Faculty of Veterinary Medicine University of Zagreb
Abstract
In this study, the antibacterial activity of a total of 16 spices at a final concentration of 2.5 % against V. parahaemolyticus at two different temperatures, 5 and 37 ºC, was tested. Anise seed, chili, cloves, cinnamon, coriander seed, cumin, curry, garlic, ginger, oregano, paprika, black and white pepper, rosemary, thyme and turmeric, were collected from a retail store from the same producer. Prior to antibacterial screening, the spices were analyzed using standard microbiological procedures for: aerobic spore forming bacteria, sulfite-reducing clostridia, yeast and molds, Enterobacteriaceae, Escherichia coli, coagulase-positive staphylococci, and the presence of Salmonella spp. and Listeria monocytogenes. For detection of anti-Vibrio activity, the same amount of V. parahaemolyticus culture in NaCl-BHI broth, at 104 cfu/mL, was added to the 5 % suspension of spices, incubated for 24 h and then inoculated onto TCBS agar. After screening, minimal inhibitory concentrations were determined for spices, which showed strong antimicrobial activity. Salmonella spp., Listeria monocytogenes, E. coli and coagulase-positive staphylococci were not detected in any of the spice samples. Aerobic spore forming bacteria were present in 93.7 %, sulfite reducing clostridia in 43.7 %, yeasts in 12.5 %, molds in 62.5 % and Enterobacteriaceae in 18.7 % of the spice samples. At 5 °C, all spices except anise and coriander seed showed antibacterial activity against V. parahaemolyticus, with viable count reduced by at least 1 log; strong antibacterial activities at this temperature were found for oregano, garlic, thyme, cloves, cinnamon, curry, rosemary, ginger and turmeric. Oregano, garlic, thyme, cloves and cinnamon showed strong antibacterial activity at 37 °C. The lowest minimal inhibitory concentration at 37 °C was 0.078 % in cloves, and at 5 °C was 0.0012 % in turmeric. The effect of the accompanying microflora of the spices on the number of V. parahaemolyticus was not observed. This result showed that some spices have potential for reducing the risk of contaminating V. parahaemolyticus in seafood, combined with low temperature.U ovom istraživanju pretražena je antibakterijska aktivnost ukupno 16 začina finalne koncentracije 2,5 % prema V. parahaemolyticus, na temperaturi od 5 i 37 ºC. Anis, čili, klinčić, cimet, korijander, kumin, curry, češnjak, đumbir, origano, paprika, crni i bijeli papar, ružmarin, timijan i kurkuma, kupljeni su u maloprodaji od istog proizvođača. Prije pretraživanja antibakterijske aktivnosti, začini su pretraženi standardnim mikrobiološkim postupcima na: aerobne sporogene bakterije, sulfitreducirajuće klostridije, kvasce i plijesni, Enterobacteriaceae, Escherichia coli, koagulaza pozitivne stafilokoke, te prisutnost bakterija Salmonella spp. i Listeria monocytogenes. Za utvrđivanje anti-vibrio aktivnosti, 5 % otopini začina dodana je kultura V. parahaemolyticus u NaCl-BHI bujonu u broju 104 cfu/mL, te je uslijedila inkubacija 24 sata, a zatim nacjepljivanje na TCBS agar. Nakon utvrđivanja antibakterijske aktivnosti, utvrđena je i minimalna inhibicijska koncentracija za začine koji su pokazali jaku aktivnost. Salmonella spp., Listeria monocytogenes, E. coli i koagulaza-pozitivni stafilokoki nisu nađeni niti u jednom uzorku začina. Aerobne sporogene bakterije utvrđene su u 93,7 %, sulfitreducirajuće klostridije u 43,7 %, kvasci u 12,5 %, plijesni u 62,5 % i Enterobacteriaceae u 18,7 % uzoraka začina. Na temperaturi od 5 °C, svi začini osim anisa i korijandera pokazali su antibakterijsku aktivnost protiv V. parahaemolyticus smanjivši ukupan broj bakterija za najmanje 1 log cfu/mL, a jaku antibakterijsku aktivnost na toj temperaturi pokazali su origano, češnjak, timijan, klinčić, cimet, curry, ružmarin, đumbir i kurkuma. Na 37 °C, origano, češnjak, timijan, klinčić i cimet su pokazali antibakterijsku aktivnost, i to jaku. Minimalna inhibicijska koncentracija na 37 °C bila je 0,078 % za klinčić, i 0,0012 % za kurkumu na 5 °C. Nije primijećen utjecaj prateće mikroflore začina na broj V. parahaemolyticus. Ovi rezultati su pokazali da neki začini imaju potencijal za smanjenje rizika od V. parahaemolyticus u proizvodima ribarstva, a u kombinaciji s niskom temperaturom
