Study On Separation And Purification Of Wood Vinegar And Its Application In Food And Environment

Wood vinegar?WV?is a kind of yellowish brown or dark brown condensate of smoke produced by slow pyrolysis of plant biomass.Chemically,water,organic acids and phenolic compounds are the typical components in WV.WV can be applied in diverse areas,such as soil improvers,feed and food additives,anti-inflammatory agents and anti-fungal drugs because of its powerful antioxidant activity,anti-inflammatory activity,anti-viral activity,antimicrobial activity and so on.This thesis focuses on the identification and isolation of major antioxidants in WV and the application of WV in the food and environmental fields,including the following four aspects.Firstly,with the aid of the double-column retention index and external standard method,the qualitative and quantitative analysis of organic compounds were conducted in five kinds of WV prepared from agroforestry wastes?Oak WV,Walnut shell WV,Corn cob WV,Rice husk WV,Peanut shell WV?,and based on Pearson correlation coefficient,standard verification and ozone oxidation,the major antioxidants in five kinds of WV were accurately identified.Secondly,the combination of distribution of acid-base,distillation and low-toxic organic solvent extraction was adopted for the separations of phenolic extractives?PCE?and organic acids'extractives?OAE?from WV,and on the basis of primary distillation,secondary distillation and liquid-liquid extraction,WV was divided into ten fractions?Fraction 1-10,Fr.1-10?.The major identified antioxidants were also isolated from WV.Thirdly,PCE was used as feed additive to improve the egg production and quality so on.Finally,based on the concept of one-step synthesis,the natural zeolite?NZ?was modified with WV,and the heavy metal?loid?adsorption capability and antimicrobial activity of the modified zeolite?MZ?was studied in aqueous solution.WV has a powerful antioxidant activity,but it is unclear which components are responsible for the antioxidant activity.The double-column retention index qualitative method was first used for identification of the major components in the five kinds of WV.Among the five kinds of WV,oak WV contains the most organic compounds?27 kinds?and has the strongest antioxidant activity.And the major antioxidants of WV were accurately identified with the aid of Pearson product-moment correlation coefficients,authentic standard samples and ozone oxidation.Our results demonstrated that phenolic compounds are mainly responsible for the powerful antioxidant activity,and 2,6-dimethoxyphenol is the most powerful antioxidant in WV.2-methoxyphenol and3-methyl-1,2-cyclopentanedione also have an important influence on the antioxidant activity of WV.Our results suggest that the contents of 2-methoxyphenol,2,6-dimethoxyphenol and 3-methyl-1,2-cyclopentanedione should act as the criteria for evaluating the antioxidant activity of WV.A new method for comprehensive utilization of WV was developed.The primary distillation,liquid-liquid extraction and secondary distillation were used to isolate the different active fractions?Fr.1-10?from WV in the new route.The antioxidant activities of all the fractions were expressed as vitamin C equivalent antioxidant capacities in mg/L using 1,1-diphenyl-2-picrylhydrazyl scavenging assay,and the antimicrobial activities against Escherichia coli?E.coli?in vitro were represented by the absorbance at a wavelength of 600 nm.The results demonstrated that the isolation of the antioxidants?Fr.6?from the residue obtained from primary distillation was satisfactory when the EtOAc/n-hexane?7/3,v/v?was used as extraction solvent and pH value was 4.0.Acetic acid had a significant antagonism effect on the antioxidant activities of phenolic and ketone compounds.The fraction?Fr.3?enriched with acetic acid exhibited high antimicrobial activity.Additionally,Fr.1 was suitable for the preparation of eco-friendly snow melt agent.Effects of different levels of WV?0.1-0.5%?and PCE from oak WV?0.033-0.6%?,OAE from oak WV and different raw materials of WV?oak and hull of spina date seed WV?in hen diets on egg production,egg fatty acid profile,water-soluble protein and lysozyme were investigated.The combination of distribution of acid-base,distillation and low-toxic organic solvent extraction was used for the separations of OAE and PCE from oak WV.The results indicated that 0.2%of WV can significantly improve the proportion of fatty acids in the eggs.After feeding the hens with the diet containing 0.2%oak WV for50 days,the egg production increased by 28.89%and the ratio of n-6/n-3 decreased by10.25%.An optimal amount of PCE?0.6%?in hen's diet can improve both egg production and the ratio of n-6/n-3 in egg yolks.With the addition of PCE at this level for 50 days,the egg production increased by 33.33%and the ratio of n-6/n-3 decreased by 25.05%.The water-soluble protein and lysozyme can also be tuned with the adjustment of PCE concentration?0.083%?,and the contents of water-soluble protein and lysozyme increased by 32.39%and 3.66%,respectively.The present work shows a new method for NZ modification with WV.Sixteen kinds of MZs,such as WV+NaOH-MZ and WV-MZ,were prepared.The optimal conditions for NZ modification with WV were determined,and the adsorption capacities towards lead(Pb²⁺),cadmium(Cd²⁺)and arsenic(As³⁺),antimicrobial activities against Escherichia coli,heavy metal?loid?fraction and characterizations of selected MZs were also investigated.The results indicated that 50-fold dilution of WV,5 g of NZ dosage,105?of drying temperature,4 h and 95?of water bath were preferred for NZ modification with WV.The WV+NaOH-MZ exhibited the best performance in heavy metal removal and the most powerful antimicrobial activity among all the zeolites.The sequence of WV+NaOH-MZ for the maximum heavy metal?loid?adsorption capacities was Pb²⁺?48.67 mg/g?>Cd²⁺?23.67 mg/g?>As³⁺?0.024 mg/g?.The WV+NaOH and WV modifications can also increase the stabilities of heavy metals in the MZs.The residual fractions of single Pb and Cd in WV-MZ and WV+NaOH-MZ were 50%,55%,34%and30%,respectively.The pore size of WV+NaOH-MZ?11.73 nm?was bigger than that of NZ or WV-MZ.Additionally,the proportion of clinoptilolite in WV+NaOH-MZ was also higher than other zeolites.The surfaces of WV+alkali-MZs were rougher than that of NZ.