The analysis of essential oils and extracts (oleoresins) from seasonings--a critical review

Development of cinnamon essential oil-loaded PBAT/thermoplastic starch active packaging films with different release behavior and antimicrobial activity

The poly (butylene adipate-co-terephthalate)/thermoplastic starch (PBAT/TPS) active packaging films containing cinnamon essential oil (CEO) were fabricated by melting blending and extrusion casting method. The effects of TPS content (0 %, 10 %, 20 %, 30 %, 40 % and 50 %) on the properties of the films and their application in largemouth bass preservation were studied. As TPS content increased from 0 % to 50 %, the water vapor permeability increased from 7.923 × 10-13 (g•cm/(cm2•s•Pa)) to 23.967 × 10-13 (g•cm/(cm2•s•Pa)), the oxygen permeability decreased from 8.642 × 10-11 (cm3•m/(m2•s•Pa)) to 3.644 × 10-11 (cm3•m/(m2•s•Pa)), the retention of CEO in the films increased. The release rate of CEO from the films into food simulant (10 % ethanol) accelerated with increasing TPS. The films exhibited different antibacterial activity against E. coli, S. aureus, and S. putrefaciens. It was closely related with the release behavior of the CEO. The films containing CEO could efficiently inhibit the decomposition of protein and the growth of microorganisms in largemouth bass. It showed that the higher TPS in the films, the better inhibitory effect. This study provided a new idea for developing PBAT/TPS active films with different release behavior of active agents and different antibacterial activity for food packaging.

Occurrence of Alkenylbenzenes in Plants: Flavours and Possibly Toxic Plant Metabolites

Alkenylbenzenes are naturally occurring secondary plant metabolites. While some of them are proven genotoxic carcinogens, other derivatives need further evaluation to clarify their toxicological properties. Furthermore, data on the occurrence of various alkenylbenzenes in plants, and especially in food products, are still limited. In this review, we tempt to give an overview of the occurrence of potentially toxic alkenylbenzenes in essential oils and extracts from plants used for flavoring purposes of foods. A focus is layed on widely known genotoxic alkenylbenzenes, such as safrole, methyleugenol, and estragole. However, essential oils and extracts that contain other alkenylbenzenes and are also often used for flavoring purposes are considered. This review may re-raise awareness of the need for quantitative occurrence data for alkenylbenzenes in certain plants but especially in final plant food supplements, processed foods, and flavored beverages as the basis for a more reliable exposure assessment of alkenylbenzenes in the future.

Structure-Odor Activity Studies on Derivatives of Aromatic and Oxygenated Monoterpenoids Synthesized by Modifying p-Cymene

Thymoquinone was recently reported as having a unique pencil-like odor and being the impact compound for the cedar-like and cedar wood-based product smell such as pencils. The compounds thymol and carvacrol are structurally related odorants commonly found in plants and foods such as thyme and oregano, also having a significant contribution to their overall aroma. However, a systematic elucidation of the sensory properties in this class of oxygenated, aromatic monoterpenoids has not been carried out. To close this gap and gain new insights into structure-odor relationships leading to pencil-like and woody odors, 19 structurally related derivatives of p-cymene starting from thymol and carvacrol were synthesized and characterized. The compounds had odor thresholds ranging from 2.0 ng/L air to 388.8 ng/L air, being lowest for thymol and carvacrol and highest for thymohydroquinone. The compounds smelled mostly thyme-like, oregano-like, and pencil-like with phenolic, earthy, and medicinal variations in their odor character, which could be successfully linked to structural motifs.

