New World Winemaker Blog

As fermentation proceeds and yeast continue to propagate, they pass along a certain amount of cellular material to future generations. In juice/must without proper yeast rehydration, a gradual reduction in cell membrane thickness and decreasing amounts of nutrient reserve transfer from generation to generation is common as fermentation continues. This had led many producers to include the use of yeast rehydration nutrients to help make their yeast ‘happy’ during the rehydration process, and lead to a healthy yeast population, essential to successful fermentation.

There are several proprietary yeast rehydration nutrients available today, including Dynastart, GoFerm, and PreFerm. They are created from autolyzed yeast cells, and provide many essential micronutrients (including membrane lipids and sterols) and vitamins (including biotin, niacin, and thiamine) that are readily absorbed by active yeast cells. Providing these during the rehydration process reactivates the yeast’s internal metabolism quicker and leads to a substantial increase in cell volume; the original structures of the yeast’s plasmatic membrane are modified, leading to better viability, increased membrane fluidity, increased resistance to ethanol (essential towards the end of ferment), increased resistance to osmotic shock due to high sugar concentration (essential at inoculation), and increased aroma production (essential for good tasting wine!). Yeasts prepared with yeast rehydration nutrients also maintain a steadier metabolic rate throughout fermentation. Less stress also means far less volatile acidity formation and negative sulfur-containing compounds (hydrogen sulfide, disulfides).

The use of yeast rehydration nutrients is recommended at a 5:6 ratio with yeast (5 parts yeast to 6 parts rehydration nutrients, usually 250 ppm yeast with 300 ppm nutrient). I tend to use the recommended rate only when I know that strenuous fermentation conditions are inevitable (high brix levels, low fermentation temperature, low turbidity juice, historically deficient juice, etc.) or during yeast starter culture propagation. For normal fermentation conditions, I tend to use a 1:1 ratio (usually 200 ppm yeast and 200 ppm yeast rehydration nutrients).Winemakers also need to be wary of legal dosages of particular ingredients (i.e. thiamine) when using yeast rehydration nutrients in conjunction with other fermentation nutrients.

Please see here for yeast rehydration preparation.

Mike Horton is a winemaker with a passion for surfing. Correction… he is a surfer with a passion for winemaking. Yeast Rehydration Nutrients was originally posted on his blog: the drifting winemaker.

My husband is obsessed with this movie and the theme song. It was his cell phone ring-tone for a while – a long while actually – drove me bonkers. I guess that is why it was the first title that popped into my head when I thought of how to describe Lactobacillus in winemaking. It used to be the bad and in many cases the ugly. If you look at articles on stuck fermentations and wine spoilage from a few years ago, Lactobacillus almost always features somewhere in the article as one of the main culprits. So it is not surprising then that sales attempts to sell Lactobacillus starter cultures for malolactic fermentation are often greeted with GREAT resistance, aggression, jaw dropping, gawking or a call for Security.

Well folks you can pick up your jaws because it seems that there are “good” guys amongst the bad and ugly ones. The two companies that are taking the lead on commercializing some good guys are Oenobrands and Lallemand. The Lallemand culture V22 is a pure Lactobacillus plantarum culture from European origin and can be used for both co-inoculation during alcoholic fermentation as well as sequential inoculation after alcoholic fermentation. The Oenobrands product, marketed under the Anchor brand and called Anchor NT 202 Co-Inoculant, is a blend of selected Oenococcus oeni and Lactobacillus plantarum strains. These strains are South African isolates.

Okay, I know what your minds are screaming…VA! Indeed something to scream about. But not in this case. These two commercial Lactobacillus plantarum cultures are homofermentative. That means they can utilize only malic acid as a carbon source to form mainly lactic acid. Other Lactobacillus strains (often present in spontaneous MLF’s) as well as Oenococcus strains  are heterofermentative, meaning they can also utilize grape sugars and citric acid and as a result form acetic acid. However, reputable commercialized Oenococcus oeni MLF starter cultures, although heterofermentative, strongly prefers malic acid as carbon source (they have been selected because of this), even during co-inoculation where grape sugars and citric acid are present in high concentrations. Not all starter cultures are suitable for co-inoculation though.

Okay so why Lactobacillus? In the case of Anchor NT 202 Co-Inoculant the Lactobacillus plantarum in this mixed culture brings aroma and roundness to the party. The Oenococcus is the workhorse bringing, security and speed to the party. The application of NT 202 Co-inoculant is also rather simplistic. You add equal amounts of sachets of bacteria and packets of NT 202 wine yeast to the juice, at the same time, before the onset of fermentation. No waiting for 24 hours. No extra calculations. Scientific research has shown this Lactobacillus plantarum strain to have a very different enzyme profile to Oenococcus oeni in general and as a result the typical varietal character of red grapes, specifically monoterpenes and norisoprenoids, are released from their non-aromatic precursors, thereby increasing wine aroma and thus quality.

So while you still need to do your best to keep the “bads” and the “uglies” out of your wines, experimenting with the “good guys” might just give you that kick @$$ competitive edge you strive to achieve in your wines…

“Some call her sister of the moon, Some say illusions are her game…”

Those of you who are into Fleetwood Mac (I shall give you a hint: A popular rock band which got together in the late 60’s), are probably intrigued by the familiar lyrics yet again, and those of you who are into biodynamics, probably enchanted by it.

