**13. Plant extracts**

*Essential Oils - Bioactive Compounds, New Perspectives and Applications*

The essential oils of some aromatic plants contain some photoactive compounds

EOs and their monoterpenes affected bone metabolism when added to the food of rats. It was demonstrated that these lipophilic compounds inhibited bone resorption [114]. It was reported that (2*E*,6*R*)-8-hydroxy-2,6-dimethyl-2-octenoic acid, a novel monoterpene, from *Cistanche salsa* had antiosteoporotic properties [115]. Pine EOs prevented bone loss in an osteoporosis model (ovariectomized rats). The monoterpenes borneol, thymol and camphor directly inhibited osteoclast resorption [114]. It was observed that inactive monoterpenes can be metabolized to their active forms *in vivo*; thus, *cis*-verbenol, a metabolite of *α*-pinene, inhibited osteoclastic resorption activity, in contrast to the parent compound *α-*pinene.

Potential activities for the treatment of Alzheimer's disease were demonstrated in a pilot open-label study involving oral administration of the EO of *Salvia lavan-*

Chinese angelica (*Angelica sinensis*) is the most important female tonic remedy in Chinese medicine. The effects of angelica EO in three assays in mice (elevated plus maze, light/dark and stress-induced hyperthermia test) suggested that angelica EO exhibited an anxiolytic-like effect [116]. A link to emotion and cognitive performance with the olfactory system was reported [117]. Moreover, the EOs could affect mood, concentration and sleep [118], while other studies had shown that EOs were

EOs from different *Lippia alba* chemotypes showed behavioral effects. Greater effects were presented by chemotype 2 (with citral and limonene), while chemotype 1, containing citral, myrcene and limonene, decreased only the number of rearings in the open-field test [121]. The EO of lemon was found to modulate the behavioral and neuronal responses related to nociception, pain and

in their composition. Psoralens present in essential oil of citru bergamia were found to effective for binding of mono and biadducts produced under UV-light. These were found to mutagenic and cytotoxic [112]. However, in the dark, this oil is not cytotoxic or mutagenic by itself. It has been noted that *Fusanus spicatus* wood essential oil was not phototoxic but was very cytotoxic. In other words, cytotoxicity seems rather antagonistic to phototoxicity. In the case of cytotoxicity, essential oils damage the cellular and organelle membranes and can act as pro-oxidants on proteins and DNA with production of reactive oxygen species (ROS), and light exposures do not add much to the overall reaction. In the case of phototoxicity, essential oils penetrate the cell without damaging the membranes or proteins and DNA. Radical reactions by excitation of certain molecules and energy transfer with production of oxygen singlet occur when cells are exposed to activating light. This may cause damage to cellular macromolecules and in some cases the formation of covalent adducts to DNA, proteins and membrane lipids. Obviously, cytotoxicity or phototoxicity depends on the type of molecules present in the essential oils and their compartmentation in the cell, producing different types of radicals with or without light exposure. However, such an antagonism is not quite a strict rule [86]. It was also found that *Citrus aurantium* dulcis (*Citrus gracilis* subf. dulcis) and *Cymbopogon citratus* essential oils were phototoxic and cytotoxic. Therefore, the potential toxicity of essential oil should be considered before use as antibacterial for

**11. Photo toxicity of essential oils**

human as well as for animals [113].

*dulaefolia* Vahl. known as Spanish sage [7].

potentially important to boost the immune system [119, 120].