A review on conventional and biotechnological approaches in white pepper production

White pepper is the dried seeds obtained from pepper berries (Piper nigrum L.) after the removal of the pericarp. It has been widely used as seasoning and condiments in food preparation. Globally, white pepper fetches a higher price compared to black pepper due to its lighter colour, preferable milder flavour and pungency. Increasing global demand of the spice outpaced the supply as the conventional production method used is laborious, lengthy and also not very hygienic. The most common conventional method is water retting but can also include pit soil, chemical, boiling, steaming and mechanical methods. The introduction of a biotechnological approach has gained a lot of interest, as it is a more rapid, convenient and hygienic method of producing white pepper. This technique involves the application of microorganisms and/or enzymes. This review highlights both conventional and latest biotechnological processes of white pepper production. © 2018 Society of Chemical Industry.

A comparative study of nutmeg (Myristica fragrans Houtt.) oleoresins obtained by conventional and green extraction techniques

This study evaluated the effect of conventional maceration and ultrasound assisted extraction techniques on the extraction yield, chemical composition and sensory characteristics of nutmeg oleoresins. Extraction was performed using material: absolute ethanol ratio 1:4, at room temperature. The volatile components of the oleoresin were identified by gas chromatography-mass spectrometry. The results of the study showed that the yield ranged from 4.55 to 9.63 %. Fifty-three compounds in the nutmeg oleoresin have been identified to account for >90 % of the total oil content. Sabinene, myristicin, elemicin, α-pinene, β-pinene, limonene, terpinen-4-ol and myristic acid were found as major compounds of all the nutmeg oleoresins obtained by different techniques. The sensory characteristics of the oleoresin were strongly influenced by the ultrasonic intensity and duration of extraction. The experimental results showed that ultrasound assisted extraction technique at 40 % of the maximal output power and 10 min produced superior quality nutmeg oleoresin with a remarkable yield.

Antioxidant activity of Piper nigrum L. essential oil extracted by supercritical CO₂ extraction and hydro-distillation

The aim of this study was to optimize the antioxidant activity of Piper nigrum L. essential oil extracted using the supercritical carbon dioxide (SC-CO₂) technique. Response surface methodology was applied using a three-factor central composite design to evaluate the effects of three independent extraction variables: pressure of 15-30 MPa, temperature of 40-50 °C and dynamic extraction time of 40-80 min. The DPPH radical scavenging method was used to evaluate the antioxidant activity of the extracts. The results showed that the best antioxidant activity was achieved at 30 MPa, 40 °C and 40 min. The extracts were analyzed by GC-FID and GC-MS. The main components extracted using SC-CO₂ extraction in optimum conditions were β-caryophyllene (25.38 ± 0.62%), limonene (15.64 ± 0.15%), sabinene (13.63 ± 0.21%), 3-carene (9.34 ± 0.04%), β-pinene (7.27 ± 0.05%), and α-pinene (4.25 ± 0.06%). The essential oil obtained through this technique was compared with the essential oil obtained using hydro-distillation. For the essential oil obtained by hydro-distillation, the most abundant compounds were β-caryophyllene (18.64 ± 0.84%), limonene (14.95 ± 0.13%), sabinene (13.19 ± 0.17%), 3-carene (8.56 ± 0.11%), β-pinene (9.71 ± 0.12%), and α-pinene (7.96 ± 0.14%). Radical scavenging activity of the extracts obtained by SC-CO₂ and hydro-distillation showed an EC₅₀ of 103.28 and 316.27 µg mL(-1) respectively.

Safety assessment of coriander (Coriandrum sativum L.) essential oil as a food ingredient

Coriander essential oil is used as a flavor ingredient, but it also has a long history as a traditional medicine. It is obtained by steam distillation of the dried fully ripe fruits (seeds) of Coriandrum sativum L. The oil is a colorless or pale yellow liquid with a characteristic odor and mild, sweet, warm and aromatic flavor; linalool is the major constituent (approximately 70%). Based on the results of a 28 day oral gavage study in rats, a NOEL for coriander oil is approximately 160 mg/kg/day. In a developmental toxicity study, the maternal NOAEL of coriander oil was 250 mg/kg/day and the developmental NOAEL was 500 mg/kg/day. Coriander oil is not clastogenic, but results of mutagenicity studies for the spice and some extracts are mixed; linalool is non-mutagenic. Coriander oil has broad-spectrum, antimicrobial activity. Coriander oil is irritating to rabbits, but not humans; it is not a sensitizer, although the whole spice may be. Based on the history of consumption of coriander oil without reported adverse effects, lack of its toxicity in limited studies and lack of toxicity of its major constituent, linalool, the use of coriander oil as an added food ingredient is considered safe at present levels of use.

