Immersing Vermentino grapes in salt water from the Indian Ocean.
The effect on flavour and microbiological activity.
By Nicolas Peterkin, Christopher Lundy, Teresa Castellani, Maria Grosso
Abstract
Margaret River is the traditional land of the First Nations Wadandi people. Wadandi means “saltwater people,” and the connection to the coast is the essence of Margaret River (Erin Larkin, 2023). The ocean surrounds the Margaret River wine region. This affects the region, with ocean breezes regulating the temperature during the growing season. The ocean is as fundamental to the terroir of Margaret River as the soil, the water, the people and the vines. Salinity in different forms is often used as a taste descriptor when talking about the wines from the region. We hope that by using ocean water (from the region) in the production of wines it will give us a better understanding of the terroir, where we grow grapes and the impact ocean water has on the wines of the region.
In March 2022 an experiment was conducted with two primary aims; to test whether ocean water impacts the flavour of the resulting wine and whether ocean water would impact the microbes commonly used in winemaking, with the thought that it could possibly used as an alternative preservative (to SO2) in the winemaking process.
In an era when climate is becoming more unpredictable and large areas of agricultural land are being affected by salinity we hope that these experiments can illuminate the challenges and possible opportunities that salt water can have on the winemaking process. It was found that immersing bunches of grapes in seawater prior to pressing impacts the flavour of the resulting wine and increases the salinity by almost triple to that of the control. The same technique, does not seem to reduce the viability of common bacteria and yeast used in winemaking.
Figure 1: Vermentino Bunch at Carpe Diem vineyards in Willyabrup
Introduction
Margaret River is the traditional land of the First Nations Wadandi people. Wadandi means “saltwater people,” and the connection to the coast is the essence of Margaret River (Erin Larkin, 2023). The ocean surrounds the Margaret River wine region. This affects the region; cool ocean breezes regulate the temperature during the growing season. The ocean is as fundamental to the terroir of Margaret River as the soil, the water, the people and the vines. Salinity in different forms is often used as a taste descriptor when talking about the wines from the region. We hope that by using ocean water (from the region) in the production of wines it will give us a better understanding of the terroir, where we grow grapes and the impact ocean water has on the wines of the region.
Salinity is often talked about in wine as a taste descriptor. Not just when talking about specific terroir, but also when referring to certain grape varieties. Both the wines from Margaret River and the grape variety Vermentino are associated with salinity as a taste descriptor. There are many different terms used, whether we talk about oyster shell, minerality, brine, nori, seaweed, calcium, and texture. It’s hoped that the resulting wine can be used as a benchmark for professionals and amateurs alike to specify the actual taste of salinity in wine, as opposed to other factors that influence the sensation of salinity but are not due to the levels of salt in wine.
Ground water salinity in Australia is increasing and causing issues in the water that is available for irrigation in many areas of Australia. This can occur due to the removal of deep-rooted perennial vegetation in favour of shallow rooted crops. Leading to a rise in the water table along with the salt water within it. Grapevines have a tolerance of 700mg/l, with many areas of Australian soil at higher levels than this (Ayers R.S. & Westcot D.W., 1996). If this continues in Australia, what effect will this have on our food production and beverage production? Will it lead to areas being unusable for both vineyards and other crops? Or will it lead to a change in the way we farm? It may mean farmers need to reintroduce those plants that utilise water more effectively and draw down on the water table to avoid excess salinity. This experiment was used to look at the effect excess salinity will have on the production of wine, the impact of flavour and effect on the microbes that are used in a winery.
Salt water/salt has been used for thousands of years in the preservation of meats and vegetables. In modern winemaking sulfur-based compounds are used in the preservation of wines, both as an antioxidant and an antimicrobial agent. There has been a recent movement towards wines without sulfur, with certain groups of people having adverse reactions to the chemical addition in wines or even the effect it has on the taste of wines. We have conducted this experiment to see whether ocean water could be used as an alternative to sulfur dioxide in modern winemaking.
Figure 2: Vermentino Bunches immersed in ocean water.
