7.1. Colour pigment adsorption by the yeast biomass
Of the proposed mechanisms by which yeast might affect the colour of red wines,
absorption to biomass appeared to be one whose investigation might be
straightforward. That yeast bound pigments was apparent from examination of
biomass from fermentations of anthocyanin supplemented media or even simple
experiments where the biomass was incubated in wine or anthocyanin preparations
(Fig. 15). To explore the basis for and variability in such pigment binding, we sought
to simplify the approach used in Sections 2.2 and 2.3. Primarily and in the first
instance we aimed to eliminate differences between strains arising out of fermentation
differences, thus biomass was added to finished wines and incubated for several days
before colour analysis was undertaken.