| As a new non-thermal processing technology,cold plasma can be used for the sterilization of food,reducing food costs without affecting the food itself.It can also be used for the processing of packaging materials to improve barrier performance and impart antibacterial activity.It can also be used for functional modification of food ingredients,improvement of seed germination rate,improvement of physicochemical properties of cereals,and degradation of pesticide residues.Studies have shown that cold plasma can degrade pure mycotoxins.This paper focuses on the effect of cold plasma technology on the reduction of wheat flour vomiting toxin and wheat secondary flour ergosterol content and the effect on physical and chemical quality after treatment.Using oxygen and helium as gas sources,wheat flour and wheat middlings with excessive vomiting toxins were treated with cold plasma for 0 s,30 s,60 s,90 s,120 s,150 s,and 180 s.The effects of cold plasma treatment on the content of emetic toxin in wheat flour and ergosterol in wheat flour were investigated;Changes in physical and chemical indicators of wheat flour and inferior flour while degrading toxins and their impact on the quality stability of wheat flour and inferior flour.The main findings are as follows:1.After cold plasma treatment,the content of vomiting toxin in wheat flour was significantly reduced.The wheat flour with excessive vomiting toxin was treated with oxygen cold plasma.When the treatment time was 30 s,the reduction rate of vomiting toxin was the highest,reaching 55.28%,and the content of vomiting toxin was reduced to 0.52μg/g.After the treatment with helium cold plasma,the vomiting toxin was not detected when the treatment time was 180 s.After the treatment of two different gas sources,the content of vomiting toxin in wheat flour reached the safe edible range,which was lower than the national limit standard(1.0 μg/g).Cold plasma treatment changed the surface physical properties of wheat flour,and the electrical conductivity increased significantly(P<0.05).The increase under helium treatment was higher than that under oxygen treatment,and the water absorption ratio of wheat flour was significantly increased(P<0.05).It is shown that the cold plasma treatment can have an etching effect on the surface of the samples,which in turn enhances their hydrophilic properties and affects the processing quality of the surface products.2.The fatty acid content of wheat flour was affected by cold plasma treatment.With the extension of treatment time,the value of free fatty acids decreased significantly(P<0.05).A total of 28 kinds of fatty acids were identified by gas chromatography,and 12 kinds of fatty acids were more than 10 μg/g.Cold plasma treatment maintained or elevated the C16:0 and C18:0 contents of major fatty acid components,while the C18:1n9c,C18:2n6c,C18:3n3 and C20:1 contents were significantly reduced(P<0.05),and the total,unsaturated,polyunsaturated,and monounsaturated fatty acid contents and the ratio of unsaturated to saturated fatty acids were significantly decreased(P<0.05),while the saturated fatty acid content increased significantly(P<0.05).3.The basic components of wheat flour changed after cold plasma treatment.The contents of reducing sugar and pentosan increased significantly(P<0.05),the contents of total soluble sugar and pectic acid tended to be stable and the content of amylose increased significantly(P<0.05),but the content of damaged starch did not change significantly.The content of free amino acid decreased significantly(P<0.05),and the content of the sulfhydryl group increased significantly under helium treatment(P<0.05).The content of the sulfhydryl group increased significantly under the condition of the 90 s treatment,while the content of the sulfhydryl group tended to be stable under oxygen treatment.The content of soluble protein increased significantly under oxygen treatment(P<0.05),and tended to be stable under helium treatment.With the extension of treatment time,the water-soluble protein,salt-soluble protein and alcohol-soluble protein of the flour under both treatment conditions were significantly higher(P<0.05),and the overall wheat gluten protein was stabilized,and polymerization occurred between protein fractions after surface treatment,resulting in higher content of large molecular weight aggregates.The content of MDA in flour increased significantly after oxygen treatment(P<0.05).However,the malondialdehyde content showed a decreasing trend after helium treatment,indicating that helium treatment may occur will reduction reaction and effectively prevent quality deterioration.4.The content of ergosterol in wheat middlings decreased significantly after cold plasma treatment.Using