New World Winemaker Blog » Bernard Mocke

A glimpse at the complexity of barrel ageing

Bernard Mocke — Fri, 24 Feb 2012 12:38:18 +0000

“I have walked across the surface of the Sun. I have witnessed events so tiny and so fast they can hardly be said to have occurred at all. But you, Adrian, you’re just a man. The world’s smartest man poses no more threat to me than does its smartest termite.” – Doctor Manhattan

The above quote by Doctor Manhattan from the 2009 movie, Watchmen, made a very big impact on me. Not only did Doctor Manhattan have extraordinary physical capabilities, but also boundless intelligence and wit. Most scintillating however, was his ability to observe and control miniscule atomic particles and impossibly fast to imagine metaphysical events. Doctor Manhattan didn’t really strike me as a lush, but I’m sure that he would have been fascinated with the chemically complex and ever changing matrix that is maturing wine.

As a former minor winemaker at quite a few cellars, my favorite place has always been the barrel maturation cellar. Barrel ageing is ostensibly one of a wine’s more important stages of evolution before bottling. But how exactly does wine change during barrel ageing and what effect does it have on the countless chemical reactions taking place in wine every second? The main effect of oak barrel ageing is twofold. Wood character is introduced (the rate and intensity is mostly dependent on fill status of the barrel) and oxygen is very slowly introduced to the wine. Generally speaking, this results in softening of the harsh tannins and flavors present at the end of fermentation. Oak is a fascinating substance, which has a profound and remarkable effect on the flavor chemistry of wine. Key oak derived compounds are tannin, lignin, cellulose and hemicellulose.

Tannin plays a vital role in barrel ageing. Although most tannin in wine comes from the grapes, some of it is also liberated by the barrel during ageing. So what exactly is the deal with tannin? An experienced winemaker will instinctively know how to optimally merge and balance the tannins extracted during the youthful stages (fermentation, skin contact and pressing) and the mature stages (barrel ageing and blending). For instance, more tannic grape varieties such as Tannat, Cabernet Sauvignon, Nebbiolo and Shiraz cannot be approached the same as the less tannic Pinot noir. Once again, winemaker experience is paramount.

OK, now hold on to your chemistry hat, here comes the hard (but interesting) bit! Phenolic compounds (consisting of natural phenols and polyphenols) in wine are largely responsible for imparting taste, colour and mouthfeel to wine. They include phenolic acid, stilbenes, flavonols, dihydroflavonols, anthocyanins, flavanol monomers (catechins) and flavanol polymers (proanthocyanidins). Natural phenols can be separated into flavonoids and non-flavonoids. The latter group includes stilbenoids such as resveratrol and phenolic acids such as benzoiz, caffeic and cinnamic acids. The former group includes anthocyanins and wait for it… tannins!

What would a good red wine be without vanilla flavors, sweet and toasty aromas and notes of tea and tobacco? Specific compounds create these nuances in finished wine, for example: volatile phenols containing vanillin; carbohydrate degradation products containing furfural, a component yielding a sweet and toasty aroma; “oak” lactones imparting a woody aroma; terpenes providing “tea” and “tobacco” notes, and hydrolysable tannins, which are important to the relative astringency of the wine. Take note, every time you’re quaffing a wine (hopefully a worthy vintage), you’re consuming everything you’ve just read above. If this doesn’t sit quite right with you, then I guess nothing much will.

They say you should have respect for your elders. So, tread lightly the next time you pass through a barrel maturation cellar. You might even see Doctor Manhattan skulking around in the dark, silent corners…

Bernard Mocke is a technical consultant for Oenobrands.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

A brief look at the evolution of winemaking technology

Bernard Mocke — Fri, 13 Jan 2012 13:52:03 +0000

If you gaze upon these images for a few moments (some might need more time), you will notice a few things. Most significant is that things tend to not only get more colorful towards the end, but also more revealing. Those of you who aren’t too thrilled by the images above might wonder what scantily clad damsels have to do with the evolution of wine technology. Best you read on then.

