T. A. Misharina

Antioxidant properties of essential oils

By the method of capillary gas-liquid chromatography, we studied the antioxidant properties and stability during the storage of hexane solutions of 14 individual essential oils from black and white pepper (Piper nigrum L.), cardamom (Elettaria cardamomum L.), nutmeg (Myristica fragrans Houtt.), mace (Myristica fragrans Houtt), juniper berry (Juniperus communis L.), fennel seed (Foeniculum vulgare Mill., var. dulce Thelling), caraway (Carvum carvi L.), dry cinnamon leaves (Cinnamomum zeylanicum Bl.), marjoram (Origanum majorana L.), laurel (Laurus nobilis L.), ginger (Zingiber officinale L.), garlic (Allium sativum L.), and clove bud (Caryophyllus aromaticus L.). We assessed the antioxidant properties by the oxidation of aliphatic aldehyde (trans-2-hexenal) into the corresponding carbonic acid. We established that essential oils of garlic, clove bud, ginger and leaves of cinnamon have the maximal efficiency of inhibiting hexenal oxidation (80!–93%), while black pepper oil has the minimal (49%). Antioxidant properties of essential oils with a high content of substituted phenols depended poorly on their concentrations in model systems. We studied the changes in the composition of essential oils during the storage of their hexane solutions for 40 days in light and compared it with the stability of essential oils stored for a year in darkness.

Antioxidant properties of essential oils from lemon, grapefruit, coriander, clove, and their mixtures

Antioxidant properties of individual essential oils from lemon (Citrus limon L.), pink grapefruit (Citrus paradisi L.), coriander (Coriandrum sativum L.), and clove (Caryophyllus aromaticus L.) buds and their mixtures were studied by capillary gas-liquid chromatography. Antioxidant activity was assessed by oxidation of the aliphatic aldehyde hexanal to the carboxylic acid. The lowest and highest antioxidant activities were exhibited by grapefruit and clove bud essential oils, respectively. Mixtures containing clove bud essential oil also strongly inhibited oxidation of hexanal. Changes in the composition of essential oils and their mixtures in the course of long-term storage in the light were studied. The stability of components of lemon and coriander essential oils in mixtures increased compared to individual essential oils.

Antioxidant Properties of Essential Oils: Autoxidation of Essential Oils from Laurel and Fennel and of Their Mixtures with Essential Oil from Coriander

Changes in the composition of essential oils from the seeds of laurel (Laurus nobilis L.) and fennel (Foeniculum vulgare Mill., var. dulce Thelling) and their mixture with essential oil from coriander were studied by capillary gas-liquid chromatography during storage in the dark and in light. Under these conditions, essential oil of laurel retained its composition for 12 months. Essential oil of fennel was rapidly oxidized in light. However, the rate of its oxidation in the dark was lower. The major component of essential oil of fennel, trans-anethol, had a lower antioxidant activity than essential oil of coriander. The mixture of essential oils from laurel and coriander possessed antioxidant properties and strongly inhibited the oxidation of components of the fennel oil.

Changes in the Composition of the Essential Oil of Marjoram during Storage

The composition of volatile components of the essential oil of marjoram plants (Majorana hortensis M.) and its stability during storage were studied by capillary gas chromatography and gas chromatography/mass spectrometry. Storage in the dark for 1 year was associated with insignificant changes in the composition of the essential oil, and its organoleptic characteristics remained largely unaffected. Storage in the light produced considerable changes in the composition of the oil, due to chemical transformations of terpenoids.

The composition of volatile components of cepe (Boletus edulis) and oyster mushrooms (Pleurotus ostreatus)

The composition of aroma compounds in cooked and canned cepe (Boletus edulis) and in cooked oyster mushrooms (Pleurotus ostreatus) is studied using capillary gas chromatography and chromatographymass spectrometry. It is found that unsaturated alcohols and ketones containing eight atoms of carbon determine the aroma of raw mushrooms and take part in the formation of the aroma of cooked mushrooms as well. The content of these compounds was the highest in canned cepes. In oyster mushrooms, the concentration of these alcohols and ketones was lower in comparison with cepes. The content of aliphatic and aromatic aldehydes was much higher in oyster mushrooms. Volatile aliphatic and heterocyclic Maillard reaction products and isomeric octenols and octenones formed the aroma of cooked and canned mushrooms.