oxygen cold plasma to treat wheat middlings,when the treatment time is 30 s,the ergosterol reduction rate is the highest,reaching 52.86%,and the ergosterol content is reduced to 1.12 μg/g.After using helium cold plasma treatment,when the treatment time is 120 s,the reduction rate of ergosterol is the highest,reaching 51.03%,and the ergosterol content is reduced to 1.17 μg/g.Cold plasma treatment changed the surface physical properties of wheat middlings,and the electrical conductivity and water absorption ratio increased significantly under the two treatments(P<0.05).5.The fatty acid composition of wheat middlings was affected by cold plasma treatment.With the extension of treatment time,the value of free fatty acids decreased significantly(P<0.05).A total of 28 fatty acids were identified by gas chromatography analysis,and 10 of them contained more than 10 μg/g.The contents of C16:0 and C18:0,the main fatty acid components,tended to increase,and the contents of C18:1n9c,C18:2n6c,C18:3n3 and C20:1 were maintained or reduced.The total fatty acid,unsaturated fatty acid,polyunsaturated fatty acid contents and unsaturated fatty acid to saturated fatty acid ratio were significantly reduced(P<0.05),while saturated fatty acid contents were significantly increased(P<0.05)and monounsaturated fatty acid contents were stabilized under helium treatment conditions,while none of the changes were significant under oxygen treatment conditions.The surface cold plasma treatment may have abrogated some of the unstable free fatty acids,thus improving the quality stability of wheat middlings.6.The basic components of wheat middlings changed after cold plasma treatment.Reducing sugars and pectic acid content were significantly increased(P<0.05);total soluble sugars content tended to be stable;pentosan,straight-chain starch and sulfhydryl content were maintained or increased;broken starch content did not change significantly;free amino acid content was significantly increased(P<0.05);soluble protein content tended to decrease.With the extension of treatment time,the contents of water-soluble protein and salt-soluble protein increased significantly(P<0.05),the contents of gliadin and glutenin tended to be stable,and the content of malondialdehyde decreased significantly(P<0.05).7.Under the condition of helium treatment,the SRC values of water,sodium bicarbonate,and sucrose increased significantly,but the SRC values of lactic acid decreased,and the SRC values of these four solvents were maintained or decreased under oxygen treatment.Both dough formation time and stabilization time were reduced,starch disintegration values and rebound were significantly lower(P<0.05),starch pasting rate was increased,enzymatic rate and amylase activity were maintained,and helium treatment conditions were more favorable to enhance dough development and starch pasting properties.The thermodynamic characteristic values of wheat flour changed after cold plasma treatment,gelatinization enthalpy,peak width,peak height,and termination temperature(Tc)all decreased significantly(P<0.05)under oxygen treatment conditions,but increased or maintained the initial Temperature(To)and peak temperature(Tp);peak width and peak height were significantly reduced(P<0.05)under helium treatment conditions,and gelatinization enthalpy,To,Tp,Tc were maintained.The peak viscosity,peak-to-valley viscosity,decay value,final viscosity,and recovery value of the treated flour were all significantly increased(P<0.05),and the gelatinization temperature and peak time were maintained or decreased.It was shown that the cold plasma treatment facilitated dough formation,enhanced dough development,improved starch properties and amylase activity of wheat flour.8.Under the condition of helium treatment,the SRC values of water,sodium bicarbonate,lactic acid,and sucrose increased significantly with the treatment time,while the SRC values of these four solvents were maintained or decreased under oxygen treatment.After cold plasma treatment,the thermodynamic characteristic values of wheat middlings changed,To,Tp,Tc and peak width increased significantly under oxygen treatment,and the enthalpy of gelatinization,and peak height tended to be stable as a whole.Under the condition of helium treatment,To and Tp increased significantly,and Tc,peak width,enthalpy of gelatinization and peak height tended to be stable.The peak viscosity,final viscosity,peak and trough viscosity,decay value and rebound value were significantly reduced after treatment(P<0.05),maintaining or reducing the pasting temperature and peak time,reducing the degree of starch rebound after treatment,and delaying starch aging to some extent. |
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