Exploring the Impact of Native Australian Flower Yeasts on Pinot Noir Rosé Fermentation
- L.A.S. Vino
- 9 hours ago
- 7 min read
Fermentation is the heart of winemaking, shaping the flavors, aromas, and textures that define the wine. While commercial yeast strains dominate the industry for their predictability, they often lead to predictable and somewhat boring flavours in wine. There is growing interest in natural ferments in the wine industry. This report explores how yeasts sourced from different native Australian flowers influence the fermentation of a Pinot Noir rosé, revealing the subtle yet significant ways nature’s microbiome can transform a the fermentation kinetics and taste of a wine.
Understanding Native Yeasts and Their Role in Fermentation
Yeasts are fungi that convert grape sugars into alcohol and carbon dioxide during fermentation. Commercial strains are selected for consistency and efficiency, but native yeasts, naturally present on grape skins and surrounding flora, offer diverse metabolic pathways. These wild yeasts can produce complex flavor compounds, contributing to the wine’s terroir—the unique environmental factors influencing its character.
Collecting yeasts from native flowers introduces a novel microbial community into the fermentation process. Multiple peer-reviewed studies and reviews report that flowers (especially nectar) commonly host high populations of yeasts, sometimes reaching tens of thousands — even >10⁵ — yeast cells per mm³ in nectar. (Herrera, C.M. (2009) Yeasts in floral nectar: a quantitative survey) Based on this information we conducted an experiment with the following hypothesis :
Can Australian flowers be used to cultivate distinct and unique yeast to ferment wine.
Do the yeast from different flowers have different fermentation kinetics and different flavours/aromas in the final wine?
Figure 1. Australian red-flowering gum (Corymbia ficifolia)
Methodology: Isolating Yeasts from Native Flowers
To explore this concept, we selected several native flowers commonly found near the vineyard. One barrel (10%) was fermented using yeasts from the red flowers of the Australian red-flowering gum (Corymbia ficifolia). A second barrel (10%) was fermented with yeasts from the white flowers of the Rottnest Island tea tree (Melaleuca lanceolata). Two barrels (20%) underwent completely spontaneous natural fermentations, while the remaining portion (60%) was fermenting using Lalvin EC1118 as a control.
We then monitored the fermentations for temperature and baume (density) to measure sugar concentration and rate or reduction. Once the wine had finished fermenting we measured: 1. The final level of sugar in the wine( residual sugar) RS. 2. Volatile Acidity 3. Malic acid concentration. 4. pH and TA (acidity) 5. Alcohol %
Fig 2. The white flowers of the Rottnest Island tea tree (Melaleuca lanceolata)
Fermentation Trials with Native Flower Yeasts
The juice: We hand picked pinot noir grapes from two different clones of pinot noir. Planted in 1980 on the edge of the Willyabrup brook in Margaret River, Western Australia. The fruit was hand picked into 10kg buckets, cooled to 5 degrees and then the following day pressed as whole bunches to stainless steel tank. The initial juice was oxidised and then a small amount of sulfur was added to the juice going into the tank. The juice from this point forward was treated under inert conditions. The juice was settled for 24 hours without any additives and then racked off gross solids to another stainless steel tank. This base wine was left in tank under inert conditions. This is the same base wine that was fermented using different yeasts. So the only variable is the yeast used.
The Ferments: We took 3 x 20L buckets and filled with flowers, topped with 10-20L of fresh pressed juice along with 2kg of hand crushed pinot noir grapes for a slight additional nutrient addition to the ferments. These were to be used as the starter cultures.
1x Lalvin EC1118 Control
1x Natural ambient yeasts + 2kg of hand crushed grapes (no flowers)
1x Australian red-flowering gum (Corymbia ficifolia).
1x Rottnest Island tea tree (Melaleuca lanceolata)
It took 3-4 days for visible signs of fermentation to begin on the flower/ natural ferments. Noted by bubbles in the ferment. Our desire was to use the juice beginning of the ferment as previous studies have found that once alcohol reaches 5-6% the native yeasts are often killed by the production of alcohol. At this point the fermenting juice was strained through a sieve leaving the flowers behind. This 20L of fermenting juice was then added to clean used barrels and topped up with 200L of non fermenting juice filling the barrel. It was really important to measure the effect of the yeasts as opposed to flavouring the ferment through the flavour of the flowers. ( For future experiments this could of been improved by diluting the fermenting juice down- starting with 20l in 200l then once this ferment begins taking another 20L of this for another ferment)
We then added Lalvin EC1118 to the tank of remaining juice, this was transferred to barrels and amphora halfway through the ferment ferment and was used as a control.
Measurements:
Throughout fermentation and following fermentation, we monitored:
Sugar consumption rates/ residual sugar
pH and acidity changes (pH /TA)
Volatile aroma compounds ( VA)
Malic Acid
Finally Sensory evaluations were conducted by a panel of trained tasters to assess differences in aroma, flavor, mouthfeel, and overall balance.
Figure 3: The native Australian flower starter cultures. The flowers were immersed in wine with grapes until the fermentation started. then the 20L of fermenting juice was strained out (leaving fhe flowers behind) .These seperate fermenting juice samples were then transferred to different barrels containing 200L of non fermenting pinot noir rose juice. This fermentation was then monitored.
