Rocky Mountain Association of Vintners and Viticulturist New Research on Oxygen and Nutrient Require

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Rocky Mountain Association of Vintners
and Viticulturist New Research on Oxygen and
Nutrient Requirements to Avoid Stuck
Fermentations

• Diana M. Burnett
• Scott Laboratories Mar 27, 2004

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Healthy Yeast Fermentations

• Yeast Selection
• Proper Yeast Rehydration
• Temperature Requirements
• Nutrients
• Sources
• Integrated Nutrition
• How do they differ?
• Timing of Nutrient Addition
• Oxygen Requirements
• Lysozyme-kill gram positive bacteria

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Yeast Selection

• Choose the right yeast for every fermentation
• Address the following factors
• Sensory Effect (neutral, esters, mouth feel)
• Temperature Tolerance
• Alcohol Tolerance
• Nitrogen Requirements
• Fermentation Speed
• See Scott Lab Handbook Chart

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Yeast Nutritional Requirements..

• Yeast Assimilable Nitrogen (YAN)
• Inorganic
• Organic
• Oxygen
• Sterols
• Unsaturated fatty acids
• Micronutrients
• Vitamins
• Minerals

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YANC OR YAN

• Yeast Available Nitrogen Content
• sum of assimilable nitrogen from Free Ammonia
  Nitrogen (FAN) plus the assimilable nitrogen from
  alpha amino acids in juice/musts.
• low levels associated with production of
  undesirable sulfide compounds and stuck
  fermentations
• Recommended levels
• 250 ppm-350 ppm or higher depending on the
  initial BRIX level.

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Analysis Methods to Determine YANC

• NOPA method (outside lab)
• FAN content
• Ammonia probe (inside or outside lab)
• Inorganic nitrogen content

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MICRONUTRIENTS VITAMINS
Pantothenate avoids H2S and VA formation,
better kinetics, less acetaldehyde, strain
sensitivity Biotin better kinetics, synergic
effect with N, increases ester production,
higher yeast viability at end
AF Thiamine better cell growth, less
acetaldehyde and VA Inositol essential for
membrane phospholipid synthesis
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MICRONUTRIENTS Minerals
Magnesium better alcohol, temperature and osmotic
resistance, higher ethanol yield, ratio CaMg
lt 1 Zinc cofactor of glycolysis enzymes,
increase alcohol tolerance, regulation of
by-products (esters, alcohols, fatty
acids) Manganese synergic effect with Zn,
shorter generation time Copper essential
element, but toxic above 1-2 mg/l Potassium must
be gt 300 mg/l at low pHs
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Rehydration Nutrient Go-Ferm/Dynastart

• 100 BIOLOGICAL INACTIVE YEAST
• INTEGRATED NUTRIENTS
• vitamins, minerals, amino and fatty acids
• USE DURING THE REHYDRATION STEP
• micronutrient bioavailability
• sponge effect, no competition
• SAFE END OF FERMENTATION
• PREVENTS METABOLIC DEVIATIONS
• H2S
• VA
• EASY TO USE

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USE OF Rehydration Nutrient
1
2
3
Inoculum
Go-Ferm 2.5 lb
Yeast 2 lb
1000 gal
suspend
rehydrate
4gal
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Rehyrdation Nutrient FERMAID
FERMAID K Do I still need it? In high sugar or
nitrogen deficient musts a YAN addition (at 1/3
AF) is still needed Rehydration Nutrient
provides about 10 mgN/l at 30 g/hl (100
a-amino) FERMAID K provides about 40 mgN/l at
30 g/hl (mix of a-amino and ammonia) DAP
provides about 60 mgN/l at 30 g/hl(100 ammonia)
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Yeast Strain Nitrogen DemandJ.M. Sablayrolles
INRA-IPV Montpellier, France
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Nitrogen Requirements of Yeasts
LOW
MEDIUM
HIGH
71B / DV10 / EC1118
K-1 / D254 / L2056 / R2 / RC212 / S6U
CY3079 / BM45 / VL1
Julien,et al 2000
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Yeast Temperature Requirements

• Yeast strains differ in temperature tolerance
• Temperature plays an important role during yeast
  multiplication
• (Lower fermentation temps (lt 77 F) slows cell
  division, thus slowing alcohol production and
  excretion)
• Temperature is the only factor with an immediate
  direct MORTAL effect on yeast
• The more yeast are stressed early in
  fermentation, the lower the peak temp it can
  tolerate.

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Oxygen Requirements

• Optimum Oxygen addition at maximum yeast cell
  density (1-3 days post yeast inoculation)
• O2 is required by yeast for lipid and sterol
  synthesis optimal cell membrane function
• For anaerobic fermentations (white wine) use
  supplements that contain unsaturated fatty acids
  and sterols
• (HINT Use Rehydration Nutrient and Fermaid K)

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Yeast Strain Oxygen Addition BenefitJ.M.
Sablayrolles INRA-IPV Montpellier, France
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PROPER YEAST REHYDRATION HANDLING
1st suspend GO-FERM
2nd add Active Dried Yeast

• Clean water (104oF)
• Suspend GO-FERM
• Add Active Dried Yeast
• 15-30 minutes
• Avoid cold shock gt18oF
• Add yeast slurry to bottom of tank

104oF
JUICE
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Practical Fermentation Nutrient Management
Summary

• Measure juice/must Yeast Assimilable Nitrogen
  Content YANC
• Rehydrate yeast with Rehydration Nutrient
• Optimum Oxygen addition at maximum yeast cell
  density (1 - 3 days after yeast inoculation)
• Make additional nutrient addition(s) if needed
• DAP at end of lag phase (6-12 hours after yeast
  inoculation)
• and/or Fermaid K at 1/3rd sugar depletion (2-4)
  days after yeast inoculation)

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Integrated Nutritional Strategy for 22 BRIX
Musts
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Lysozyme

• Degrades the cell wall of gram positive bacteria
• Oenococcus, Lactobacillus, Pediococcus
• Not effective against gram negative bacteria or
  yeast
• Acetobacter, Brettanomyces
• Naturally occurring enzyme isolated commercially
  from egg whites by Fordras
• 20 tons of egg whites yield 6 kilos of Lysozyme
• The egg cracking machine breaks 180,000 eggs/hour

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Lysozyme versus SO2

• Lysozyme
• Most effective at high pH
• No antioxidant properties
• Only kills gram positive bacteria
• In whites no sensory effect, in reds will complex
  with tannins and anthocyanins and precipitate

• SO2
• Most effective at low pH
• Antioxidant
• Kills bacteria and at high levels inhibits yeast
• Sensory implications

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Lysozyme allows winemakers to greatly reduce SO2
levels. It is not able to completely replace SO2.
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Lysozyme and its uses

• To start off fermentation clean
• To delay MLF in red wines
• To partially (or completely) block MLF
• When blending partial and complete MLF wines
• In sluggish or stuck fermentations
• Stabilizing wines after MLF
• In sparkling wines for more persistent, tiny
  bubbles

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Scott Laboratories
Thank you!!

• Contacts
• DianaB_at_scottlab.com
• cell 707 696-8304
• TomA_at_scottlab.com
• Cell 707 322-4500