Pre-Harvest Workshop

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Pre-Harvest Workshop

• August 5, 2002

Bruce Zoecklein Virginia Tech Lisa Van de
Water Director, The Wine Lab and Pacific Rim
Enology Service Richard Carey President, Vitis
Research Mary Davis-Barton VDACS
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Enology-Grape Chemistry Group Workshops

• Juice and Wine Analysis.
• Jan. 7 8, 2003, VT Campus.
• Fee 350, before November 1.
• Tannin and Color Measurement Workshop.
• Jan. 16, 2003, VT Campus.
• Fee 250, before December 1.
• Additional information posted at
• www.vtwines.info

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Pre-Harvest WorkshopProgram

• HACCP
• Yeast nutrition
• Fermentation issues
• Process management issues
• Delestage / Microoxygenation
• Lees management
• H2S / mercaptans
• Remission photometry
• VDACS marketing

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Establishing a HACCP-like Plan

• Bruce Zoecklein
• Head, Enology-Grape Chemistry Group
• Department of Food Science Technology
• Virginia Tech

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HACCP What is it?
Virginia Tech
Hazard Analysis Critical Control Point system
A means of assuring quality through the
identification and monitoring of critical points
during the production process.
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HACCP What is it?

• 1960s developed for space food program
• Adopted by food processors to minimize the risk
  of contamination in food products
• Wine quality and stylistic control
• Integration of chemical, physical,
  microbiological, and sensory analyses

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Problem WinesExtension Wine Analysis VT

• High pH
• Insufficient SO2 / Excessive O2
• Incomplete primary and/or secondary fermentation
• High concentration of microflora at bottling
• Inadequate protein stabilization
• Improper vineyard / wine additives

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HACCP
Virginia Tech

• Looks at processing/product from start to finish
• Determines where hazards occur (critical control
  points, or CCPs)
• Establishes controls where these hazards occur
• Establishes means to monitor CCPs

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HACCP

• Produce a flow chart beginning in the vineyards
  and ending with delivery
• Note critical points at each stage
• Rank CCPs in terms of importance
• List control methods
• Determine
• When to analyze.
• Why every analysis is performed.
• Where the analysis fits into the scheme of
  quality wine production.
• What is the specific range for results.
• What to do if the results are not within
  specification.

Virginia Tech
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Establishing a HACCP-Like Plan
Virginia Tech
VINEYARD
AGING
BOTTLING
CRUSHING/PRESSING
JUICE/MUST
BLENDING
FERMENTATION
MATURATION
FREE RUN
PRESSINGS
CLARIFICATION
COMPLETED FERMENTATION
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Enology Components of a HACCP-Like Plan

• Vineyard spray materials
• Crop load
• Solar exposure of the fruit
• Degree of leaf shading
• Fruit maturity, including tannin maturity
• Uniformity of fruit maturity
• Berry size
• Fruit rot

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Grape Sampling for Red Fruit
Virginia Tech

• Vineyard sampling
• Degree of asynchronous ripening
• Type of samples
• Sample size
• Sampling area
• Block vs. sub-block
• Side of the canopy
• Sample processing method

Importance Varietal character/fruit, balance,
phenol maturity, style Accuracy Accuracy
Varietal character, fruit balance, phenol
maturity, style Accuracy
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Maturity Gauges for Red Fruit
Importance Varietal character, fruit
intensity Tannin balance, style Maturity,
color Structural balance, processing
decisions Processing decisions
Virginia Tech

• Aroma
• Tannin maturity
• Skins
• Seed, seed numbers
• Color
• Berry size/weight
• Berry softness

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Maturity Gauges for Red Fruit
Virginia Tech

• Degree of berry shriveling
• Sugar per berry
• Brix
• TA
• pH

Importance Varietal character/fruit, tannin
balance Maturation/dehydration/ rehydration
Potential alcohol, structural
balance Structural balance Structural balance,
stability, longevity
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HACCP-Like Plan
Quality Indicators
Virginia Tech
VINEYARD SAMPLING
CRUSHING/PRESSING Rot culling, temperature, SO2,
enzymes
JUICE/MUST Sensory, ºBrix, pH, NSS,
fermentable N, TA, SO2, temp, oxygen,
enzymes
FERMENTATION Adjustment, ºBrix, pH, TA,
fermentable N, Sensory, temp Yeast (strain,
inoc. vol., budding, viability, purity)
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Red Wine HACCP-Like Plan

