Mechanism Of Wheat Malt Modifying Wheat Dough And Its Effect On Short Biscuits Quality

Germination accumulates a large amount of hydrolases which beak down nutrients such as starch,protein and cellulose in wheat.These changes alter physicochemical composition,nutritional value,and food processing characteristics of wheat.Based on brewing malt processing,wheat malts with different degree of germination were prepared.The characteristic of whole malted wheat flours(WWMF)was investigated,including physichemical composition,processing characteristics and antioxidant capacity.The effects of WWMF on physicochemical and antioxidant capacity of short biscuits were studied.Meanwhile the influences of adding skinless wheat malt flour(SWMF)on wheat dough properties and physicochemical and sensory properties of short biscuits were also explored.The main results are as follows:(1)With the extension of germination period,starch content in malted wheat gradually decreased while dietary fiber content increased significantly.And the contents of protein and ash in WWMF increased obviously at the later stage of germination.The water solubility index and swelling capacity of WWMF were significantly improved.However,the water absorption,oil absorption and emulsion capacities,emulsion stability,foam expansion,and foam stability were deteriorated.The rebound of starch disappeared and the peak viscosity of gelatinization decreased significantly after the first germination day.The starch in the malt belongs to A,the 2 θ rotation angle gradually decreases at 15.5°,19.7°and 23.4° and the crystallinity decreased during germination.(2)With the increase of SWMF addition,the development and stability times,resistance to extension,extensibility,and energy of wheat dough were significantly reduced.At the same time,the gluten strength was also reduced significantly.When the amount of SWMF was more than 10%,the tensile test could not be completed due to the excessive fluidity and viscosity of the dough.When the amount of SWMF was 2.5 ～ 5.0%,the gluten strength of the dough decreased and the plasticity of the dough increased.When the amount of SWMF was 1%,the rebound of dough starch was reduced by 84.21%,indicating that the addition of SWMF could improve anti-aging performance of wheat dough and its products.In addition,the storage modulus,loss modulus,and water freedom of the dough significantly reduced.When the SWMF addition amount was more than 2.5%,the gluten sheet structure appearred,and the gluten structure was severely damaged.(3)With the increase of SWMF,the hardness of short biscuits decreased,while the crispness and ductility increased.For short biscuits added by SWMF,the redness increased,brightness decreased,and the flavor substances improved.When SWMF amount was no more than 5%,the short biscuits tasted crispy and gained high sensory score.However when SWMF addition reached to 10%,the sensory,plasticity and chewiness of the short biscuits became worse.WWMF could significantly improve the crispness and decrease the hardness of the short biscuits.Furthermore,the texture and formability of the short biscuits became better when wheat malt germinated at 2 ～ 5 days was used.(4)During the germination progress,,the extractable polyphenols(EPP)and hydrolysable polyphenols(HPP)content in WWMF increased significantly,and the non-extractable proanthocyanidins(NEPA)increased at first and then decreased.However,the antioxidant capacity of EPP,HPP and NEPA in WWMF was significantly enhanced.In incorported with WWMF short biscuits,HPP increased significantly with the increase of germination time;the EPP and NEPA content in the short biscuits increased first and then decreased.When the WWMF with the germination time at 2 ～ 4 day was added,the content of EPP and NEPA in short biscuits was higher.