Metabolism of myristicin by Depressaria pastinacella CYP6AB3v2 and inhibition by its metabolite

Although methylenedioxyphenyl (MDP) compounds, such as myristicin, are useful in the management of insecticide-resistant insects, the molecular mechanisms for their action in mammals and insects have not been elucidated. In this study, GC-MS analyses of methanol extracts of foliage of wild parsnip (Pastinaca sativa) have identified myristicin as a substrate for CYP6AB3v2, an imperatorin-metabolizing cytochrome P450 monooxygenase from Depressaria pastinacella (parsnip webworm). In contrast with its strong inhibitory effects on many mammalian P450s, myristicin is effectively metabolized by CYP6AB3v2 (V(max) and K(m) of 97.9 pmol/min/pmol P450 and 17.9 microM, respectively) at a rate exceeding that recorded previously for imperatorin, the only other known substrate for this highly specialized enzyme. The myristicin metabolite of CYP6AB3v2 is 1-(3',4'-methylenedioxy-5'-methoxyphenyl)-2,3-epoxypropane. Molecular dockings have indicated that, unlike other epoxide metabolites of furanocoumarins, this epoxide metabolite is likely to remain in the CYP6AB3v2 catalytic site due to its low binding energy (-31.0 kcal/mol). Inhibition assays indicate that myristicin acts as a mixed inhibitor of this insect P450 and suggest that the epoxide metabolite may be an intermediate involved in the formation of P450-methylenedioxyphenyl complexes.

Essential oils: their antibacterial properties and potential applications in foods--a review

In vitro studies have demonstrated antibacterial activity of essential oils (EOs) against Listeria monocytogenes, Salmonella typhimurium, Escherichia coli O157:H7, Shigella dysenteria, Bacillus cereus and Staphylococcus aureus at levels between 0.2 and 10 microl ml(-1). Gram-negative organisms are slightly less susceptible than gram-positive bacteria. A number of EO components has been identified as effective antibacterials, e.g. carvacrol, thymol, eugenol, perillaldehyde, cinnamaldehyde and cinnamic acid, having minimum inhibitory concentrations (MICs) of 0.05-5 microl ml(-1) in vitro. A higher concentration is needed to achieve the same effect in foods. Studies with fresh meat, meat products, fish, milk, dairy products, vegetables, fruit and cooked rice have shown that the concentration needed to achieve a significant antibacterial effect is around 0.5-20 microl g(-1) in foods and about 0.1-10 microl ml(-1) in solutions for washing fruit and vegetables. EOs comprise a large number of components and it is likely that their mode of action involves several targets in the bacterial cell. The hydrophobicity of EOs enables them to partition in the lipids of the cell membrane and mitochondria, rendering them permeable and leading to leakage of cell contents. Physical conditions that improve the action of EOs are low pH, low temperature and low oxygen levels. Synergism has been observed between carvacrol and its precursor p-cymene and between cinnamaldehyde and eugenol. Synergy between EO components and mild preservation methods has also been observed. Some EO components are legally registered flavourings in the EU and the USA. Undesirable organoleptic effects can be limited by careful selection of EOs according to the type of food.

Antibacterial activity of selected plant essential oils against Escherichia coli O157:H7

AIMS

To quantify the antibacterial properties of five essential oils (EO) on a non-toxigenic strain of Escherichia coli O157:H7 in the presence and absence of a stabilizer and an emulsifier and at three different temperatures.

