Commercial Yeast Inoculation: Selected Strains and Their Character

Commercial yeast inoculation is the addition of a measured dose of selected, commercially produced yeast to juice or must, so that a chosen strain conducts the alcoholic fermentation rather than the natural microflora present on the grapes or in the winery. Decanter notes that yeast in wine is commonly associated with the species Saccharomyces cerevisiae, and that cultivated strains were originally isolated from ambient yeasts. The AWRI counts more than 200 strains commercially available for winemaking. Traditionally these have been strains of S. cerevisiae, but the AWRI notes that yeast breeding research has made new hybrid strains available, such as AWRI2526, which is sold commercially by AB Biotek and was developed to add flavour and aroma complexity to wines. Suppliers also sell non-Saccharomyces species: Lallemand's LEVEL range includes pure cultures of Torulaspora delbrueckii and Lachancea thermotolerans, each used in sequential inoculation ahead of a Saccharomyces cerevisiae yeast.

• The AWRI's generic inoculation rate for active dry wine yeast (ADWY) is 0.25 g/L (25 g/hL) of juice; high solids musts are typically inoculated at 0.20 g/kg (approximately 20 g/hL) because of their smaller liquid volume.
• Lallemand's technical datasheets give a dosage rate of 20 to 40 g/hL for its LALVIN EC1118, 71B, QA23 and RC212 strains.
• Lallemand writes that EC1118 is considered by many to be the universal yeast, and that its fast implantation efficiently controls the indigenous microflora.

Decanter describes yeasts as single-cell microorganisms responsible for the enzymes that convert six-carbon sugar molecules into ethyl alcohol and carbon dioxide while releasing heat, and notes that yeasts also produce small amounts of volatile compounds, such as esters, aldehydes and sulphur, that contribute to a wine's aroma and flavour. In an uninoculated ferment, the AWRI reports (citing Varela et al. 2017) that non-Saccharomyces yeasts dominate the early stages, whereas the majority of the alcoholic fermentation is conducted by Saccharomyces yeast. Decanter adds that non-Saccharomyces wild yeasts tend to give way to S. cerevisiae when alcohol in the must goes significantly higher than 5% abv, or when there is enough sulphur dioxide to restrict them. The AWRI advises that the juice or must should equal or exceed 15°C when inoculated, to advantage the yeast culture over indigenous strains, and that active fermentation typically initiates within 24 hours. The AWRI states that nitrogen affects the rate and completion of fermentation, that there is a direct relationship between yeast assimilable nitrogen (YAN) levels, yeast cell growth and fermentation rate, and that yeasts vary in their nitrogen requirements, with low, medium and high nitrogen demand strains.

• If a strain's nitrogen requirement is not met, the AWRI warns that this can lead to sluggish or stuck fermentations and in turn to off-flavours and winemaking faults; it provides a calculator for diammonium phosphate (DAP) additions to increase YAN.
• Once active fermentation begins, the AWRI notes that temperature changes exceeding 3-5°C per day have been reported to partially inactivate budding yeast.
• Lallemand's datasheets list each strain's competitive 'Killer K2' factor status: active for EC1118 and QA23, neutral for RC212 and sensitive for 71B.

The AWRI states that different strains produce different aroma and flavour compounds, and Decanter quotes Benjamin Lewin MW that the influence of yeasts is most evident in aromatic wines, because 'small changes in the concentrations of key components can greatly affect varietal character'. Lallemand's datasheets describe what each of its reference strains does. LALVIN 71B is a high ester producer, mainly isoamyl acetate, and Decanter reports that the banana notes of Beaujolais Nouveau are believed to come from isoamyl acetate formed by strain 71B. Lallemand says 71B can metabolize a portion of the malic acid in musts, between 20 and 40% of it, softening the wine palate. LALVIN QA23, per Lallemand, has a very high β-glucosidase activity, which cleaves non-volatile aromatic compounds into their volatile state, and is a proven thiol converter highly recommended for Sauvignon Blanc; Lallemand says it enhances citrus fruit aromas including lime and grapefruit. Lallemand says LALVIN RC212 helps produce Pinot Noir with structure, ripe cherry, bright fruit and spicy characters, and Lallemand reports that, compared to other yeast recommended for Pinot Noir, it gives greater anthocyanin content and higher color intensity because of the limited adsorption of polyphenols on its cell walls.

• Lallemand highly recommends QA23 for varieties rich in terpenes, such as Riesling, noting that many terpenes are bound to glucosides.
• Lallemand states that 71B adsorbs a part of the polyphenolic compounds on its cell wall, limiting the harshness of the tannic structure of primeur red wines.
• Decanter notes that the CY3079 yeast can increase the hazelnut and brioche notes of Chardonnay.

Decanter calls the choice between ambient ('wild') yeasts and cultivated strains one of the most controversial subjects in winemaking. The case for inoculation is risk control. The AWRI identifies one of the main risks of uninoculated fermentation as high levels of acetic acid or ethyl acetate forming early in the ferment, produced by Hansenula and Kloeckera spp., which may dominate ferments early when no SO2 is present, and advises against uninoculated fermentation in years with significant disease pressure. Decanter adds the risk of unwanted strains such as Brettanomyces, notes that wild Saccharomyces yeasts can also be ineffective and unpredictable, and says many modern winemaking operations choose pre-selected yeast strains to ensure a smoother, more controlled fermentation. The case against, as Decanter reports it, is that defenders of wild fermentation argue a single cultured strain leads to somewhat artificial flavours or a lack of diversity between wines; some winemakers instead experiment with blends of cultured yeasts. The AWRI calls the effective rehydration of active dry wine yeast paramount in obtaining a healthy and viable inoculum, and its generic procedure is to pre-heat water to 38-40°C, sprinkle the yeast slowly and evenly over 5-10 times its weight in water, avoid clumps, and then cool the culture slowly to within 5-10°C of the juice or must, in steps of 5-10°C over a period of 10-20 minutes.