**12. Other activities**

**166**

Plant extracts have shown a considerable promise in a range of applications in the food industry and several plant extracts enjoy GRAS status. The antimicrobial activities of plant extracts may reside in a variety of different components and several extracts owing to their phytochemical constituents have been shown to have antimicrobial activity. The antibacterial activity is most likely due to the combined effects of adsorption of polyphenols to bacterial membranes with membrane disruption and subsequent leakage of cellular contents [126, 127], and the generation of hydroperoxides from polyphenols [128]. Plant extracts also showed antifungal activity against a wide range of fungi, antioxidant and antimutagenic activities [129] and inhibited lipid oxidation in foods [130]. Although numerous studies have been done *in vitro* to evaluate the antimicrobial activity of plant extracts, very few studies are available for food products, probably because plant extracts did not produce as marked inhibition as many of the pure compounds in foods. The reduced effectiveness may be attributed to the use of crude extracts in most studies. As the crude extracts generally contain flavonoids in glycosidic form, where the sugar present in them decreases effectiveness against some bacteria [131, 132].

Dietary herbs and spices have been traditionally used as food additives throughout the world not only to improve the sensory characteristics of foods but also to extend their shelf life by reducing or eliminating survival of pathogenic bacteria. Herbs and spices are rich in phenolic compounds and besides exerting antimicrobial effect they may preserve the foods by reducing lipid oxidation as they are reported to have significant antioxidant activity [133]. A wide variety of phenolic substances derived from herbs and spices possess potent bio- logical activities, which contribute to their preservative potential [134]. Careaga et al. [135] reported that 1.5 ml/100 g of capsicum ex- tract was sufficient to prevent the growth of *Salmonella typhimurium* in raw beef but that 3 ml/100 g was required for a bactericidal effect against *P. aeruginosa*. Treatment with hydrosol of thyme, black cumin, sage, rosemary and bay leaf was reported to reduce *S. typhimurium* and *E. coli* O157:H7 in apple and carrots [136]. Black cumin ethanolic extract applied in a marinade base for raw trout was found to reduce aerobic plate count, yeast, and coliforms [137]. Lee et al. [138] observed that the addition of green tea or rosemary (1 or 3%) to rice cakes significantly reduced the levels of *B. cereus* and *S. aureus* during 3 days storage at room temperature (22°C). Ahn et al. [139] reported that a range of plant extracts are useful for reduction of pathogens associated with cooked beef, however, Uhart et al. [140] reported that spices inactivate *S. typhimurium* DT104 in *in vitro* condition, but the activity decreased considerably when added to a complex food system such as ground beef. Kim et al. [141] observed that ground beef samples did not show significant difference in *L. monocytogenes*, *S. aureus* and total bacterial counts after treatment with green and jasmine tea as compare to untreated samples, however, a slight reduction in viable count of *Salmonella enterica Serotype Enteritidis* and *Listeria monocytogenes* in ground beef by watersoluble arrowroot tea extract (upto 6% w/w) was reported [142]. Combination of

different plant extracts showed better preservative effects on meat as rosemary extracts and dry powders of orange and lemon applied to beef meatballs were found to be effective in controlling bacterial spoilage during 12 days storage period at 8°C [143]. Mixtures of Scutellaria, honeysuckle, Forsythia and cinnamon or cinnamon, rosemary and clove oil showed 1.81–2.32-log reductions in microbial counts as compare to control in vacuum-packaged fresh pork during 28 days storage [144]. Yin and Cheng [145] reported that the antimicrobial properties of garlic are due to organosulfur compounds. Freshly ground garlic, when added to mayonnaise at a concentration of 1% reduced *Salmonella* count [146]. Garlic also has been shown to reduce the levels of *E. coli* in ground meat [147]. Sallam et al. [148] observed that addition of fresh garlic and garlic powder controlled microbial contamination and preserved chicken sausages. Species of the genus *Mentha* (family *Lamiaceae*) are a rich source of polyphenolic compounds, flavonoids, terpenoids, and other volatile compounds, which imparts it a strong antimicrobial property [149]. Nguyen and Mittal [150] reported more than 8 log reductions in the artificially inoculated pasteurized tomato juice when mint was used as a preservative.