Results: How Native Flower Yeasts Shaped the Rosé
Each yeast strain produced a distinct fermentation profile:
Australian red-flowering gum (Corymbia ficifolia)
Ferment: The ferment began on the 12th of February and was still active on the 17th of March sitting at a baume of -1.4. 33 days fermenting. We left the barrel to slowly finish and the wine finally finished on the 7th of April 53 days after it began.
Tasting profile: Sweet strawberry, gum, white pear, Australiana, mild eucalypt. On the pallate, broad and full, round full of flavour but no line or length, lacks acid/
Finished wine details:
Volatile acidity: 0.73g/l
Malic 0.03g/l
Residual Sugar: 2.37g/l
Rottnest Island tea tree (Melaleuca lanceolata)
Ferment: The ferment began on the 12th of February and was still active on the 17th of March sitting at baume or -1.4. 33 days fermenting. We left the barrel to slowly finish and the wine finally finished on the 4th of April 50 days after it began.
Tasting profile: Aromas of mint, medicinal notes, chartreuse, herbal, nettle, very aromatic. The wine is alive with flavour. Has a real zip and energy to it, its slightly out of balance but really interesting.
Finished wine details:
Volatile acidity: 0.53g/l
Malic 0.3g/l
Residual Sugar: 0.52g/l
Natural Fermentation
Ferment: The ferment began on the 12th of February and was still active on the 17th of March sitting at 7.5g/l of RS. 33 days fermenting. We left the barrel to slowly finish and the wine finally finished on the 10th of April 56 days after it began.
Tasting profile: Ironically has a floral character or white flowers like elderflower, cooked strawberry in the oven. Strawberry pie. Overall a full pallet weight, caramel notes, round, lacking balance
Finished wine details:
Volatile acidity: 0.48g/l
Malic: 2.64g/l
Residual Sugar: 0.93g/l
Lalvin EC1118 Control 25g/HL
Ferment: The ferment began on the 12th of February and finished on the 27th. 15 days fermenting until it was dry. Cooling was used on the tank fermenting at 16 degrees It was transferred to oak at 4 baume. It was a clean steady ferment.
Tasting profile: musk stick, lollies, banana lollies, red apple skin, bread, salty. On the pallate, linear, fresh, textured with beautiful line and length. Lacks the character, flavour and personality of hte other ferments but makes up for it in structure and simple aromatics.
Volatile acidity: 0.29g/l
Malic: 3.02g/l
Residual Sugar: 0.11g/l
L.A.S. Vino Albino Pinot (Final Blended wine)
The final blend consists of one barrel (10%) was fermented using yeasts from the red flowers of the Australian red-flowering gum (Corymbia ficifolia). A second barrel (10%) was fermented with yeasts from the white flowers of the Rottnest Island tea tree (Melaleuca lanceolata). Two barrels (20%) underwent completely spontaneous natural fermentations, while the remaining portion (50%) was fermented using inoculated yeast. Of this, 20% was fermented in clay, 10% Chardonnay was fermented separately and blended with the wine giving roundness and mid palate weight. The final analysis of the wine is below. It tastes delicious and is beautifully balanced. Flavours of apple skin,strawberry, cream toffee roasted pear, sea salt flakes. We feel the flower ferments give layers of complexity to the wine int terms of texture, flavour & aroma. The combined blend is better than the individual ferments alone.
pH 3.39
TA 6.57g/l
Alc 12.9%
RS 1.02g/L
VA 0.53g/l
Malic 1.83g/l
Practical Implications for Winemakers
Firstly, lets answer the hypothesises outlined at the beginning of the experiment
Can Australian flowers be used to cultivate distinct and unique yeast to ferment wine.
Yes. Australian flowers can be used to cultivate distinct and unique yeast to ferment the wine. All of the ferments finished within an acceptable range of VA, RS and balance. The resulting wines were balanced when tasted
Do the yeast from different flowers have different fermentation kinetics and different flavours/aromas in the final wine?
Yes. The yeast from different flowers have different fermentation kinetics, flavours and aromas. They had different flavours and fermentation kinetics to each other and also to the control and to a natural fermenation using ambient winery and vineyard yeasts.
Using native flower yeasts offers winemakers a way to craft rosés with unique sensory profiles that reflect their vineyard’s surrounding ecosystem. This approach can:
Enhance the expression of terroir through microbial diversity
Introduce novel flavor and aroma compounds not achievable with commercial yeasts
Support sustainable and low-intervention winemaking practices
However, challenges include managing fermentation consistency. The natural and flower ferments took 4x longer to finish than the innoculated ferment. Natural malolactic fermentation went through and some of the ferments had residual sugar. In summary if you want consistent and reliable results use a store bought yeast. If you are willing to take your time and take on a bit of risk the complexity and flavour from the flower ferments and natural ferments adds complexity and additional layers of flavours to the wine creating a wine thats far more interesting.
Future Directions in Native Yeast Research
Further research could explore:
Combining multiple native yeast strains for co-fermentation effects
Long-term aging potential of wines fermented with native flower yeasts
Impact on other grape varieties and wine styles
Using different flowers.
Actually testing the juice to determine what yeasts are actually present in the fermenting juice. It was looked into and to test the fermenting juice samples was far too expensive.
The final product: All of the native flower ferments were combined with a touch of chardonnay to create the L.A.S. Vino Albino Pinot. Each of these separate fermentations brings its own character—layering flavour, texture, and complexity. This year we also introduced a new Chardonnay vineyard to the blend, which we feel beautifully rounds out the mid-palate.
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