RECENT interest in natural materials, especially plant extracts, has increased as natural food preservatives following the rise of antimicrobial resistance, as well as the bad reputation of industrial preservatives of consumers. This study aims to evaluate the potential use of plant extracts as an effective and safe alternative for food preservation. Also, it provides factors influencing anti-bacterial effect using meat-based and milk-based models.
Ethanolic plant extracts produced extremely important antimicrobial effects via inhibiting the tested multi-drug resistant bacteria. Sumac (Rhus coriaria) found to be the most effective extract producing inhibition zones average 27mm, followed by clove, rosemary and lemon (24mm, 21mm and 18mm, respectively), Whereas black pepper showed intermediate activity (10-16mm). The aqueous extracts showed lower activity. The combination of sumac with clove and clove with rosemary produced additive effect in most cases, whereas, sumac with rosemary produced synergistic effect in all cases. On the other hand, combination of sumac with clove and rosemary produced antagonistic effect.
The interaction or reaction of plant extracts with food components reduced the antibacterial effects of plant extracts; therefore, higher concentrations of used extracts were required to do the same effects in meat-based and milk-based models as in microbiological medium. The results indicated that plant extracts possessing antimicrobial activity can be used as ideal food preservatives after taken into account the reaction and interaction between food components and extract.