Utilization of hardwood hemicellulosic hydrolyzate by two yeasts for xylitol production

National audienc

Alcoholic cofermentation of lignocellulosic sugars using a membrane recycle bioreactor

National audienc

Xylitol production from xylose by two yeast strains : sugar tolerance

International audienc

Utilization of hardwood hemicellulosic hydrolyzate by two yeasts for xylitol production

National audienc

Alcoholic cofermentation of lignocellulosic sugars using a membrane recycle bioreactor

National audienc

Combined effect of volatile antimicrobial agents on the growth of Penicillium notatum

International audienceWidely used antimicrobial volatile organic compounds, such as sulphur dioxide and ethanol but also selected aroma compounds such as carvacrol, allyl isothiocyanate (AITC) and cinnamaldehyde, were tested single and in binary combination for their effect on Penicillium notatum growth in vapour phase at 30 °C. Aroma compounds were more efficient compared to sulphur dioxide and ethanol. AITC and cinnamaldehyde had the highest inhibition activity on the growth of P. notatum with minimum inhibitory concentration (MIC) of 3.8 and 3.9 μmol/L of air, respectively. The impact of agents combined two by two was assessed using two criteria, the increase of growth delay and the reduction of growth rate. A synergistic activity was identified for six combinations; ethanol/carvacrol, sulphur dioxide/carvacrol, sulphur dioxide/AITC, sulphur dioxide/cinnamaldehyde, AITC/cinnamaldehyde and cinnamaldehyde/carvacrol. The advantage of these combinations is to reduce the concentration of each agent and their relative impact in organoleptic properties

Antimicrobial activity of carvacrol related to its chemical structure.

International audienceAims: To investigate the relation between the chemical structure and the antimicrobial activity of carvacrol, eugenol, menthol and two synthesized carvacrol derivative compounds: carvacrol methyl ether and carvacryl acetate against bacteria, Escherichia coli, Pseudomonas fluorescens, Staphylococcus aureus, Lactobacillus plantarum, Bacillus subtilis, a yeast Saccharomyces cerevisiae and one fungi Botrytis cinerea.Methods and Results: The antimicrobial activity was tested in liquid and vapour phases, by both broth liquid and microatmosphere methods, respectively. The same classification of the compound's antimicrobial efficiency was found with both methods. Eugenol and menthol exhibited a weaker antimicrobial activity than carvacrol, the most hydrophobic compound. Carvacryl acetate and carvacrol methyl ether were not efficient, indicating that the presence of a free hydroxyl group is essential for antimicrobial activity.Conclusions: The different extents of antimicrobial aroma compounds’ efficiency showed that hydrophobicity is an important factor and the presence of a free hydroxyl group and a delocalized system allows proton exchange.Significance and Impact of the Study: This study has identified the importance of the hydrophobicity and the chemical structure of phenolic aroma compounds for antimicrobial activity and may contribute to a most rational use of these compounds as antimicrobial agent

Biological production of xylitol from hemicellulosic biomass: effect of the carbon source on the aldose reductase activity in Candida guilliermondii

National audienc