Transcript ucce.ucdavis.edu

Design of Fining Trials and Fining Trial
Assessment
Anita Oberholster
Wine Fining
• “To add an adsorptive or reactive substance
to reduce or remove the concentration of
one or more undesirable components.”
• Fining agents grouped according to chemical
nature and mode of action
– Earths: bentonite
– Proteins: gelatin, isinglass, casein, albumin
– Carbons: activated charcoal
– Synthetic polymers: PVPP
– Colloids: agar or gum arabic
– Etc. many combinations available these days
Why fine?
• To improve clarity and stability of wine
• Remove possible faults
• Reason for fining will determine optimal
fining agent or agents
– Protein (haze forming potential)
– Phenolic compounds (tannin)
• Soften wine
• Reduce bitterness and astringency
– Metal ions
– Off-character or off-character-forming potential
Morris and Main (1995)
Solving Wine Production Problems
Harbertson, The Guide to Fining Wine
Fining Trials
• Fining trials are critical to determine impact
of additions, thus avoid unnecessary fining
and over-fining
• Fining should be investigated at different
levels
• Objective is to achieve goal with the smallest
possible amount of fining agent
• Many different agents can achieve same goal
– If not satisfied with results, try another fining
agent
Morris and Main (1995)
Fining Trials
• For consistent results – closely mimic winery
preparation methods, temp, mixing, timing
• Effectiveness of fining agents reduced by
50% with improper preparation
– Follow supplier recommendations
• Fining agents are not sterile
– Store properly, could be source of microbes
Morris and Main (1995)
Fining Trials
• Fining agents have to be removed from wine
– Some react quickly and can be removed
immediately
– Carbon and PVPP can be filtered out
immediately
– Others needs to settle (10-15 days) – bentonite
etc.
Morris and Main (1995)
Fining Trial Assessments
• Fining for protein stability
– Testing protein stability of fined wines with
heating and chilling
– Many different methods used, example
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6 hrs at 80oC followed by 12 hrs at 4oC
2 hrs at 80oC followed by cooling in ice to room temp
48 hrs at 50oC followed by cooling to room temp
90 min at 90C, cooling in ice to room temp
• Fining for clarity
– Nephelometric measure of turbidity
• Amount of light scattered by suspended particles
Fining Trial Assessments
– Visual inspection of clarity
• Turbidity values of <10 NTU will appear clear to naked
eye
– Penlight flashlight in darkened room
• If light passes through treated wine unimpeded 0.5
– 3.5 NTU
Morris and Main (1995)
Bentonite
• Bentonite is electrostatic and neg charged
• Reacts with positively charged components
• Mostly used for protein fining in white
wines/juice
• Will also react with color and phenol
compounds
• Removes some aroma compounds (<13%)
– Although remove herbaceous aromas more than
varietal aromas
Morris and Main (1995); Armanda and Falqué (2006)
Bentonite
• Also used to remove polyphenoloxidase from
juice
• Ca2+ and Na+ available
• Na+ most effective as it hydrates best
• Bentonite should be prepared in water as
swelling is required, limited ability in alcohol
containing solutions
• Bentonite prepared in hot water, allowed to
set for 24 to 48 hrs to hydrate, agglomerated
formulation can be mixed in cold water
Morris and Main (1995)
Bentonite conditions
• Age of bentonite had no signf effect
• Method of addition – no influence
• Mixing speed – does have influence
– Need to mimic in lab the mixing speed in winery
• Signf influence of mixing, need to do
duplicates analyses in lab to ensure reliability
Weiss et al. (2001) Am. J. Enol. Viti. 52(3): 275-279
Protein Fining Agents
• White wine: used for clarification and
improved stabilization
• Red wine: clarification and reduction of
phenolic compounds
• Most common agents
– Casein, Gelatin, Albumin, Isinglass
– Now also vegetable origin proteins; glutin
(wheat), legumes, white lupin, pea proteins –
“allergen free”
Fining for Astringency
• Phenolics - main contributors to bitterness
and astringency
– Bitterness and astringency increases with
increased mDP
– Ratio of astringency to bitterness increase with
mDP
– ‘Coarseness’ and ‘dryness’ of astringency
increase with galloylation
– The larger the tannin the better it interacts with
protein up to a point
Gawel et al. (1998) Austr. J. Grape Wine Res.(6) 74; Vidal et al. (2003) J. Sci . Food Agric. (83) 564
Oberholster, Francis, Iland, Waters (2009) Austr. J. Grape Wine Res. (15) 59-69
Fining for Astringency
• Sensory properties of pigments
– Anthocyanins have no taste or mouthfeel
– Pol. Pigments add to astringency “dry”, “grippy”,
“viscosity”, “fine emery”
Gawel et al. (1998) Austr. J. Grape Wine Res.(6) 74; Vidal et al. (2003) J. Sci . Food Agric. (83) 564
Oberholster, Francis, Iland, Waters (2009) Austr. J. Grape Wine Res. (15) 59-69
Protein Fining Agents
• Casein
– Derived from milk, represents different protein
species of low MW (<30 kDa)
• Gelatin
– Derived from animal collagen (skin or bones)
– Bloom number 75-100 suitable for wine (20-25
kDa)
– Different MW ranges
– In white wines, counter fined with Kieselsol or
tannin to prevent over fining
Protein Fining Agents
• Egg albumin
– Egg whites (1-8 per 30 gal barral, av 2-4)
• I egg white 3-4 g active product
• Prepared in 0.7% salt solution (1:2 v/v)
• Isinglass
– Produced from fish bladder
Fining for Astringency
• Test efficiency of removing different MW
tannins (F1 – 1.5; F2 – 3.4; F3 – 4.9)
– Casein more effective than K+casein
– Low MW gelatine 20% all tannin fractions
– High MW gelatine minor effect (<5%) on F3
– Isinglass did not remove F2, although F1 and F3
• Swim bladder isinglass>>fish skin isinglass
– Egg albumin removed all but most effective F3
(24%)
Cosme (2009) Am. J. Enol. Vitic. 60(1)
Fining for Astringency
• Protein fining agents remove color, with egg
albumin removing the least
• Sarni-Manchado (1999) found that gelatin
preferentially remove the more galloylated
PA’s
– Coarse and drying astringency
• Fining with plant proteins
– Maury et al. (2003) found different wheat glutins
and white lupin removed the same phenols as
gelatin
Sarni-Manchado et al. (1999)Am. J. Enol. Vitic. 50(1); Maury et al. (2003) Am. J. Enol. Vitic. 54(2)
Fining for Astringency
• Gelatin and egg albumin  mDP of tannin by
26,4 and 25.2 %
• This study in contrast found that egg
albumin removed more color than gelatin
• Found cross-flow microfiltration (CF)
removed similar tannin to protein fining but
more color
• Tasting – no signf diffr between controls and
protein fined wine, CF diffr
Oberholster et al. (2013) Food Chem. 138, p: 1275–1281
Fining for Bitterness and Color
• PVPP and Carbon
– Used to remove small phenolics – bitter
components
– Remove color (oxidative browning, pinking)
– Carbon easily strip wine of both desirable and
undesirable components
Summarize
• Determine possible fining agents for goal
• Do fining trials with different fining agents to
obtain same goal
• Evaluate best fining agent, optimal addition
Thank you
Questions?