Modification Of Buckwheat Flour By Extruder And Effects On Noodle Quality

Buckwheat is important food resource.Owing to its food chemistry or nutritional properties,buckwheat-based food is considered as highly functional food by eastern countries.Convenient as well as high-addition-buckwheat food can guide people to consume buckwheat-based food and restrict part of chronic diseases.In order to determine the influences of modified buckwheat flour by extrusion on quality of buckwheat noodles,and to explain how modified buckwheat flour changes the noodles quality to further provide theoretical guidance to the produce of buckwheat noodles,through response surface experiment,buckwheat flour,the raw material,was extruded using a twin-screw extruder.Using ANOVA analysis,correlation analysis,and regression analysis,etc.obtains the significant element that might affect quality properties of buckwheat noodles.Based on single-factor experiment,sensory evaluation,TPA,low-field nuclear magnetic resonance(LF-NMR),scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FTIR)microscopy were used to check the cooking,texture,sensory properties and the interaction among water,starch(native and extruded)and gluten through changes of water status/distribution and inner-structure so as to try to explain the changes of cooking,texture and sensory properties of buckwheat noodles.The main conclusions are as follows:(1)Extrusion could be used to modify the physico-chemical properties such as dynamic viscosity,water absorption and water solution and so on.Moisture content,barrel temperature and screw speed is the most important for dynamic viscosity,water absorption and water solution,respectively.Dynamic viscosity is important factor to noodle quality.(2)Extruded buckwheat flour with higher dynamic viscosity(>7.37 Pa·s)and low particle size(<75μm)were helpful for fresh noodles to lower breakage ratio,improve texture as well as sensory quality with more buckwheat flour(50%).As for cooking loss,better cooking method is important.(3)Extruded buckwheat flour with higher dynamic viscosity(>7.37 Pa·s)and medium particle size(106~125μm)were helpful for dried noodles to lower breakage ratio,improve texture as well as sensory quality with more buckwheat flour(50%).Better cooking method is important to lower cooking loss.(4)Starch gelatinization,rather than degradation,mainly contributed to the change of water status/distribution.MBFNs indicated weaker combination and more tightly bound water that is important to enhance the formation and development of gluten network.(5)Glue-water model preliminary give an explanation to the formation of gluten network and changes of noodle qualities.High-dynamic-viscosity modified buckwheat flour,like glue in terms of function,could paste starch,protein and other compounds together to form network structure like gluten network,contributing to denser internal structure and more uniform and continuous gluten network.This is important for the modification of cooking and eating quality of noodles.Low-dynamic-viscosity modified buckwheat flour diluted gluten and then weakened gluten network.As for partical size,it has no effect on water status/distribution,probably having link between noodle quality and compound variety owing to screening.