396 Handbook of herbs and spices
(Herodez et al., 2003). Therefore, recently, the food industry has sought natural
antioxidants because there have been some concerns about the safety and toxicity of
synthetic antioxidants. Many herbs are excellent sources of natural antioxidants, and
their consumption in the diet may thus contribute to the daily antioxidant intake.
Lemon balm possesses a remarkable antioxidative activity of its phenolic antioxidants
such as rosmarinic and caffeic acids (Labuda et al., 2002). This very high concentration
of antioxidants may contribute to the total intake of plant antioxidants in a normal
diet, and is suggested to be a better source of dietary antioxidants than many other
foods such as fruit, cereals and vegetables (Dragland et al., 2003). A study also
showed that lemon balm extract decreases serum cholesterol and lipid levels in the
hyperlipidemic animals (Bolkent et al., 2005). This suggests that extract of lemon
balm as a preventive agent could be used for hyperlipidemia disease.
Lemon balm also has a potential use in agriculture with its allelopathic effect and
content of allelochemicals. It was stated that powder of lemon balm inhibits the
germination and growth of some weed seeds such as Amaranthus caudatus, Digitaria
sanguinalis and Lactuca sativa (Kato-Noguchi, 2003). This allelopathic nature of
Table 23.1 Some standards and specifications of raw material and essential oil of lemon balm
Harvest and raw material specifications
Harvesting period At the end of buttoning period and appearance of the first
flower (June–October), in sunny, warm and non-windy days
Harvesting method By cutting the plants and defoliating them as soon as possible
(it is very difficult to defoliate the withered plants)
Processing Naturally or artificially drying at maximum 35 ∞C.
Steam-distillation of essential oil
Storage Dry, clean rooms
Component specifications
Essential oil content 0.02–0.2%
Main components Citronellal (30–40%), citrale (20–30%)
Other components Methyl-citronellate, (+)-ocimene, citronellol, nerol, geraniol,
b-caryophyllene, germacrene D
Quality of the essential oil
Source Bulgaria
Appearance Transparent liquid
Colour Light yellow to yellow-brown, red brown
Aroma Citric-rose, fresh with lemon smell
Relative density at 20 ∞C 0.870–0.906
Optical rotation –3∞ to –11∞
Refraction number at 20 ∞C 1.460–1.480
Ester number 20 to 46
Ester number after acetylation 150 to 220
Acid number Not more than 2.5
Chemical composition Linallol, citronellal, citral, b-caryophyllene
(gas chromatography)
Source United Kingdom
Appearance Clear mobile oil
Aroma Characteristics green, lemon scented aroma
Colour Pale yellow
Optical rotation –20 ± 2 ∞
Refractive index at 20 ∞C 1.4854 ± 0.005
Specific gravity at 20 ∞C 0.888 ± 0.005
Source: IENICA, 2004.