Materials and Methods
Materials
-2 tonnes of Vermentino from Carpe Diem vineyards (Split into 2 batches)
-Ocean water from Gracetown, Margaret River.
-Sulfur Dioxide
-EC1118 Yeast 20g/hl
-4 x 1 tonne plastic omni bins to hold grape bunches
-2 x 225L stainless steel barrels
-2 x 225L oak barrels (5 year old)
Method
On the 4th of March 2022 two tonnes of vermentino bunches were hand-picked from Carpe Diem vineyard in Willyabrup, Margaret River. The fruit was hand-picked and sorted to eliminate any bunches with disease.
The fruit was placed into four x 1 tonne plastic omni bins, with the following weights, with a combined weight of 1999kg. The fruit was chilled for 5 hours before two of the four bins were taken to Gracetown beach at sunset. We filled two bins with ocean water, immersing all the whole bunches in water prior to taking them back to the winery to be chilled.
The four bins (2 bins Vermentino bunches & Sea water) + (2 bins Vermentino bunches & no sea water) were chilled at 5 degrees for 48 hours. This was done to reduce oxidation and microbiological reactions that could occur at warmer temperatures, especially in the fruit not immersed in water.
After 41 hours the salt water was drained from the Vermentino bunches and the fruit weighed again. After draining the ocean water, the fruit immersed in Salt water was 1% heavier than before. This was either due some residual water remaining in the bin or the grapes themselves taking in the water through diffusion through the skins.
The fruit was pressed separately at the exact same pressure using an airbag press and pressed to separate tanks. The first difference seen was the colour. The salt water pressed juice was vibrant and green, while the juice without salt water was brown and oxidised. This could have occurred due to the vermentino with no salt water being exposed to oxygen for 41 hours while chilling. There was also a taste difference with the juice. The salt water juice had a brine character with the (no salt water) juice lacking this.
Following this the wine was transferred to 2 x 225L stainless steel (S/S) barrels and 2x 225L (5 year old) oak barrels.
*One S/S barrel contained vermentino juice post ocean water immersion with no sulfur .
*One S/S barrel contained vermentino juice with no salt water immersion with no sulfur.
*One oak barrel contained vermentino juice post ocean water immersion with sulfur
*One oak barrel contained vermentino juice with no salt water immersion with sulfur.
Stainless steel barrels were used for the fruit without sulfur to reduce the effects of oxidation.
All barrels were inoculated with 20g/hl of EC1118. We inoculated to eliminate any variables that would occur through natural fermentation. EC1118 being noted as a strong neutral yeast that finishes fermentation. We did not add malolactic bacteria to the barrels. However, malolactic fermentation went through in the barrels that did not have sulfur added to them.
The wine was left to mature in vessel until mid-January with lees stirring occurring monthly. The room was insulated and was 18-20 degrees. The wine was then analysed separately, blended, and bottled. We individually bottled 12 bottles from each barrel to see how the wine would mature. Blending occurred after several trials to obtain the most balanced, interesting but also delicious wine.
The final blend of wine is
200L *One oak barrel contained vermentino juice with no ocean water with no sulfur
200L *One oak barrel contained vermentino juice with no ocean water immersion with sulfur.
170L *One S/S barrel contained vermentino juice after ocean water immersion with sulfur. 570L Total Blend.
Essentially 30% of the sea water immersed vermentino was added to the final blend. The final wine was left to mature in bottle for 5 months before release.
Results
Fermentation
With the inoculation of 20g/hl of EC1118 went through smoothly for all wines. Primary fermentation: The immersion in ocean water and salinity of the wine did not influence the fermentation of the wines. Both batches finished ferment with low levels of residual sugar. The addition of SO2 did not influence primary fermentation.
Secondary (Malolactic Fermentation): Malolactic bacteria were not added to any of the vessels and this seemed to occur naturally. The immersion in ocean water and salinity of the wine did not influence malolactic fermentation of the wines. Both batches of wines with and without immersion in sea water went through malolactic fermentation. However, the addition of 40ppm of SO2 did inhibit malolactic fermentation.
