New World Winemaker Blog

“Don’t make a big monkey dance about choosing a yeast, just decide if you want esters or thiols!” This is one of the more memorable sentences that was uttered by Christoph Hammel during my recent harvest stint at his cellar in Germany. Before I put this sentence into context, I should mention that the Hammel Weingut has been in business since 1723. This proud winemaking tradition is continued by veteran and outspoken winemaker, Christoph Hammel. His skills include a combination of modern thinking, creative planning and solid experience based on many years of making wine with a scientific yet artistic touch.

Christoph is such a staunch believer in Anchor Wine Yeast, I guess that you could even call him an Anchorfile. He has repeatedly achieved success on a variety of grape varieties such as Grüner veltliner (fermented with Anchor Exotics and Anchor Alchemy I), Scheurebe (Anchor Alchemy II), Sauvignon blanc (Anchor Alchemy II), Dornfelder + Portugieser Rosé (Anchor Alchemy I and II), Müller-Thurgau (Anchor Alchemy I), Chardonnay + Weissburgunder (Anchor Alchemy I) and Sylvaner (Anchor VIN 2000), Riesling (Anchor VIN 13 and Anchor Exotics). Of special interest will be some the combinations of yeasts that Christoph likes to co-inoculate, such as VIN 13/NT 116 (also Anchor) and VIN 13/NT 116 together with Laffort X5. I have seen that these combinations have a massive effect on floral, fruity and tropical aromas, but no negative effect on fermentation kinetics.

Alex Halberstadt has the following to say about Sylvaner: “Nobody dreams about Sylvaner. Mentioning it in a group of wine people is akin to professing an interest in the finer points of cardboard fabrication. The grape bums people out.”

However, even a neutral grape variety such as Sylvaner stands to gain from these mixtures. For example, I inoculated Sylvaner with NT 116/VIN 7/X5 (as per Christoph’s instructions). Some of the tasting notes that I made over the course of the fermentation were: “tea leaf, fig, apple, floral, banana, grapefruit, spicy, curry, herbal, white pepper, grapefruit, and apricot”. In theory a more complex wine is possible because of the ester and thiol production of these yeasts and this is exactly what you’ll get in real life!

Something else that Christoph does, is oxygenation of the must and water mixture during yeast rehydration. In the photo below, you’ll see the white bin in which yeast is rehydrated and behind the bin you’ll see an oxygen tank.

Typically, the rehydration mixture is cooled down at 5ºC increments (with ample time intervals) until a temperature difference of approximately 5ºC is observed between the rehydration mixture and the must to be inoculated. Note that during all this, the rehydration mixture is continuously oxygenated by adding a steady trickle of oxygen. The rehydrated and happy yeast is then simply pumped to the tank in question. Christoph swears by this method and cannot remember the last time he suffered a stuck ferment. For more information on the science behind this, you are welcome to read my previous blog titled: “Is your yeast on sterols?”

More to follow…

Bernard Mocke is a technical consultant for Oenobrands.

Recent crackdowns on doping in sport have made all of us more aware of the effects of performance enhancing supplements. This got me thinking. What if winemakers could come up with a legal magic potion for yeast? Like the magic potion that enabled Asterix and Obelix to defeat the Romans time after time. Something that would give mere mortal yeasts super human (rather super yeast) qualities?

An increasing worldwide trend is longer “hang-time”. Delaying harvest might increase berry aroma and decrease acidity, but it creates a unique problem for our little athletes. Increased sugar leads to increased alcohol levels in wine made with these grapes. Fermenting yeast thus run the risk of being smothered in the alcohol they produce as a result of them snacking on sugar. Fortuitously, there is a magic potion that you can give your yeast to boost their viability during fermentation.

First, let’s look at the definition of sterols: “Any of various alcohols having the structure of a steroid, usually with a hydroxyl group (OH) attached to the third carbon atom. Sterols are found in the tissues of animals, plants, fungi, and yeasts and include cholesterol and ergosterol.” Here comes the interesting part. Sterols and unsaturated fatty acids (UFA’s) are survival factors during fermentation, but oxygen is needed for the synthesis of said survival factors. With insufficient amounts, the yeast cell membrane functions poorly, especially during highly anaerobic conditions and especially with increasing ethanol levels. Inadequate sterol concentrations around flux controlling proteins in the yeast cell membrane cause damage to the cell membrane and ultimately results in cell death (read: stuck or sluggish ferment!). The key role between oxygen and sterols now becomes evident. Simply put, controlled and timely oxygen addition = more sterol synthesis = better ethanol resistance = happy yeast = happy winemaker.

In my previous life, I’ve found it useful to add oxygen to red ferments anytime from a third of the way through alcoholic fermentation, up to halfway. This roughly corresponds with the end of the cell growth phase and research has shown that an oxygen addition of five to ten mg/L has a very positive effect on cell viability. Another trick is to combine oxygenation and nutrient addition with a pump-over or punchdown. Complex yeast nutrients contain inactivated yeast, which is a good source of sterols. The abovementioned trick also counteracts reductivity, which every winemaker deals with at some stage.

Research is ongoing to gain more insights into how yeast sterol uptake and synthesis affects cell viability. Ergosterol is one of the main compounds being studied, but I’ve also read a paper which outlines the addition of cholesterol to a fermentation! Fermenting yeast are just as happy with cholesterol as they are with ergosterol, but I seriously doubt if winemakers will be chucking cholesterol by the bucketful into their wholesome red wines!

