Effects Of Sterilization Methods On Flavonoids Composition And Properties Of Sea Buckthorn Juice

The fruit of sea buckthorn?Hippophae rhamnoides L?is rich in various nutrients.Flavonoids are the main functional components of sea buckthorn,which can reduce the risk of cardiovascular disease and diabetes,and also play an anti-tumor effect.The flavonoids have an important influence on the color flavor and activity of sea buckthorn juice.Thus,it is of great significance for the accurate quantification of flavonoids.However,the current determination methods are not uniform.At the same time,the component of flavonoids is different and the heat treatment can affect its composition.There is currently no study for the processing treatment of flavonoids.In this paper,the effects of different methods on the determination of total flavonoids in sea buckthorn juice are studied systematically with Chinese sea buckthorn juice.The effects of different sterilization methods on the composition and content of flavonoids are investigated and combined with the changes of basic properties and antioxidant activity of sea buckthorn juice to clarify the best sterilization method for sea buckthorn juice processing.The determination result indicates:the determining wavelengths are 510 nm,420 nm and350 nm in the NaNO₂-Al?NO₃?₃-NaOH coloration method,AlCl₃-CH₄O coloration method and UV spectroscopy method respectively.The determining results of the total flavonoids are1.19 mg·mL^-1,0.42 mg·mL^-1 and 2.47 mg·mL^-1;the RSD values are 7%,25%,and 7%.The determining result of total flavonoids is 2.49 mg·mL^-1 by HPLC.The UV spectroscopy method is more accurate.What's more,this method can be operated easily,use little additional chemical reagents,which is environment friendly method,and is the ideal method of determining total flavonoids in sea buckthorn juice.It is confirmed that the flavonoids of sea buckthorn juice contain rutin,quercetin isorhamnetin,and five kinds of glycosides,namely isorhamnetin-3-O-sophoroside-7-O rhamnoside,quercetin-3-glucoside-7-rhamnoside,myricetin-3-rhamnosyl-glucoside,kaempferol-3-rhamnosyl-glucoside,isorhamnetin-3-O-glucoside-7-O-rhamnoside.The myricetin-3-rhamnosyl-glucoside is firstly identified in sea buckthorn juice.The flavonoid aglycone is relatively low in seabuckthorn juice,and most of it exists in the form of flavonoid glycosides.The most abundant is the disaccharide glycoside,while the most prominent is isorhamnetin-3-O-glucoside-7-O-rhamnoside,which is 3050.19?g·mL^-1,The highest content of monomer is isorhamnetin,which is 563.76?g·mL^-1.The extraction content increase significantly after sterilization treatment,and reach a significant level?P<0.05?.The difference value of high temperature sterilization is the largest and increases from 0.63 g to 0.99 g.The heat treatment can change the sensory index of sea buckthorn juice.The change of color difference is reaching at a significant level in different sterilization treatments?P<0.05?,and the color difference value of high temperature sterilization is the largest.Ultra-high temperature instant sterilization greatly improve the sourness and bitterness of sea buckthorn juice;reduced salty taste,umami taste and sweetness,and the sensory difference is the largest,while the difference in high temperature sterilization is the least.?P<0.05?.The anti-oxidation ability of sea buckthorn juice is enhanced after sterilization treatment,and the inhibition ability of high-temperature sterilization is the strongest?P<0.05?.Therefore,it is recommended to use high temperature sterilization in the consideration of the flavonoids content and antioxidants.The best method for the determination of flavonoids in sea buckthorn is established by this study,which provide a method basis for the accurate quantification of flavonoids in sea buckthorn processing.The law of thermal variation of sea buckthorn flavonoids is also clarified.The study provides a reference for the determination of total flavonoids and functional food development of seabuckthorn.