During an ancient and alcohol fueled conversation, a chef expressed his discontent at the notion of wine research. His bottom line was that you cannot drink research. After a few moments of thought (which was remarkably difficult at that time), I pointed out the obvious improvement of wine during the past 100 years. Also the availability of science and technology allowing for the abundance of excellent wines which are currently available. Just like the evolution of the bikini, science allows you to make things more revealing. To strip things down to the basics and to fulfill a very important need…

Alcoholic fermentation by yeast is a natural and beautiful thing. One might even call it a simple process. Nonetheless, this seemingly simple process is governed by hundreds of thousands of elements, chemicals, enzymes and micro-organisms. Louis Pasteur, often called the father of microbiology, paved the way for the identification, enumeration and understanding of all micro-organisms. His humble beginnings in the early 1860’s allowed him to conclude that micro-organism can lead to wine, beer and milk spoilage. Back then, all germs were seen as the enemy. Who would have thought that more than 150 years later, we add specific yeast and bacterial cultures to wine in order to make better wines. You can practically get a wine yeast for any grape variety, winemaking condition and style that you desire. In 1953, James D. Watson and Francis Crick suggested the first correct double-helix model of DNA structure, which with ongoing research and refinement allowed us to study yeast genes and this helped us with the continuing selection and improvement of yeast strains for specific new world winemaking conditions.

Enzymes have also come a long way since their discovery in 1833 by Payen and Persoz, who treated an aqueous extract of malt with ethanol and precipitated a heat-labile substance which promoted the hydrolysis of starch. Nowadays, it is hard to imagine any commercial winery without the use of all the different enzymes. Not only do enzymes improve wine quality, but they also make life easier for the winemaker. For example, a settling AND skin contact enzyme like Rapidase Expression (Oenobrands) allows for a single addition at crushing of white grapes. Not only is varietal character enhanced, but more than ample enzyme activity remains after pressing in the settling tank.

Remarkable advances have also been made in cellar and wine treatment machinery. This is not surprising, seeing that our club wielding, cave-dwelling ancestors already tried their hand (or should I rather say claw) at winemaking back in the spry 4000 BC’s. The oldest known winery is located in the “Areni-1″ cave in the Vayots Dzor Province of Armenia. This winery, which is over six thousand years old, contains a wine press, fermentation vats, jars, and cups. Archaeologists also found grape seeds and vines of the species Vitis vinifera. Gravity was all the rage before pumps were designed, but there is a refreshing new push towards using gravity again in modern cellars.

Wine treatment was also not left behind. Where in the past, winemakers had to deal inventively with maladies such as high alcohol, volatile acidity, Brettanomyces-taint etc., the advent of reverse osmosis and spinning cones offers cost effective solutions.

Sir Francis Bacon said in 1597: “Knowledge is power.” Science allows humans to empower themselves. And to feel smarter. If you don’t believe this, just think of how smart you usually are after a few glasses of wine…

Bernard Mocke is a technical consultant for Oenobrands.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Winemaking in the Rhineland-Pfalz: Part 2

Bernard Mocke — Thu, 01 Dec 2011 23:00:49 +0000

During my recent harvest stint in Germany, my host, Christoph Hammel uttered many memorable (and some that I am not allowed to mention here) pearls of wisdom. He told me about a meeting where some of the biggest names in German winemaking and professors associated with the wine industry were present. A very well know professor publically stated that his belief system does not have any room for the theory that yeasts impart any aroma to a wine fermentation. At this, Christoph got up and glibly replied: “My dear sir, it is not a question of belief. It is a question of knowledge.” The subsequent pandemonium that ensued was apparently quite noteworthy (hence the photo above).

Christoph is a big believer in using technology, specifically technology that can be used to make wine, and wine processing, better. Even more specifically, he is a big believer in additions. He always said to me that he makes wine that people want to drink and if this can be achieved with the addition of enzymes and other winemaking tools, so be it. Every addition that he does is done for a reason. One thing can be said with certainty and that is that Christoph believes in the “interventionist” approach to winemaking. A lot of winemakers like to claim that their wine is made “naturally” and with the least possible human intervention, but Christoph is at the complete opposite of the spectrum. He has some pretty far out and amazing ideas and some might even call him a renegade or a cowboy after hearing about his yeast mixing and addition regimes!

As far as the additions are concerned, Optiwhite (Lallemand) is one of his stalwarts. This is usually added at the beginning of fermentation. β-glucanase and β-glycosidase enzymes are added at the end of fermentation (at about 0°Brix). Depending on the structure and quality of a specific wine, ascorbic acid is also added right at the end of fermentation. DAP is added at three stages and is sometimes even added in divided dosages during the day, depending on the fermentation bouquet. In addition to DAP addition, thiamine is added to all musts. This is done simultaneously with sugar addition. It is well known that fungal infection on grapes depletes thiamine and it is therefore an excellent prophylactic measurement against stuck, sluggish or smelly ferments. For each addition, a cost to benefit decision is made. For instance, light and easy drinking wines will not get all the bells and whistles. The more expensive wines will get a full range of stuff added.

