Study On The Improvement Effect Of Cold Plasma Treatment On Peanut Quality

As a new physical processing technology,cold plasma has been used in food sterilization,crop breeding,material modification,etc.because of its non-thermal,high efficiency,and environmental friendliness.Therefore,it has good application potential for improving peanut quality.In this paper,high-protein and high-oil peanuts were treated with cold plasma(150 W,0,1,4,5,6,8,10 min)using argon as the gas source.The biochemical analysis,instrument detection and other technical means were used to study the changes of physicochemical properties,lipid and protein physicochemical properties,and phenolic content of different varieties of peanuts before and after treatment,to further study and analyze the quality(lipid,protein physicochemical properties)changes of artificially aged peanuts under the optimal processing conditions(6 min),and provide a theoretical basis for the application of this technology in peanut processing and storage.The main findings are as follows:(1)The germination rates of high-protein and high-oil peanut seeds were significantly increased after cold plasma treatment,and the germination rates of the two types of peanuts reached their maximum values of 90.3% and 80.3%,respectively,at 6 min.After treatment,the color indexes L~* and a~* of the above two kinds of peanut seed coats increased significantly,and the electrical conductivity also increased significantly,and the relevant change trends were all positively correlated with the treatment time.Compared with the untreated control groups,the activities of peroxidase and lipase in the two peanuts were significantly decreased after treatment,and the related enzyme activities decreased to the lowest at 10 min;the activity of superoxide dismutase reached the highest value at 6 min,significantly increased by 50.91% and 47.07% respectively.It showed that the technical treatment could enhance the vigor of peanut seeds,inhibit the activity of bad endogenous enzymes and improve the physiological and chemical characteristics of the peanut.(2)After cold plasma treatment,the peroxide value and acid value of the two peanuts were significantly reduced,and the protein water absorption,emulsifying properties,and solubility were significantly enhanced,and all reached the maximum value at 6 min.However,there were no significant differences in crude fat,crude protein and fatty acid composition.It was indicated that the technical treatment could improve the lipid quality and protein physicochemical properties under the premise of maintaining the original basic composition of peanuts,thereby delaying the deterioration of peanut quality.(3)The contents of total phenols,flavonoids and proanthocyanidins in the two peanut red coats after cold plasma treatment were significantly increased compared with the untreated controls,and all reached the maximum at 6 min,while the content of resveratrol did not change significantly.The results of transcriptome sequencing analysis showed that the expression of chalcone synthase,chalcone-flavonoid isomerase,deoxychalcone synthase and other genes in the flavonoid metabolic pathway was enhanced,which can catalyze the conversion of dihydroflavonols into flavonols,Anthocyanins,flavonoids and other substances,and anthocyanins undergo glycosylation and other modifications to form procyanidins.It indicated that the technical treatment had a positive effect on the increase of the content of phenolic substances in peanut red coats.(4)The crude fat and crude protein contents of the two artificially aged peanuts did not change significantly before and after treatment(0 min,6 min),and the acid value and peroxide value of the treated samples were significantly lower than those of the untreated controls.The results of GC-MS analysis showed that the contents of n-hexanol,valeraldehyde,decanal,γ-butyrolactone and other volatile substances in the two artificially aged peanuts were significantly reduced after treatment,and the contents of n-dodecane and n-heptadecane were significantly increased.The protein solubility,water absorption and emulsifying properties of the two artificially aged peanuts were significantly improved after treatment(6 min).The results of SDS-PAGE and particle size analysis showed that the high molecular weight proteins in two artificially aged peanuts with treatment changed to low molecular weight proteins,and the particle size became smaller,indicating that cold plasma treatment can cause protein depolymerization.After treatment,the content of free sulfhydryl groups in the two peanuts was significantly increased by 20.5% and 16.2%,respectively,and the content of disulfide bonds was significantly decreased by 5.3% and 4.6%,respectively.The results of FTIR and UV spectroscopy showed that the α-helix and β-turn in the secondary structure of the protein were obviously converted to β-sheet and random coil,the maximum UV absorption wavelength was blue-shifted,and the internal chromophore groups were exposed.It showed that the dense and ordered protein structure is transformed into a loose and disordered state.