| Tulipa edulis is a genus of the genus Tulipaceae.It is a perennial herb that is born in sunny hillsides or weeds and is distributed in the northeast to the Yangtze River.The bulb of the Tulipa edulis is a Chinese medicinal material,the Bubus Tulipae,which has the effects of inhibiting bacteria,detoxifying and dispersing,and performing blood stasis.It can treat sore throat,phlegm,soreness,and postpartum stagnation.In recent years,it has been found that the Tulipa edulis is rich in a variety of alkaloids such as colchicine,and is an effective substance for anticancer,and has remarkable effects in treating breast diseases and the like.At present,the research on the Tulipa edulis is mainly focused on the research of the grass,biological characteristics and cultivation and breeding,but there are few reports on the research of flavonoids.Therefore,this paper is intended to prepare the flavonoids from the Tulipa edulis leaf by using the Tulipa edulis leaf as the material,and explore its extraction process,stability,in vitro antioxidant activity,antibacterial activity and application in strawberry antisepsis preservation,aiming at providing reference for the preservation of strawberries and other fruits and vegetables.At the same time,it also provides a theoretical basis for the development and utilization of the Tulipa edulis resources.1.Preparation of flavonoids from the Tulipa edulis.The effects of single factor such as ethanol volume fraction,solid-liquid ratio and extraction time on the extraction rate of flavonoids were studied.Based on this,the optimal extraction process was determined by orthogonal test.The results showed that the optimum extraction process of flavonoids was:1:20(g/mL),ethanol volume fraction of 65%,extraction time of 80 min,extraction temperature of 65?,and extraction rate of flavonoids from Tulipa edulis was 3.46.%.2.The stability of the Tulipa edulis flavonoids.The effects of temperature,pH,oxidant,reducing agent,light and food additives on the stability of flavonoids were measured.The results showed that it was stable at 85 ?,protected from light and acidic environment.The food additives sucrose and NaCl and oxidant H2O2 had little effect on the stability,but the food additive citric acid and ascorbic acid and reducing agent Na2SO3 had certain stability impact.3.Antioxidant activity of flavonoids in the wild.The anti-oxidation activity of flavonoids on hydroxyl radicals,DPPH free radicals and superoxide anion radicals was determined to evaluate their antioxidant activity in vitro.The results showed that when the concentration of flavonoids was 5 mg/mL,the scavenging rates of DPPH free radicals,hydroxyl radicals and superoxide anion radicals were 63.57%,53.77%and 44.53%,respectively,and they had certain reducing ability.4.Antibacterial activity of flavonoids from the Tulipa edulis.Filter paper and two-fold dilution method were used to determine the antibacterial activity of the Tulipa edulis flavonoids.The results showed that the inhibition zone diameters of Escherichia coli,Staphylococcus aureus,Bacillus thuringiensis,and strawberry mixed bacteria were 12.4 mm,11.2 mm,10.8 mm,and 8.3 mm,respectively,when the concentration of flavonoids was 100 mg/mL.The minimum inhibitory concentration(MIC)of flavonoids on Escherichia coli,Staphylococcus aureus,Bacillus thuringiensis and strawberry mixed bacteria were 6.25,12.5,25,50 mg/mL,respectively.Therefore,the Tulipa edulis flavonoids have certain antibacterial activity.5.The anti-corrosion and preservation effect of the Tulipa edulis flavonoids on the post-harvest "Benihoppe" strawberry.The "Benihoppe" strawberry was soaked with different concentrations of 5,10,20 mg/mL for 5 min,and the preservation effect of"Benihoppe" strawberry was determined.The results showed that the flavonoids of the Tulipa edulis could reduce the weight loss rate and spoilage rate of postharvest"Benihoppe" strawberry,reduce the loss of sugar content,soluble sugar and Vc content,better maintain the activity of SOD and reduce the formation of MDA. |
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