New World Winemaker Blog

During a recent overseas trip, a colleague of mine once again lamented the joys of travelling. This trip kicked off with a baggage issue that ruined her dinner. Other jolly events included fishing her phone out of a toilet, missing a train, almost being run over by an expressionless Parisian, being kicked by a drunken teenager in Lille and finally a screaming taxi driver in Montpellier. Friendly people… the French. But the inside of a fermenting tank can also be a chaotic and even deadly place for yeast.

Modern winemaking can be very stressful and winemakers are putting increasing pressure on their minuscule friends. No, I’m serous! Pressure can indeed be a limiting factor; especially where low pH and high ethanol is concerned. Trapped carbon dioxide gas not only creates turbulence in a tank, but also contributes to a gradual increase in pressure. Pressures upward of 600 kPa (6 atm) typically stop yeast growth (think secondary fermentation of sparkling wine), but not necessarily alcoholic fermentation. In the book “Wine Science: Principles and Applications” by R.S. Jackson, it is stated that a pressure of 3000 kPa (30 atm) and upwards will completely inhibit alcoholic fermentation! What hardy fellows they are, these yeasts!

The use of pressure to control or stop yeast growth is not uncommon in German wineries, but high pressures can cause other problems. Spoilage organisms such as Lactobacillus, Torulopsis and Kloeckera are less sensitive to pressure and can cause a myriad of problems. The latter micro-organism is particularly pesky, as it is quite sulphur dioxide resistant, ferments at temperatures as low as 10°C and can produce high levels of ethyl acetate and amyl acetate.

Some beer brewers postulate that higher pressures have a positive aromatic effect on their ferments, but clear guidelines during vinification have not been established. At least there are many other ways to boost aroma, so don’t be depressed.

Bernard Mocke is a technical consultant for Oenobrands

On 15 February 2013, asteroid 2012 DA14 missed earth by a mere 27,700 kilometers. This ancient 130,000 ton asteroid, spanning 45 meters in diameter, would have released the same amount of energy as a detonating 2.5 megaton atomic bomb, had it collided with the earth. It looks like 15 February 2013 was global meteor day, as a 9 ton behemoth caused widespread panic and injuries as it seared through the sky above Chebarkul, a town in central Russia. Not really cataclysmic, these events, but certainly significant enough to put the thought of mass extinction into our minds.

Not only humans (and don’t forget the dinosaurs) are subject to mass extinction. Micro-organisms are intimately sensitive to changes in their environment. Take a tank of fermenting must. The savvy winemaker will manipulate this very complex environment to suit his and the fermenting yeast’s specific needs, but under certain conditions the yeast population can very quickly become extinct.

The eventual fate of the wine yeast is death. After churning out ethanol, flavour compounds and a myriad of other chemical compounds during its usually short life, the yeast unceremoniously dies. But still their job is not done. These dead cells (lees) also have a very important role, but for now the focus will be on some of the causes of death of fermenting wine yeasts.

Temperature, ethanol concentration, osmotic stress, pH, toxins, pressure, sulphur dioxide and volatile acidity can separately or in combination make your little buddies extinct. So best you follow this multi-part blog, as the next installments will focus on the specific factors listed above.

You might not be able to dodge projectiles from outer space, but you can do a lot to keep your little fermenting soldiers happy and alive right until the end.

Bernard Mocke is a technical consultant for Oenobrands

On September 24, at the 1988 Seoul Olympic games, the rivalry between Ben Johnson and Carl Lewis came to a head when Johnson won the 100 meter sprint in a time of 9.79 seconds. Subsequent drug tests revealed that Johnson used Stanazolol, a banned substance and he was promptly stripped of his gold medal. Back in the present, after nearly a decade of alleged doping, Lance Armstrong came clean about his use of various banned substances that surely contributed to him winning seven Tour de France titles.

In 1985, German laboratories uncovered the widespread use of diethylene glycol in Austrian wines. This toxic substance (the diethylene glycol, not the Austrian wines!) made late harvest wines sweeter and more full-bodied. Jail sentences and heavy fines were handed down to key players in this scandal.

