The Effects Of Gaseous Ozone On The Quality Characteristics Of Tartary Buckwheat Flour And Fresh Tartary Buckwheat Noodles Were Analyzed Based On Starch

Noodle,one of the major staple foods for Asian people,have gained increasing popularity due to its convenience,nutritional value and palatability.With the new trends in consumer demands for functional noodle products,fresh Tartary buckwheat noodles（FBN）,a ’drug homologous food’,have caught more and more attention.FBN are more susceptible to spoilage and have a short shelf-life due to the high water content（30%～35%）,abundant nutritional components,and high initial microbial count.Therefore,it is necessary to extend the shelf-life of FBN by taking effective measures.Ozone,a strong oxidant,has been used in many areas,such as water treatment,food processing and various environmental applications,and also has been used to treat staple cereals and flour to modify their processing characteristics which is generally recognized as safe.In this study,the microbial count,and physicochemical properties of buckwheat-based composite flour treated with gaseous ozone and the quality characteristics of fresh buckwheat noodles made from ozonetreated Tartary buckwheat-based composite flour（OTBF）were investigated.Furthermore,the structural,physiochemical and digestive properties of oxidized Tartary buckwheat starch（OTBS）were discussed,being possible to provide some theoretical guidance for the application of ozone treatment in buckwheat products from the perspective of buckwheat starch.The results were as follows:（1）Compared with the native Tartary buckwheat-based composite flour（TBF）,gaseous ozone treatment（at the flow of 2.4 g/h for 0,2.5,7.5 and 15 min）reduced the microbial total plate count and increased the dough water absorption,dough development time,dough stability time and CIEL*value of the OTBF.Meanwhile,the peak viscosity,trough viscosity,final viscosity,setback value,swelling capacity and solubility of the flour were increased by ozone treatment for 2.5 min while OTBF-7.5 and OTBF-15 possessed the decreased index described above,which still higher than those of the control group.（2）Compared with the FBN made from native TBF,the FBN made from OTBF has higher hardness and springiness,and lower adhesiveness.During the whole storage period,the increased TPC and decreased L*were delayed and the shelf-life of FBN was prolonged by ozone treatment What’s more,shelf-life of fresh noodles made from OTBF-15 was extended to 96 h and the sensory characteristics were maintained,but the cooking loss of FBN-15 increased after being treated by gaseous ozone.（3）Compared with the native Tartary buckwheat starch（TBS）,a progressively reduced smoothness and integrity as well as lessened area of FITC fluorescent coloration under the gradual enhanced processing conditions（2.5,7.5,15 and 20 min at flow of 2.4 g/h）were observed,which indicated that the morphology of Tartary buckwheat starch particles was changed by gaseous ozone treatment.The ordered structure and double helixes structure were enhanced by the intermolecular oxidation cross-linking in OTBS for 2.5 and 7.5 min（OTBS-2.5 and OTBS-7.5）,forming starch suspension with relatively high viscosity while an opposite tendency was observed in OTBS for 15 and 20 min（OTBS-15 and OTBS-20）due to the degradation reaction with the increased contents of amylose and carboxyl and carbonyl groups,and decreased breakdown viscosity,setback viscosity,swelling power and solubility and crystalline region.（4）In terms of the thermal,rheological and gel properties,considering the gelatinization enthalpy（AH）and the viscoelasticity of newly formed starch gel of OTBS at short-medium time were higher than those of native starch,as well as the contents of resistant starch in moderately oxidized starch（OTBS-2.5 and OTBS-7.5）was relatively high.On the other hand,the gelatinization enthalpy（ΔH）and the viscoelasticity of newly formed starch gel of OTBS-15 and OTBS-20 as well as the content of resistant starch decreased,while the contents of rapidly digestible starch and slowly digestible starch increased.Finally,based on the analyses of the correlation,the changes of starch granules in surface flatness,integrity,laminated structure,carbonyl and carboxyl and amylose/amylopectin contents caused by gaseous ozone treatment,will further lead to the changes of the physicochemical properties such as viscosity,water absorption,swelling power and solubility and gelatinization enthalpy of OTBS,which will eventually be reflected in the hardness,elasticity,cohesiveness,chewiness and cooking loss and other quality characteristics of FBN.Above all,it’s an effective way to improve or modify the quality of Tartary buckwheat flour and Tartary buckwheat starch by using moderate gaseous ozone treatment.