Turmeric, a tropical herb of *Zingiberaceae* family is used in Indian cuisine mainly for its coloring and flavoring characteristics, and curcumin is the active constituent of turmeric responsible for its preservative action [151]. Even, the byproducts of curcumin manufacture were found to have high biological activity [152, 153]. Turmeric extract (1.5%, v/v) alone or in combination with shallot extract (1.5% each, v/v) were found to retain quality characteristics of vacuum-packaged rainbow trout (*Oncorhynchus mykiss*) during a refrigerated storage of over a period of 20 days [154].

Cinnamon is the source of cinnamon bark, fruit, leaf and their essential oils and many *Cinnamomum* species yield a volatile oil on distillation with different aroma characteristics and composition [155, 156]. Extracts of the cinnamon bark and fruit and cinnamon oil have been reported to possess antimicrobial, antioxidant and antimutagenic activities [157]. Cinnamon was found to reduce the levels of *E. coli* in apple juice [158]. Yuste and Fung [159] reported up to 6 log cfu/ml reductions of artificially inoculated *L. monocytogenes* in pasteurized apple juice with 0.1–0.3% (w/v) of ground cinnamon after 1 h of incubation, and no further growth of the microorganism occurred during 7 days of storage. Ceylan et al. [158] reported that the addition of 0.3% (w/v) cinnamon powder gradually decreased the counts of *E. coli* O157:H7 in pasteurized apple juice, whereas only 2 log cfu/ml reduction of *E. coli* O157:H7 in unpasteurized apple cider was reported even by addition of 2% (w/v) cinnamon powder [160].

*Punica granatum* L. has a rich history of traditional use of its bark, leaves, flowers, fruits and seeds to ameliorate diseases. The presence of phytocompounds in the pomegranate extracts such as phenols, tannins and flavonoids as major active constituents may be responsible for these medicinal values [161, 162]. Several studies have reported the efficacy of various extracts from the different parts of pomegranate plant against the growth of Gram positive and Gram negative bacteria [163]. Aqueous and ethanolic fruit shell extracts of *P. granatum* were found to have antibacterial activity against different strains of *E. coli* [164], *Salmonella* Typhi [165], and it inhibited Staphylococcal enterotoxin A production [166]. Various other solvent extracts from the rind of *P. granatum* also showed antibacterial activity against enterohaemorrhagic *E. coli* and food spoilage bacteria [162]. Pomegranate peel extracts were used to enhance the shelf life of chicken meat products by controlling oxidative rancidity and bacterial growth [167].

Various species of *Garcinia* contains several secondary metabolites which exhibit a wide range of biological and pharmacological activities such as antimicrobial, antioxidant, antitumour-promoting and cytotoxic activities [168].

**169**

*Essential Oil as Antimicrobial Agents: Efficacy, Stability, and Safety Issues for Food Application*

Seabuckthorn has been widely used in traditional medicines, mainly of Tibetian,

Mongolian, Chinese and Middle Asian cultures [176, 177] for the treatment of asthma, skin diseases, gastric ulcers, lung disorders, cough, diarrhea, and menstrual disorder [178]. The health benefits of *Hippophae rhamnoides* oils, juice, leaves and bark are also well known and they have been used to treat several diseases [179]. All parts of the seabuckthorn plant are considered to be rich source of a large number of bioactive substances and are reported to have antimicrobial [180], antioxidant [181], and antimutagenic activities [182]; and antitumoral, hepato-protective and immunumodulatory [183], anti-platelet aggregating [184], anti-inflammatory [185], and radio-protective properties [186]. The leaf extract was reported to have better immunomodulatory effect than fruit extracts [183]. Jelly prepared by using seabuckthorn berries showed microbiological stability at ambient temperature and 37°C for a period of 6 months [187]. Various other plant extracts were found to be effective against *L. monocytogenes* in refrigerated meat products [188, 189]. The effect of a mixture of oregano and cranberry (0.1 mg of phenolic/ml) on beef slices and cod fish filet was studied by Lin et al. [190] and they observed that at pH 7, phytochemicals have no significant effect on cell numbers after 18 h of incubation, but at pH 6.0, differences in viable cell counts were observed in beef and fish slices. The oregano-cranberry extract mixture showed higher log reduction in viable counts than the slices treated with either oregano or cranberry extract [190]. Ruiz et al. [191] also reported that although rosemary extract was not able to completely eliminate *L. monocytogenes* in ready-to-eat vacuum-packaged diced turkey and ham, it significantly decreased the counts when used along with nisin. Cranberry powder alone at 1, 2, and 3% levels resulted in 2–4 log cfu/g reduction in growth of *L. monocytogenes* compared to the control (treated with nitrite, p ≤ 0.05), and similar effect on growth was seen when it was combined with cherry powder, lime powder and grape seed extracts in a cured cooked meat model system [192]. Grape seed extract and pine bark extract were used to control the growth of artificially inoculated bacteria on the surface of raw ground beef during refrigerated storage [193]. The combination of grape seed extract and nisin gave the greatest inhibitory activity with reductions of *L. monocytogenes* populations to undetectable levels after 21 days indicating potential of natural antimicrobials to control the growth and

