Essential oils
Essential oil fractions and oleoresins derived from spices are used widely in the food industry to provide flavour. Some of the main essential oils and their origins are shown in the table below.
Determining the quality and purity of essential oils faces similar difficulties to establishing the quality of raw spices, given the accepted variations in and mixing of varieties within a particular spice. There are, however, a number of properties that can be used to set quality standards. These include physical characteristics such as:
- specific gravity
- molecular refractive index
- optical rotation
- solubility
It is also possible to use chemical properties to benchmark quality. These include determination of acids, esters, alcohols, aldehydes and ketones, phenols and iodine number. Some specific flavour tests for halogens can also be used to set standards (Guenther 1972).
| Major essential oils - their production and adulterants | |||
| Essential oil | Origin | Major countries | Adulterants employed |
| Bergamot oil | Citrus auranticum (Rutaceae) | Italy, Ivory Coast, Brazil, Argentina, Spain, Russia | synthetic linalool and linalyl acetate, orange and lime terpenes |
| Cassia oil | Cinnamonum cassia (Lauraceae) | China, Indonesia, Vietnam, Taiwan | cinnamaldehyde |
| Cinnamon oil | Cinnamonum zeylanicum (Lauraceae) | Sri Lanka, India | leaf oil to bark oil and cinnamaldehyde |
| Clove leaf oil | Eugenia caryophyllata (Myritaceae) | Madagascar, Indonesia, Tanzania, Brazil, Sri Lanka | clove stem oil |
| Clove bud oil | Eugenia caryophyllata (Myritaceae) | Indonesia, Madagascar, Indonesia, Tanzania, Brazil, Sri Lanka | clove stem oil, leaf oil, eugenol and stem oil terpenes |
| Coriander oil | Coriandrum sativum (Umbelliferae) | Russia | synthetic linalool |
| Cornmint oil | Mentha arvensis (Labiatae) | China, Brazil, India, Paraguay, Taiwan, Thailand, North Korea, Japan | not a commercially attractive proposition |
| Dill oil | Anethum graveolens (Umbelliferae) | US, Hungary, Bulgaria, Russia, Egypt | distilled orange terpenes |
| Eucalyptus oil | Eucalyptus globus (Myrtaceae) | Portugal, S. Africa, Spain, China, India, Austria, Paraguay | - |
| Garlic oil | Allium sativum (Liliaceae) | Mexico, Italy, Egypt | nature identical raw materials |
| Ginger oil | Zingiber officinale (Zingiberaceae) | China, India | not often adulterated |
| Grapefruit | Citrus paradisi (Rutaceae) | Brazil, US, Israel, Argentina, New Zealand | orange terpenes |
| Lemon oil | Citrus limon (Rutaceae) | Argentina, US, Italy, Brazil, Greece, Spain, Australia, Peru | distilled oil and terpenes |
| Lemongrass | Citrus flexuosus and C. citratus (Gramineae) | India, China, Guatemala, Brazil, Russia, Sri Lanka, Haiti, Russia | synthetic citral |
| Lime oil | Citrus aurantifolia (Rutaceae) | Mexico, Peru, Haiti, Brazil Ivory Coast, Cuba, Ghana, Jamaica, China | synthetic terpineol terpinolene and other components of lime terpenes |
| Litsea cubeba oil | Litsea cubeba (Lauraceae) | China | synthetic citral |
| Nutmeg | Myristica fragrens (Myristicaceae) | Indonesia, Sri Lanka | terpenes and nature identical raw materials |
| Sweet orange oil | Citrus sinensis (Rutaceae) | Brazil, US, Israel, Italy, Australia | adulteration infrequent but higher priced oils diluted with cheaper substitutes |
| Peppermint oil | Mentha piperita (Labiatae) | US, Russia, Yugoslavia, Hungary, France | cornmint oil, terpenes |
| Rose oil | Rosa damascena (Rosaceae) | Turkey, Russia, Bulgaria, Morocco | nature identical components such as citronellol and geraniol |
| Rosemary oil | Rosamarinus officinalis (Labiatae) | Spain, Morocco, Tunisia, Russia, Yugoslavia, Turkey | camphor and eucalyptus fraction |
| Spearmint oil | Mentha spicata (Labiatae) | US, China, Italy, Brazil, Japan, France | laevo carvone |
| Star anise oil | Illicium verum (Magnoliaceae) | China, Vietnam, North Korea, Russia | anethole |
| Tangerine oil | Citrus reticulata (Rutaceae) | Brazil, US, Russia, Spain, South Africa | synthetic methyl-n-methyl anthranilate |
Tags: essential, oils, herbs, spices, cooking