In vitro assessment of antimicrobial activity of carvacrol, thymol and cinnamaldehyde towards Salmonella serotype Typhimurium DT104: effects of pig diets and emulsification in hydrocolloids

Abstract

Aims: To determine the effect of pig diets in vitro on the antimicrobial activity of carvacrol, thymol and cinnamaldehyde, and to identify an emulsifier/stabilizer that can stabilize the essential oil (EO) components in aqueous solution and retain their antimicrobial activity in the presence of the diets. Methods and Results: Emulsification of essential oil components with hydrocolloid solution was achieved by blending with a Polytron. Antimicrobial activity was measured through in vitro assays to determine the inhibition of bacterial growth by measuring the optical density at 600 nm or plating on nutrition agar after incubation of the mixtures of an EO component with the culture of Salmonella serotype Typhimurium DT104 in the presence or absence of pig diets. The results generated through the in vitro assays indicated that pig diets were able to abolish the antimicrobial activity of EOs. Xanthan, fenugreek and yellow mustard gums were the best in forming stable emulsions of five different EO components among ten different plant polysaccharides and surfactants examined. Emulsification of all the EO components in the fenugreek gum solution did not alter their antimicrobial activity. However, the antimicrobial activity of geraniol was significantly reduced when emulsified with other polysaccharides and surfactants. Both fenugreek and xanthan gum solutions were unable to protect the antimicrobial activity of carvacrol and thymol when mixed with the diets. Although cinnamaldehyde required no emulsification, but a high concentration (equivalent to at least three times of minimum bactericidal concentration for cinnamon oil) to inhibit Salmonella growth significantly in the presence of the diets, emulsification in fenugreek gum appeared to be essential for cinnamaldehyde solution to retain its antimicrobial activity during storage. Conclusions: The diets for newly weaned pigs were a significant factor limiting the antimicrobial activity of EOs and their components. Cinnamaldehyde required a high concentration to retain its antimicrobial activity in the diets, in addition to its requirement for emulsification to stabilize its activity during the storage. Significance and Impact of the Study: The assay with the diets used in this study for measuring the antimicrobial activity can be used in vitro for rapid and effective screening of potential antimicrobials for swine production. This study has identified polysaccharides that are able to stabilize EO component solutions. It has also identified cinnamaldehyde for further in vivo studies that may have potential in future application in controlling Salmonella and possibly other enteric pathogens in swine production.

Effect of probiotics and herbals on health and shedding of resistant escherichia coli in piglets

“…Some herbals contain essential oils with strong antimicrobial activity, particularly, phenolic structures, which damage cell membrane of bacteria (Lambert et al, 2001), but with little inhibition towards Lactobacillus spp. (Si et al, 2006), that can be seen in our study, too. Buckwheat flour has demonstrated the potential of prebiotic.…”

Modulation of Plasma Antioxidant Activity in Weaned Piglets by Plant Polyphenols

“…In other words, the concentration composition of an arbitrary mixture could be fitted to a model based on these uniform designed mixtures. The in vitro antioxidant or antimicrobial activity of plant extracts and oil has been recognised for many years (Bagchi et al, 1997;Lu and Foo, 2000;Tepe et al, 2004;Si et al, 2006;Lee et al, 2009). Data from multiple studies have demonstrated that plant extracts possess a spectrum of activity against different pathogens.…”

Cytotoxic, anti-carcinogenic and antioxidant properties of the most frequent plant volatiles

“…They manifested a synergistic bactericidal effect [19]. Carvacrol, cinnamaldehyde, thymol and oregano oil inhibit significantly the growth of Clostridium perfringens in commercial meat products [20,21]. The utility of selected aroma-compounds (citral, trans-cinnamaldehyde, (-)-perillaldehyde, (-)-citronellal, eugenol and carvacrol) for the reduction of bacteria in a room was investigated by Sato et al [22].…”