Exploring the Impact of Native Australian Flower Yeasts on Pinot Noir Rosé Fermentation

L.A.S. Vino
Dec 16, 2025
7 min read

Updated: 4 days ago

Fermentation is the heart of winemaking. It shapes the flavors, aromas, and textures that define the wine. While commercial yeast strains dominate the industry for their predictability, they often lead to somewhat boring flavors. There is a growing interest in natural ferments and their effect on flavor. This report explores how yeasts sourced from different native Australian flowers influence the fermentation of a Pinot Noir rosé. We reveal the subtle yet significant ways nature’s microbiome can transform fermentation kinetics and the taste of wine.

Movie 1: Perfect pinot noir bunches grown from 45 year old vines in Willyabrup, Margaret River Australia for L.A.S. Vino

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. However, 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 report that flowers, especially nectar, commonly host high populations of yeasts. Sometimes, these can reach tens of thousands—over 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 hypotheses:

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 flavors/aromas in the final wine?

Methodology: Isolating Yeasts from Native Flowers

To explore this concept, we selected several native flowers commonly found near the vineyard. One barrel was fermented using yeasts from the red flowers of the Australian red-flowering gum (Corymbia ficifolia). A second barrel was fermented with yeasts from the white flowers of the Rottnest Island tea tree (Melaleuca lanceolata). One barrel underwent completely spontaneous natural fermentations, while the remaining barrels were inoculated and fermented using Lalvin EC1118 as a control.

We monitored the fermentations for temperature and baume (density) to measure sugar concentration and rate of reduction. Once the wine had finished fermenting, we measured:

The final level of sugar in the wine (residual sugar, RS).
Volatile acidity.
Malic acid concentration.
pH and TA (acidity).
Alcohol percentage.

Fermentation Trials with Native Flower Yeasts

The Juice

We handpicked Pinot Noir grapes from two different clones planted in 1980 on the edge of the Willyabrup brook in Margaret River, Western Australia. The fruit was handpicked into 10kg buckets, cooled to 5 degrees, and then pressed as whole bunches into a stainless steel tank. The initial juice was oxidized, and a small amount of sulfur (20ppm) was added to the juice going into the tank. From this point forward, the juice was treated under inert conditions. It was settled for 24 hours without any additives and then racked off gross solids to another stainless steel tank. This base juice was left in the tank under inert conditions. This is the same juice that was fermented using different yeasts from flowers. The only variable in each of the batches was the yeast used.

The Ferments

We took 3 x 20L buckets and filled them with flowers, topped with 10-20L of fresh pressed juice along with 2kg of hand-crushed Pinot Noir grapes for additional nutrients. These were 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 in the flower/natural ferments, noted by bubbles in the ferment. Our desire was to use the juice from the beginning of the ferment. Previous studies have shown that once alcohol reaches 5-6%, the unique native yeasts are often killed by the production of alcohol, with the dominant yeast finishing the ferment. 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 (but used) barrels and topped up with 200L of non-fermenting juice, filling the barrel. It was crucial to measure the effect of the yeasts, as opposed to flavoring the ferment through the flavor of the flowers. For future experiments, this could be improved by diluting the fermenting juice down—starting with 20L in 200L, then once this ferment begins, taking 20L of this for another ferment.

We then added Lalvin EC1118 yeast to the tank of remaining juice, which was transferred to barrels and amphora halfway through the ferment and 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.

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. It fermented for 33 days until the sugar level was under 10g/l. 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, flavors of Australiana, mild eucalypt. On the palate, broad and full, round with flavor but lacking line or length, and 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 a baume of -1.4. It fermented for 33 days until under 10g/l sugar. We left the barrel to slowly finish, and the wine completely finished fermenting on the 4th of April, 50 days after it began.
Tasting profile: Aromas of mint, medicinal notes, chartreuse, herbal, nettle. The wine is alive with flavor. It has a real zip and energy to it, slightly out of balance but very 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. It fermented for 33 days. 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, it has a floral character of white flowers like elderflower, cooked strawberry in the oven, and strawberry pie. Overall, it has a full palate weight, caramel notes, round but 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. It fermented for 15 days 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 palate, linear, fresh, textured with beautiful line and length. It lacks the character, flavor, and personality of the other ferments but makes up for it in structure and simple aromatics.
Finished wine details:

- 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%) 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, and 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. Flavors of apple skin, strawberry, cream toffee, roasted pear, and sea salt flakes. We feel the flower ferments give layers of complexity to the wine in terms of texture, flavor, and 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

Movie 2: Fermenting pinot noir rosé juice for L.A.S. Vino

Practical Implications for Winemakers

Firstly, let's answer the hypotheses 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 wine. All of the ferments finished within an acceptable range of VA, RS, and balance. The resulting wines were balanced when tasted. However, it is noted that the ferment with commercial yeast finished four times quicker than the natural and flower ferments. It was consistent and a very clean, easy ferment.
Do the yeast from different flowers have different fermentation kinetics and different flavors/aromas in the final wine?
Yes. The yeast from different flowers exhibit different fermentation kinetics, flavors, and aromas. They had different flavors and fermentation kinetics compared to each other and also to the control and to a natural fermentation using ambient winery and vineyard yeasts. There were differing levels of malic acid remaining in the wine, different levels of VA, and also residual sugar.

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.
Offer a unique selling point for the product.

However, challenges include managing fermentation consistency. The natural and flower ferments took four times longer to finish than the inoculated ferment. Natural malolactic fermentation occurred, 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 flavor from the flower ferments and natural ferments add depth and additional layers of flavor to the wine, creating something 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.
Microbial testing of the fermenting juice to determine what yeasts are actually present in the fermenting juice. It was looked into, but testing the fermenting juice samples was far too expensive.

Scientific report for download here ->