• Fruit handling and non-soluble solids
• Degree of crushing/destemming, whole cluster
  pressing, short vatting, extended skin contact
• Cold soak
• Sulfur dioxide addition, pre- and
  post-fermentation
• Nutrient addition, timing
• Acid addition
• Tannin addition
• Chaptalization, and the Brix to alcohol
  conversion rate
• Chaptalization material
• Barrel/wood fermentation
• Enzyme addition

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HACCP-Like Plan
Quality Indicators
Virginia Tech
VINEYARD SAMPLING
CRUSHING/PRESSING Rot culling, temperature, SO2,
enzymes
JUICE/MUST Sensory, ºBrix, pH, NSS,
fermentable N, TA, SO2, temp, oxygen,
enzymes
FERMENTATION Adjustment, ºBrix, pH, TA,
fermentable N, Sensory, temp Yeast (strain,
inoc. vol., budding, viability, purity)
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Red Wine HACCP-Like Plan

• Yeast, uninoculated, fermentation rate,
  polysaccharide/manoprotein, sulfur dioxide
  producer, TA reducer
• Cap management/Delestage
• Bleeding
• Size and shape of fermentor
• Fermentation temperature
• Pre- and post-fermentation aeration
  (microoxygenation)
• Alcohol at dejuicing
• Free-run and press run
• Storage sur lie

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White Wine HACCP for Each Cultivar / Block / Lot

• Vineyard spray materials
• Crop load
• Solar exposure of the fruit
• Degree of leaf shading
• Fruit maturity, including tannin maturity
• Uniformity of fruit maturity
• Berry size
• Fruit rot

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White Wine HACCP for Each Cultivar / Block / Lot

• Fruit temperature
• Whole cluster / crush and drain
• Skin contact time / temperature
• Prefermentation clarification
• Enzymes, bentonite, time / temp
• Prefermentation additions
• Sulfur dioxide, acid, tannin
• Nutrient addition(s), timing

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White Wine HACCP for Each Cultivar / Block / Lot

• Chaptalization Brix to alcohol conversion
• Chaptalization material
• Oxygen management
• Yeast(s)
• Fermentation vessel, type, size, and shape
• Fermentation temperature
• Mid-fermentation racking
• Fermentation with Bentonite
• Lees contact
• O2 and SO2 management

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HACCP-Like Plan
Quality Indicators
Virginia Tech
FREE RUN PRESSINGS Sensory, tannin, and
color MLF (strain, inoc. vol., purity)
COMPLETED Sensory, ºBrix, reducing sugar,
pH, TA, alcohol, MLF status,
FERMENTATION oxygen, SO2, protein stability,
bitartrate stability
CLARIFICATION Sensory, oxygen, protein
stability, bitartrate stability
MATURATION Sensory, oxygen, SO2, MLF
status
BLENDING Sensory, physical,
chemical, biological stability
BOTTLING Sensory, fill level, SO2,
oxygen, micro., materials QC
AGING Sensory, storage temp., temp.
fluxes, optimum release date
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Methods Precision Limits

• Method
• TA
• Alcohol Ebulliometry
• Formol Titration for N
• Sulfur Dioxide A-O
• Bitartrate Stability Conductivity
• pH
• Residual Sugar
• VA

• Precision Limit
• 0.2 g/L (2)
• 0.1
• 2 - 3
• 1 mg/L (free, bound)
• 2 mg/L (total)
• 0.1 ()
• 0.1
• 0.1
• 0.1

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Common Sources of Lab Errors
Virginia Tech

• Human error
• Equipment problem or instrumental drift
• Inappropriate methods or procedures
• Bad reagents (improperly prepared, beyond shelf
  life)
• Variable lab environment (temperature, humidity,
  ventilation changes)
• Poor sampling

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HACCP Summary

• Define the production process, quality/style
  indicators, and their recommended values.
• Identify critical control points in the process
  where specific chemical methods can monitor
  quality indicators.
• Establish and carry out analysis methods that
  will give measures of quality/style indicators at
  each control point.
• Compare measured values with recommended values.
• Decide on action to modify any quality
  deficiencies.
• Carry out that action.
• Assess the result of that action by further
  analysis.

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Basic Elements of In-House Evaluation

• Fully understand the objective(s)
• Evaluate representative samples
• Select (and train) evaluators
• Minimize prejudice and bias
• Establish that differences exist
• Employ consistent tasting format
• Interpret results appropriately

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Virginia Tech Enology-Grape Chemistry Group
Enology Notes, electronic newsjournal e-mail
bzoeckle_at_vt.edu put ADD in subject line
Web address www.fst.vt.edu/zoecklein/index.html
or www.vtwines.info