Where all the fun happens…

This week we take a look at what happens inside the winery laboratory!

OK, “fun” might be a bit of a stretch, but for a science geek like me, it is!

Over the course of the last few months, as I have led you through some of the key steps of making wine, I have alluded to this placed called the “laboratory”. If you’re imagining a corner of the winery where geeky, glasses-and-white-lab-coat-wearing people spend their days playing with beakers and test tubes, well….. actually, you’d be pretty much spot on. However, if science (or learning about it) is your thing, it is one of the most exciting and fascinating places in the winery.

It is also one of the most important. The winemaker relies on data from “the lab” (that’s what all the cool kids call it!) to make key decisions during the winemaking process. What many people don’t understand is that winemaking is highly scientific. That’s where Rob, and his background as a (maths and) science teacher, comes in very handy and probably why he is so good at it. He understands the importance of getting things right.

So what happens in this place of wonder and awe?

There are a number of tests that the laboratory can perform during the lifespan of a wine… from pre-harvest of the grapes to bottling of the finished wine.

Let’s take a closer look at a few of the key tests…

Measurement of residual sugar

By now, you should be getting pretty familiar with this. Previously we’ve talked about measuring Baumé in grape juice to determine when the grapes are ready to pick. We’ve also looked at how the same measurement is used to determine whether the ferment is progressing and when it has finished. Considering this measurement is taken a few times before harvesting the grapes and then usually twice a day during fermentation, it’s easy to see that this is one of the most basic but important tools a winemaker has.

Without going into too much detail there are a number of instruments which can be used to take this measurement. If you are lucky enough to work in a laboratory which has a digital refractometer, then life is easy. Smaller wineries though rely on a piece of equipment called a hydrometer.

A hydrometer is usually made of glass, and consists of a cylindrical stem and a bulb weighted with mercury or lead to make it float upright. The juice or wine is poured into a graduated cylinder, and the hydrometer is gently lowered into the liquid until it floats freely. Hydrometers have a scale inside the stem, so that the person using it can read the Baume measurement.

Measurement of pH

If you can think back to your high school science days, you may remember a term called pH. It’s a tricky concept to grasp, but basically, it is a measure of acid in a liquid. Acids exist in different forms, and one of these forms is free hydrogen ions. pH measures the concentration of hydrogen ions, which are important in that they influence chemical reactions in the juice or wine. Concentrations of these ions in solutions are very low, so chemists invented a scale for expressing acid condition in all sorts of liquids (not just wine). This scale ranges from 0 – 14. Pure water is neutral at pH 7, lemon juice sits around pH 2 and grape juice and wine usually sits in the range of pH 3 – 4.

The thing to remember about pH in wine is that the higher the pH, the greater chance of oxidation. During the winemaking process, some of these free ions are used up through chemical reaction so the pH increases. Acid additions are often made with the aim of achieving an acid level which is in balance with the sugar, alcohol and fruit in any particular wine.

It’s a very delicate process, one which needs constant monitoring to ensure the levels are optimum. In the laboratory, pH is measured using a pH meter.



Testing sulphur dioxide levels

As we discussed a couple of weeks ago, the production and addition of sulphur dioxide is an important element in the process of making wine. It is also important to make sure the level of sulphur in the wine is just enough to help prevent oxidation, and at the same time keeping the level as low as possible.

This is a pretty involved test. I have included the below video for those of you who are interested. But be warned… it is of the educational, not entertaining variety. I won’t be offended if you don’t press play!

I could go on…

… and on, but I won’t (for now)! I’ll stop before I lose you all, but I may come back to the lab every now and then to chat about other important tests (unless I get a resounding “no! please don’t!” from you all in the comments section).

If you are particularly interested in this side of wine-making, please let me know via the comments. I’m happy to answer any questions you may have.

Wooden you like to know more about barrels?

Herbs growing in a wine barrelI know. I’m so sorry… I promise that will be the last pun!

So, other than making a great place to grow your herbs when they’re cut in half, what are barrels for? And why are they important in the winemaking process?

Why oak?

Most red wines and some white wines are stored in wooden barrels made from oak. Why oak in particular? Well, there are a few reasons why it has become the wood of choice:

  • the cellular structure and density of it prevents leakage
  • it bends easily without cracking
  • the physical dimensions of an oak barrel do not change considerably at different levels of humidity
  • oak contains tannins that protect it against insects
  • oak contains flavour compounds, which are complimentary to wines.

Although more than 600 species of oak can be found globally, only a handful are suitable for making wine barrels. The location of the trees is also important and they are usually sourced from areas in which they grow the tallest and straightest.

How are barrels made?

The making of a wine barrel is a tricky process, so I’ll leave it to a real-life cooper tell you how it’s done…


What type of oak has Rob been using recently?

When it comes to Somerled wines, Rob prefers a specific brand of French oak barrels called Chassin – sourced from a small family-owned cooperage in Burgundy. They are his particular favourite for the Chardonnay and Pinot Noir. He really likes the soft, fairly gentle spiciness of the new barrels. It doesn’t tend to dominate the flavour of the wine. That is, as long as he uses them in conjunction with older, more mature barrels.

What do we mean by that? Well, obviously a barrel can be used more than once. And the older it gets the less intense the oak flavours. So, for Rob, it’s important not to have the oak overpower the delicate fruit flavours of his wine. Therefore, he always stores his wine in a mixture of old and new barrels. Once the wine is fully matured and ready for bottling, some of the barrels will have a more intense oak flavour than others. When it’s all mixed together before bottling, this will even out to exactly the balance Rob is looking for.