If Christoph was not such an excellent winemaker, I would have said that he missed his true calling in life: A chef! A chef who is forever mixing, adding and tasting, mixing, adding and tasting…

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Winemaking in the Rheinland-Pfalz

Bernard Mocke — Fri, 14 Oct 2011 09:14:33 +0000

“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.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Are your yeasts on sterols?

Bernard Mocke — Fri, 02 Sep 2011 11:46:51 +0000

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.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Flash Gordon in hot water after colour extraction incident at winery!

Bernard Mocke — Fri, 26 Aug 2011 10:26:14 +0000

If the title of this blog caught your eye, my ploy worked. Please accept my apologies; Flash Gordon will not be featured here. Or any other superheroes, for that matter. I will however elaborate on Flash Détente and its super colour-extraction abilities.

Of late, growing interest in colour extraction (especially in California) has led to the evolution of thermovinification into Flash-Détente. During thermovinification, the temperature of crushed red grapes is raised to 60˚C for anything from one to 24 hours. Thermophiles (pardon the pun) claim that increased tannin and colour extraction is to be had with thermovinification. The logic behind this is sound, as the high temperature breaks down cell structures. This in turn releases pigments, tannins and volatile compounds in the absence of ethanol. In the absence of alcohol, chemical bonds are formed between anthocyanin pigments and other phenols which stabilizes colour in the resulting wine. Should this concept give you cold feet, you might want to opt for cold soaking. During cold soaking, crushed grapes are soaked in their own chilly juices and pumped over for a few days in an effort to extract more colour.

Not impressed yet? Enter Flash-Détente, which is basically thermovinification on steroids. Grapes are briefly (two to five minutes) heated to 85˚C and then cooled in a vacuum. Cell walls pop, juices fly and a myriad of aroma and colour compounds are released. The vaporised water (with volatile compounds trapped within) is then chilled in a condensing column, after which the winemaker is left with the decision of adding the fluid fraction back to the main tank or not. Seeing that this condensate is full of pyrazines and in the case of lower quality grapes, rot and mold aroma compounds, the winemaker usually discards the condensate. This is however a double- edged sword, as varietal and fruity aromas is also lost in the condensate. Then again, the heat application inhibits enzymes such as polyphenol oxidase and laccase, which are often present in lower quality grapes. The effect of this heat on Brettanomyces is still ambiguous. Other benefits of extracting colour earlier are; improvement of purple hues in wine, fermentation at lower temperature and usage of different yeast strains. It is also speculated that the softer and rounder tannins are better extracted with water and heat, while the harsher tannins might be brought out where ethanol is the solvent.

Many traditional winemakers believe that Flash-Détente is for higher yield facilities, where often quantity outweighs quality (sic). It has been said that the loss of varietal character often results in a one-dimensional, soulless wine. As with all other winemaking decisions, the decision to go with or without thermovinification is an important one. Current studies on thermovinification are focusing on changing tannin concentrations in must with an increase in temperature and how varietal character is affected.

With a price-tag of $2 million for a Flash-Détente set-up, winemaker experience will be key in the decision to employ this system or not. Like they say, talk is cheap.

Bernard Mocke is a technical consultant for Oenobrands.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Why an alternative to bentonite might help save the world…

Bernard Mocke — Fri, 12 Aug 2011 13:00:24 +0000

Nowadays, going green is all the rage. People are driving electric cars, industrial carbon dioxide emissions are scrutinised and even flatulent cows are not escaping the wrath of greenies. So what does this have to do with the wine industry?

I’ve recently learned that bentonite is a big culprit, leading to wine losses equivalent to that of New Zealand’s annual white wine production. This loss of 1-3% represents 120,000-360,000 tonnes of grapes. The related liberation of greenhouse gases for irrigation, harvesting, pressing and processing of this amount of grapes was estimated at 36,000-225,000 tonnes of carbon dioxide per year. Unfortunately for mother nature, bentonite fining is an effective and simple method for the removal of haze-forming proteins.

Apart from wine that is trapped and lost in bentonite lees (up to 3%, even with subsequent rotary drum vacuum filtration-RDV), a considerable reduction in varietal character is also inadvertently effected when bentonite fining is done. It is well known that aroma and flavour molecules in wine can be adsorbed by bentonite, which in turn leads to an unwanted decline in wine quality. Further oxidation during recovery from the bentonite lees merely adds to the aforementioned decline.

