| Oat has high nutritional value and is widely distributed.Its yield and planting area rank the sixth among cereal crops.However,at present,the utilization of oat resources is unreasonable and inadequate.Most oat resources are used as animal feed or sold directly by extrusion into cereal,lacking of intensive processing and high value utilization.Under the background of "Healthy China 2030",people pay more and more attention to the structure and application of functional dietary fiber.Oats are rich in dietary fiber,and β-glucan is the main active substance.Oats contain rich dietary fiber,β-glucan is the main active substance,has good functional properties and physiological activities.In 2014,the National Health and Family Planning Commission officially approved oat beta-glucan as a new food raw material.Therefore,the application of β-glucan from oats to bread products is one of the ways to realize its high-value application.At present,commercially available bread products are often directly added in the form of oat granules,oatmeal or oatmeal flour,but some consumers find it difficult to accept the grain feeling and taste of oatmeal,and there will be dry choke problem when eating.The addition of oat β-glucan not only does not affect the taste of bread,but also endowing it with better functional activity.In view of the above problems,this topic carries out the following research:(1)Oat β-glucan(OB-20)was prepared by water extraction and alcohol precipitation method with naked oat as raw material.Compared with commercially available oat β-glucan(OB-Ca),the water,ash,total sugar content,total phenol content,uronic acid content,protein content,glucan content,reducing sugar content and other components of both were analyzed.The rheological properties,foaming properties and foaming stability of two oat β-glucan were measured simultaneously.(2)By infrared spectroscopy(FTIR),ultraviolet spectroscopy(UV),scanning electron microscopy(SEM),X-ray diffraction(XRD)and gel permeation chromatography(GPC),the structural characteristics of two oat β-glucans were studied,and the antioxidant capacity and α-amylase inhibitory activities of the two oat β-glucans were determined,which laid a foundation for the development of bread products in the future.(3)With oat β-glucan as additive,a functional oat β-glucan bread with high consumer tolerance,palatability and good quality was developed.Based on the single factor response surface experiment,the optimal process conditions of adding commercially available oat β-glucan bread(WB with OB-Ca)and the preparation of oat β-glucan bread(WB with OB-20)were optimized,and the effects of different levels of oat β-glucan on the texture of bread were determined under the optimal process conditions.The optimal amount of β-glucan was determined,and the moisture content,fat content,total starch content,specific volume,color and storage stability of bread were compared and analyzed.The results are as follows:(1)OBG-20 moisture content,uronic acid content and reducing sugar content were 7.81%±0.05%,2.64%±0.04% and 7.45%±0.23%,respectively.The water content of OBG-CA was 9.31%±0.14%,uronic acid content was 10.28%±0.05% and reducing sugar content was 20.48%±0.11%.The total phenol and protein contents of both were lower.The content of β-glucan in OB-20 was 1.20 times that of Ob-Ca.The steadystate rheological tests showed that the two oat β-glucans showed shear dilution phenomenon of pseudoplastic fluid in the concentration range of 2 mg/m L to 8 mg/m L.The apparent viscosity of OB-20 was significantly dependent on the concentration,while the apparent viscosity of Ob-Ca was little affected by the concentration,suggesting that some starch might exist in the fluid.The effervescence and stability of OB-20 are better than that of OB-Ca.When the concentration is 4%(w/w),the effervescence and stability of OB-20 are 1.39 times and 1.74 times of the latter,respectively.(2)FTIR showed that both oat β-glucans had carbohydrate absorption peaks,and glucose molecules were connected by β-glucoside bonds.SEM observed that the apparent morphology of OB-20 was flake,spheroid and filamentous,while Ob-Ca showed concave spheroid,which was probably formed by spray drying.The results of XRD indicate that there may be some impurities such as starch in OB-Ca,forming more regular crystal regions,while the dispersion peak of OB-20 is amorphous.The molecular weight distribution determined by GPC showed that OBG-20 had good uniformity and high purity.α-amylase activity inhibition test demonstrated that oat β-glucan could inhibit starch absorption,which proved that β-glucan had potential hypoglycemic effect.In addition,the antioxidant capacity of OB-20 was better than that of the same concentration of OB-Ca.(3)The single factor experiment was carried out with the addition levels of yeast,sugar and salt.The Box-Behnken central group method was used to optimize the process conditions of bread,and the texture parameters were used as evaluation indexes to obtain the optimal formula.The optimal addition levels of OB-20 and OB-Ca were determined to be 0.17 g/20 g bread powder.Compared with the quality characteristics and storage stability of ordinary bread(WB),WB with OB-CA and WB with OB-20,it was found that the addition of oat β-glucan,especially WB with OB-20,could significantly increase the specific volume of bread and reduce the hardness,chewing and stickiness.Increase the storage stability,prolong the preservation time of bread.The oat-based β-glucan bread developed in this study is soft,delicious and of good quality.It can not only be used as a dietary supplement for daily intake of oat-based β-glucan,but also has certain hypoglycemic effect,which enrichis the nutritional value and taste of bread,improves the utilization degree of high value of oat-based and increases the types of oat-based deep processing products.Laying the foundation for the development of functional bread. |
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