Likhitwitayawuid et al. [169, 170] reported antimalarial activity of xanthones isolated from the bark of *G. dulcis* and *G*. *cowa*. Crude extracts as well as partially purified compounds from different parts of some species of Garcinia have shown antibacterial potential [171]. A polyisoprenylated benzophenone (garcinol) isolated from stem bark of *G. huillensis* has been shown to be active against Gram positive and Gram negative cocci, mycobacteria and fungi but inactive against Gram negative enteric bacilli, yeast and viruses [172]. Alpha-mangostin, rubraxanthone, and xanthochymol isolated from *G. mangostana*, *G. diocia* and *G. subelliptica*, respectively, showed strong antibacterial activity against both methicillin-resistant and methicillin-sensitive *S. aureus* [173, 174]. Crude extracts of leaves, fruits, root, stem and trunk bark of *G. atroviridis* exhibited antibacterial activity with the root extract showing the strongest inhibition, while the fruit and leaf extracts exhibited significant antifungal activity against *Cladosporium herbrum* [168]. Crude extracts

of *G. indica* also showed antiaflatoxigenic properties [175].

recontamination of *L. monocytogenes* on meat products [194].

Dried plum puree was found to reduce *E. coli* and *Salmonella* in ground meat [195]. Karapinar and Sengun [196] recommended use of unripe grape juice for enhancing the safety of salad vegetables. Grape pomace extract and olive extracts showed antimicrobial activity in apple juice [197]. Grape seed extract (1%) and rosemary oleoresin (1%) reduced the populations of *E. coli* O157:H7, *S. typhimurium* and *L. monocytogenes* after 9 days in raw ground beef [193]. Owen and Palombo

*DOI: http://dx.doi.org/10.5772/intechopen.92305*

### *Essential Oil as Antimicrobial Agents: Efficacy, Stability, and Safety Issues for Food Application DOI: http://dx.doi.org/10.5772/intechopen.92305*

Likhitwitayawuid et al. [169, 170] reported antimalarial activity of xanthones isolated from the bark of *G. dulcis* and *G*. *cowa*. Crude extracts as well as partially purified compounds from different parts of some species of Garcinia have shown antibacterial potential [171]. A polyisoprenylated benzophenone (garcinol) isolated from stem bark of *G. huillensis* has been shown to be active against Gram positive and Gram negative cocci, mycobacteria and fungi but inactive against Gram negative enteric bacilli, yeast and viruses [172]. Alpha-mangostin, rubraxanthone, and xanthochymol isolated from *G. mangostana*, *G. diocia* and *G. subelliptica*, respectively, showed strong antibacterial activity against both methicillin-resistant and methicillin-sensitive *S. aureus* [173, 174]. Crude extracts of leaves, fruits, root, stem and trunk bark of *G. atroviridis* exhibited antibacterial activity with the root extract showing the strongest inhibition, while the fruit and leaf extracts exhibited significant antifungal activity against *Cladosporium herbrum* [168]. Crude extracts of *G. indica* also showed antiaflatoxigenic properties [175].

