Comparison of Antimicrobial Effect of Parstinaca sativa (Zardak) and Daucus carota on Listeria monocytogenes

The antilisterial properties of some vegetables such as Daucus carota have already been reported, but there is no report on Zardak (Parstinaca sativa). The objective of this study was comparison of the inhibitory effect of Zardak and Daucus carota (shredded and concentrations of juice) on two suspensions of Listeria (L.) monocytogenes. In this experimental study, contamination of two carrot cultivars was examined according to national standard no. 8035-1. Then carrot treatments prepared. Two suspensions (103 and 105 CFU/ml) of L. monocytogenes serotype 1295 PTCC inoculated on shredded and concentrations of carrot juices. After 1 and 24 h in refrigerator, inoculations were cultured on Listeria Selective Agar. The results reported according to the difference between the typical Listeria colonies on inoculated and control plates. Data were analyzed by Kruskal-Wallis test. P-Values lower than 0.05 was considered significant. Carrot samples had no Listeria contamination. Statistical analysis showed both cultivars had significant inhibitory effect on L. monocytogenes, but it is more in Zardak than Daucus carota (p<0.005). The inhibitory effect of Zardak was shown on both bacterial concentrations, but Daucus carota effect only on 103 CFU/ml. The effect of Zardak became more after 24 h in refrigerator than 1 h (p<0.05), but it made no difference in Daucus carota. Whole carrot juice had more effect than other treatments (p<0.05). We noticed fresh carrots had no inhibitory effect, but it could be seen by keeping carrots in refrigerated or room temperature for 4 days. Both Zardak and Daucus carota have antilisterial properties, but the effect of Zardak was more significant. Variable inhibitory conditions would be objectives of other researches. On the other hand, probability of extracting antilisterial compounds from Zardak and using as a natural food preservative is suggested