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New World Wine Maker Blog

Gone with the Wine: The Great Wine Love Affair

Wine is the ex-boyfriend I will never get over. My first love if I may be so bold. I met him when I was barely 18. I was old enough to want to get to know him and to prove to myself that I had progressed from the cocktails and ciders of my underage drinking youth. But, I was young enough to ignore all his flaws and too stubborn to admit it.

He was sweet. Sickly sweet. He made me giddy and reckless, and to be honest he always left me with a headache. Blushed and looking at him with rose-tinted glasses I was blissfully happy. We only met out in clubs and bars where the atmosphere was frivolous and care-free. It was a tumultuous relationship. Each time I woke up with a pounding headache and skin littered with blemishes from the sugar, and I swore it would be the last. But how could I write off the fun times I had had? For every morning plagued with hangovers, was a night filled with happy stories and memories that made my heart swell.

But alas, it was a love that could not survive the test of time. After one too many headaches, disapproval from my family and the promise of something new I broke off all ties.

As with any break up the time that followed was filled with ups and downs. The “ups” consisted of the excitement of new wines – why not try a fruity Sauvignon blanc, a flirty Chardonnay or… maybe even the bold and robust Cabernet Sauvignon rumoured to steal everyone’s heart. But with any great love story there was the inevitable “down”, the retreat. A late night out in town and I found myself with a glass of a sickly impersonation of the wine I once loved.

Except, it doesn’t taste quite as good anymore. Sure the memories are there and I can appreciate it for what it once meant to me. But we have both moved on. The sugary affront does not agree with me and I insult him disguising his flaws with ice and mixers. He remains the fun easy-going wine to be drunk by those not looking for commitment. They have come to experience wine without the work that is required to go into a mature relationship. I, however, have moved onto wines which I can introduce to my parents, I can eat meals with them and can take them to celebrations with friends.

With this knowledge I was inspired to try even newer and bolder wines. With my friends encouraging me and my peers guiding me I stumbled across my first grassy Sauvignon blanc. A summer love affair. A transitional wine as I refer to it now. It helped me move past my alliance to the sweet rosés. But winter came too quickly and I had to progress to richer red wines. Full of body, young fruits and the hint of mocha chocolate, they kept me warm at night. Once again I was drunk and rosy cheeked with infatuation. But something was still off. These wines lacked the depth and balance I was looking for.

So again I had to grow. I stumbled from these entry-level wines and learnt to look deeper. I stopped taking a wine for its label and fancy descriptions. I got to know them for who they were and what they had been through. I discovered the bolder wines, wines which have aged and matured. They are not dominated by fruity flirtations or cool, but somewhat overwrought, oak-y personalities. These wines have been developed and hid more beneath the surface. The subtleties are often missed and they are appreciated by few.

By now my heart no longer belongs to just one. I have pledged allegiance to Bordeaux blends, but I could never say farewell to my flamboyant champagne, nor could I turn away a sneaky Sauvignon or even some dominating Cabernet. I am committed to Chenin but I could never stray from Syrah. And my heart longs for Riesling but I can be persuaded with a Pinotage.

I am older and wiser. I have learnt what I do not like and what I do, the body, the character, the aftertaste. I have developed along with the wines, together we grow and mature. But in every new, complex wine I endeavour there will always be the faint memory of where I started. And sure enough, the next day the headache will return. Just as it always did when I was young and 18 and drunk off my first wine.

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Deacidification with Malolactic Fermentation

Malolactic fermentation (MLF) is a common processing technique used to biologically convert the malic acid to lactic acid and carbon dioxide (Krieger 2005). The conversion of malic to lactic acid is considered a deacidification technique. MLF is conducted through proliferation of native lactic acid bacteria (LAB), of which the three existing genera in wine are Lactobacillus, Oenococcus, and Pediococcus (Krieger 2005, Iland et al. 2007), or by inoculation of commercial LAB strains. The process of MLF has several chemical and sensory alterations to the wine (Waterhouse et al. 2016):

  • Decrease in titratable acidity (TA).
  • Increase in pH.
  • Decrease in sourness of the wine.
  • Potential development of the “buttery” aroma or flavor due to increased diacetyl production.

