Study On Antimicrobial, Antioxidant Activity Of Clove Extracts And It's Effect On Postharvest Quality Of Fruits And Vegetables

Clove is traditional natural plant in China, have an extensive activities in the aspects of antimicrobial activity, flavoring agent, antibacterial materials in food and so on. In recent years, there had been found that it had bigger value at anti-cancer, anti- oxidize anti- decrepitude etc. The objective of this project is to study the fragrance compounds of clove oils usage GC-MS analysis, and also to discuss the stability of main active compounds from clove oil; to measure the free radical scavenging activities on DPPH·of clove oil; to study the antimicrobial effect of clove oils applied in main pathogens of grapes, Chinese dates and the fresh-keeping effect between clove oil and other natural plants essential oil applied in cherry were also studied. This research would provides a necessity to guide on developing and using clove oil on antisepticise and fresh-keeping.(1) Five pathogens were isolated and identified from fruit and vegetables, antimicrobial effect of clove oils on there were studied. Results showed minimum inhibitory concentration (MIC) of clove oil on Botrytis cinerea, Alternaria spp. Emericella nidulans were 3.13 mg/mL, on Rhizopus was 6.25 mg/Ml; minimum bactericidal concentration (MBC) of clove oil on Botrytis cinerea was 3.13 mg/mL, on Rhizopus,Alternaria spp and Emericella nidulans were 6.25 mg/mL. Eugenol and Eugenol acetate of 0.35 mg/mL all can completely inhibit the growth of Botrytis cinerea and Alternaria spp. Antimicrobial acitivity of Eugenol acetate stronger than Eugenol, whileβ-caryophyllene could not inhibite the growth of the phathogens and also have no positive impact on the antimicrobial acitivity of Eugenol and Eugenol acetate.(2) Supercritical fluid extraction (SFE) of essential oil from clove buds with CO2 was explored. Results showed the clove essential oil extraction rate by SFE was highest (18.4%) within three extraction methods, the extraction time was shortest (2h), and no chemical reagents residues in the final essential oils and low energy consumed. 23 fragrance compounds were identified by the GC-MS, the main chemical compounds were eugenol, eugenol acetate andβ-caryophyllene, their relative content higher than 90%. Along with the extractiom times increasing, the content of the eugenol presents increased, the content of eugenol acetate have no obvious change ,and theβ-caryophyllene decreased. Stability experiments showed that the Eugenol and eugenol acetate showed higher stability in the neuter medium, they still have better heat stability after 5 hours in a 60℃constant temperature bath, but the irradiation of nature light will cause its absorbance decreased lightly.(3) Scavenging ability on 1,1-diphenyl-2-picryhydrazyl (DPPH·) radicals of clove oil showed the speed of scavenge was quick and about 3 minutes have reached stabilization. The variety of DPPH·remain rate was slow with the time increasing, better than BHT, the antioxidant activity was equal to BHT. The main active chemical compound of clove oil was Eugenol which have high speed on scavenging DPPH·, about 30 seconds have attained stabilization, but the eugenol acetate attained stability in the 30 minutes. Theβ-caryophyllene has no antioxidant activity and there was no conjunction function with eugenol and eugenol acetate.(4) Clove essential oil suffocating process could effectively suppress storage rotten of green pepper. After 28 days at room temperature, the rotten rate of green pepper which treated by 3.0μL/L suffocating clove essential oil was comparison's 47.6%, the rotten index reduces 58.1% compared to the comparison, simultaneously clove essential oil processing also slowed down the SSC, titrate acid(TA) and VC content dropment of green pepper.(5) 4 suffocating kinds of plant essential oil—clove essential oil, citronella essential oil, leaf essential oil of Artemisia argyi and lemon essential oil—could effectively control the occurrence of rotten and fruit peduncle turning brown in cherry storage, they were advantageous in maintains the cherry degree of hardness, they can maintain the content of SSC, TA and Vc, the flavor and the feeling of mouth surpasses the comparison. Clove essential oil and citronella essential oil processing effect is obvious, leaf essential oil of Artemisia argyi and lemon essential oil treated next best. Mustard essential oil processes easily to have the chemical damage, the function of maintains freshness not to be ideal.