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Essential oils are gaining interest from the academic and industrial communities as they have been associated with a possible antimicrobial activity against a wide range of microorganisms. Not many studies are known about the effect of essential oils on useful bacteria in fermentative processes. The present study investigated the possibility of flavouring yoghurt with essential oils. Five oils (mint, clove, cinnamon, sage, orange) extracted by hydrodistillation in a Clevenger-type equipment were tested. Each oil was tested in three concentrations (0.01%, 0.05% and 0.1%). The coagulation capacity of the milk was monitored by measuring the pH at regular intervals (1 hour) and it was found that at no oil concentration was the fermentative capacity of the lactic acid bacteria used in this study inhibited. Sensory analysis led to the conclusion that yoghurt flavoured with orange oil scored highest. [ABSTRACT FROM AUTHOR]

Essential oils have been mainly used in aromatherapy, but they have gained the attention of the food industry in the last decade due to their ability to control the growth of pathogenic microorganisms. The essential oil content of plant tissue varies according to the stage of development of the plant, the parts of the plant (leaves, flowers, roots, etc.) as well as the method of extraction. Commonly used techniques for extracting essential oils include hydrodistillation, steam distillation (Chialva et al.,1982), solvent extraction, (Chialva et al.,1982) and CO2 extraction (Takeoka et al.,1985). The composition of the extracted oil may vary from one extraction method to another. The essential oils used in this study were: clove, peppermint, cinnamon, sage, orange. Observations were made on extraction yield, MIC for Lactobacillus bulgaricus, and comparative antimicrobial activity with two commonly used antibiotics. [ABSTRACT FROM AUTHOR]