Based on this basic experiment we have deduced that salinity up to 2900mg/l does not have an inhibitory effect microbiologically to the common microbes (yeast and bacteria) used in winemaking. This was a very simple test, measuring residual sugar for primary ferment and the level of malic acid for secondary ferment.
Taste/Observations
Colour: The first real difference was noted when pressing the wine. The juice from the grapes immersed in sea water was bright, vibrant green/yellow and cloudy. The juice from the grapes left without sea water for 41 hours was a dull brown colour. This brown colour would indicate that the juice with no sea water immersion was oxidised during pressing, with the sea water immersion minimising the influence of oxidation. This could have been either due to increased salinity in the juice or due to the bunches being immersed in sea water limiting the exposure to oxygen during the 41 hours in the fridge. In future experiments it would be interesting to keep the bunches with no sea water immersed in carbon dioxide to limit the effects. Post fermentation however the colours of all the wines were the same.
Taste: Tasting with a group of winemakers, it was found that salinity influences the taste of the wines. The wines immersed in sea water have a brine character, and the increased salinity decreases the sensation of acid. It makes the wine round almost flabby with a round texture in the mouth. Aromatically the wines were quite consistent, with differences in oxidative characters occurring due to the lack of sulfur more than the addition of ocean water. What’s interesting is that salinity is often associated with high acid wines, being a character that some higher acid wines have. The actual perception of increased salinity has almost the opposite effect, rounding out the sensation of acidity the palate. We found tasting the different wines that the batch with higher acid (OCEAN WATER/SULFUR) balanced the salt. The (NO SULFUR/ OCEAN WATER) wine was difficult to drink and enjoy. The lack of sulfur led to the wine going through malolactic fermentation, reducing the acid level, leaving the wine quite flabby, viscous, and briny. Note; this wine was not included in the final blend and was used as the base of a vermouth using native herbs collected from beside the ocean.
Conductivity/Salinity.
Reference: Sea water normal salinity is 3500mg/l
1. OCEAN WATER/ SULFUR
Electrical Conductivity: 528mS/m
Salinity: 2900mg/L
2. NO OCEAN WATER /SULFUR
Electrical Conductivity: 197mS/m
Salinity: 1100mg/l
3. OCEAN WATER / NO SULFUR
Electrical Conductivity: 529mS/m
Salinity: 2900mg/l
4. NO OCEAN WATER/ NO SULFUR
Electrical Conductivity: 164 mS/m
Salinity: 900 mg/l
Based on the above results, the immersion in ocean water for 41 hours increased both the conductivity and the salinity in the final wines. Its also noted that the addition of 40ppm of SO2 seems to increase the salinity of the wines mildly. Given that the normal salinity of sea water is 3500mg/l, immersing the wine in ocean water led to measurable difference in the salinity of the resulting wines. Almost reaching the salinity of the ocean itself.
Final analysis of the finished wine.
2022 LV Vermentino (Combined Results) bottled wine:
F/T SO2 – 7/67mg/l
pH 3.24
TA 6.21
Alc 12.5%
Glucose 0.24g/l
Fructose 0.85g/l
Combined RS 1.08g/l
VA 0.44g/l
Malic 1.32 g/l
Conductivity 255 mS/m
Salinity 1400mg/l
Figure 3: Vermentino Juice after pressing. Brown juice on left is control. Glass on right is from Juice immersed in ocean water for 41 hours.
Discussion
Based on the results it was shown that immersing bunches of Vermentino in ocean water for 41 hours leads to an increase in the conductivity and salinity of the resulting wine. With the wine from bunches immersed in sea water rising from 900mg/l to 2900mg/l. (Ocean water is normally 3500mg/l).
