The Importance of Juice Clarification, SO 2 and Sorbate In The Production of Premium

Transcription

1 The Importance of Juice Clarification, SO 2 and Sorbate In The Production of Premium Table Wines T.E. STEINER DEPT. of Horticulture and Crop Sciences The Ohio State University/OARDC Wooster, Ohio 44691

2 Juice Clarification Juice clarification prior to fermentation is an important aspect in producing a high quality white table wine

3 Advantages of Juice Clarification Produce clean, fruity and delicate wines Production of less higher alcohols with better varietal characteristics Less off odors, particularly hydrogen sulfide Produces wines with less harsh and rough characteristics

4 Disadvantages of Juice Clarification Excess juice clarification has characterized some varietals as being less complex Must with excess juice clarification of less then.2% insoluble solids may lead to lengthened fermentations

5 Juice Clarification Practices Natural settling and racking Addition of pectic enzymes with natural settling and racking Addition of fining materials with natural settling and racking. (ex. bentonite) Centrifugation

6 Factors Influencing Amount of Juice Insoluble Solids Fruit condition - sound fruit yields less solids Maturity - over ripe grapes tend to produce higher insoluble solids Variety - certain varieties are recognized for producing high insoluble solids Fruit temperature - high temperature grapes produce higher insoluble solids

7 Juice Clarification Practices Juice clarification should take place at 50-55ºF to provide a more efficient separation Add pectic enzymes based on manufactures instructions, settle for 12 hours and rack off Addition i of bentonite (250 mg/l) or other fining agent while mixing slightly, settle for appropriate time and rack off

8 Clarification in Relation to Higher Alcohol Concentration Higher Alcohols mg/l Free Run Light Heavy Press Press Pressing Treatment Clear Turbid Gallander et al, (1983)

9 Seyval Blanc - Settling Study Score Aroma Taste Enzyme Bentonite Enz./Bent. Polyclar Natural Control Gallander et al, (1991)

10 Percent Solids (vol/vol) In Relation To Pressing Fractions % Solids (V Vol/Vol) Season WC FR LP HP

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13 Influence of Pressing Fractions on Pinot Gris Wine Quality Press Trt. ph Total Acidity % ETOH % VA Total phenols Across Seasons WC 3.12a 0.81a 13.2a 0.04a 196.7c FR 3.12a 0.76b 13.0b 0.04a 231.3a Light 3.12a 0.78b 13.2a 0.04a04a 219.7ab Heavy 3.12a 0.76b 13.3a 0.04a 211.3bc

14 Sensory Panel Data: (Overall Quality) Score WC 3 FR 2 LP HP 1 0 Quality 2002 Descriptor

15 The Proper Use Of Sulfur Dioxide and Sorbate

16 Importance of sulfur dioxide As an antioxidant Protects musts and wines from browning Binding of acetaldehyde Antiseptic activity it Prevents microbiological spoilage in wines from microorganisms i such as acetic acid bacteria, lactic acid bacteria, molds, and wild yeast At certain levels SO 2 may promote a rapid and complete clarification of must and wine

17 Disadvantages of sulfur dioxide use Sensory Excessive amounts can cause a metallic and harsh character to wines High levels of free sulfur dioxide add a pungent aroma or sharpness in the nose Color Bleaching of color from red varieties Incomplete fermentation's Cold instability with higher h amounts used

18 Sulfur Dioxide facts Some people can be allergic to SO 2 Especially steroid dependent asthmatics It does not cause headaches Headaches more related to biogenic amines Yeast strains will naturally produce SO 2 up to 15 mg/l (strain dependent) Legal limit set at 350 mg/l

19 Sources of Sulfur Dioxide Addition i of sulfur dioxide id gas Addition of potassium metabisulfite (wt./vol.) Addition of aqueous sulfur dioxide id (vol./vol.) potassium metabisulfite 1 ml of a 6.6% solution will add 10 ppm/gal.

20 Forms of sulfur dioxide id Free Includes (molecular, bisulfite and sulfite) forms not chemically bound to other wine constituents Bound Sulfur dioxide forms that combine with other wine constituents Total Refers to the amount of free plus bound SO 2

21 Chemistry of sulfur dioxide SO 2 + H 2O H 2SO 3 H 2 SO 3 HSO 3- + H + HSO = +H + 3 SO 3 Sulfite Sulfurous (molecular) Bisulfite

22 Free SO 2 Binding Sites Acetaldehyde Pyruvate 2-Ketoglutarate Malvadin-3-glucoside Glucose Other wine constituents t Source:

23 Influence of ph on SO 2 forms - = ph %SO 2 %HSO 3 %SO

24 Conversion factors ppm % mg/l Mult. Factor 100, , , ,

25 Essential times for SO 2 addition Crushed grapes or must Amount based on condition of grapes, temperature and ph Immediately after alcoholic fermentation Amount based upon wine style and variety Wine storage Treat wines at regular intervals with additional amounts to prevent oxidation and spoilage Pre-bottling Adjust to.8 ppm molecular based on wine ph

26 Addition of SO prior to bottling 2 to obtain.8 ppm (molecular) ph Free SO 2 ph Free SO Source: C. Smith, Enology Briefs, Feb/March, 1982, Univ.. of Calif.., Davis

27 Formula to calculate SO 2 addition to crushed grapes Wt. Of K 2 S 2 O 5 = Y x Z x 1.72 Where:Y = weight of crushed grapes (9.0 lbs. per gal.) Z = multiplication li factor of desired d ppm SO = conversion factor to change SO 2 to K 2 S 2 O 5

28 Formula to calculate SO 2 addition to wine Wt of K 2 S 2 O 5 = Y x 3.8 x 1.72 x Z 1000 Where: Y= volume of wine in gallons 3.8 =conversion factor to change gallons to liters 1.72 = conversion factor to change SO 2 to K 2S 2O 5 Z = desired ppm SO = conversion of mg/l to gm/l

29 Importance of sorbic acid As a chemical preservative sorbic acid is used to protect against yeast and mold growth and spoilage generally in wines that contain some residual sugar

30 Disadvantages of sorbic acid Sensory Certain people can detect sorbic acid levels normally found in wines Sensory threshold reported at 135 mg/l Malolactic bacteria may convert sorbic acid to an undesirable odor (Geranium) Use in conjunction with proper amount of SO 2

31 Sources of sorbic acid Potassium sorbate Salts of sorbic acid are used due to their greater solubility in water Higher amounts used may cause concern for cold instability

32 Forms of sorbic acid Sorbic acid behaves like sulfur dioxide in that the undissociated molecule is the most effective form in preventing yeast growth. Therefore as ph decreases, the greater the percent of undissociated acid.

33 Essential times for addition of sorbic acid In general, sorbic acid is added d prior to bottling to prevent further fermentations and off flavors. A general range of mg/l of sorbic acid is usually used at time of bottling. Legal limit is 300 mg/l

34 Formula to calculate potassium sorbate addition to wine Wt. Of potassium sorbate = Y x 3.8 x 1.34 x Z Where: Y = volume of wine in gallons = conversion factor to change gallons to liters (L/gal.) 1.34 = conversion factor to change sorbic acid to K - sorbate Z = desired ppm (mg/l) of SO 2 to be added 1000 = convert mg/l to gm/l

35 THANK YOU! Todd Steiner Enology Program Manager and Outreach Specialist OARDC Dept. Of Horticulture & Crop Science Phone: (330)