Before you go on a witch-hunt and banish bentonite from your cellar, there is good news. It was found that in-line dosing in conjunction with RDV can significantly decrease wine losses. A short description of in-line dosing: Untreated wine is pumped from a storage tank to an injection point, where bentonite slurry (supplied from a slurry tank) is continuously injected into wine or juice. A static mixer disperses the slurry, ensuring even contact between wine and bentonite. A contact period of five minutes in pipe work is allowed before centrifugation is used to separate wine and bentonite. The problem with in-line dosing is that it is not yet widely used and installation can be costly.

Batch fining combined with RDV remains the most popular method in countries such as France, Italy, Spain, California (ostensibly a country), Australia, Germany, South Africa and New Zealand. Collectively, their white wine production represent 40% of all wine produced globally. The amount of bentonite required for protein stability varies according to a number of factors, such as year, fruit type and growing region. The report that I studied in Grapegrower and Winemaker Magazine (in preparation for writing this blog) indicated that with all factors taken into account, a dose of one gram of bentonite per litre of white wine will be assumed.

Let’s have a look at some more numbers relating to the use of bentonite in the above mentioned countries. They produced 80% of all white wine in 2008/2009 and revenue loss was more than US$820 000 per year. If the value of domestically sold wine is added to the export values of white wine, the aforementioned figure climbs to a staggering US$1 billion!

The scourge of pollution is slowly suffocating earth and with an estimated 80-250 million kWh energy requirement annually, we can’t afford not to research alternatives to bentonite fining. Keep watching this space!

Bernard Mocke is a technical consultant for Oenobrands

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Red winemaking at Morgenster

Bernard Mocke — Fri, 15 Jul 2011 09:35:27 +0000

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.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Sauvignon blanc production – Vergelegen Winery

Bernard Mocke — Thu, 23 Jun 2011 13:43:21 +0000

With quotes like: “Don’t steal, rape, or murder – or make Pinotage” and “We need to separate admiration for the person from awe of the wine. I would much rather that critics dislike me and appreciate my wine than the other way around,” André van Rensburg remains one of South Africa’s most controversial, most successful and most scientific winemakers. André does not focus on awards and neither will I in this introduction, so let’s get on with how he makes Sauvignon blanc!

Harvesting of the 10 to 23 year old blocks took place earlier this year, with most of the grapes being harvested between 3 and 18 February. Harvesting usually starts with the young blocks during the second week of February. From the yield of 5.5 tonnes/hectare, 630 to 678 L of juice is obtained. The high quality of the fruit becomes evident from the fact that a pH above 3.2 is nowhere to be found in any of the settling tanks. Grape processing during crushing is minimised by up to 10% whole bunch pressing. Rapidase Expression (Oenobrands) is added during crushing while Novoclair (Novo) and PVPP is added at the settling tanks. André maintains that skin contact more than two hours is excessive, because ample “skin contact” happens during ripening. Cold settling at 5°C lasts for 48 to 96 hours and some tanks get additional lees rubbing for added aromatic complexity.

According to André, Anchor VIN 7 (Oenobrands) is the ultimate yeast for Sauvignon blanc fermentation. He sometimes supplements his favourite yeast with combinations of QA23 (Lallemand), Anchor Alchemy I and II (Oenobrands) and has even made red wine with VIN 7 in the past! Yeast is added (he does this himself) at 14 to 15°C. Temperature during the lag phase peaks at 17°C, but is then reduced to 12°C for a day after 2°Brix has been converted. After this the temperature is kept between 14 to 16°C and then held at 16°C when the sugar concentration is less than 5°Brix. Fermentation usually completes after 10 to 14 days, with residual sugar less than 2g/L. Nutrient additions are done at 20°Brix, 18°Brix and 15°Brix. He uses Fermaid K (Lallemand) and liquid ammonia (legal in South Africa) as yeast nutrients. Inactivated yeast cells are added during the second day of fermentation. As far as YAN’s go, every tank’s YAN is checked and then increased to 320mg/L. A typical YAN value prior to supplementation is 250mg/L. Ageing on yeast gross lees is done for four to six months and for the reserve, up to eight months. During the first two months, the wine is held at 20°C and stirred weekly for 30 minutes. Beta-glucanase enzyme from Novo is added to the lees after fermentation.

The wine is stabilised four to six months after fermentation, by careful addition of bentonite at a dosage of no more than 50g/hL. Bottling takes place August to September (October for the reserve) and is released for sale directly after bottling. The standard Savvy sells for $17 or £8.99 and the reserve for $25 or £15.

Bernard Mocke is a technical consultant for Anchor Wine Yeast.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Sauvignon blanc production – Flagstone winery

Bernard Mocke — Thu, 16 Jun 2011 23:00:52 +0000

Gerhard Swart, Flagstone’s winemaker, is no stranger to awards. His Free Run Sauvignon blanc has consistently received high accolades over the past years and this comes as no surprise considering the care that goes into his Sauvignon blanc.