Commercial strains, Oenococcus oeni, are often preferred as this strain of LAB best conducts MLF (Waterhouse et al. 2016). O. oeni is relatively predictable in its ability to convert malic to lactic acid, and several commercial strains have various capabilities of producing the byproduct, diacetyl. Diacetyl gives rise to a buttery flavor or aroma that is desired in some styles of wine, such as oak aged Chardonnay.

When to Inoculate for MLF

LAB inoculation can be integrated into wine processing at several stages of production:

  • Before primary fermentation,
  • During primary fermentation,
  • Near the end of primary fermentation,
  • After primary fermentation is complete (Iland et al. 2007).

Each stage in which LAB can be added to the wine will offer a number of advantages and disadvantages to the winemaker. Ultimately, when LAB inoculation occurs can affect wine quality.

When winemakers add LAB to the wine, if desired, is a stylistic choice by the winemaker. There are some styles of wine that may not require MLF (e.g., unoaked Chardonnay), integrate partial MLF (e.g., sparkling wines), and others that encourage a full conversion of malic acid through MLF (e.g., many red wine blends). In cooler grape growing regions, the utilization of MLF is a natural deacidification process that can help decrease the perception of acidity, or sourness, in the wine. Malic acid, the primary acid affiliated with apples, has a much harsher taste than lactic acid, the primary acid in milk. In general, most American consumers tend to enjoy wines with moderate acidity (Krieger 2005), and MLF may be a practical tool to manipulate the wine’s acidity and stability.


Malolactic Fermentation (MLF) is a biological conversion of malic acid (the organic acid associated with the taste of apples) to lactic acid (the primary acid associated with milk). This conversion softens wine sourness perception and manipulates the acidity content. Photo by: Denise M. Gardner


Native or Spontaneous MLF

Additionally, some winemakers opt to utilize the native LAB to undergo MLF, though this can be unpredictable and tricky. Some wine processing techniques, such as juice clarification, can aid in the removal of native LAB and inhibit an adequate biomass of cells from forming to undergo MLF (Krieger 2005). Furthermore, some strains of native LAB can give rise to off-flavors or spoilage characteristics that may degrade wine quality.

Factors that Inhibit LAB

Nonetheless, even when using commercial strains of LAB, MLF can offer several challenges to winemakers. MLF is not always easy to complete efficiently. Several factors can contribute to a sluggish or stuck MLF including:

  • Inhibition by sulfur dioxide, alcohol, temperature or oxygen.
  • Inadequate nutrition.
  • Competition from other microorganisms (e.g., acetic acid bacteria, native LAB).
  • Presence of copper ions or residual pesticides (Iland et al. 2007).

A stuck MLF can be a difficult winemaking situation. Wines are usually left unprotected with very little sulfur dioxide in the wine. Additionally, wines are usually maintained within the ideal LAB growing temperature, around 68°F. However, this warmer temperature is also ideal for a number of potential spoilage microorganisms to grow. Warm temperatures and a lack of adequate antimicrobial protection offer ideal conditions for growth of spoilage microorganisms.

How to Monitor MLF

Many wineries find it affordable and convenient to monitor MLF progression through paper chromatography. Both Enartis USA and Midwest Supplies offer decent protocols for paper chromatography that are available online and free.

However, to ensure that your MLF is completed, it is best to use enzymatic analysis to determine the concentration of malic acid and lactic acid in your wine. While this analysis can be completed in a winery’s lab with access to a spectrophotometer, proper pipettes, and an enzymatic kit, wines can also be submitted to a commercial wine lab for completion confirmation.