Seabuckthorn has been widely used in traditional medicines, mainly of Tibetian, Mongolian, Chinese and Middle Asian cultures [176, 177] for the treatment of asthma, skin diseases, gastric ulcers, lung disorders, cough, diarrhea, and menstrual disorder [178]. The health benefits of *Hippophae rhamnoides* oils, juice, leaves and bark are also well known and they have been used to treat several diseases [179]. All parts of the seabuckthorn plant are considered to be rich source of a large number of bioactive substances and are reported to have antimicrobial [180], antioxidant [181], and antimutagenic activities [182]; and antitumoral, hepato-protective and immunumodulatory [183], anti-platelet aggregating [184], anti-inflammatory [185], and radio-protective properties [186]. The leaf extract was reported to have better immunomodulatory effect than fruit extracts [183]. Jelly prepared by using seabuckthorn berries showed microbiological stability at ambient temperature and 37°C for a period of 6 months [187]. Various other plant extracts were found to be effective against *L. monocytogenes* in refrigerated meat products [188, 189]. The effect of a mixture of oregano and cranberry (0.1 mg of phenolic/ml) on beef slices and cod fish filet was studied by Lin et al. [190] and they observed that at pH 7, phytochemicals have no significant effect on cell numbers after 18 h of incubation, but at pH 6.0, differences in viable cell counts were observed in beef and fish slices. The oregano-cranberry extract mixture showed higher log reduction in viable counts than the slices treated with either oregano or cranberry extract [190]. Ruiz et al. [191] also reported that although rosemary extract was not able to completely eliminate *L. monocytogenes* in ready-to-eat vacuum-packaged diced turkey and ham, it significantly decreased the counts when used along with nisin. Cranberry powder alone at 1, 2, and 3% levels resulted in 2–4 log cfu/g reduction in growth of *L. monocytogenes* compared to the control (treated with nitrite, p ≤ 0.05), and similar effect on growth was seen when it was combined with cherry powder, lime powder and grape seed extracts in a cured cooked meat model system [192]. Grape seed extract and pine bark extract were used to control the growth of artificially inoculated bacteria on the surface of raw ground beef during refrigerated storage [193]. The combination of grape seed extract and nisin gave the greatest inhibitory activity with reductions of *L. monocytogenes* populations to undetectable levels after 21 days indicating potential of natural antimicrobials to control the growth and recontamination of *L. monocytogenes* on meat products [194].

Dried plum puree was found to reduce *E. coli* and *Salmonella* in ground meat [195]. Karapinar and Sengun [196] recommended use of unripe grape juice for enhancing the safety of salad vegetables. Grape pomace extract and olive extracts showed antimicrobial activity in apple juice [197]. Grape seed extract (1%) and rosemary oleoresin (1%) reduced the populations of *E. coli* O157:H7, *S. typhimurium* and *L. monocytogenes* after 9 days in raw ground beef [193]. Owen and Palombo

*Essential Oils - Bioactive Compounds, New Perspectives and Applications*

pasteurized tomato juice when mint was used as a preservative.

Turmeric, a tropical herb of *Zingiberaceae* family is used in Indian cuisine mainly for its coloring and flavoring characteristics, and curcumin is the active constituent of turmeric responsible for its preservative action [151]. Even, the byproducts of curcumin manufacture were found to have high biological activity [152, 153]. Turmeric extract (1.5%, v/v) alone or in combination with shallot extract (1.5% each, v/v) were found to retain quality characteristics of vacuum-packaged rainbow trout (*Oncorhynchus mykiss*) during a refrigerated storage of over a period of

