Effects of drying methods on the juglone content and antibacterial activity of green walnut husk

To explore the relationship between dry method and antibacterial activity of green walnut husk, the antibacterial activities of natural drying ( P₁) , hot-air drying ( P₂) and vacuum freeze drying ( P₃) of green walnut husk were evaluated, using Escherichia coli, Staphylococcus aureus and Zythia versoniana Sacc.as test microorganisms in this paper.Results showed that the three samples all had strong inhibition, and presented a dose-response relationship, namely M₁> M₂> M₃ ( dose of walnut green husk extract were respectively 100 ( M₁) , 80 ( M₂) , and 60 ( M₃) mg/m L) .The drying methods were characterized by P₃> P₂>P₁.For P₁, P₂ and P₃, the minimum inhibition concentration ( MIC) of E.coli and Zythia versoniana Sacc.were consistent.The doses were 20, 15 and 10 mg/m L respectively.The MIC of Staphylococcus aureus were 15, 10, and 5 mg/m L.The juglone content of samples were respectively 8.04 ( P₁) , 9.46 ( P₂) , and 11.84 ( P₃) mg/g, significant positive correlation with antibacterial activity ( p < 0.01) .In conclusion, the drying methods could affect the juglone content and antibacterial activity of green walnut husk, vacuum freeze drying was an ideal way.