat polished graded ratio, stability time increased and softness decreased, wheat paste property increased. Polished-graded milling wheat flour dough have limited fermentation ability, normal gas deliverability, good fermentation tolerance, higher gas permeability.2. Volatile compound in wheat flour have alcohols, aldehydes, furans, aromatic and hydrocarbons, etc. Characteristic flavor compounds are mainly alcohols and aldehydes in wheat flour. With raising the flour yield, content of alcohols and aldehydes decreased, content of 2-pentylfuran increased. Kinds of hydrocarbons increased. For polished-graded milling process, content of 1-hexanol, hexanal, nonanal, naphthalene, styrene, 2-naphthalene in commomly milled wheat flour(CWF) are significantly higher than polished-graded milling wheat flour(PWF). Content of 2-pentyl-furan, ethanol, hexanal, benzaldehyde have no significant correlation to fatty acid composition.3. The appearance shape, color, structure, elasticity, stick teeth, flavor of steamed bread have no significant difference when wheat flour is 35%~60%. The hardness of steamed bread increased, springiness, resilience decreased, internal structure become rough, sensory scores significant decreased with raising the flour yield when the flour yield >60%. The hardness of PWF steamed bread is significantly higher than CWF steamed bread, the springiness, resilience of PWF steamed bread is significantly lower than CWF steamed bread. Sensory scores contain specific volume, appearance, color, structure, elasticitity of PWF steamed bread are significantly lower than CWF steamed bread.4. The results of electric nose experiment show that significant difference of volatile components was found in low flour yield and high flour yield wheat flour. CWF steamed bread and PWF wheat steamed bread have significant difference. Significant difference of volatile components was found in low polished-graded and high polished-graded wheat bread. The main volatile components in steamed bread are alcohols, aldehydes and furans. There are mang kinds of hydrocarbons that have no characteristic flavor due to the high threshold. Alcohols included ethanol, 3-methyl-1-butanol, 1-hexanol, 2-methyl-1-propanol, etc. The content of ethanol is the highest in steamed bread volatile components. Aldehydes included hexanal, heptanal, octanal, decanal, etc. The main of Furans was 2-pentyl furan. The article not detected a typical product of non-enzymatic Maillard reaction, such as pyrazines. The content of mainly volatile compounds in wheat flour bread had no significant positive correlation to fatty acid composition..