Only a small sample is required to monitor MLF by paper chromatography. Photo by: Denise M. Gardner



Iland, P., P. Grbin, M. Grinbergs, L. Schmidtke, and A. Soden. 2007. Microbiological Analysis of Grapes and Wine: Techniques and Concepts. Patrick Iland Wine Promotions Pty. Ltd. Australia. ISBN: 978-0-9581605-3-7

Krieger, S. 2005. The history of malolactic bacteria in wine. In Malolactic Fermentation in Wine: Understanding the Science and the Practice. Lallemand, Inc. Montreal, Canada. ISBN: 0-9739147-0-X

Waterhouse, A.L., G.L. Sacks, and D.W. Jeffery. 2016. Understanding Wine Chemistry. John Wiley and Sons, Ltd. United Kingdom. ISBN: 978-1-118-62780-8

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Meet Corlea Fourie – Winemaker at Bosman Vineyards

Q. When and where were you born ? 

“1980 in Johannesburg”.  “However my Dad moved the family to Bloemfontein and I grew up and went to school there.”

Where did you study ?

“I did a Bsc Agric Oenology at Stellenbosch University and I was in the class 2003.”

Q. Do you consider your approach to winemaking to be different to others ? 

“I know I have many wine friends that feel the same way about certain things we do but then our approach is personal.”

Q. How involved do you get in the vineyard ? 

“As I work for one of the most prominent vine nurseries in the Southern Hemisphere I am surrounded by an amazing viticultural team.  I’m responsible for vineyard to wine goal outcomes so I do try to get to the vineyards as much as possible. That said, it’s still something I have to work at. There is always something pulling me away!”

Q. Do you have any varieties you prefer to work with ?

“Chenin blanc is my very dear favourite!  Some people consider me to be a chenin junkie!””

Q. Have you been influenced by any particular winemaker or by a wine region?  

“After visiting the Loire I have picked up a touch of sentiment for the valley.  Many winemakers have influenced my thoughts on wine, here and abroad.  Wine is, to some extent, a social experiment with so many tastes and thoughts.  It is dynamic. ”

Q. What would you consider your greatest achievement as a winemaker ?

“Achievements are dynamic too. You are measured by your consumer’s pleasure by the wine in the glass. Every season brings new challenges and opportunities.”

Q. What “secrets” have you “developed” that make your wines different to others ?

“No secrets. I have a young team who work with me and madness in their methods are freely shared. I do try, and do have a soft touch though.”

Q. How important is modern winemaking equipment in your winemaking ?

The answer is straight and to the point. “It is.” And continues “We do not need to work harder but smarter. Modern equipment usually helps with this.”

Q. How did you come to be at Bosman Vineyards ?

“I had been doing some consulting work in the area and came across Petrus and we were both making small batches of experimental wines on a neighbouring farm.  He was busy in renovating a 250 year old cellar on his family farm and Petrus invited me to join him. It was like a dream come true although we struggled to figure out how to use all the equipment! Hard to believe that is ten vintages ago!  In that time we have made some great wines.”

Q. In general ? 

“Although growing up mainly in the Free State with no vineyards in sight I spent family holidays in the Cape Winelands where my elder sister lived. After finishing school and doing a “Gap Year” mainly in the hospitality industry, I started my studies. I was prompted by my love for biology and science which led me into wine. I did a harvest as a practical and this introduced me to my future husband who was the winemaker at the farm of my choice!   We are now raising a family with a twelve year old daughter and a pigeon pair of twins aged seven.   I look forward to achieving my personal goals as a winemaker whilst working in a dynamic industry.  Lots of good stuff to look forward to. “

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The Grape Fun of Harvest

March 2017, my very first harvest. As a student, you never quite know what to expect beyond your textbook, and so when our harvest finally started, we all eagerly queued up in the minute cellar beneath the JH Neethling building, not quite knowing what challenges awaited us. To be honest, we were thrown in the deep end, but I’ve come to learn that knowing how to swim is an important skill to have in the cellar.