Let’s take a closer look at how this wine is made. The Sauvignon blanc is harvested from vineyards that are 8 to 12 years old during February and March. Yield is 6 to 8 tonnes/ha. Upon arrival, the grapes are stored overnight in a cold room at 0 to 2°C. The cool grapes are then fed into the crusher under a carbon dioxide blanket. Rapidase Expression (Oenobrands), sulphur dioxide and ascorbic acid are added sequentially at the crusher. Tannin Galacool is added during crushing when Botrytis infection is evident. The crushed grapes and juice is then pumped into a skin contact tank and kept at 2 to 4°C for 18 hours. Free run juice from the skin contact tank is pumped to another tank and skins are pumped to a Velo Evolution Press (the press was designed so that grapes can be pressed in a reductive environment of nitrogen gas). Viniclar (PVPP, Laffort) is added to the free run juice before settling. The press juice is then pumped to another tank. Fining agents such as Polylact (PVPP and casein) and gelatine are added to the press juice. Settling enzyme, Rapidase Vino Super (Oenobrands) is added at the settling tank and this lasts for 2 days at 12 to 13°C.

All Sauvignon blanc fluffy lees is combined and kept at 3 to 5°C. Total sulphur dioxide levels are kept at 35 to 40 ppm. After sheet filtration of the fluffy lees, fermentation is initiated and Turbicell is added to increase the NTU level (sheet filtration decreases this too much and can lead to nutrient deficiencies). A typical minimum NTU level of 80 to 100 is sufficient for Sauvignon blanc ferments.

Gerhard uses the following yeasts for his Sauvignon blanc ferments: Anchor Alchemy I and II (Oenobrands) contributes floral, gooseberry and tropical flavours; Anchor VIN 7 (Oenobrands) makes a big contribution towards tropical aromas; X5 (Laffort) adds boxwood, lychee and passion fruit aromas; QA 23 (Lallemand) makes a contribution similar to the Alchemy yeasts and VL 3 (Laffort) produces a waft of khaki bush. Different yeasts add complexity to the wine. Dynastart (Laffort) is added at yeast rehydration and Nutristart (Laffort) is added when needed. Thiazote (Laffort) is added in 3 stages: after 3°B has been fermented, at 16°B and at 12°B. Inoculation is done at 12 to 13°C and fermentation at 12 to 16°C. Fermentation lasts 2 to 3 weeks after which ageing on gross lees (2 weeks) and fine lees (3 to 4 months) follows. Evolution in wine aroma is monitored during fermentation and ageing by regular tasting and chemical analysis.

The Sauvignon blanc is stabilised at the end of June, bottled at the end of July and released in September. Protein stability is done after final blending, right before bottling. All Sauvignon blanc is treated with bentonite after blending.

The Free Run Sauvignon blanc sells for £10 in the UK.

Bernard Mocke is a Technical Consultant for Anchor Wine Yeast.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Winemaking in the Twilight Zone

Bernard Mocke — Fri, 20 May 2011 11:35:21 +0000

You’re traveling through another dimension, a dimension not only of sight and sound but of mind; a journey into a wondrous land whose boundaries are that of imagination. That’s the signpost up ahead — your next stop, the Twilight Zone.

—Rod Serling

As a child, my favourite show was “The Twilight Zone”. It was an imaginative place, filled with uncertainty, adventure, terror and discovery. While these elements will keep any youngster nailed to his seat, a winemaker should tread lightly when entering “The Twilight Zone”.

Wine yeast companies usually offer broad ranges of yeast and bacteria, with bio-converters for every wine style or grape variety imaginable. There is a downside to this myriad of yeasts… Winemakers sometimes avoid browsing through pages of technical hoopla, allowing themselves instead to be guided through the fermentation process and beyond by some vague, intuitive notion. I am all for adventure and discovery, but tend to shy away from uncertainty and terror. Be that as it may, some winemakers wittingly step into “The Twilight Zone”. Here are some examples of lesser known (and sometimes risky) fermentation techniques.

Yeast rehydration is a critical process that paves the way for a successful ferment. However, I know a winemaker who never does this for his barrel fermented Chardonnay. He simply adds the powdered yeast to the must by pouring it directly into the bunghole. His rationale behind this is a very steady and gentle onset of fermentation! Might I add that I rate his Chardonnay as one of the best I’ve tasted. I know another winemaker who adds un-rehydrated dry yeast to his freshly crushed grapes. He said that the action of the pump does a good job of dispersing the microbes into the must. I’ve also heard of a winemaker who rehydrates his yeast in warm must (how would one heat up a bucket of must?) and guess what? According to him he has not experienced problems until this year! Yeah, if you believe that…

In the olden days (realise that the past forms an integral part of “The Twilight Zone”), winemakers lacked the technology that we have today. Cooling down fermenting must during 1930 to 1950 presented a major challenge. One questionable technique included running must in the channels and gutters between tanks and blowing air over it with a fan, before pumping it back into a fermentation tank.

