**2.2 EOs from other plants**

*Essential Oils - Oils of Nature*

anti-inflammatory, anti-viral activities and antiprotozoal agent [10]. Among various techniques for extending the shelf-life of refrigerated seafood products, the application of biopolymer-based edible coatings and films are regularly the method of choice. Edible coatings from polysaccharides, proteins, and lipids can extend the shelf life of foods by functioning as a solute, gas, and vapor barriers [11]. Thus, essential oil incorporation into edible coatings or packaging can prevent the food

Therefore, great attention has been arisen to identified and used EOs in the food industry. This chapter provides an overview of antioxidant and antimicrobial activities of EOs derived from different sources and their potential organoleptic

Algae extracts are proven to be rich sources of metabolites with a wide range of biological activities such as anti-microbial, anti-oxidant, and pharmaceutical activities [13], thus, several extraction methods have been performed to preparation of algal extract [14] and evaluated their nutritional and pharmacological applications, however, a few number of studies focused on the characterization and composition of EOs from algal extracts. Hence, some scientific efforts have been dedicated to study essential oil composition of algae extracts. The GC-MS analysis of chemical composition shows the presence of different groups of essential oil in micro and

*Asparagopsis taxiformis* is species of red algae (Rhodophyta) which its EOs consist of bromine and iodine-containing haloforms with the smaller amount of other halogenated methanes and several halogenated ethanes, ethanols, formaldehydes, acetaldehydes, acetones, 2-propanols, 2-acetoxypropanes, propenes, epoxypropanes, acroleins, butenones, halogenated acetic and acrylic acids [15]. Two other red seaweeds (Rhodophyta) *Laurencia obtusa* and *Laurencia obtusa* var. pyramidata are also rich in EOs and 28 components in the oil of *L. obtusa* and 27 components in the oil of *L. obtusa* var. *pyramidata* were identified and 2,6-dimethyl-4-oxa-endo-

In addition, the brown macroalgae (Phaeophyta) such as *Colpomenia sinuosa*, *Dictyota dichotoma*, *Dictyota dichotoma* var. *implexa*, *Petalonia fascia* and *Scytosiphon lomentaria* are rich in the EOs. The GC/MS analysis discovered the components including hydrocarbons, terpenes, acids, phenols, sulfur-containing compound, aldehydes, naphthalene skeleton and alcohols in *C. sinuosa*, *D. dichotoma*, *D. dichotoma* var. *implexa*, *P. fascia* and *S. lomentaria*. Among these brown seaweeds, *S. lomentaria* is rich in crown ether (18-crown-6-ether). Moreover, the presence of dihexylsulfide in essential oil profile of *C. sinuosa* revealed the potential of *C. sinuosa* for supplying the rare sulfur-containing compound in seaweeds [17]. Ref. [17] discovered the eight (58.41%) for *D. dichotoma* var. *implexa*, 12 (83.53%) for *D. dichotoma*, 4 (91.71%) for *P. fascia*, 6 (87.89%) for *S. lomentaria* and 14 (74.17%)

Recently, there is interest in the microalgae as well as macroalgae for development of EOs. For this respect, the 50 total compositions of the EOs from *Dunaliella salina* extract were identified and octadecanoic acid, methyl ester (27.43%), hexadecanoic acid, methyl ester (Cas) methyl palmitate (24.82%), 9,12,15-octadecatrienoic acid, ethyl ester, (Z,Z,Z) (7.39%), octadecanoic acid (5.03%), pentadecanoic

spoilage and extend the food shelf life in particular fish products [12].

beneficial and applications in shelf life extension of raw fishes.

tricyclodecane was the highest account in both red algae [16].

compounds for *C. sinuosa* in total composition of their essential oil.

acid (3.60%) were detected as major compounds [18].

**2. Chemical composition of EOs**

**2.1 EOs from algae**

macroalgae.

**192**

So many researches inquired into the chemical composition of the EOs obtained from various sources including *Thymus ulgaris, Nigella sativa, Achillea millefolium, Curcuma zedoaria*, *Rosmarinus officinalis* etc. A summary of these investigations is reported in **Table 1**. In an outstanding study, the essential oil composition of thyme (*Thymus ulgaris* L*.*) was investigated by capillary GC/MS evaluation method. The effect of vegetative cycle on the variation of EOs chemical composition was looked over, as well. Generally, the oil was had high amounts of monoterpene


#### **Table 1.**

*Some investigations performed to investigate the chemical composition of EOs.*

phenols (carvacrol and thymol) and their related monoterpene hydrocarbon precursors (*p*-cymene and γ-terpinene), that demonstrated integrated effects of the different collection periods and seasons on the chemical composition of EOs. The EOs obtained from old plant included much lower quantities of monoterpene hydrocarbones (mostly γ-terpinene) and the highest quantities of the oxygenated monoterpenes (linalool and borneol), monoterpene phenols (mostly thymol) and their derivatives (mostly carvacrol methyl ether), sesquiterpenes (mostly β-caryophyllene) and their oxygenated derivatives (e.g., caryophyllene oxide). A characteristic presence of camphor and thymodihydroquinone was also discovered in the old plant EOs [19].

The EOs obtained by hydrodistillation from flowering Thyme (*Thymis vulgaris* L.) was investigated by GC/FID and GC/MS. The yield of extraction in this study was reported as 1%, in which 43 chemical compounds (97.85% of total constituents) were identified. The EOs extracted from flowering Thyme were mainly consisted of camphor (38.54%), camphene (17.19%), α-pinene (9.35%), 1, 8-cineole (5.44%), borneol (4.91%) and β-pinene (3.90%) [20].

In an another research, seven EOs of *N. sativa*, which were all extracted by soxhlet extraction and steam distillation, were analyzed by GC/MS. A total of 32 compounds were identified. The major fraction of every EOs was a mixture of monoterpenes. The major components were thymoquinone (30–48%), *p*-cymene (7–15%), carvacrol (6–12%), 4-terpineol (2–7%), t-anethole (1–4%) and the sesquiterpene longifolene (1–8%). Very small quantities of the esters of special un/ saturated fatty acids were also detected [21].

Curcumin, the yellowish pigment of turmeric, is generated from turmeric oleoresin. In a study performed in order to investigate the antibacterial activity of turmeric oil extracted by hexane and fractionated by silica gel column chromatography, GC/MS analysis identified 13 major components in turmeric oil, fraction I, and fraction II. *ar-*turmerone (62.0%), *trans-â*-farnesene (6.6%), turmerone (5.1%), and curlone (3.9%) were found to be the major compounds in turmeric oil whereas fraction II contained *ar-*turmerone (77.9%), curlone (5.3%), and turmerone (5.2%) [22].

Rosemary (*Rosmarinus officinalis* L.), a member of mint family, is an ordinary aromatic shrub grown in various places around the world [23]. Some researchers has assessed the chemical composition of rosemary EOs to understand the reason of biological activities such as antimicrobial activity. In an experimentation 22 components were identified from this plant by GC/MS. The major constituents were 1,8-cineole (26.54%), α-pinene (20.14%), Camphor (12.88%), and camphene (11.38%) [24].