Cinnamon is the source of cinnamon bark, fruit, leaf and their essential oils and many *Cinnamomum* species yield a volatile oil on distillation with different aroma characteristics and composition [155, 156]. Extracts of the cinnamon bark and fruit and cinnamon oil have been reported to possess antimicrobial, antioxidant and antimutagenic activities [157]. Cinnamon was found to reduce the levels of *E. coli* in apple juice [158]. Yuste and Fung [159] reported up to 6 log cfu/ml reductions of artificially inoculated *L. monocytogenes* in pasteurized apple juice with 0.1–0.3% (w/v) of ground cinnamon after 1 h of incubation, and no further growth of the microorganism occurred during 7 days of storage. Ceylan et al. [158] reported that the addition of 0.3% (w/v) cinnamon powder gradually decreased the counts of *E. coli* O157:H7 in pasteurized apple juice, whereas only 2 log cfu/ml reduction of *E. coli* O157:H7 in unpasteurized apple cider was reported even by addition of 2%

*Punica granatum* L. has a rich history of traditional use of its bark, leaves, flowers, fruits and seeds to ameliorate diseases. The presence of phytocompounds in the pomegranate extracts such as phenols, tannins and flavonoids as major active constituents may be responsible for these medicinal values [161, 162]. Several studies have reported the efficacy of various extracts from the different parts of pomegranate plant against the growth of Gram positive and Gram negative bacteria [163]. Aqueous and ethanolic fruit shell extracts of *P. granatum* were found to have antibacterial activity against different strains of *E. coli* [164], *Salmonella* Typhi [165], and it inhibited Staphylococcal enterotoxin A production [166]. Various other solvent extracts from the rind of *P. granatum* also showed antibacterial activity against enterohaemorrhagic *E. coli* and food spoilage bacteria [162]. Pomegranate peel extracts were used to enhance the shelf life of chicken meat products by controlling

Various species of *Garcinia* contains several secondary metabolites which exhibit a wide range of biological and pharmacological activities such as antimicrobial, antioxidant, antitumour-promoting and cytotoxic activities [168].

different plant extracts showed better preservative effects on meat as rosemary extracts and dry powders of orange and lemon applied to beef meatballs were found to be effective in controlling bacterial spoilage during 12 days storage period at 8°C [143]. Mixtures of Scutellaria, honeysuckle, Forsythia and cinnamon or cinnamon, rosemary and clove oil showed 1.81–2.32-log reductions in microbial counts as compare to control in vacuum-packaged fresh pork during 28 days storage [144]. Yin and Cheng [145] reported that the antimicrobial properties of garlic are due to organosulfur compounds. Freshly ground garlic, when added to mayonnaise at a concentration of 1% reduced *Salmonella* count [146]. Garlic also has been shown to reduce the levels of *E. coli* in ground meat [147]. Sallam et al. [148] observed that addition of fresh garlic and garlic powder controlled microbial contamination and preserved chicken sausages. Species of the genus *Mentha* (family *Lamiaceae*) are a rich source of polyphenolic compounds, flavonoids, terpenoids, and other volatile compounds, which imparts it a strong antimicrobial property [149]. Nguyen and Mittal [150] reported more than 8 log reductions in the artificially inoculated

**168**

20 days [154].

(w/v) cinnamon powder [160].

oxidative rancidity and bacterial growth [167].

[198] investigated the ability of *Eremophila duttonii* and *E. alternifolia* to control the growth of *L. monocytogenes* in full cream milk, skim milk, diluted homogenates of salami, pate and brie cheese, and reported that both the extracts inhibited the growth of *L. monocytogenes* in salami at 37°C, only *E. duttonii* extract was effective in pate at 4°C storage, and growth of *L. monocytogenes* was not affected by both the extracts in other products. Reduction in microbial load by water-soluble extract from pine needles of *Cedrus deodara* in fresh-squeezed tomato juice [199] and by the extracts from cinnamon stick, oregano, clove, pomegranate peel and grape seeds in raw pork over 9 days storage at ambient temperature was reported by Shan et al. [130].