Two of my greatest passions in life are sport and wine. I therefore find it very interesting (and amusing) that both are prone to doping. As is the case in sport, a wide array of biological and chemical substances are available for use in viticulture and winemaking. Grape growers and winemakers are privy to these substances and some use them to save money, aid the winemaking process and influence the quality of finished wine.

DDT, which was once a very popular pesticide, has been banned since the early 1970’s in the USA, but reports still indicate sporadic use. Things get more interesting as we move out of the vineyard and into the cellar, so put on your doping hat. The use of sulphuric acid in winemaking (to alter pH) is illegal in South Africa, but I have a source that says that this practice is still rife. As is the addition of water to must to lower potential alcohol and increase yield. Legal alternatives are available, such as reverse osmosis and the spinning cone technique, but they do not come without a fair share of controversy. I’ve also heard of cellars (locally and international) that harvest Sauvignon blanc very green and then simply add sugar in order to get to a desired alcohol level, whilst maintaining certain green aromas.

As for alcoholic fermentation, the use of GMO yeast is completely taboo. The thing is, the world is a pretty big place, so if a certain Asian country decides to use a GMO yeast that massively boosts esters and produces less alcohol, who will know? I’ve also read an article about a commercial cellar in Europe that got caught out for using a GMO yeast that can degrade 100%of the malic acid in wine.

Excellent legal alternatives are of course available.  Oenobrands offers a focused range of nutrients, non-GMO yeasts, a world first bacterial co-inoculant and enzymes for various winemaking styles, so there is really no need to break the law. Remember, cheating is for dopes. Just ask my friend, Tiger.

Bernard Mocke is a technical consultant for Oenobrands

“If I was a winemaker and I made wine that tasted the same five years in a row, I would consider myself a failure.” This statement was greeted by a soft gasp of shock and then an uncomfortable silence that settled around the dinner table. The identity of the person who made the opening statement will forever remain a mystery, but I will try to shed some light upon the unique (and sometimes volatile) relationship between the winemaker, the marketing team and the consumer.

‘Death of a Salesman’ is a 1949 play written by American playwright Arthur Miller. It tells the story of Willy Loman, a failed salesman, who ultimately commits suicide. This flawed, but valiant deed marked the end of an unremarkable sales career. The reality is this: salespeople in the wine business are still under increasing pressure, as is the winemaker as well as the consumer. Seeing that the consumer has to fork out hard earned cash to enjoy some wine, it is up to the marketing team to convince the consumer to buy the winemaker’s wine. It is thus clear that there needs to be very good communication between the winemaker and the marketing team. All of this is old hat. What might not be that apparent, is that there exists two extreme opposite paradigms in the winemaking world.

Paradigm one: Based on extensive market research, the winemaker obtains information on existing markets and what their requirements are. Here the winemaker relies heavily on the interpretation and rendition of current markets by die marketing team. Past experience, current trends and forecasts are buzz words here. A quality level for each market segment is determined and wine is made and marketed according to the consumer preference of each segment. Forgive me, for I’m of course greatly reducing the complexity of the science that is involved in marketing and market research. If I may simplify even further, within this scenario the winemaker makes what the different markets want.

Paradigm two: The winemaker makes wine according to his taste and whims. The market is ostensibly much smaller than those described in paradigm one, seeing that consumers need to share the taste of the winemaker or need to adapt. During my stint in a big cellar in California, I met a highly eccentric winemaker who personified the second paradigm of winemaking. He was of the opinion that winemakers like him are part of a dying breed and winemakers should not be dictated by market preferences. In his own words: “If you like my wine, you buy it. If you don’t like it, *$#@* off!” I really liked this cowboy and I decided to stir the pot a little by pointing out that I’ve had excellent wines from wineries/winemakers representing both of the above mentioned paradigms. You can just imagine the earful that I got then…

Let’s revert to the opening statement: “If I was a winemaker and I made wine that tasted the same five years in a row, I would consider myself a failure.” Theoretically, an exceptional year will yield exceptional wine. This will probably change (improve?) the taste of the wine, if compared to a standard. The million dollar question is: Will your market accept the different taste or will you be met with a lynch mob?

You might want to ponder this whilst having a glass of wine. After all… “In vino veritas.”

Bernard Mocke is a technical consultant for Oenobrands