METHODS AND RESULTS

Five EOs known to exhibit antibacterial properties were screened by disc diffusion assay and the most active were selected for further study in microdilution colorimetric assays. Oregano (Origanum vulgare) and thyme (Thymus vulgaris; light and red varieties) EO had the strongest bacteriostatic and bactericidal properties, followed by bay (Pimenta racemosa) and clove bud (Eugenia caryophyllata synonym: Syzygium aromaticum) EO. Oregano oil was colicidal at 625 microl l(-1) at 10, 20 and 37 degrees C. The addition of 0.05% (w/v) agar as stabilizer reinforced the antibacterial properties, particularly at 10 degrees C, whereas 0.25% (w/v) lecithin reduced antibacterial activity. Scanning electron micrographs showed extensive morphological changes to treated cells.

CONCLUSIONS

Oregano and thyme EO possess significant in vitro colicidal and colistatic properties, which are exhibited in a broad temperature range and substantially improved by the addition of agar as stabilizer. Bay and clove bud EO are less active. Lecithin diminished antibacterial properties. The bactericidal concentration of oregano EO irreversibly damaged E. coli O157:H7 cells within 1 min.

SIGNIFICANCE AND IMPACT OF THE STUDY

Oregano and light thyme EO, particularly when enhanced by agar stabilizer, may be effective in reducing the number or preventing the growth of E. coli O157:H7 in foods.

Sedanolide, a natural phthalide from celery seed oil: effect on hydrogen peroxide and tert-butyl hydroperoxide-induced toxicity in HepG2 and CaCo-2 human cell lines

Sedanolide is a natural compound occurring in edible umbelliferous plants. Celery seed oil, a significant source of sedanolide, is used as an herbal remedy to treat inflammatory-associated conditions such as gout and rheumatism. The objective of this study was to assess the potential protective properties of sedanolide against hydrogen peroxide (H(2)O(2))- and tert-butyl hydroperoxide (tBOOH)-induced toxicity in HepG2 and CaCo-2 cells. Viability of HepG2 and CaCo-2 cells was unaffected by a 24-h exposure to sedanolide (7-500 microM), however, when the cells were cultured in sedanolide-free medium for a further two cell cycles (72 h), a decrease in cell viability was observed for HepG2 cells previously exposed to 500 microM of the compound. Cells pretreated with sedanolide (100 microM for 24 h) and exposed to either H(2)O(2) or tBOOH did not exhibit statistically significant difference in viability from controls. A significant increase (p < 0.05) in DNA strand breaks, as measured by the comet assay, was observed in HepG2 but not CaCo-2 cells following a 24-h incubation with 500 microM sedanolide. Sedanolide did not modulate H(2)O(2)- and tBOOH-induced DNA damage. Sedanolide is relatively nontoxic to cells in culture, however, the protection it afforded against H(2)O(2)- and tBOOH-induced toxicity was not statistically significant.

Murine Cyp1a-1 induction in mouse hepatoma Hepa-1C1C7 cells by myristicin

Mouse hepatoma Hepa-1c1c7 (Hepa-1) cells were treated with myristicin to assess the role of myristicin in the process of Cyp1a-1 induction. Treatment of Hepa-1 cells with myristicin increased Cyp1a-1 transcription in a dose-dependent manner as shown by analysis of 7-ethoxyresorufin O-deethylase activity, Cyp1a-1 protein level, and Cyp1a-1 mRNA. Myristicin, however, did not competitively displace [3H]2,3,7,8-tetrachlorodibenzo-p-dioxin from the Hepa-1 cytosolic aryl hydrocarbon (Ah) receptor in a competitive Ah receptor binding analysis using sucrose density gradient sedimentation and did not affect formation of DNA-protein complexes between the Ah receptor and its DRE target in a gel mobility shift assay using oligonucleotides corresponding to DRE 3 of the Cyp1a-1. These results suggest that the induction of Cyp1a-1 gene expression by myristicin in Hepa-1 cells might occur through an Ah receptor-independent pathway.

