Article Figures & Data
Figures
- Figure 1
Main pathways for citric acid metabolism by Oenococcus oeni (Nielsen and Richelieu 1999).
Tables
- Table 1
Effect of pH on the concentration of molecular sulfur dioxide (SO2) in a wine with a free SO2 concentration of 50 mg/L (Divol et al. 2012).
pH Molecular SO2 (mg/L) Molecular SO2 (% free SO2) 2.8 4.64 9.28 3.0 3.03 6.06 3.2 1.96 3.91 3.4 1.25 2.51 3.6 0.80 1.60 3.8 0.51 1.01 4.0 0.32 0.64 4.2 0.20 0.41 - Table 2
Details of defects associated with malolactic fermentation (MLF).
Defect Conditions increasing susceptibility Compounds modified Compounds produced Sensory effects Source Increased pH High pH, high climatic temperatures, uncontrolled/spontaneous MLF, malic acid addition Malic acid Lactic acid; ethyl lactate and ethyl acetate; propanoic acid; 2-methyl; 3-hydroxy-2,2,4-trimethylpentyl ester Flavors described as lactic, wet wool/wet dog, rancid, cheesy, sweaty Keng et al. 2025 Color instability High pH, high climatic temperatures, oxygen exposure Anthocyanins Glycosidases, anthocyanidins, monomeric anthocyanins Reduced color intensity, oxidation with increased pH Tofalo et al. 2021, Burns and Osborne 2013, Bartowsky and Krieger-Weber 2020 Increased alcohol/fusel alcohols High pH, high climatic temperatures, high alcohol, oxygen exposure a-Keto acids Fusel aldehydes, fusel alcohols Burning/tingling sensation; flavors described as solvent-like, boozy, and bitter Hazelwood et al. 2008, Lerm et al. 2010, de-la-Fuente-Blanco et al. 2024 Ropiness High pH, high climatic temperatures, more common in white wine Glucose Extracellular polysaccharides, glucan Increased viscosity, gelatinous substances Ciezack et al. 2010, Dimopoulou and Dols-Lafargue 2021 Mousiness High pH, oxidative conditions, uncontrolled/spontaneous MLF Amino acids N-heterocyclic compounds, 2-acetyltetrahydropyridine, 2-acetyl-1-pyrroline Mousiness Costello et al. 2001 Citric acid degradation High pH, uncontrolled MLF Citric acid Acetic acid, diacetyl, acetoin Volatile acidity, buttery and nutty flavors Nielsen and Richelieu 1999 Tartaric acid degradation High pH Tartaric acid Lactic acid, acetic acid Increased pH, volatile acidity, effervescence, lactic flavors Krumperman and Vaughn 1966 Glycerol degradation High pH (>4.0), high climatic temperatures, high postharvest temperatures (>20°C), low alcohol/low fermentable sugar, press wines, wines with prolonged lees aging Glycerol 3-Hydroxypropionaldehyde, acrolein, acetic acid Bitterness, volatile acidity Bauer et al. 2010, Popescu-Mitroi et al. 2014 - Table 3
Comparison of lactic acid bacteria (LAB) inhibitors for control of malolactic fermentation (MLF). MIC, minimal inhibitory concentration.
Inhibitor Mode of action Effective concentration/conditions Advantages Limitations/drawbacks Source Molecular SO2 Disrupts LAB metabolic processes, antimicrobial against yeast and bacteria Effectiveness declines with higher pH, requires careful dosing Widely available, dual antimicrobial and antioxidant role, reported fruity aromatic intensity Can cause allergic reactions, may lead to hydrogen sulfide formation, less effective at high pH Fang and Dalmasso 1993, Gerbaux et al. 1997, Divol et al. 2012, Quirós et al. 2012, Prusova et al. 2024 Lysozyme Enzyme hydrolyzing Gram-positive bacterial cell walls, leading to lysis 500 mg/L in must inhibited MLF, 250 mg/L post-MLF stabilized wines Effective SO2 alternative, selective for LAB May cause haze, phenol precipitation, color loss in reds; heat instability in whites; some Pediococcus spp. strains exhibit resistance Lerm et al. 2010, Bartowsky et al. 2004, Coulon et al. 2012, Bartowksy and Krieger-Weber 2020 Fumaric acid Inhibits LAB metabolism, slight acidification ≥300 mg/L prevented MLF, 600 mg/L halted ongoing MLF Enhances freshness and acidity perception, preserves phenolic/color stability, reduces SO2 needs Efficacy in very high pH wines not fully established, limited pH effect, low solubility (~15 g/L in wine) Fang and Dalmasso 1993, Morata et al. 2019, Gancel et al. 2022, Prusova et al. 2024 Nisin Polypeptide bacteriocin, disrupts cell wall synthesis and ion channels MIC ~0.024 mg/L for Oenococcus oeni; 50 mg/L reduced SO2 requirements Very potent against LAB, synergistic with SO2, not known to affect sensory properties While generally recognized as safe as a food additive, nisin is not yet approved for use in winemaking in all regions. Daeschel et al. 1991, Rojo-Bezares et al. 2007, Fernández-Pérez et al. 2018 Chitosan Biopolymer disrupts Gram-positive microbial growth, also antioxidant Applied during fermentation and aging Natural product, antimicrobial, controls oxidation, limited sensory effects May alter yeast dynamics, effectiveness as an MLF inhibitor depends on target LAB strain and dosage, found ineffective in some cases at inhibiting MLF during longer aging periods Scansani et al. 2020, Miot-Sertier et al. 2022, Moulis et al. 2023, Prusova et al. 2024
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