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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

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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

      • 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

    Gawelet 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”

    Gawelet 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?


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