Paneldiscussie Brouwland 26 mei 2007

[Amberbock]

Ik vond volgend artikel betreffende olijf olie en gist kwaliteit :

Het artikel gaat over toevoeging van "linoleic acid" hetgeen 10% van de vetzuren van olijfolie uitmaakt. In het artikel wordt het linoleic acid gemengd met ethanol om het zo te kunnen oplossen en beter te kunnen doseren. 

Ik denk dat het toevoegen van olijfolie even belangrijk is tijdens starter productie om zo met een kwalitatief hoogstaande gist aan de hoofdvergisting te kunnen beginnen.  Dus volgende keer voeg ik zeker enkele druppels olijfolie toe bij mijn starter als test.


Alle artikels van J.Inst.Brew zijn online gratis beschikbaar.

Veel leesplezier

Amberbock.

The Effects of Linoleic Acid Supplementation of Cropped Yeast on its Subsequent Fermentation Performance and Acetate Ester Synthesis
N. Moonjai, 1, 2 K. J. Verstrepen, 1 F. R. Delvaux, 1 G. Derdelinckx, 1 and H. Verachtert 1
1 Centre for Malting and Brewing Science, Faculty of Agricultural and Applied Biological Sciences, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, 3001 Heverlee, Belgium
2 Corresponding author : E-mail: Nareerat.Moonjai@student.kuleuven.ac.be

J. Inst. Brew. 108(2), 227-235, 2002  |   VIEW ARTICLE

ABSTRACT
For beer wort fermentation the addition of unsaturated fatty acids has sometimes been suggested as an alternative to wort oxygenation. This can however negatively affect the synthesis of acetate esters and consequently beer flavour. This work investigates the effect of supplementing a cropped yeast with an unsaturated fatty acid on the fermentation performance of the pitching yeast. Cropped yeast is in a different physiological state to yeast pitched in unfermented wort. Using a synthetic medium for the fermentations, it was found that the incubation of cropped yeast with linoleic acid resulted in two important changes in the yeasts composition: (1) the ratio of unsaturated fatty acids to total fatty acids increased from 0.53 to 0.66 and (2) the ratio of trehalose to glycogen increased from 0.17 to 0.49. The performance of this yeast in subsequent fermentations was compared to unsupplemented yeast under three conditions: medium pre-aeration, de-aerated medium and de-aerated medium with newly added unsaturated fatty acid. It was found that the supplemented pitching yeast showed growth, attenuation and ethanol formation profiles similar to those obtained with unsupplemented yeast in pre-aerated medium, which simulated the normal brewing practice. Compared to fermentations with unsaturated fatty acids added to the medium, the supplemented cropped yeast did not induce a reduction in acetate ester synthesis. Results indicated that the supplementation of cropped yeast with unsaturated fatty acids could be an interesting alternative to wort oxygenation to restore the optimal membrane fluidity of the yeast.