One of the primary aims of the experiment was to measure the effect this level of salinity would have the normal microbiological activity that occurs in a winery. We tested whether this level of salinity would affect the primary fermentation (yeast) converting sugar to alcohol and secondary (bacterial) malolactic fermentation converting malic acid to lactic acid. To do this we measured the levels of both sugar (glucose and fructose) and also malic acid in the wines that came from grapes immersed in salt water and compared them to the control. We found that salinity did not affect either primary or secondary fermentation in any way. By observing the juices it seemed as though it had an antioxidative effect during pressing. The resulting wine however it did not seem to limit the effect of oxidation with the barrel containing (ocean water and no sulfur) to have an oxidative character in the smell of the final wine.
The second aim of the experiment was to see whether the addition of sea water to the bunches would affect the flavour of wine. Going into this experiment we didn’t know how the salt water would affect the wine. There was a thought that depending on the level of salt/sugar within the grape and the permeability of the grape skin that water could leave the grape into salt water giving concentration to the resulting grapes. The same thing that occurs if grapes are picked and left in the sun. This didn’t occur. The main differences in flavour seemed to occur due to the level of salinity and the level of acid of the wine. Wines without sulfur went through malolactic fermentation leading to lower levels of acid. This made the salinity more pronounced. It is interesting comparing the actual flavour, taste and texture of a wine with high levels of salinity vs what is often described as salinity by those tasting wines. Its very different. It's hoped the release of this wine will be tasted by those interested in wine and those writing about wine so they have a benchmark for what salinity tastes like, in comparison to maybe those flavours that are associated with the ocean such as nori, oyster shell or minerality.
Making wines with this level of salinity doesn’t pose challenges in fermentation but does impact the taste of the resulting wine. In large levels its very challenging on the palate. However at small levels it can create texture, lead to interesting flavours and a create a point of difference in a wine. If winemakers are encountering these levels of salinity in their wines they can use blending as a tool from other (non- saline) vineyards as a tool to create drinkable high quality wines. If salinity is becoming more of an issue in vineyards across Australia, the release of this wine can be used as a starting point of what to expect, it could change the varieties planted, that work well with increased salinity, alter rootstocks used or new farming methods could be considered to reduce the salinity to a level that is palatable to the drinker.
Margaret River is associated with the ocean. Its’ part of the terroir and is often linked to the flavour of the wines in the region. The vermentino produced and released should give an indication of how ocean water and salinity impacts the flavour of wine from the region. In the future it could be beneficial to measure the salinity of all grapes that come into the winery, to see if there is an association with actual measurable salinity and the way people describe certain varieties.
Improvements: This was a very elemental and basic experiment conducted in non-lab based conditions. There are many ways this experiment could be improved. We would have liked to have washed the grapes with water to see if residual salt was inside the grapes or just on the skin of the berries. We would have liked to stored the grapes not immersed in sea water in a non oxidative environment for 41 hours. More tools of measurement would have been helpful, such as something to measure the osmotic potential and the transfer of salt across the grape skins. We could have also tested for different microbes using a microscope. Different varieties could be used. Different times immersed in water. Crushing the fruit and doing skin contact post ferment. Its hoped that instead of viewing this as a technical scientific report. That the information gained in this experiment could be used as a starting point for further more formal scientific exploration in the field.
Figure 4: The final bottled product.
Conclusion
Two hypotheses were tested in this experiment. The first hypothesis was whether ocean water could be used as an alternative to sulfur as a preservative and whether it would reduce the viability of the common yeasts and bacteria used in the winery. It was found that immersing bunches of grapes in ocean water, raising the salinity in the final wine from 900mg/l to 2900mg/l did not prevent either primary yeast driven fermentation or secondary malolactic fermentation. The second was whether immersing grapes in ocean water would effect the flavour of the resulting wine. We found that through tasting the four different batches of wines made there is a notable effect on the flavour of the resulting wine. With the salinity in both ground water and soils rising in certain areas of Australia this can pose an issue to the growth of crops and the flavour of the produce. We found that above a certain threshold salinity leads to wines that aren’t enjoyable to drink, especially in wines with lower acid levels. However on a more positive note, we found that through blending it is possible to make this higher level of salinity into a positive and interesting facet of the resulting wine. The final wine produced is with the addition of 30% sea immersed vermentino is much more interesting, textured and flavoursome than the wine without.