• The AWRI advises following the manufacturer's instructions first; Lallemand's LALVIN datasheets specify rehydration in 10 times the yeast's weight in water at 35 °C to 40 °C, a 20 minute wait, and a total rehydration time not exceeding 45 minutes.
• For highly clarified juices, high °Brix/°Baume musts or musts with inhibitory residual SO2, the AWRI says a higher inoculum may be used at up to twice the normal rate.
• Lallemand recommends one of its GO-FERM yeast protectors during rehydration for musts with high alcohol potential (above 13% v/v), low turbidity (below 80 NTU) or other challenging conditions.
• When water alone is used for rehydration, the AWRI says the yeast should be inoculated immediately once the cooling steps are complete, to avoid inactivation of the cells.

Lallemand's datasheets document the origins of four of its LALVIN strains. EC1118 was isolated from nature in the French region of high-quality sparkling wine; Lallemand lists an optimum fermentation temperature range of 10 to 30 °C, alcohol tolerance up to 18% v/v, a short lag phase and a high fermentation rate, highly recommends it for sparkling secondary fermentation, and recommends it for white, rosé and red wine production. 71B was isolated by INRAe (National Agricultural Research Institute) in Narbonne, France; Lallemand bills it as the yeast for primeur and fruity young wines and lists an optimum range of 15 to 30 °C and alcohol tolerance up to 14% v/v. RC212, also called Bourgorouge, was selected from nature by the BIVB for its ability to ferment a traditional heavier style Burgundian Pinot Noir; Lallemand calls it the 'reference' strain for the production of quality Pinot Noir worldwide and lists an optimum range of 18-30°C and alcohol tolerance up to 16% v/v. QA23 was selected in Portugal's Vinhos Verdes region by the University of Tras os Montes e Alto Douro (UTAD) in co-operation with the Viticultural Commission of the Region Vinhos Verdes; Lallemand lists an optimum range of 14 to 28 °C and alcohol tolerance up to 16% v/v.

• Lallemand describes EC1118 as having an elegant and low impact sensory profile, allowing its use for sparkling, white and red wines.
• RC212, per Lallemand, enhances the polyphenolic content of grape types such as Pinot Noir, Grenache, Gamay and Zinfandel.
• Lallemand describes QA23 as a very reliable, clean fermenter that tends to ferment well with a low VA production even in clarified juice low in nutrients.

The AWRI lists nitrogen first among the practical and logistical considerations when choosing a strain: it advises knowing the YAN concentration in the must prior to fermentation and understanding the nitrogen demand of the chosen yeast. Lallemand's datasheets show how widely the other parameters vary. Alcohol tolerance runs from up to 14% v/v for 71B, to up to 16% v/v for QA23 and RC212, to up to 18% v/v for EC1118, while LEVEL2 LAKTIA, a Lachancea thermotolerans culture, has an alcohol tolerance below 10% v/v and is used in sequential inoculation with a Saccharomyces cerevisiae yeast. Lallemand rates 71B as having a very low nutritional requirement, QA23 a very low nutritional requirement at any temperature from 18 to 28 °C, EC1118 a low relative nutritional requirement and RC212 an average nutritional requirement. For acidity, Lallemand says LEVEL2 LAKTIA helps re-equilibrate the acidity of wines, especially those from hot climates, thanks to a significant by-production of lactic acid; the second inoculation with Saccharomyces cerevisiae follows after 24 to 72 hours, and delaying it leads to increased lactic acid production. LEVEL BIODIVA, a Torulaspora delbrueckii culture, is selected to enhance aromatic and mouthfeel complexity, with the Saccharomyces cerevisiae inoculation following a density drop of 10 to 15 points (1.5 to 4°Brix).

• Lallemand says LEVEL BIODIVA's low volatile acid production and tolerance to osmotic shock make it particularly well-adapted for fermenting late harvest and ice wines.
• Lallemand's datasheet lists high nitrogen requirements and high glycerol production for LEVEL2 LAKTIA.
• Both LEVEL datasheets call for a free SO2 level lower than 15 mg/L in white wines before inoculation, and a 25 g/hL dose rehydrated in water between 20 °C and 30 °C.

Primary sources (the Australian Wine Research Institute, and Lallemand Oenology's own technical datasheets for its own strains): https://www.awri.com.au/industry_support/winemaking_resources/wine_fermentation/yeast-rehydration/, https://www.awri.com.au/industry_support/winemaking_resources/winemaking-practices/winemaking-treatment-yeast-choice/, https://products.lallemandwine.com/storage/files/wine-yeasts/139-technical-datasheet-cp-1711100448.pdf, https://products.lallemandwine.com/storage/files/wine-yeasts/191-technical-datasheet-cp-1711125142.pdf, https://products.lallemandwine.com/storage/files/wine-yeasts/145-technical-datasheet-cp-1711101134.pdf, https://products.lallemandwine.com/storage/files/wine-yeasts/148-technical-datasheet-cp-1711101955.pdf, https://products.lallemandwine.com/storage/files/wine-yeasts/170-technical-datasheet-us-1733841051.pdf, https://products.lallemandwine.com/storage/files/wine-yeasts/224-technical-datasheet-us-1733842997.pdf. Secondary: https://www.decanter.com/learn/wine-yeast-45474/. Last verified 2026-09-28