Study On The Bacteriostasis Of The Extract Of Dracocephalum Rupestre Hance And Its Application In Fresh Keeping

In the first part of this paper,the antibacterial activity of Dracocephalum rupestre Hance extract was studied.The diameter of the bacteriostatic circle was measured by the double plate transparent circle method,and the minimum inhibitory concentration(MIC)was measured by the double dilution method The inhibition of several food borne spoilage bacteria,such as coli and Salmonella.The results showed that the ethanol extract and water extract of Dracocephalum rupestre Hance had obvious inhibitory effect on Staphylococcus aureus,among which n-butanol phase had the best inhibitory effect,the diameter of bacteriostatic circle was 23.58 ± 0.52 mm,MIC was 3.55mg/ml.The minimum inhibitory concentration was20.58mg/ml in petroleum ether phase,12.64mg/ml in dichloromethane phase and 6.25mg/ml in ethyl acetate phase.However,only n-butanol can inhibit Escherichia coli and Salmonella,and the minimum inhibitory concentration is 25.45mg/ml and 37.25mg/ml.The antibacterial activity of alcohol extracted n-butanol extract from Dracocephalum rupestre Hance was stable to ultraviolet light,while that of low temperature(-18 ?)and high temperature(121 ?)decreased to some extent.The antibacterial activity of alcohol extracted n-butanol phase extract from Dracocephalum rupestre Hance decreased in alkaline environment,which can avoid alkaline environment in use to achieve better antibacterial effect.Secondly,the alcohol extracted n-butanol extract of yanqinglan was compounded with chitosan to prepare three kinds of composite preservatives with 0.1%,0.3% and 0.5% of yanqinglan extract.After soaking in the preservative for 1 min,the orange was dried in the air and stored at 4 ? and 18 ?respectively.The physiological indexes of each phase were measured during the storage period.The results showed that when the storage temperature was 4 ?,the added amount of yanqinglan extract was The 0.1%chitosan composite preservative coating treatment can prolong the storage period of the orange to 40 days.Compared with the control group,the treatment group can reduce the rate of corruption and weight loss,and maintain the content of soluble solids,vitamin C,titratable acid and reducing sugar in a high level.The0.1% Chitosan composite preservative coating treatment can also keep the sand The activities of peroxidase and superoxide dismutase in Tangju fruit can inhibit the accumulation of malondialdehyde and achieve better preservation effect.