Finally, as a farewell to our foray into “The Twilight Zone” of fermentation, I once did a tour of a private cellar in Germany. The winemaker, in a desperate attempt to get his stuck tanks to start fermenting, scraped the mouldy walls and inoculated the tanks with the centuries old yeasts and fungi. The resulting wine tasted like a horse had a bath in it. Scary isn’t it?

Bernard Mocke is a Technical Consultant for Anchor Wine Yeast.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Focus on Chardonnay: part 2

Bernard Mocke — Thu, 21 Apr 2011 23:00:26 +0000

Jan van Rooyen, the new winemaker at Avontuur Winery, South Africa (2011 being his first full vintage at Avontuur) is no stranger when it comes to making delicious Chardonnay. As a seasoned vintner with many years experience, Jan plans to make the 2011 Chardonnay at Avontuur a memorable one.

Jan accentuated the fact that he wants to make a wooded Chardonnay this year that is for the Chardonnay lover. In other words, a wine with elegance, power and poise. However, this wine should be fully integrated with the wood without obscuring any of the minerality or the fine balance between the apricot, citrus and coconut components.

Different Chardonnay clones from vines as old as 12 years were being harvested on the day of this interview, at 24.5°Brix. The yield per hectare was estimated at 3 to 4 tons and the juice yield at 650 L per ton. Novoclair Speed (for settling), gelatin and kieselsol are added at the crusher after which the grapes are left to cold settle at 12°C for 24 to 48 hours. Fermicru LVCB (Oenobrands) was selected as the yeast strain, due to its ability to produce a wine with balanced fruit and minerality. After the yeast is added at 15°C, fermentation typically lasts for 3 weeks at a temperature of 18 to 20°C. Jan believes that a clean and steady fermentation is best achieved at this temperature. Nutrient additions are added in the form of Anchorferm (Oenobrands) or Bioferm (Bio Springer) and later liquid ammonia is added to get the YAN up to 300mg/L.

Proper wood integration with the developing Chardonnay is monitored with great vigilance. The wine is kept on the gross lees in the barrel for 12 months, with lees stirring initiated after fermentation is complete. Batonnage is only done for the first 3 to 6 months (depending on how Jan feels the wine is developing) of barrel ageing. Jan is adamant that the wine should rest peacefully after the vigour of harvest and therefore batonnage happens only once or twice a month. All barrels are tasted according to Jan’s schedule and should a reductive barrel be detected (I did mention that Jan is very meticulous), heavy lees stirring is done on the barrel and if possible, the old lees is substituted with fresh lees. An even spread of first, second and third French barrels are used.

After the oxidative stability of the wine has been ensured (typically after 12 months in barrel), it is ready for bottling. Jan describes this process by using an exquisite metaphor; he simply sees the wine leaving the barrel as a rebirth and then the wine waiting in the tank before bottling as a gentle awakening.

Bernard Mocke is a technical consultant for Anchor Wine Yeast.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Adding water to wine: time to take a sober look part 2

Bernard Mocke — Fri, 25 Mar 2011 08:30:08 +0000

Part one of this blog gave us some background on high Brix grapes, musts and the resulting high alcohol wine. The easiest (but not always legal) way to counter the effects of a potential high alcohol ferment is to add water to the must. This is usually done prior to fermentation. In warmer viticultural countries, winemakers often employ this technique to dilute musts from grape varieties that are harvested at 27 to 30ºB or higher! The arguments against this moist method are quite watered down by now, but the critics have a valid point. For instance, when you add sugar to wine (chaptalization, as it is called in France), you mainly alter the production of alcohol in the finished wine. However, the addition of water dilutes and impacts an innumerable amount of aroma, tannic and other chemical constituents. So there are obviously two sides to this rather soggy debate.

