Study On Antibacterial Activities Of Propolis Extracts And Its Application On Preservation Of Cooling Beef

In the paper, extracts of propolis prepared by ethanol extraction and supercritical CO2 extraction were taken as the research objects. Effective chemical components of ethanol extracts of propolis(EEP) and supercritical CO2 extracts of propolis(SCEP) were determined, and antibacterial activities of them were studied. EEP solution and SCEP solution were used to soak beef ,then these beef were packaged with vacuum packagings and preserved under the condition of 4℃to study on application of EEP solution and SCEP solution on the preservation of chilled beef.1. EEP solution and SCEP solution were diluted into 2.5 %, 2.0 %, 1.5 %, 1.0 %, 0.5 %, 0.1 %. Disc diffusion tests were used to study on antibacterial activities of each group of EEP and SCEP against Escherichia coli,Staphylococcus aureus,Salmonella Lignieres,Bacillus cereus,Penicillium chrysogenum and mixed bacteria of beef surface.The results of research showed: Higher the concentrations of EEP solution and SCEP solution were, better the antibacterial activities were. EEP solution and SCEP solution were quite active against gram-positive bacteria and were not significant against gram-negative bacteria.2. Ultrasonic treatment is the choosed treatment which could enhance antibacterial activities of extracsts of propolis best among heating treatment, microwave treatment and ultrasonic treatment.3. The samples of chilled beef were treated with the EEP solution and SCEP solution, according to the programe of quadratic-general rotation experiment. After twenty-day preservation under the condition of 4℃,the samples were evaluated by the values of TVB-N, the results of evalution showed: (1)The values of TVB-N and the coding values of four influencing factors which were concentration of propolis extracts solution (X1), ultrasonic treatment time (X2), ultrasonic power (X3) and ultrasonic frequency(X4), were viewed as independent variables.The regression equation of group EEP: YA =0.07116+ 0.00689X1+0.00288X2+ 0.00409X3- 0.002182X4+ 0.00318X12+ 0.00244X22-0.00096X32 -0.00432X42 -0.00291X1X2+ 0.00023X1X3-+0.00043X1X4 -0.00394X2X3 -0.00339X2X4+ 0.00109X3X4 The regression equation of group SCEP: Ys=0.0652+0.00664X1-0.00293 X2+0.00473 X3+0.00155 X4+0.00340 X12-0.00161 X22-0.00258 X32-0.00313 X42-0.00358 X1X2-0.00124 X1X3+0.00010 X1X4+0.00115 X2X3-0.00016 X2X4-0.00038 X3X4(2)The rankings of each factor influenting to the value of TVB-N were: In group EEP, concentration of solution,ultrasonic power,ultrasonic treatment time , ultrasonic frequency;In group SCEP,concentration of solution,ultrasonic power,ultrasonic treatment time, ultrasonic frequency.(3)According to the mathematical models, the optimal schemes were that: In group EEP, concentration of solution was 2.0 %, ultrasonic treatment time was 150 s, ultrasonic power was 400 W, ultrasonic frequency was 60 KHz; In group SCEP,concentration of solution was 2.0 %, ultrasonic treatment time was 150 s, ultrasonic power was 350 W, ultrasonic frequency was 60 KHz.(4) According to the mathematical models, the interactions of influencing factors were that. In group EEP, ultrasonic treatment time and ultrasonic frequency had the effect of synergistic interaction. When the values of codes of two factors were low at the same time, Y was big. Ultrasonic power and ultrasonic frequency had the effect of synergistic interaction. In group SCEP, concentration of solution and ultrasonic power had the effect of synergistic interaction. When the values of codes of two factors were high at the same time, Y was big. Concentration of solution and ultrasonic frequency had the effect of synergistic interaction.4. After determination of TBARS, colony count and drip loss, the preserving quality of chilled beef was analyzed by fuzzy comprehensive evaluation. The process was that: confirmation of the factors, confirmation of remark and the equal weight integrate, fuzzy transition and normalization, confirmed the results and made order. The results of fuzzy comprehensive evaluation showed that: the sensory character of the chilled beef which were treated with SCEP solution and EEP solution were much better than the ones which treated with no preservatives. It also proved that SCEP solution and EEP solution were effective roles on the preservation of chilled beef.5. The results which analysised by HPLC on the base of luteolin, galangin, apigenin, kaempferol, myricetin, chrysin, rutin and qurecentin as standard samples showed that, the leaching rate of main flavonoids from EEP was 16.32 %, and the leaching rate of main flavonoids from SCEP was 3.17 %. Making reference to results which analysised by GC-MS to analysis on the content of volatile compounds (terpenes, phenols and alcohols, aldehydes and ketones, aromatic acids and its esters etc.) in EEP and SCEP.