From famine plants to tasty and fragrant spices: Three Lamiaceae of general dietary relevance in traditional cuisine of Trás-os-Montes (Portugal)

The chemical composition and nutritional value of three Lamiaceae often used as spices in Portuguese traditional cuisine: Ground ivy (Glechoma hederaceae L.), oregano (Origanum vulgare subsp. virens (Hoffmanns. & Link) Ietswaart) and mastic thyme (Thymus mastichina L.) were determined. Chemical composition evaluation included moisture, total fat content, crude protein, ash, carbohydrates, and nutritional value determination. The macronutrient profile revealed that these spices are rich sources of carbohydrates and that an edible portion of 100 g assures, on average, 161 Kcal. The composition in individual sugars was determined by high performance liquid chromatography coupled to a refraction index detector (HPLC/RID), being this methodology completely validated. All the compounds were separated in a period of time of 15 min; the method used proved to be sensitive, reproducible and accurate. Fructose, glucose, sucrose and raffinose were the most abundant sugars. The analysis of fatty acid composition, performed by gas chromatography coupled to a flame ionization detector (GC/FID), allowed the quantification of twenty two fatty acids. Polyunsaturated fatty acids and, in particular, α-linolenic and linoleic acids, were predominant.