The objective of this research was to determine the influence of controlled atmosphere and controlled atmosphere with the addition of tea tree or cardamom essential oil on the kinetics of changes in vitamin C content, chlorophyll pigments and on the total number of microorganisms and anaerobic titre during storage of two cultivars of savoy cabbage: 'OWASA and 'WIROSA. The cabbage was stored at 0-1°C under controlled atmosphere (CA) composed of 4% CO 2 , 3% O 2 and 93% N 2 , in CA with the addition of tea tree oil (oil 1) or cardamom essential oil (oil 2) at the concentration of 15 ppm, and in the air (K). It was proved that, irrespective of the presence of an essential oil, CA slowed down the degradation of vitamin C and chlorophyll pigments in the stored vegetables. The controlled atmosphere prolonged the period when vegetables maintained their high biological value during cold storage. The tea tree essential oil added to CA improved the general microbiological quality of the stored cabbage, causing a reduction in the total number of microorganisms by two logarithmic units after 1-2 months of storage, while the cardamom essential oil decreased it by one logarithmic unit related to CA free from essential oil.

In recent years there has been an increasing interest in the use of natural substances, and some questions concerning the safety of synthetic compounds have encouraged more detailed studies of plant resources. Essential oils, odorous and volatile products of plant secondary metabolism, have a wide application in folk medicine, food flavouring and preservation as well as in fragrance industries. The antimicrobial properties of essential oils have been known for many centuries. In recent years (1987-2001), a large number of essential oils and their constituents have been investigated for their antimicrobial properties against some bacteria and fungi in more than 500 reports. This paper reviews the classical methods commonly used for the evaluation of essential oils antibacterial and antifungal activities. The agar diffusion method (paper disc and well) and the dilution method (agar and liquid broth) as well as turbidimetric and impedimetric monitoring of microorganism growth in the presence of tested essential oils are described. Factors influencing the in vitro antimicrobial activity of essential oils and the mechanisms of essential oils action on microorganisms are reported. This paper gives an overview on the susceptibility of human and food-borne bacteria and fungi towards different essential oils and their constituents. Essential oils of spices and herbs (thyme, origanum, mint, cinnamon, salvia and clove) were found to possess the strongest antimicrobial properties among many tested.