More and more animal food are including herbal food-supplements in place of synthetic drugs
such as antibiotics. This may be due to the detrimental effects of synthetic drugs.
Consequently, many scientific experiments have been conducted to determine whether the use
of aromatic plants and the addition of essential oils to the food do improve the health and the
growth of the animals.
In order to validly repeat and compare these experiments, knowing the exact amounts of
active components in the herbal ingredients in animal-food products is of vital importance.
Due to the minute amount of a wide variety of phytochemicals from plant extracts present in a
given animal food, sensitive methods for their analysis are needed.
In this study, crushed fruits of caraway (Carum carvi) or fennel (Foeniculum vulgare), were
added to a standard broiler´s diet at a rate of 0.2%, 0.4%, 0.8% and 2%. The supplemented
feed and as a control, the standard broiler´s diet without added herbs were extracted with
steam distillation, microdistillation and dichloromethane (DCM).To compensate for the
variability of the extraction method, camphor was used as an internal standard to our samples
during extraction, and as an internal standard for gaschromatography hexadecane or decane
Steam distillation: 10 grams of each food sample was distilled with a Clevenger-equipment at
a rate of 32 drops per minute for 90 minutes.
Microdistillation: 0.4 grams of each food sample was added to a heated (HOT) vial and
connected through a capillary to a cooled (COOL) vial. The samples were all distillated with
a special temperature protocol
DCM-extraction: 25 ml dichloromethane were added to 2.5 grams of each food sample. The
samples were extracted for 1 hour in an ultrasounic bath at room temperature and then filtered.
The volatile components of our extracts were analysed with gaschromatography. In caraway
the amount of limonene and carvone were measured, as they are the most important
components of the essential oil of caraway.
It was found that limonene was best extracted by steam distillation. Very low concentrations
of carvone were best extracted by steam distillation, higher concentrations of carvon were
best extracted by microdistillation.
In fennel the amount of fenchone and anethole were measured, as they are the most importent
components of the essential oil of fennel.
Fenchone was best extracted by steam distillation, anethole was best extracted by
The recovery, which implies the correctness of a method, accounted for steam distillation
113,87%, for microdistillation 103,78% and for DCM-extraction 67,7%.
The CV, which implies the precision of a method, accounted for steam distillation 17,2%, for
microdistillation 17,4% and for DCM-Extraction 20,2%.
In conclusion, all three test methods were found suitable for determinating essential oils
present in aromatic feed additives. The DCM-extraction is a fast and easy method, but at low
concentrations of active components it shows a much lower recovery than the steam
distillation and the microdistillation.