Bernard Mocke is a technical consultant for Oenobrands.

The cooperative Vinicola de Villarobledo has been the only winery from La Mancha region to win a Gold award at wine contest – Nuevo Vino 2011 – held in Madrid on the 15^th of June this year. This was the first time the cooperative winery presented a wine to this contest.

Martin Pardin (technical director of the cooperative) explains he wanted to innovate and create a very complex and unique red wine, adapted to modern demand for fruitiness, roundness and complexity in red wine. Grapes from Syrah, Tempranillo and Garnacha were partially destemmed, crushed and barrel fermented separately in 3^rd fill French oak barrels. Martin used an extraction enzyme and a new yeast from Oenobrands, Anchor Exotics SPH, in all barrels. This yeast is an interspecies hybrid between Saccharomyces cerevisiae and Saccharomyces paradoxus. It is the only yeast of its kind worldwide. Fermentation took ten days at temperature range 18-27 °C, with four hand pigeage daily. For yeast nutrition, Biovin (bio-regulator of La Littorale) has been added after density of 1040. Martin was very happy with the results obtained with Anchor Exotics SPH as it satisfied his need to create a “highly fruity and complex red wine, different from a standard red wine of La Mancha region”.

Malolactic fermentation started spontaneously immediately after alcoholic fermentation and was completed within one month. The wines from the three varieties were blended and stored for five months. No fining was applied before bottling and Mannostab (Laffort) was added to secure tartrate stability.

Martin is very happy with the recognition this award gives to his winery and region, since all the other wines awarded came from other prestigious Spanish wine regions. He plans to increase production with his approach and will continue use of Anchor Exotics SPH as “a perfect tool to help him achieve complexity and fruitiness “. At the moment the wine is only available for sale in Spain but an extension of production in 2011 will allow the winery to have the wine available for export markets.

Patrice Pellerin is the technical manager for Oenobrands.

Over the years, South African winemaker, Henry Kotzé, has refined his winemaking mantra to one of minimal interference and maximal expression of variety by means of selecting the best terroir possible. Experience speaks for itself and Henry was appointed winemaker at Morgenster in 2009. Previously, Henry’s oenological skills were honed during his stints at Vergelegen, Boschendal, Neil Ellis and Eikendal (all highly acclaimed South African wineries.) Henry’s focus at Morgenster is on red wine where he works with the classical Bordeaux grape varieties (Cabernet Sauvignon, Cabernet franc, Petit Verdot and Merlot) and Italian grape varieties (Sangiovese and Nebbiolo).

The first vines on the farm were planted in 1994 and the average age of the vineyards is 15 years. The grapes are usually harvested, depending on the fickle weather of course, late February. Average yield is 5.5 tonnes per hectare and juice yield is 700 litres per tonne.

Now, let’s get started with the winemaking section of this blog. This is what Henry had to say: “As the grapes are destemmed and crushed (about 10% is whole bunch pressed), I’ll add an Enartis red wine enzyme for colour extraction. Cold soaking is done for two to four days at less than 10°C. Only one pump-over a day is needed and this is done slowly and gently, to facilitate maximum extraction.” As he says this, he glances longingly at his mud encrusted mountain bike and then back to me. I realise that he’s probably very busy and has not been getting a lot of sleep (the plight of every winemaker!), so I hurry on with my questions. As for the Bordeaux varietals, Henry elaborated about two of his favourite yeasts: “I inoculate Anchor NT 202 and Anchor WE 372 (Oenobrands) at 15°C. NT 202 has always been a stalwart and works well with the wine style that we like to embrace at Morgenster. It is also easy controllable with temperature alterations.

As for WE 372, it is a slower fermenter which really enhances the varietal character of the grapes I am working with. WE 372 makes a particularly powerful contribution towards red berry and fruity aromas when I’m working with Merlot. For my Italian varietals, I use selected Lallemand yeasts. A typical fermentation is done at 26 to 28°C for seven to ten days. I also use a lot of oxygen during fermentations for maximum colour extraction. As an activator I use Laffort Dynastart and Anchor Nutrivin (Oenobrands) and DAP during fermentation.” Henry also formed part of a group of winemakers in South Africa who tried the new Anchor NT 202 Co-Inoculant MLF starter culture (Oenobrands) in 2011.

He says: “I tried the Co-inoculant on a batch Petit Verdot this vintage and was pleasantly surprised with the results, since MLF took only 14 days to complete after AF finished. This usually takes three to five weeks. I usually inoculate all my red wines with Lallemand bacteria, but intend to use the Co-inoculant again next year and in bigger amounts.” Henry explains post-AF as follows: “Extended maceration on skins can last a few days or up to two weeks. After MLF, the wine is racked and three rackings are done during 18 months of barrel ageing. Beta-glucanase (Enartis) is used during ageing.

Optimal filtering would be done with a 1.6 micron candle filter, but where VA is 0.6g/L or higher, I will use a 0.45 micron candle filter.” Henry has his wine bottled during December and January after which it is released three years later. As for the premium Morgenster wines, expect to pay US $69 and US $33 for the Lourensriver Valley range.

Bernard Mocke is a technical Consultant for Anchor Wine Yeast.