With our Felcos and refractometers at the ready, we were set loose on the poor Welgevallen vineyards. I don’t think anyone was quite as enthusiastic to wake up at 5am (to take the routine ballings) as I was during that period. I was adamant that our group had to be in the vineyard to take readings while it was still cool in the mornings, and so by 6 we were ready to sample our rows and get a grip on our harvest. I don’t think the other group members quite enjoyed me pointing out that there was a possibility that a few of the grapes we’d been tasting more than likely contained a bit of an extra protein factor (worms, bugs etc).

You’d think that the enthusiasm would have worn off after week 1, but I ended up spending my weekend work shifts begging my bosses, at a boutique winery, to let me help out with punch downs too. This is where things got a little bit more interesting and a whole lot messier.

The plastic fermenters were just a little bit too tall for me to use the pigeage (punchdown) stick, initially I decided to only use my hands to do the punch downs (with help from the tasting room manager and one of the winemakers). I quickly came to the realisation that the customers (I am a wine steward) might not take to my now purple stained fingers, hands, arms, elbows…you get the idea. I then had the very bright idea to climb on top of the tanks, that had a rim thickness of only 5 cm. But wait, the cellar antics and health and safety infringements don’t stop there, I was wearing open sandals with no grip – yikes!

After boosting myself on top of the tank, my boss handed me the punchdown stick and I proceeded to break through the bubbling shiraz pomace at a steady pace. Not long after, I realised that there was a cooling plate in the tank, and so I thought, “Hmm, no problem, I’ll just press down lightly until I just touch the plate”. Just as I leaned in, my boss decided to move the cooling plate, and all I could see was certain death flashing before my eyes. In all honesty, there are worse ways to go than falling into a big tub of wine. After flailing in mid-air for what felt like a few seconds, I managed to grab hold of a thin hook that just happened to be perfectly positioned on the wall behind me. With only two fingers, I managed to pull myself up.

I would have been slightly more shaken if the tanks were slightly taller and fuller – in reality I could probably have just stood up, had I fallen in. What did I say earlier about learning how to swim?

So, after an interesting weekend in the cellar, I made my way back to Stellenbosch (to be in the department’s cellar). After telling one of the experimental winemakers, Edmund, about my weekend’s antics, he made 100% certain that I was always wearing my cellar boots, whether I had decided to rock it out in my gumboots and a sundress or hippy pants, he would spot me from the moment I set foot into the cellar. On one occasion, I was not wearing my boots and my dreaded sandals made a reappearance. I thought I could get away with only doing lab analyses that day, but alas! – I was caught red-handed and promptly reminded of the importance of wearing closed shoes in the cellar. The other winemaker, Marisa, threatened to throw things at the students’ toes if she caught our feet armed with anything other than closed, non-slip cellar boots.

Although my sandals didn’t make a reappearance, my hippy pants definitely did. I now call them my grape pants, because they’re grape to wear… pun intended. Pressing red grapes (merlot) while wearing lightly coloured pants, leaning over the little press and getting elbow deep into grape skins, while you’re supposed to be monitoring and adjusting the press’ pressure is not the smartest thing to do. The pressure on the grapes was just a little bit too high, causing berries to rapidly pop (explode) rather than lightly being crushed and squeezed. The other group members and I ended up looking like we had just facilitated a berry genocide, with gory bits and pieces of grapes and deep red juice splattered all over ourselves! Needless to say, the grape hippy pants were covered!

After two cellar mishaps in one week, one of my lecturers suggested that I leave these stories out of my harvest internship interviews. Although I ignored this advice (made for an interesting interview), I am now a reformed cellar-mishap-maker and have decided to take health and safety hazards a little more seriously, but I can’t promise that the hippy pants won’t make a grand come-back!

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Understanding and measuring tannins in red wines

by Jose Luis Aleixandre-Tudo, Mihaela Minhea & Wessel du Toit 

The importance of phenolic compounds on wine quality require methods that accurately measure the tannin content.

