Effects Of Wheat A-,B-Type Starch On Dough Characteristics And Steamed Bread Quality

At present,most of the domestic and foreign research on wheat A-and B-type starch granules is to study their formation mechanism and physical and chemical properties,as well as the impact on the quality of bread and noodles.Wheat endosperm starch granules are separately extracted and purified into A-,B-type starch granules to study its impact on the quality of steamed bread is rarely reported in China.In this project,the three components of A-,B-type starch,protein and water-soluble matter with higher purity are separated from the raw material of wheat flour by the method of separation and reorganization.Reorganize the separated components according to the dry basis ratio of the total starch,crude protein,and Water-soluble substance components in the original powder,and adjust the A-type and B-type starch weight ratio of when the total starch ratio is unchanged.The specific scheme is:the proportion of A-and B-type starch in the total starch changes in a gradient,and the weight percentage of small-sized B-type starch in the reconstituted flour 1-12 in the total starch is 0%,5%,10%,15%,20%,25%,30%,35%,40%,45%,50%,60%.Using the original flour as a control,through the exploration of the basic quality of the reconstituted flour,the rheological properties of the dough,the quality of the steamed bread,and the characteristics of starch,in order to further study the role of starch in the dough and flour products and for the improvement of wheat quality and food processing provides direction and theoretical reference.The results are as follows:1.The particle shape,particle size distribution,crystallinity,solubility and swelling potential,gelatinization characteristics and basic quality indicators of the recombinant powder were measured and analyzed on the separated A-and B-type starch.The results showed that:A-type starch particles are disc-shaped or lens-shaped,with the particle size of4.5?m-49.62?m,and the peak particle size is 20.05?m;B-type particles starch are spherical or polygonal,with the particle size is mostly less than 10?m,and the peak particle size is 1.08?m,5.17?m,31.44?m,respectively.A-type starch crystallinity is greater than B-type,A-type starch solubility,gelatinization temperature,ash content,crude protein content are significantly less than B-type starch,while swelling potential,viscosity index,decay value,retrogradation value,crude starch content,amylose content,amylopectin content,amylose ratio are significantly greater than B-type starch.The crude protein content and ash content of the recombinant flour showed an upward trend,while the wet gluten content,gluten index and falling value showed a small-scale fluctuation trend.2.Determination and analysis of the dough rheological properties,dough moisture distribution,and dough microstructure for reconstituted flour.The results showed that:As the proportion of B-type starch in the total starch increased,the water absorption rate of the reconstituted flour increased significantly;the stability time of reconstituted flour dough showed a downward trend;there was no obvious change law in the weakening degree;the powder quality index of recombinant flour 1-9?B-type accounted for 0%-40%?showed an upward trend as a whole.During the proofing period from 45 min to 90 min to 135 min,the stretching area of the recombinant flour showed a fluctuating trend;when the proofing time is 45 min,the tensile resistance,the maximum tensile resistance and the stretching ratio of the recombinant flour are all less than 90 min and 135 min,and the extension of the recombinant flour showed a downward trend.The P value of the reconstituted powder showed a gradual upward trend;the L value and G value,on the contrary,showed a downward trend;there is no obvious change law of W value;the P/L value showed an upward trend;the Ie value showed a gradual downward trend,and the Ie values of the reorganized flour 7-12 were all 0.The change trends of the recombined flour Hm value,h value,H'm value,V_?,and V_?are basically the same,showing three segments of"rising first and then decreasing"trend,and the overall Hm value and h value show a downward trend;there is a completely opposite trend between R and V_?and V_?;Tx has no clear change law,showing volatility.The proportion of combined water and free water of the reconstituted flour showed a three-segment"first decline and then rising"trend;semi-bound water showed the opposite trend.When the proportion of B-type starch is in the range of25%-40%,the internal network structure of the dough presents a compact and continuous state.3.The height-diameter ratio,specific volume,color,sensory evaluation and texture characteristics of the steamed bread made from the reconstituted flour were analyzed.The results showed that:The specific volume of the steamed bread showed a downward trend as the proportion of B-type starch in the total starch increased,and the height-to-diameter ratio showed a trend of rising first and then tending to be gentle.The steamed bread core color value L*showed a downward trend,and the a*and b*values showed an upward trend.When the proportion of B-type starch in the total starch is 15%-25%,the steamed bread with a total score close to the original flour can be obtained,but the internal structure is worse than the original flour;when the proportion of B-type starch is 30%-35%,the total score of the reconstructed flour bread is higher than that of the original flour.The hardness and chewability of steamed bread showed a trend of"first decline,then rise and then fall";adhesion showed an upward trend;the elasticity and cohesion showed a small range of volatility changes,and the resilience showed a two-stage"first decline and then rise"trend.4.The broken starch content,thermodynamic properties,gelatinization characteristics,rheological properties,crystallization characteristics,and molecular structure of total starch in the reconstituted flour were measured and analyzed.The results showed that:As the proportion of B-type starch in total starch increased,the damage Starch content showed an upward trend.The gelatinization temperature of starch showed an upward trend;the viscosity index showed a downward trend;the attenuation value and the retrogradation value have a small range of volatility,and the overall trend is a downward trend.Both T₀ and T_C of starch showed a rising trend within a small range;T_P showed a slight upward trend;the overall change of?H is more regular,with B-type starch accounting for 0%-10%,showing a volatile change,and B-type starch accounting for 15%-60%,showing a downward trend.The change trend of T₀,T_C,T_P is in accordance with the change trend of the gelatinization temperature index in the measurement results of starch gelatinization characteristics.In the determination of starch rheological properties,the modulus basically increases with the increase of frequency;in the test frequency range,G'of all test samples is always greater than G'',and the tan?value is less than 1.The crystallinity of starch showed a gradual downward trend.There is no obvious change law in the infrared absorption spectrum of starch.The ratio of 1047/1022 cm-1 fluctuates and the overall trend is downward.