Study On Flaxseed Steamed Bread And Its Characteristics

Flaxseed,as the seed of herbaceous flax,is rich in ?-linolenic acid,high-quality protein,dietary fiber,lignans and a variety of active substances.It has the health functions such as regulating lipid metabolism,reducing blood glucose and lipid,improving atherosclerosis,cardiovascular and cerebrovascular diseases and preventing cancer and has become a popular health food in Europe and the United States.It has gradually become an important source of daily diet.At present,some progress has been made in the research of flaxseed in China,especially in bread and biscuit.However,there are few reports about traditional staple food.In order to evaluate the effect of flaxseed powder on the quality of steamed bread,the wheat flour and flaxseed powder had been selected as the main experimental materials to make dough and steamed bread.The physicochemical properties,antioxidant activities,processing characteristics and shelf life of flaxseed powder,dough and its steamed bread were analyzed.The main conclusions are as follows:(1)The contents of crude protein,crude fat,crude fiber and trace elements in flaxseed powder were significantly higher than those in wheat flour.In terms of fatty acid composition,linolenic acid and oleic acid are the main fatty acids in flaxseed,while linoleic acid and palmitic acid are the main fatty acids in wheat flour.The addition of flaxseed reduced the brightness,the final viscosity,breakdown and setback of wheat flour.The antioxidant capacity of flaxseed in different forms was studied.The results showed that defatted flaxseed powder had relatively strong antioxidant activity.(2)The effects of flaxseed powder content,moisture content,wake-up time and yeast content on the quality of steamed bread were studied.The results showed that all of these factors had significant effects on the quality of steamed bread.The optimal processing conditions of steamed bread were as follows: flaxseed powder content was 12%,water added was 60%,proof time was 90 min and yeast content was 0.6%.(3)The addition of flaxseed powder had a certain effect on the thermomechanical properties of mixed dough.The results showed that when the addition of flaxseed powder was less than 10%,the thermomechanical properties of the mixed dough were better.According to the tensile properties,the resistance to extension and extensibility of the mixed dough showed a tendency to decrease with the increase of flaxseed powder addition.The microstructure of the mixed dough showed that the continuity of gluten network structure in the mixed dough was destroyed with the increase of flaxseed powder.When the addition of flaxseed powder was 12%,the gluten network structure of dough was obviously destroyed,and the starch granules of wheat fall off obviously.(4)The addition of flaxseed powder reduced the specific volume,darkened the color and decreased the brightness of steamed bread,which had adverse effects on the internal structure and elasticity of the product,but improved its the flavor and chewiness,and endowed the steamed bread with unique flaxseed flavor.With the increase of the proportion of flaxseed powder,the hardness and chewiness of steamed bread increased significantly,the elasticity and cohesion decreased.The total content of 17 kinds of amino acids in the steamed bread was 12.38% ? 22.76%.The higher content of amino acids were glutamic acid and proline,and the lower were cysteine and methionine.A total of 72 volatile compounds were detected in steamed bread.There were 21 kinds of volatile compounds in the steamed bread,among which the content of alcohols was higher.The antioxidant capacity of steamed bread was significantly enhanced with the increase of flaxseed powder,and the digestibility of steamed bread was slow after adding flaxseed powder.In addition,the induction period was shortened.