Retention of essential oil components sorbed by native cornstarch during storage

Changes in the content of essential oil components sorbed by native dry cornstarch during storage were studied by the method of capillary gas chromatography. The composition of volatile substances changed insignificantly, and the sample retained its organoleptic characteristics throughout storage for 3 months. Up to 70–80% of monoterpene hydrocarbons and lower sulfides disappeared after 6 months. The loss of terpene alcohols, acetates, and ketones did not exceed 10%. Storage was accompanied by an increase in the content of essential oil components bound to the surface of starch granules.

Formation of flavor of dry champignons (Agaricus bisporus L.)

The composition of aroma compounds of dry champignons (Agaricus bisporus L.) were identified using capillary gas chromatography and chromatography-mass spectrometry. In total, 56 compounds were identified. It was found that the flavor of dry mushrooms was formed by the volatile compounds produced as a result of enzymatic and oxidative conversion of unsaturated fatty acids as well as in the Maillard reaction. Unsaturated alcohols and ketones containing eight carbon atoms determined the mushroom note of the product. The specific aroma of dry mushrooms was determined by a complex composition of substituted sul- fur-, oxygen-, and nitrogen-containing heterocyclic compounds as well as by aliphatic carbonyl compounds and methional. It was found that the concentrations of volatile carbonylic and heterocyclic compounds increased after the addition of a mixture of amino acids to mushrooms before drying. As a result, the intensity of the aroma of dry mushrooms increased.

GC evaluation of flavour compound sorption from water solutions by corn starch cryotextures obtained by freezing

Sorption of essential oil aroma components, n-alcohols and linalool by starch corn cryotexture was studied. Results show that terpene hydrocarbons of Rosmarinus officinalis L. essential oil are sorbed quantitatively from 0.05% water solution by cryotexture due to hydrophobic interactions with starch polysaccharides. Aroma compounds with oxygen atoms within the molecule are sorbed two times less. A templating effect with glucose, sucrose, maltose and some essential oil components was observed. Sorption of n-alcohols C4, C6, C8, linalool and their mixture with alkyl acetates in concentration 0.5-15 mmol/l was carried out. Individual octanol is sorbed by cryotexture on 88%, hexanol on 20%, linalool on 25%. Butanol is not sorbed at the chosen concentration. Synergism in sorption of hexanol from mixture with octanol and alkyl acetates was observed, while a suppression effect of octanol sorption was found for the same mixture.

Antiradical properties of oregano, thyme, and savory essential oils

In model reactions with the stable free 2,2-diphenyl-1-picrylhydrazyl radical, the antiradical properties of essential oils of thyme (Thymus vulgare), oregano (Origanum vulgare), and savory (Saturejahortensis) that are similar in the qualitative composition, but differ in the quantitative content of the main components, were studied and compared with the properties of synthetic antioxidant ionol. The reaction rates of components of essential oils with the radical were almost identical for all essential oils and were twice the reaction rate of ionol. The antiradical efficiency values were close to each other for all essential oils and by an order of magnitude smaller than for ionol.

Oregano essential oil as an inhibitor of higher fatty acid oxidation

Inhibition of the oxidation of fatty acids methyl esters by oregano essential oil was studied using capillary gas chromatography. A mixture of fatty acids which contained saturated, mono-, di-, and polyunsaturated acids with 16–24 carbon atoms was extracted from mice brain. Changes in the composition of esters in hexane solutions both in the presence of oregano essential oil and without it were examined during their autooxidation in light for 1 year. It was found that the oxidation rate of unsaturated fatty acids increases with increasing degree of their unsaturation. Oregano essential oil inhibited the oxidation process. Antioxidant activity of the oil increased with increase of its concentration. It was shown that carvacrol and thymol are the main antioxidant components of oregano oil.