Tannins are phenolic compounds that play an important role in the astringency perception of red wines. Tannins also are very complex molecules with different sizes and conformations. The decrease in the astringency intensity during ageing is due to different phenomena, including cleavage reactions (appearance of smaller less astringent molecules), precipitation from solution, due to insolubility situations, conformational arrangements (shape of the tannins molecule) and interactions with other components (such as anthocyanins). Precipitation based methods (BSA and MCP tannins assays) are highly suitable for routine tannin analysis. Both methods positively correlate with each other and also with the astringency intensities measured by a sensory panel.


Tannins are phenolic compounds that are involved in red wine mouthfeel attributes. They are also thought to play a very important role in the astringency perception. When drinking red wine, the tannin compounds interact with the salivary proteins, creating a macromolecular complex that precipitates from solution and causes a drying and puckering mouthfeel sensation, also known as astringency.1 The intensity of this feeling depends on many factors. The size and conformation of the molecules, the combination with other wine components and the levels found in wine define the astringency intensity.

It is also known that the wine astringency decreases over the ageing process.2,3 This behaviour that was initially attributed to a decrease in the total tannin content present in the wine, is nowadays ascribed to different phenomena. Starting with the assumptions that tannins polymerise during ageing and that the ability of the tannins to elicit astringency increases with tannin size (i.e. the bigger the molecule, and the higher the number of sites available to interact with the salivary proteins, the higher the ability to combine and precipitate proteins)2 other phenomena that explains the decrease in the astringency intensity needs also to be playing role. First of all, cleavage reactions, which means large tannin molecules break down giving rise to smaller, less astringent tannins, have been proposed by some researchers.4 Moreover, molecular conformational arrangements have also been identified as a possible reason.5 Bigger and larger tannin molecules can also be too bulky (which means that due to the molecular conformation, the active binding sites are not available to interact with the salivary proteins). In this specific scenario larger tannin won’t give rise to an increased astringency perception. It is also well accepted that anthocyanins play an indirect role in wine astringency. The anthocyanin-tannin molecules cause a reduction on the ability of the newly formed polymeric pigment to interact with salivary protein thus reducing astringency (phenomenon that could also be related to the abovementioned conformation rearrangement scenario).6 The later phenomena together with the precipitation of tannins from solution, due to insolubility conditions, may explain why the wine astringency softens during ageing.

Tannin measurement by acid hydrolysis

The quantification of tannins has been challenging researchers over the past years as these compounds are of a very diverse nature, a fact that makes it difficult to estimate their concentrations. However, a number of methodologies are currently available for the measurement of the wine tannin levels. A method that has been commonly used for a long time exploits the ability of the tannin molecules to break down in a heated acid environment (acid hydrolysis method).7 The individual molecules show a red coloration after the heating process and can then be measured by quantifying the intensity of the red tonality using a conventional spectrophotometer. This method that is used worldwide presents a number of limitations. It does not take into account the structure of the tannin pool and it also does not consider other components (anthocyanins) that can interfere in the reaction and measurement. Due to this, the tannin concentration in wine is often overestimated and it is common to observe an increase in the wine total tannin content during ageing. Nevertheless, the method also has some advantages as the ease of implementation and reliability.

Tannin measurement by precipitation

Once understood that the astringency perception is caused by the precipitation of the salivary proteins after the interaction with the tannin molecules, the following question comes into our minds: Why not using the same principle that occurs naturally in our mouth to measure tannins? Based on this reasoning two new methods for tannin analysis were recently developed. The first one relies on the interaction of tannins with an animal protein. This method uses bovine protein and is known as the bovine serum albumin protein or BSA method.8,9 The first step of the method consists of the precipitation of the tannin compounds after interaction with the BSA protein. However, a further step is required as the protein shows similar spectral properties than the tannin compounds and cannot therefore be quantified at the maximum absorption band of the tannin molecules. The reaction of the tannin complex with ferric chloride, that gives rise to blue coloured compounds, is thus measured …


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Parings for seasonal parties

The holiday times and merry seasons are filled with good food and great wine. One wine and food paring can either make or break the party that you have been planning for the last two months. To help prevent these regrettable situations, here are a few tips to help you on your way to a delicious holiday season.