It is a science although not regarded as one. It has many truths, although not acknowledged by too many. Some facts though, that I can put on the table, remain in my view, significant:

 1. I grew up spending time with Cousin Riaan in Chenin blanc and Shiraz vineyards, almost 20 years ago, dusting vines with sulfur no more than 3 or 4 times during season. All dry land vineyards. 30 tons per hectare. Today we might not survive if we do not put down a few systemic sprays and a couple of contact sprays. What happened? Are we not treating symptoms instead of zooming in on the reason for these symptoms? Our focus is simply on “pumping the soil” full of required elements to sustain next year’s bottom line. We spray the vine with all sorts of funny things when it shows symptoms of illnesses, disease, pests or deficiencies, instead of zooming in on the variables that cause the distress We have forgotten how to treat and respect the well being of a living entity in our quest to “push the yield”…no wonder we have such chaos in our crops.

2. I have stuck my hand into soil managed biodynamically, but almost broke my fingers trying to get into the first few millimeters of the neighbor’s.

3. Many studies confirmed significantly higher concentrations humus in biodynamically farmed soils, hence more diverse populations of soil microbes and higher concentrations of more diverse populations of microbes on the grapes.

4. I could not find mealy bug on the biodynamically farmed vines, nor those of the neighbor’s. The difference though was that the mealy bugs moved back to where it prefers to live – underground on the roots of a diverse population of plants (even though some are regarded as weeds). Luckily of course Chlorpyrifos (or by the household name Dursban) got rid of the mealy bug via ant control. Unfortunately bees are not to keen on Dursban either.

5. Lower costs of farming biodynamically have been researched and verified by many studies, despite a slightly lower yield.

6. The slightly lower yield justifies itself in better quality grapes and wine. Higher phenolic concentrations, smaller berries and slightly lighter clusters.

7. “Better” wines? I have my personal convictions when it comes to this “sensitive”, abstract term.

My personal conviction on Biodynamics is that scientists and critics do not need to ask whether BD can be regarded as a scientific category or even point out that part of the scientific community looks at it with skepticism and marks it as dogmatic. There are over 4200 farms around the world that are certified as BD, the numbers are increasing, so it is clearly worthy of more respect and attention that it currently enjoys.

Biodynamics make sense to me because I simply believe in things I experience with my God-given senses.

 I suppose I will be outlawed as a “winemaker with a scientific approach”, just the way I was (still am I suppose), outlawed as a traditional winemaker, because I produced a “non-typical” Coffee Pinotage style. Whatever typical or traditional may mean…

Bertus Fourie is a winemaker, turned Enology lecturer and creator of the Barista coffee Pinotage.

“Large egg-shaped vessels have been appearing in increasing numbers at high end wineries on the West Coast, stirring a mixture of bafflement, warm, return-to-the-womb associations and fears of an alien invasion…” Field Maloney, Wine & Spirits, February 2009

Very funny intro. Alien invasion is exactly what describes the image that went through my head when I saw these egg shaped tanks for the first time. I immediately thought of the 1993 movie: Coneheads, hence the image.  From the moment I saw a picture of these tanks – and I must embarrassingly admit it was only last year – I have wanted to investigate this amusing (to me) new movement in winemaking. It looks rather funny in a cellar. It looks like a giant hatchery where large prehistoric flying reptiles are about to emerge from any second.

The tanks are made from concrete and they are in an egg shape. Why the concrete? Well apparently concrete allows for a micro oxygenation effect on the wine like barrels do, except without adding wood flavors. Why the egg shape? It apparently creates a vortex in the wine and allows for lees to stay in suspension so stirring is not necessary. Lees in suspension has various advantages, hence the practice of batonnage.

The mastermind behind these tanks is Marc Nomblot who on request of biodynamics winemaker, Michel Chapoutier, built the first one in 2001. This caught on quickly and to use the the description of Jeffrey Iverson, these egg shaped tanks are now “hatching in wineries all over the world.”

I recently visited the hatchery of Boekenhoutskloof winery in Franschhoek, South Africa (yes the eggs have reached the southern tip of Africa). They ferment Grenache blanc in their eggs. They start fermentation in stainless steel tanks on skins, so no settling, and press anywhere from 25 – 50% into the fermentation. The must is then pumped with all its lees into the eggs. Fermentation is conducted at 16 – 18°C; they use a coil for cooling (Franschhoek is a tad warmer than the Rhône). The coil only goes into the egg for about an hour at a time. These concrete eggs are great insulators, compared to stainless steel that is conductive. Fermentation is about seven to ten days with Lalvin ICV-GRE yeast (Lallemand). After fermentation the wine stays in the eggs for 10 months. To the winemaker the biggest attribute from using the eggs is the incredible mouthfeel one can obtain this way.  This Grenache blanc forms part of of a white blend called Wolftrap white. Even though Boekenhoutskloof is not a biodynamic winery they do embrace some of the principles, such as these egg tanks, and plan to expand their hatchery on an ongoing basis. They have also started to expand the usage to other grape varieties.

So certainly with “biodynamic”, “natural” and “non-interventionist” winemaking being the buzz words at the moment, I reckon these eggs are here to stay for a while. Personally I believe in interventionist winemaking, but here is a concept that even makes sense to me. I’m just not so sure about racking during certain moon cycles though. ..

Boekenhoutskloof winemaker Jean Smit and some of their eggs.

Karien O’Kennedy is the Online Communications Manager for Oenobrands and knows the odd thing or two about fermentation and winemaking.