Chemoprevention of benzo[a]pyrene-induced forestomach cancer in mice by natural phthalides from celery seed oil

Bioassay-directed fractionation of celery seed oil from the plant Apium graveolens (Umbelliferae) led to the isolation of five natural products, including d-limonene, p-mentha-2,8-dien-1-ol, p-mentha-8(9)-en-1,2-diol, 3-n-butyl phthalide, and sedanolide. Of these compounds p-mentha-2,8-dien-1-ol,3-n-butyl phthalide, and sedanolide exhibited high activities to induce the detoxifying enzyme glutathione S-transferase (GST) in the target tissues of female A/J mice. 3-n-Butyl phthalide and sedanolide (20 mg/dose every two days for a total of 3 doses) increased GST activity 4.5-5.9 and 3.2-5.2 times over the controls in the mouse liver and small intestinal mucosa, respectively. At the same dose, p-mentha-2,8-dien-1-ol induced GST activity about 3.7-fold above that of the controls. Thus, these compounds were further tested for their ability to inhibit benzo[a]pyrene- (BP) induced tumorigenesis in mice. After treatment with 3-n-butyl phthalide and sedanolide, the tumor incidence was reduced from 68% to 30% and 11%, respectively. About 67% and 83% reduction in tumor multiplicity was also observed with 3-n-butyl phthalide and sedanolide. p-Mentha-2,8-dien-1-ol produced only a small or no significant reduction of forestomach tumor formation. The data indicating that 3-n-butyl phthalide and sedanolide were both active in tumor inhibition and GST assays suggested a correlation between the inhibitory activity and the GST-inducing ability. The phthalides are known to determine the characteristic odor of celery. The results suggest that phthalides, as a class of bioactive natural products occurring in edible umbelliferous plants, may be effective chemopreventive agents.

Inhibition of carcinogenesis by naturally-occurring and synthetic compounds

A continuing study of chemopreventive agents has focused on three categories of naturally-occurring compounds that inhibit carcinogen activation and are effective in preventing carcinogen-induced neoplasia when administered at short time intervals prior to carcinogen challenge. The three are: aromatic isothiocyanates found in cruciferous vegetables, monoterpenes from citrus fruits and caraway seed oils, and organosulfur compounds occurring in Allium species. The short time-interval effects could be significant in terms of their impact on responses of humans to carcinogen exposures. The capacity of sodium cyanate, cruciferous vegetables, orange oil, benzyl isothiocyanate, and D-limonene to act as both blocking and suppressing agents has been discussed. Two possible mechanisms for this multiphase activity were presented. The first is that these inhibitory substances activate a complex integrated defense mechanism against toxic compounds which entails both blocking and suppressing components. The blocking component is the initial line of defense, and the suppressing component constitutes a "fail-safe" backup to assure that if any of the toxic material attacks cellular constituents, its effects will be nullified. The second possible mechanism considered is that the inhibitors, because of high reactivity, have multiple biological effects that are separate and not part of a single, coordinated response. Inhibitors that have both blocking and suppressing effects could be particularly useful as chemopreventive agents.

Turmeric--chemistry, technology, and quality

Turmeric is a minor spice in the West, but a major one in the East. It is valued by Westerners mainly, if not solely, on account of its color, but to the Asians both color and aroma are equally important. This review critically appraises the existing knowledge on the chemistry of the functionally important constituents, the processing of the spice into wholes, powder, and oleoresins, and the objective methods and standards available for evaluation of quality. The importance of the mild (but persistent) aroma, and the lack of detailed knowledge on the significant volatiles are discussed. Some unpublished data on significant aroma components, a tristimulus study of color, and subjective evaluations of quality are summarized. Other areas briefly discussed are the production and trade, curry powder, allied spices, and biosynthetic and physiological aspects. The confusion existing in the literature on the nomenclature of species included in the genus Curcuma is pointed out. In view of the growing importance of turmeric and its extracts as a natural food color, recent results on toxicological aspects are discussed. The areas in which research is needed are indicated at the end.