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Lactic Acid Spoilage Lucy Joseph Department of Viticulture and Enology U.C. Davis

Common LAB Found in Vineyards and Wineries • – Lb. brevis, Lb. casei, Lb. hilgardii, Lb. mali, Lb. plantarum, Lb. lindneri, Lb. kunkeei • Pediococcus – Pd. damnosus, Pd. parvulus, Pd. pentosaceus, Pd. ethanolidurans • Oenococcus – O. oeni • Lactococcus

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Lactobacillus brevis 1000x Lactobacillus casei

Lactobacillus kunkeei Lactobacillus delbrueckii

Oenococcus oeni

Bright Field Phase Contrast

400x

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Oenococcus and Pediococcus

1000x

Stuck or Sluggish Fermentations

• Bacteria can cause stuck or sluggish fermentations

• Competition for nutrients

• Direct inhibition of yeast growth or fermentation

• Induction of the [GAR+] prion state in yeast

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[GAR+] Induction Assay

Bacterial Induction of [GAR+]

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Bacterial Induction and Inhibition of [GAR+]

Bacteria Yeast UCD932 UCD strain #Wine Isolate Genus/species Induction Inhibition No Effect Lactobacillus brevis 169 Yes‐ wine X 24 Yes ‐ wine X 276 Yes‐ must X Lactobacillus casei 4Yes‐ wine X 170 Yes‐ wine X Lactobacillus curvatus 491 Yes‐ wine X Lactobacillus delbrueckii 249 Yes‐wine X Lactobacillus hilgardi 6Yes‐ wine X 10 Yes‐ wine X 16 Yes‐ wine X 125 Yes‐ wine X Lactobacillus kunkeei 26 Yes‐ wine X Lactobacillus mali 509 Yes‐ wine X 510 Yes‐ wine X Lactobacillus plantarum 511 Yes‐ wine X 517 Yes‐ wine X 519 Yes‐ wine X 101 Yes ‐ wine X 1 unknown X Lactobacillus sakei 494 Yes ‐ wine X Oenococcus kitahare 311 No‐ Sochu X 159 Yes‐ wine X 261 No‐ cider; France X Pediococcus parvulus 512 Yes‐ wine X 520 Yes‐ wine X 521 Yes‐ wine X 515 Yes ‐ wine X

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Spoilage Compounds Produced by

Bacteria Compound Sensory Effect Precursor Lactic acid bacteria Acetic Acid Vinegar, pungent, sour Tartaric and malic acids Lactic acid bacteria Ethyl acetate Nail polish remover Ethanol, acetic acid Lactobacillus/Oenococcus Diacetyl Butter, nutty, caramel Citric acid, pyruvate Lactobacillus/Pediococcus 2‐Ethoxy‐3,5‐hexadiene Geranium leaves Sorbic acid, ethanol

Lactobacillus/Oenococcus 2‐Acetyl‐tetrahydropyridine Mousy Ethanol (acetaldehyde), lysine

Lactobacillus/Oenococcus 2‐Ethyltetrahydropyridine Mousy Ethanol (acetaldehyde) Lactobacillus/Oenococcus 2‐Acetyl‐1‐pyrroline Mousy Ethanol (acetaldehyde), ornithine

Lactobacillus/Pediococcus Acrolein (+ anthocyanin) Bitter Glycerol Pediococcus b‐D‐Glucan Ropy, viscous, oily Glucose Oenococcus Mannitol Viscous, sweet Fructose Lactic acid bacteria Skatole (indole) Fecal Tryptophan Lactic acid bacteria Biogenic Amines None (headache) Amino acids

Letters in Applied Microbiology 48 (2009) 149–156 ; E.J. Bartowsky

Diacetyl

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Mousy 2‐ethyltetrahydropyridine 2‐acetyltetrahydopyridine ETHP and ATHP

Mousy 2‐acetylpyrroline APY

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Bitter Acrolein Taint

Bitter Acrolein Taint

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Skatole and Indole

Mannitol Taint

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Mannitol Taint

B‐D Glucan

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Geranium Taint

Ethanol

2‐Ethoxy‐3,5‐hexadiene

Suspect Lactic Acid Bacteria When… Aroma/Flavor Lactic Acid Bacteria Mousy, Rancid Corn Chips X Metallic X Artificial Floral X Vinegar, Acetic Acid X Nail Polish Remover, Ethyl Acetate X

Butter, diacetyl X Bitter X Animal, Fecal, Fur X Viscous, Oily, Sweet X

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Biogenic Amines

Biogenic Amines

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Detection of Lactic Acid Bacteria

• Microscopy • Light • Fluorescent • Plating • Differential • Selective • QPCR • Scorpion ‐ ETS • Veriflow – Invisible Sentinel • Gene Disc ‐ Pall

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Writing about spoiled wines by lactic acid bacteria:

Preventing Bacterial Spoilage “Best Practices” • Wine is a hostile environment for bacteria • pH 3.6 or less • Ethanol up to 16% • High levels of phenolic compounds

• SO2 addition at crush • Cold Storage at 15o C (60o F) • Avoid Stuck Fermentations • Carefully control nutrient additions

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Preventing Bacterial Spoilage

• Chemical additions Sulfur Dioxide Lysozyme DMDC (Velcorin)

• Physical Treatments Fining Filtering

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