Efeito do quitosano na viabilidade de Brettanomyces bruxellensis e na produção ...

• Author(s): Reis, Marta Lopes Egídio
• Date: 2014
• Persistent ID: http://hdl.handle.net/10400.5/6878
• Origin: Repositório da UTL
• Subject(s): Brettanomyces bruxellensis; chitosan; 4-ethylphenol; cellular growth; wine; contamination
• Document Type: Master Thesis
• Language: Portuguese
• Advisor(s): Ferreira, Manuel Malfeito

Description

Mestrado em Engenharia Alimentar - Qualidade e Segurança Alimentar - Instituto Superior de Agronomia The spoilage yeast, Brettanomyces bruxellensis, can cause the formation of film in storage wine, sediments, gas production and the production of unpleasant tastes and flavors to the consumer. Chitosan is presented as a potential product to control the yeast that alter the wine. Under laboratory conditions the effect of chitosan at different concentrations was tested in the growth of various B. bruxellensis strains in synthetic medium and wine. Viability was followed in plate with GYP medium, by hemocytometer counting with vital staining. Production of 4-ethylphenol was also analyzed. In synthetic medium it was possible to control the growth with 1 g/L of chitosan. In wine the necessary concentrations were lower, because it is a more stressful environment. With lower concentrations and with poorly adapted cells it was possible to control, the growth of the strains tested with 0,1 g/L and 0,05 g/L. However, when chitosan is added after the exponential phase, it is only possible to control the growth with 0,5 g/L. The production of 4-ethiphenol only reached significant values, over 800μg/L, on the wine trial with well adapted cells. The results in this trial show that the effect of chitosan is dependent of the strain, cellular concentration, growth stage of the cells and that the production of 4-ethylphenol was significant only in wine with well adapted cells. The usage of chitosan has no effect on the VBNC stage of the cells.