THURSDAY. 6
thSeptember-15:00-16:10
PARALLEL SESSION
Food fermentation : New approaches / Safet
y
Effect of nutrient depletion on parietal adsorption activit
y
of
s
accharom
y
ces cere
v
isiae selected for
w
inemaking
R
ossan
a
SID
A
R
I
,
And
r
ea
CA
R
I
D
I
Mediterranea University of Reggio Calabria, Department of Scienze e Tecnologie Agr o-ForestalieAmbientali, ReggioCalabria, ITALY
Corresponding author: rossana.sidari@unirc.it
The aim ofthis work was to investigate the effect of carbon and nitrogen availability on colouradsorption activity of selectedwine yeasts, testing themin poor and rich media in the presence of colouredphenolic compounds from grapeskins.Elevenautochthonous Calabrian
yeast strains of the species Saccharomyces cerevisiae -previously selected as wine starter
based on their different aptitude to adsorb grape pigments ontheir cell-wall -and 2 control strains of S.cerevisiae BY4742 andLl278b weregrown on(a)grape skinagar (Caridietal.,
2007), containingblack grapeskin powder 4%and dextrose 5%, 2% or 0.1%, (b)synthetic lowammonium dextrose agar (Zaragoza ve Gancedo, 2000) supplemented withblack grape
skinpowder 4%andcontainingdextrose 2%or 0.1%,and (c) yeast peptone dextrose agar as
controImedium.After incubation at28°C for lOdays,strains were processed for Red-Green
-Blue analysis by Photoshop CS, thatgives low or highvalues foryeast able (darkbiomass) or unable (lightbiomass) to adsorb coloured compounds, respectively. The effect ofnutrient availability is not univocalfor the l3 yeaststrains that exhibit significant differences for the
colour parameters. Interestingly, depletion in (a) nitrogen or (b) carbon and nitrogen
determines a decrease in the yeast adsorption activity, possibly due to yeast overcoming nutrient stress by phenolic compounds that seem to have a role as nutrient supplements.
There isampie evidence for the effects of nutrient depletion on transcriptional activation or repression of specific genes in Saccharomyces cerevisiae, as those connected to pseudohyphal growth and flocculation. The relevant literature and the present results have
been discussed considering, above all, the oenological consequences for wine starter
selection. Thisresearchwas also supportedby Calabria Region, ResearchFund APQ, Action
3, "Miglioramento delleproduzioni vitivinicole della zona delCirò", leader winery: Caparra
&Siciliani.