Let’s first tackle the way the food interacts with the wine:

Sweetness and Umami in food both can increase the perception of bitterness, astringency, acidity and the warming effect of alcohol in wine. It can decrease the perception of body, sweetness and fruitiness in wine.

Acidity in food can decrease the perception of body, sweetness and fruitiness in wine. It increases the perception of acidity in wine – have you ever eaten a lemon with a crisp sauvignon blanc?

Salt in food can increase the perception of body in the wine and decrease the perception of bitterness, astringency and the acidity in wine. It can also enhance fruitiness and soften the tannins of the wine.

Bitterness in food will obviously enhance the perception of bitterness in wine (no dark chocolate with fresh out of the barrel Shiraz)

If you live more on the wild side and are preparing a chilli dish it’s important to note that chilli heat in food increases the perception of bitterness, astringency, acidity and the effect of alcohol in wine and it can decrease the perception of body, richness, sweetness and fruitiness in wine.

There are some high risk foods that need to be paired with specific wine styles in order to ensure that the combination is palatable.

Dishes high in sugar should be paired with a wine that has at least as much sugar as the dish.

Umami in the food will emphasise the astringency and bitterness of the tannins and thus the wine needs to have the necessary components, such as concentrated fruit flavours to be able to cope with the change in the wine. High levels of umami in the wine can be balanced by the addition of acid or salt providing this keeps with the character of the dish.

Dishes high in bitterness will emphasise the bitterness in the wine.  White wines or low-tannin reds should be considered.

Dishes with high concentration of chilli heat should be paired with white wines or low-tannin reds, each with low levels or alcohol. A wines fruitiness and sweetness can also be reduced by chilli heat so consider wines with higher levels of fruitiness and sweetness to make the effect less severe.


If you haven’t gotten around to designing a menu for that holiday party coming up soon here are some good ideas for meals and wine pairings. Please note that the pairing is based on wine styles rather than a specific brand. It’s very important to work from light style wines and progress to the heavier reds and finish off with a desert wine.

Starter:  An impressive, easy to make and relatively pocket friendly idea is Parma ham and melon cube skewers.

Parma ham is relatively high in fat and thus an acidic white wine would be recommended, preferably a fruit driven Sauvignon blanc or Chenin blanc should be paired with this meal in order to cut through the richness of the fat and have the tropical fruit compliment the sweet melon.

Main: A classic and all around crowd pleaser is pot roast beef prepared with an assortment of roasted vegetables.

Most recipes already contain a dry red wine; a good pairing would also be a dry red wine with a lower acid that has smooth tannins and a lower astringency.  If you are partial to a Shiraz, Cabernet sauvignon or a red blend an older vintage is recommend as the tannins would have mellowed out and the wine would have an overall smoother mouth feel as well as a beautiful spiciness that will pair well with the roast. A more pocket friendly idea would be a Merlot or a Pinotage that has been grown in a warmer region providing subtle winter spices with a beautiful fruitiness and smokiness that will pair well with the roast.

Desert: A traditional trifle containing jelly, custard, Swiss roll slices, a drizzle of brandy/sherry/fruit juice, peach slices, whipped cream on top with granadilla drizzled over for aesthetic appeal.

The trifle can be served with a natural sweet, late harvest or even noble late harvest.  It is important not to oversaturate the trifle with brandy or sherry to ensure that the fruit flavours pair well with the wine, in my opinion if a pairing is conducted, tropical fruit juice should be used instead. A honey and stone fruit driven style is recommended.

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