**3. Control of** *Salmonella* **in foods**

High temperatures used in cooking and in pasteurization processes have been regarded as the treatment of choice for the destruction of *Salmonella* in eggs, milk and meat products. Humphrey et al. (1980) showed that to kill *Salmonella* present in the egg yolk, the yolk temperature had to be raised to >8O°C. Boiling for over 6 to 10 min was required inactivate approximately 107 cfu *S. enteritidis* in the yolk of shell eggs, depending on the method of boiling (Chantarapanont et al., 2000). Kuo et al. (1997) determined that UV radiation significantly reduced *S. typhimurium* inoculated on shell eggs. Directional microwave technology resulted in more than 2-log reduction of *S. enteritidis* in shell eggs without causing any detrimental effects to quality reviewed by Lakins et al. (2008). The effectiveness of steam treatments on meat and poultry has been investigated, which the presence of a number of pathogens may be reduced by the application of steam to meat surfaces, mostly gram negative enteric pathogens, such as *Escherichia coli* O157:H7 and a number of

Inhibitory Effect of Plant Extracts on Salmonella spp. 337

Plant contain a variety of substance called "phytochemicals" (divided into two groups; primary and secondary metabolite), which are naturally occurring biochemicals in plants that give plants their color, flavor, smell and texture. Plant secondary metabolite differ from ubiquitous primary metabolite (e.g. carbohydrate, proteins, fats, nucleic acid) (Bako and Aguh, 2007), that have a scientifically proven effect on human health. The most important of these bioactive constituents of plants are alkaloids, tannins, flavonoids, anthraquinone,

Extraction is the first important step for the recovery and purification of active ingredients of plant materials. Several extraction techniques and solvents are used for obtain antioxidant and antimicrobial extract from plant origin. The general techniques of medicinal plant extraction include maceration, percolation, hot continuous extraction (Soxhlet), solvent extraction, counter-current extraction, microwave-assisted extraction, ultrasound extraction (sonication), supercritical fluid extraction (Chen et al., 1992; Bicchi et al., 2000; Kaufmann and Christen, 2002). For solvent extraction method, polar solvents (such as organic acids), solvents of intermediate polarity (such as methanol, ethanol, acetone, and dichloromethane) and solvents of low polarity (such as hexane and chloroform) are used to extract plant secondary metabolites, which the extracts obtained from the same plant material with different solvent characteristics have distinct physical and biological properties. Lapornik, et al. (2005) reported that ethanol and methanol extracts of red and black currant contain twice more anthocyanins and polyphenols than water extracts, extracts made from grape marc had seven times higher values than water extracts. Among the five different Indian medical plants, methanol extract showed more antibacterial activity and moderate activity with aqueous, ethyl acetate and chloroform extract (Ashokkumar et al., 2010), while the morepolar solvent extracts (BuOH and water extracts) in Korean herbal medicines gave higher antioxidant activity than that of non-polar solvent extracts (hexane and EtOAC extracts) (Kang et al., 2003). Moreover, the chemical compound of extracts from particular plant species can vary according to the geographic origin, harvesting period and parts of the plant use. Nwokocha et al. (2011) found that all secondary metabolites analyzed were present in all tissues (leaf, stem, root and seed) studied but at different concentrations. A spatial and seasonal impact on the total phenolic content has been reported for *Poacynum henersonii* 

Essential oils are a volatile liquid aromatic compound which extracted from plant cell. The cells are location in specific parts of the plant such as bark, flowers, leave, seed, peel and root. Table 1 shows the plant organ contains essential oil and their essential oil constitutes. Distillation (water distillation, water and steam distillation, steam distillation) is the most commonly used method for produces essential oils on the commercial basis (Rasooli, 2007). Some volatile oils cannot be distilled without decomposition are thus are usually obtained by expression (such as lemon oil or orange oil). The effect of diffrent distillation methods on oil content and composition of aromatic plants have been reported. The water-distillation of the rose-scented geranium (*Pelargonium* sp.) gave a higher oil yield (0.16–0.22%) than did water-steam-distillation (0.09–0.12%) or steam-distillation methods (0.06–0.18%) (Kiran et al., 2005). The oil of *Satureja rechingeri* Jamzad in full owering stage obtained by hydrodistillation, water- and steam-distillation and direct steam-distillation consisted of twenty, seventeen and twenty-two compounds, respectively, which the major constituents were

other phenolic compound and essential oil (Kisangau et al, 2007).

collected at three sites in China (Hong et al., 2003).

carvacrol and p-cymene (Sedkon et al., 2007).

**5. Plant extract** 

*Salmonella* serotypes (James et al., 2000; Phebus et al., 1997; Whyte et al., 2003). Following the published report by Porto-Fett et al., 2010, the fermentation and drying and/or high pressure processing of contaminated dry sausage or pork are effective for inactivating *Salmonella* spp. High-pressure treatment of milk is considered to be the most promising alternative to traditional thermal treatments. Metrick et al., (1989) indicated that the pressure treatments of 310 and 379MPa/15 min at ambient temperature were required for a 3-log reduction in colony forming units (cfu) of *S. seftenberg* 775W.
