Effect of the Essential Oils from Parsley and Fennel Seeds on the Growth of Lactobacillus Casei Subsp Rhamnosus

Abstract

In this paper the key odorants effects of parsley ( Petroselinum crispum Hoffm) and fennel ( Foeniculum vulgare ) in the growth of Lactobacillus casei subsp rhamnosus , were studied. Parsley and fennel essential oils were obtained by hydrodistillation with 0.14% yield from parsley and 1% from fennel. All experiments were carried out in a 2L jar fermenter with an initial volume of 1.5L at 42°C, and the constant, adjusted to 200 rpm. Lactobacilli suspensions were incubated at 42°C for 12hr at 200 rpm and then a 10% (v/v) of the bacterial suspension was added to the cultures. The culture pH was maintained at 6.25 by automatic addition of 25% (w/w) NH 4 OH. For that purpose, batch cultures on MRS medium containing 15 g.L -1 of glucose were realized: the first fermentation is considered as a control, the second is characterized by the addition of 20 μL of the parsley essential oil in the growth exponential phase and the third contains additionally 20 μL of the fennel essential oil. The results show that Lactobacillus casei subsp rhamnosus can produce up to 10.96 g.L -1 and 13.78 gL -1 of lactic acid on the control fermentation and on the second fermentation, respectively. The addition of the fennel essential oil provokes an inhibition of the Lactobacillus casei subsp rhamnosus growth which is translated by the obtained weak lactic acid concentration of 5.14 g.L -1 .