Biological Activities And Chemical Profiles Of Wood Vinegar From Bitter Almond Shell

According to differences in acidity, organic acids and phenols from bitter almond shellwood vinegar which obtained by pyrolysis technology were enriched based on pH gradientextraction method and the biological activities and chemical profiles of wood vinegar frombitter almond shell were investigated. The results were reported as follows:(1) Taking bitter almond shell wood vinegar collected from the whole temperatureranges as experiment materials, methods of separating organic acids and phenols were probedby pH gradient extraction method based on the differences of acidity and separationtechnology was demonstrated. The fraction A5and A6extracted by50g/L and60g/L NaHCO3had a high content of organic acids， which were1.66and1.91times than the content oforganic acids of OA, respectively. The fraction P3extracted by40g/L NaOH had the highestcontent of phenolic compounds (1570.370mg/L),1.95times more than that of the originalorganic components of wood vinegar.(2) The antibacterial activities of A1-A6and P1-P4against three food spoilage strains,Staphylococus aureus Rosenbach, Bacillus subtilis, Escherichia coli were investigated.Results showed that A5which enriched by50g/L NaHCO3exhibited the highest antimicrobialactivity against testing strains and NaOH solvent extraction P1-P4had certain antimicrobialactivity but they were less than A5.(3) Based on the tests of extracellular proteins contents and growth curve of such foodspoilage strains, the inhibiting mechanism of A5was investigated. The effect of A5caused theincrease of thallus extracellular proteins contents and destroyed the normal growth curve.According to the SDS-PAGE picture, electrophoresis band of Staphylococus aureusRosenbach thallus proteins contents was disappearing or shallowing when A5added whichmean that A5affect the synthesis of bacterial proteins and may block protein expression inbacteria.(4) The antibacterial activities of four traditional Chinese medicines, Syringa, Scutellariabaicalensis Georgi、Flos Sophorae and Flos Lonicerae against three testing strains were investigated. Syringa ethanol extract had strong inhibitory effect on all tested bacteria(bacteriostatic circle diameter more than15mm) and had strongest effect on Escherichia coli(bacteriostatic circle diameter more than20mm).(5) In order to improve the inhibitory effect against gram-negative bacterium andgram-positive bacterium, through orthogonal array design, using inhibitory rate as index, theoptimum formulation of composite preservative was determined for the purpose of exploringeffective and potential natural food preservative. According to the analysis of orthogonal test,formulation of composite preservative was25%20mg/ml Syringa ethanol extract and75%20mg/ml A5. MIC of composite preservative against Staphylococus aureus Rosenbach,Bacillus subtilis and Escherichia coli were2.50mg/ml、2.75mg/ml、2.50mg/ml, respectivelyand it had better antibacterial activity than A5, Syringa ethanol extract and chemicalpreservatives, such as sodium benzoate and potassium sorbate. The antibacterial activities ofcomposite preservative had good thermostability and ph stability.(6) Based on the trend of mold hyphae growth, the inhibition activities of A1-A6andP1-P4against Mucor、Rhizopus、Penicillium glaucum were demonstrated. A1-A6hadinhibition effect on all testing strains in36h. A5had the strongest effect and the antibacterialactivity was positively correlated with the concentration of A5. P1-P4had inhibition effect onall testing strains in24h but the antibacterial activities were weaker than that of A5. ApplyingA5in the strawberry preservation test, results showed that preservative effect of A5wassignificant and indicated the lowest disease index of strawberry after4d of storage in25℃.(7) The inhibition activities of A1-A6and P1-P4against Alternaria solani、Verticilliumdahliae、Physalospora Piricola、Venturia Pyrina、Sclerotinia Sclerotiornm、LolletotrichumGloeosporioides were investigated. The inhibition activity of P3was higher that P1、P2、P4.A5had the strongest effect among A1-A6composition and the inhibition rates of A5againsttesting strains were1.32,1.39,1.40,1.54,1.42,1.81times than that of P3.(8) The experiment for testing anti-oxidative activity revealed that A1-A6had lowerantioxidant activity according to their values of scavenging activities of DPPH and inhibitionrates of linoleic acid peroxidation. Compared with others, P3had the strongest anti-oxidativeactivity and had the great good thermostability and storage stability. The antioxidation of P3could keep in high level in pH4-7but it decreased gradually in pH8-11. Besides, lipidoxidation experiments indicated that P3had a remarkable antioxidant effects on lard oil, plantoil and nut oil and the antioxidant effects were better than BHT.(9) P3had been separated detailedly by column chromatography. Though testing thetotal phenols contents, values of scavenging activities of DPPH and inhibition rates of linoleicacid peroxidation of every separated fraction,2,6-dimethyl phenol had been demonstrated in one separated fractions by GC-MS, which had highest content of phenolic compositions andstrongest antioxidant activity among all collected fractions, stronger than those of originalliquids before separating.