In California, the addition of water may only be done to prevent a stuck fermentation. Section 17010(a) of the California Administrative Code states: “…and no water in excess of the minimum amount necessary to facilitate normal fermentation may be used in the production or cellar treatment of any grape wine…”. In the less liberal South Africa, the addition of water to must is still in breach of EU wine law and in all probability will still be illegal for quite some time. Some producers (notably in California) take watering back a further step. After bleeding off some of the juice (saignée), water is added to the tank. The initial step drastically alters the juice to skin ratio and decreases the amount of sugar in the must. The watering back further dilutes the sugar concentration. I have heard (and don’t have the hard facts) that another method to eventually reduce alcohol is applied in Australia. It is legal to add water that has been removed from juice via reverse osmosis to other juice or wine seeing that it originates from grapes and not the “black snake.”

Winemakers all over the world are probably most comfortable with reverse osmosis to remove access alcohol in finished wine. Portable units are available that can be used to treat your high alcohol wine and thus effect a significant decrease in alcohol concentration. Another technique is the spinning cone technique, which fractionates wine. After alcohol is removed, the desired volatile components are simply added back to the wine. The downside to these techniques is that important aroma compounds and mouthfeel can be lost. As a winemaker once elegantly put it after treating a high alcohol wine with reverse osmosis: “The alcohol level is acceptable, but now we’re stuck with a bland, soulless wine.”

The winemaker will ultimately decide how the alcohol issue should be remedied. To those that believe that no superior winemaker has ever added water to wine, I guess the American Army policy of “Don’t ask, don’t tell” (Google it if you don’t know what I’m talking about) will be interesting and enlightening reading.

Bernard Mocke is a technical consultant for Anchor Wine Yeast.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Adding water to wine part 1: Time to take a sober look

Bernard Mocke — Fri, 04 Mar 2011 09:14:38 +0000

One of my favourite stories from the Bible is the one where Jesus turned water into wine during the marriage at Cana. Despite this incredible event, asking most winemakers today whether they dose their ferments with water is like asking somebody about his brother in jail… you just don’t talk about it.

The International Organisation of Vine and Wine (OIV, if you parlez français) prohibits the addition of water in all of its 44 member states, which includes countries such as South Africa, Australia, Chile, Brazil, Uruguay, New Zealand, Austria, Croatia, Czech Republic, France, Germany, Hungary, Italy, Israel, Slovenia, Spain and Turkey. But why is the addition of water such a touchy topic? To answer this, we’ll have to hop into the vineyards and consider the interaction between the sun and the water content of ripening grapes.

Research done in Australia on Shiraz (Australia’s most planted grape variety) showed that ripening grape bunches can lose up to 20% of their weight (all of it water) at the end stage of ripening. The effect of the sun is obvious. This exodus of water basically concentrates sugar, which is further increased by the ripening effect of the sun. Wine producers in the southern hemisphere (i.e. Australia and South Africa) and even northern hemisphere (California) are often faced with the imbalance between grape sugars and tannins (and all the other critical flavour compounds). The problem is thus: sugars develop and build up during the harvest. Often, the heady tannins and usual aroma suspects arrive when the party is almost over, or in other words, when the grapes are already overripe. French winemakers critical of watering back wine (this should more or less include all of them) often state that sugars in their grapes develop more slowly and is thus in concert with phenolic ripeness. For an interesting debate, just mention the word ‘chaptalization’ the next time you encounter one of these winemakers.

Winemakers fiddling with overripe grapes can encounter various problems. Simply put, high sugar musts can lead to stuck ferments, even when inoculated with commercial yeasts. If the commercial yeast does however have a sweet tooth and is impervious to high alcohol levels, a high alcohol wine can result, where an alcohol level of 15% or higher is common. The Lower Alcohol Lobby frowns upon high alcohol wines (for various health, safety and other socio-political reasons) and is a powerful driving force behind many health initiatives and various research projects at leading universities. Another factor is tax that is levied on alcohol in some countries.

What is a winemaker to do, apart from having grapes picked earlier and fermenting with yeasts that have a lower alcohol conversion factor? (The latter doesn’t really exist.) There are a few techniques available, of which adding water to wine is paramount in this blog. But you will have to wait for part two of this blog to read all about these controversial techniques.

Bernard Mocke is a technical consultant for Anchor Wine Yeast.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

Wine, the social lubricant

Bernard Mocke — Thu, 03 Feb 2011 23:00:51 +0000

Homer Simpson once said: “Beer: The cause of, and solution to, all of life’s problems.” This perfectly illustrates the dual role of alcohol in society. It is known that alcohol is a social lubricant and people all over have been applying this effect for thousands of years. Humans invariably find themselves in embarrassing yet amusing social situations and I’ve found that my trusty companion, my glass of wine, is often the culprit. My best stories always involve wine in some way, so allow me to share a few.