How long can a barrel be used for before it needs to be turned into a pot for my herbs?

Barrels do have a certain life expectancy when it comes to their use in changing the colour, flavour, tannin profile and texture of wine. However, barrels are also useful simply as maturation vessels, due to the slow update of oxygen through the oak into the wine. The oldest barrels Rob uses were produced in 2009… at this stage, those barrels are no longer adding to the flavour profile of the wine.

Do barrels come in different sizes?

They sure do! The most commons sizes used today are a 300 litre barrel (also known as a Hogshead) and a 225 litre barrel (also known as a Barrique). Rob prefers to use hogsheads as it is generally easier to control the amount of oak and the rate of development. The smaller the barrel, the larger the number of barrels needed to store the wine and the greater the surface area to wine ratio… therefore the oakier (technical term!) the wine.

Back in the 70’s, Rob remembers using more of the 500 litre barrels (or puncheons) than anything else. The maturation was much slower in this size, but they were also very difficult to handle. These days, special racks designed to carried by forklift are specifically designed to hold hogsheads and barriques.


(Reference: Stern, Eric.2012. The Complexities of Barrels. Wine Business Monthly.
May 2012: 28-39.)

Any news from the winery?

Things have slowed down considerably in the winery as the wines do their thing.

Somerled Sauvignon BlancThe Sauvignon Blanc is going through the fining process as we speak. It’s still pretty cloudy and gritty (as you can see in the photo), but the bentonite Rob is using with help to settle out the solids and prepare the wine for filtering and bottling.

Everything else is ticking along as it should!

The vintage 2018 story continues…

So, last week I suggested that Rob’s most hectic day of vintage was behind him. I’m not going to say that I jinxed him, but perhaps that prediction was a little premature!

Sauvignon Blanc in the vineyard at Summertown in the Adelaide Hills
A beautiful Adelaide Hills morning in the Sauvignon Blanc just before picking

Another big day for Rob…

Our sauvignon blanc grapes were hand-picked last Friday and Rob was very happy with the fruit. Although it was a very warm day, after a few hours in the cold room, they had cooled down and were loaded into the press at about 5.45am Saturday morning – of course, Rob was at the winery to oversee this. Who needs sleep?!

Why do the grapes need to be cool before they go into the press? The fermentation needs to be slow. So, if the grapes start out warm then the ferment goes too quickly, and it won’t develop the flavours Rob is looking for.

Sauvignon Blanc juice from the press The press


Freshly pressed sauvignon blanc juiceThe Baumé was lowish (11.2) and that is exactly how Rob wants it. The juice is perfect with lovely aromas and flavours, and such an attractive green tint. All up 3000 litres of juice came out of the grapes. This will be used for both the 2018 Somerled Sauvignon Blanc and the Fumé Blanc (in quantities yet to be determined by the winemaker!).

Since then the juice has been chilling while all of the solids from the grapes are settling to the bottom. This leaves 90% of the juice nice and clear. It will then be “racked” off the lees, yeast will be added, and it will be wine in a couple of weeks. Easy right??!!

The last of the Adelaide Hills fruit makes it to the winery…

Chardonnay grapes

This week sees the last of our fruit from the Adelaide Hills being harvested.  This is happening as I type at Kim Anderson’s vineyard in Charleston. It started this morning (Friday) at around 2:00am.  Chardonnay is first (see picture), followed by Pinot Noir for dry red.

The chardonnay was at 12.2 Baumé a couple of days ago. It should be ideal by the time it gets to the winery (Rob likes it to be around 12.5). The pinot was tested at 13.8 Baumé. This is as high as Rob would like to see it go… the colour and flavour look terrific.

Both these varieties are machine harvested. While machines are definitely faster, they aren’t as gentle as human hands, so some of the berries may be inadvertently crushed during the picking process. This is something you want to avoid with sparkling and sauvignon blanc. However, with Rob’s chardonnay and pinot, a bit of skin contact with the juice is no disadvantage. It was a nice chilly night here in the Hills last night, so perfect conditions for picking.

Also, because it has been machine harvested, the Chardonnay will need to be destemmed and pumped straight into the press.

The Pinot Noir will be put through the crusher/destemmer and pumped to a little open fermenter, where yeast will be added. It will ferment away in contact with the skins for around a week. Don’t forget that all the colour is in the skins, so this gives maximum opportunity to extract all the colour and also tannins into the fermenting juice.

Pressing versus crushing – what’s the difference? When making white wine, the fruit is usually pressed before primary fermentation. This is a gentle process which minimises the amount of skin contact with the juice. For red wines though, the grapes are first crushed to maximise the amount of skin contact (for colour and flavour) and pressed after fermentation to squeeze out the remainder of the juice and remove the skins and seeds, etc. Of course, there are many ways to make red and white wines, so you will see variations on these processes depending on the style.

All of Rob’s hard work has, quite frankly, worn me out… so, I’m off for a week of R&R with the family. But never fear! Your guest blogger, Lucy will be taking the reigns next week. Go easy on her!

Gelati Party!

In the meantime, if you’re looking for something to do on Sunday 25th March you should plan a trip to Hahndorf and our Gelati Party! It’s “Crush Take 2” (with, fingers crossed, much cooler weather this time) where Somerled, Scott & La Prova Wines and Hersey Vineyard will be joining forces on the lawn (behind the Scott cellar door at 102 Main Street, Hahndorf) for a celebration of cool jazz music, delicious dude food, amazing wine and, of course, Gelati!

I mean, why wouldn’t you be there?