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Study On High-Energy Electron-Beam Irradiation On The Quality And Sterilization Technology Of Ophiopogon Japonicus And Rheum Officinale

Posted on:2022-03-12Degree:MasterType:Thesis
Country:ChinaCandidate:Y HeFull Text:PDF
GTID:2544307124964309Subject:Biology
Abstract/Summary:PDF Full Text Request
Ophiopogon japonicus and Rhubarb are two important traditional Chinese medicines,which are rich in various nutrients and active ingredients.Their decoction pieces and preparations are widely used in the field of medicine and health products.However,Ophiopogon japonicus are rich in polysaccharides,and it is difficult to dry after harvest of Rhubarb cause the large in tuber.They are susceptible to microbial contamination during storage.The conventional method of decontamination was fumigation with sulfur,to prevent insects and moulds and prolong its shelf life.However,it is strictly limited by the problems of high residue and destruction of active components,which is now being increasingly restricted for the residues of harmful substances and the destruction of active ingredients.High-energy electron-beam irradiation(EBI)technology is a kind of green cold processing method.Its unique properties,especially suitable for low density and small volume products,are increasingly favored by researchers and applications.However,there are few studies on the application of EBI in the storage of traditional Chinese medicines,and the research of the technology related to the irradiation of medicinal herbs is weak.It is very important to establishing appropriate processing techniques for different products to ensure the effectiveness and improving the efficiency of the irradiation.Moreover,it is also of great significance to improve the sanitary quality of Chinese herbal medicine and guarantee the safety of medication.In this study,Ophiopogon japonicus(O.japonicus)and Rhubarb were irradiated by high-energy electron-beam with different doses of 2,3,5,7,10,13,15,and 25 kGy,and the non-irradiated(CK)and sulfur-fumigated samples were used as control.The effects of EBI on microbial,physicochemical and bioactive components,and antioxidant activity during storage were measured on the 0 th,180 th and 360 th days after irradiation,respectively.Combined with analytic hierarchy process(AHP),the effects of EBI on the quality of O.japonicus and Rhubarb were comprehensively evaluated to select the appropriate irradiation dose.Then,the processing techniques of O.japonicus and Rhubarb were explored with different stacking thicknesses,irradiation doses and irradiation methods.The results are as follows:(1)The total aerobic microbial count(TAMC)and total yeast and mould count(TYMC)in O.japonicus were significantly reduced by the EBI treatment.The contents of TAMC and TYMC in CK group were 5.57 and 3.53 log CFU/g,respectively,which exceeded the microbial limit standard of Chinese pharmacopoeia(TAMC and TYMC were 5 and 3 log CFU/g,respectively).EBI treatment at 2 kGy reduced both TAMC and TYMC to less than 1 log CFU/g,and the microbial content was controlled below the pharmacopoeia standard during the 180-day of storage.EBI significantly increased the content of total saponins,an increase of 10.16%over the control were observed at 25 kGy.And the antioxidant activity was enhanced,but did not significant effect the moisture,extracts,ash,total flavonoids,total polysaccharides,total phenolics,methylophiopogonanone A and methylophiopogonanone B.(2)EBI treatment helpful in reduction of microbial growth during storage.At the doses range of 3~5 kGy,the TAMC and TYMC were always lower than that stipulated in pharmacopoeia during 360 days of storage.No microorganism was detected at 7 kGy or above,and complete sterilization.Irradiation treatment could maintain the stability of physicochemical properties,active component content and antioxidant activity of O.japonicus during storage,and little effect on appearance traits.In summary,irradiation at 2~3 kGy can effectively extend the storage period to 180 days,which can be used for short-term storage after irradiation.After 7~10 kGy treatment,O.japonicus maintained a high hygienic standard throughout the storage period,and each index could meet the pharmacopoeia standard,which was suitable for long-term storage(about 360 days)after irradiation.(3)The initial microbial populations in Rhubarb was far beyond the microbial limits standardof Chinese pharmacopoeia.Irradiation at dose of 3 to 5 kGy reduced the microbial content of Rhubarb below the detection limit,and the storage period was extended to 360 days.The irradiation of 7 kGy and above reached complete sterilization.Irradiation treatment could significantly increased the content of water-soluble extracts of Rhubarb,slightly improved the congtent of anthraquinones,no significant effect on its moisture and total ash.Moreover,the quality of Rhubarb was maintained during storage treated by EBI,and all the index meet the requirements of Chinese Pharmacopoeia.Comprehensive evaluation results showed that 3~5kGy could effectively reduced microbial populations in Rhubarb(<1.0 log CFU/g),which was suitable for short-term storage(about 180 days)after irradiation.7~10 kGy irradiation treatment keep the microbial content at a low level in one year storage period and maintain the content of active components,which is suitable for long-term storage after irradiation(about360 days).(4)The medicinal materials of O.japonicus were irradiated at doses of 2,4 and 6 kGy.The results showed that EBI at 2 kGy could effectively reduce the microbial populations of O.japonicus,both TAMC and TYMC reached the microbial limits standard stipulated in the Chinese pharmacopoeia.And slightly increase the total saponin content,no significant effect on other active components and antioxidant activities of O.japonicus,The Hunter color values were decreased after electron-beam irradiation,mainly presented with the increased in red-green value a~*.The results of principal component analysis(PCA)and linear discriminant analysis(LDA)show that there were no obviously effects on flavor at dose of 2 kGy.(5)Dose uniformity 1.2 as the irradiation processing standard,and the results showed that the stacking thickness of O.japonicus was about 4 cm and that of Rhubarb was 4~6 cm under one-side irradiation.When irradiation process was carried out by two-side,the suitable thickness for O.japonicus was about 10 cm and that of Rhubarb was about 14 cm.The highest absorbed dose was in the middle,indicating that the electron beam could effectively penetrate,and the unevenness was controlled below 1.2,which met the requirements of irradiation processing.
Keywords/Search Tags:High-energy electron-beam, Ophiopogon japonicus, Rheum palmatum, microbial, antioxidant
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