Thyme as a food preservative
Due to their antimicrobial and antioxidant qualities numerous aromatic plants, such as thyme, have been used and are still being used as food preservatives. As was described before, the essential oils of thyme present a marked antimicrobial activity. This activity has been demonstrated to include bacteria responsible for alterations in food. Aureli carried out a study on the antimicrobial activity of diverse essential oils of plants widely used in the food industry against Listeria monocytogenes (bacteria implicated in alterations in food). Only the essential oils of cinnamon, clove, marjoram, pepper and thyme presented antimicrobial activity.
Researchers have also demonstrated that a number of aromatic plants, including thyme, have a marked antifungal activity against food spoiling fungi. The high antimycotic activity of clove and thyme was tested for their possible use as preservatives for agricultural commodities by El-Maraghy. Both species completely inhibited aflatoxin production in lentil seeds for an eight week incubation period.
Antioxidant activity can also be responsible for a preservative activity, especially in preventing oxidation of lipids in food. This was studied by Budincevic who tested ethanol extracts of T. marschallianus using tallow and lard as the substrates, at 60 °C in the Rancimat apparatus. The extracts showed antioxidant effects with the substrates processed at 60 °C but not at 100 °C. Adding citric and malic acid a synergistic effect could be observed. Dorman et al. () demonstrated the antioxidant activity of the essential oil of Thymus vulgaris in TBARS using egg yolk, one-day old chicken liver or muscles from mature chickens.
Botsoglou evaluated the effect of dietary thyme on the oxidative stability of egg shells over a 60-day refrigerated storage period. In addition, the influence of dietary thyme and of the storage time on the oxidative stability of liquid yolks adjusted to various pH values and agitated in the presence of light was investigated. Results show that malonaldehyde was not produced during the storage of egg shells. It was also evident that thyme treatment reduced the oxidation of liquid yolk, which was significantly increased by light and acidity. The authors proposed that thymol is the most important antioxidant component of thyme, but that there must be other components in thyme which act synergisticly with thymol.
The cosmetic uses of thyme
Thyme oil, in general, is used in many cosmetic preparations, such as deodorants, because of its capacity to suppress smells and for its antimicrobial properties. The oil finds some use in soap perfumes where its power and freshness can introduce a hint of medicinal notes, often desirable in certain types of soap or detergent. The oil exerts an excellent masking effect over tarry odors. Added to lotions perfumes or colognes in trace amounts, thyme oil may lend body and sweet freshness. Therefore it is used in the composition of cosmetic creams and milks, eau-de-cologne (frequently accompanied by lemon and bergamot), and soapy solutions to disinfect surgeons’ hands. These cosmetic products are useful to fight acne and skin complaints.
The essential oil of thyme and thymol are also used in the production of toothpaste and mouthwashes. This essential oil peroxidised to 10 per cent in a soapy solution destroys the microbial flora in the oral cavity in 3 min.
The culinary uses of thyme
Thyme is widely used as a seasoning especially in the Mediterranean kitchen. It has a strong but agreeable aroma and is pleasant in greasy or fatty food, such as sausages, bacon and other fatty meats and even strong cheeses. Along with rosemary it constitutes a highly recommended seasoning for pizzas and similar products. It can be added (with care) to sauces, soups, meat and fish dishes. The fresh leaves give flavour to salads. In the liquor industry thyme is used to give flavour and aroma, Thymus moroderi being the aromatic plant used to produce the ‘Licor de Cantueso’ and Thymus vulgaris participating in the formulation of several liquorices produced in the Spanish Eastern and Balearic regions.
Selections from the book: “Thyme. The genus Thymus”. Edited by Elisabeth Stahl-Biskup. Series: “Medicinal and Aromatic Plants — Industrial Profiles”. 2002.