For instance, have you ever been to a dinner or other event where you bring an expensive bottle of wine, only to be offered some dreadful plonk? This happened to me recently. As I presented the host with my exquisite Semillon/Sauvignon blanc blend, he promptly put it down (literally and figuratively) and opened a bottle of sweet wine that had a poorly designed picture of an intoxicated mule on the label. Shortly afterwards, somebody pointed out that I was making frequent trips to the kitchen. The host was obviously most unimpressed when he learned that I was tossing his plonk and replacing it with my marvellous mixture.

Quite some time ago at a dinner, nail-polish remover masquerading as a Bordeaux blend was served. The winemaker responsible for this concoction was present and eventually sought my opinion on his wine. I quickly ran through my options for escape and realised that if I pretended to like the wine, I would be doomed to spend the rest of the evening trying to remove nail-polish remover from my palate. My sarcastic wit got the better of me and I replied that my girlfriend had run out of nail-polish remover and his wine would be a good substitute. I was unpopular for a couple of hours, but at least I got to recover and nurture my pallet with a tastier red option.

The coup de grace of all my faux pas happened years ago when I was a waiter at a highly esteemed restaurant. After clearing wine glasses from a table surrounded by raucous Brits and making my way to the kitchen, I noticed something bobbing around in a glass of red wine. After brief inspection, I was horrified to discover a set of dentures submerged in the wine. Instantly thereafter a loud commotion ensued at said table, led by a high pitched shrilling voice. With laughter echoing from the kitchen and with a red face, I approached the dreaded table and noticed with relief that most of the Brits were laughing. The now standing owner of the dentures and source of the earlier shrill babbling, an octogenarian, poked me in the chest with a bony finger and cackled: “Oi, there is only on thing dearer to me than my teeth and that is me wine!” I was naturally dumbfounded and my rescue came when one of the Brits glibly quipped: “And by the looks of it, she really got her teeth into it…” .

Bernard Mocke is a technical consultant for Anchor Wine Yeast.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke

In search of minerality, the ghost in the glass

Bernard Mocke — Thu, 16 Dec 2010 23:00:37 +0000

Elusive, indefinable, subtle, intangible, vague, mysterious, obscure, esoteric… these are all words that describe the inability to define or explain the concept of minerality in wine.

Webster’s dictionary defines the word ‘mineral’ as follows: “An inorganic species or substance occurring in nature, having a definite chemical composition and usually a distinct crystalline form.” But how does this translate to what is swirling around in your glass of wine? Instead of trying to explain how a chunk of soil ends up in your wine, I will try to focus on how it impacts the very essence of your wine experience.

The first time that I conclusively decided that minerality exists in wine, was in 2007, when I tasted a lovely barrel fermented Chardonnay from the Hemel and Aarde Valley in Hermanus, one of the most beautiful coastal towns in South Africa. As I was sipping this heavenly elixir, the winemaker was rambling on about terroir, soil types, racy acidity and minerality. He scooped up a handful of dirt and had me smell and even taste some of the smaller pebbles. It was right there and then that my mind and palate made the connection between what I was tasting and what the mineral debate was about. So-called wine pundits often use the term ‘minerality’ to describe a wine they’re unsure of, but in practical terms descriptors such as limestone, chalky, metal, flint, graphite, pencil lead and quartz are used.

I’ve experienced this phenomenon in South African and foreign wines e.g. Sauvignon blanc, Chardonnay, Riesling, Semillon, Pinot noir and even Cabernet Franc. I should add that red wines (as opposed to white wines) often lack distinct minerality as it is often masked by the more abundant phenolic and tannic compounds. Nowadays, my palate is more sophisticated and whether I drink a sublime Sauvignon blanc or a charming Chardonnay, I always first seek minerality, which makes my eyes haze over and conjures forth romantic images of rolling hills and soil teeming with potential. Next, I seek out those transient pockets of flintiness that dance on the edges of my tongue and which ever so often go hand in hand with racy, firm acidity. Why not try this: lick the poles of a small battery. This electrifying experience should leave you with a coppery or metallic taste in your mouth. If you can imagine greatly diminishing this effect, then you’re getting closer to ‘sol exprimé comme le liquide’ (soil expressed as liquid).

I think too much focus is being put on explaining single sources of minerality, as humans invariably tend to do. Synergy defines a situation where the sum is greater than the parts. Simply put, terroir, viticultural technique and winemaking style will all add together to yield a single product. A product, unimaginable in its chemical complexity, yet unfathomably single in its ability to please and unify humans all over the world.

Bernard Mocke is a technical consultant for Anchor Wine Yeast.

This NewWorldWinemakerBlog.com post was written by Bernard Mocke