Sunday, February 17, 2013

Cabernet Sauvignon and Its Parents (and Grandparents)

All European wine grapes are the same species ie. Vitis vinifera.
It is widely conceded that this cultivated species came from the wild race subspecies Vitis sylvestris found over southern Europe and western Asia.
The different varieties we are familiar with today are a result of centuries or probably millennia of natural cross pollination.
Many wine grapes are also the result man made crosses even to the point of crossing different wine grape species.
Up until recently is was not possible to tell what the origin of the current wine grape varieties were.
But with DNA profiling  the puzzle is slowly being unravelled.
It is estimated there are over 10,000 grape varieties with around 1500 being used for wine production. Only a small percentage have been genetically analyzed.
I have spent the day in the Cabernet Sauvignon block, green pruning, spraying, mowing and net mending.
I got to wondering where this variety, which is the classic Bordeaux red wine grape, came from and did some research.

 Surprisingly it turns out that Cabernet Sauvignon is not so old.
It was a chance crossing between Cabernet Franc and Sauvignon Blanc in a French vineyard some time during the 17th century.
Cabernet Franc is a very old variety and is said to be selected from wild vines.
Sauvignon Blanc on the other hand is a natural cross of Traminer and Chenin Blanc.
Traminer is one of the oldest European varieties and is said to be selected from wild vines.
Chenin Blanc is indigenous to the Loire Valley (Anjou), France and is reputed to have been in that area at least since the 9th century.
So there you have it.
Many countries are researching and developing hybrids. Our CSIRO already have a few in the field and in production eg. Tarrango (Touriga Nacional x Sultana) and Taminga ( a cross of a previously created crossing Merbein 29-56 and Traminer).
And the natural evolution also continues outside the realm of hybridization. Two different coloured Cabernet Sauvignon grapes are indigenous to Australia.
A chance discovery of pinky bronze fruit on a Cabernet Sauvignon vine in 1977 provided Cleggett Wines the opportunity to propagate this single cane cutting (called a sport in horticultural terms) at their Langhorne Creek (South Australia) vineyard.
This Bronze Cabernet Sauvignon grape is registered as Malian.
Several years later in 1991 through the same process of nature a White Cabernet Sauvignon grape was identified and subsequently registered as Shalistin.

Wednesday, February 13, 2013

Preparation for Vintage 2013

The main pre-vintage task is to get all the equipment clean as well as check out the integrity of some components. The acid environment of the wine making process can be harsh on tank seals, piping, gaskets and plastic airlocks
This includes the crusher, fermenter, basket press, tanks and even the picking baskets and shears.
While we cleaned up thoroughly after last vintage, a year's (and in our case 2 year's) dirt and grime can build up and everything needs to be pulled apart and done again.
It is absolutely critical to have good winery cleanliness and sanitation as dirty equipment does nothing but invite unwanted bacteria and yeasts to spoil the wine.
There are three important words used for getting equipment ready for clean winemaking.
The terms cleaning, sanitizing and sterilizing are used interchangeably.
But all three mean very different things.
Cleaning refers to the physical removal of visible dirt, grunge and old wine deposits. This is usually done with a hose with a jet spray, scrubbing brushes, scouring pads and old towels plus lots of detergent and elbow grease.
Sanitizing means doing something to equipment to reduce the microbial load to an acceptable level ie. killing spoilage microorganisms with heat or a chemical solution.
Sterilizing is another step altogether and one that goes beyond the scope of anything that can be done practically in a winery environment ie. making it completely free of bacteria or other microorganisms.
Sanitizing takes place just before equipment use.

The most common sanitizing solution used in small wineries is a strong sulphite solution.
I usually dissolve 3g potassium metabisulphite and 12g of citric acid in 4L of water. This yields about a  500 ppm solution of sulphur dioxide (SO2) which is very effective as most wine spoilage microbes are sensitive to it at this concentration.
The acid addition essentially makes the sulfur dioxide more effective ie. the SO2 consists of molecular (unionised) sulphur dioxide, the bisulphite anion and the sulphite anion with the proportions of these depending mainly on the pH.
Molecular SO2 is the most germicidal.
The more acid the solution,  the higher the proportion of molecular sulphur dioxide.
All the physically clean surfaces are rinsed well, let dry and then sprayed with the sulfur/citric acid solution. After it has been in contact for about 5 to 10 minutes the surfaces are rinsed again with clean water.
And then we are ready to go.

Saturday, February 09, 2013

The Mystery May Be Solved.

This year we lost three calves out of the six born.
We have never had such a high mortality rate.
The vet said it was the very wet season that had caused a tick plague and that young animals were very susceptible to the tick toxin.
We received our rural rates notice the other day. This comes from a state government instrumentality that deals with pasture protection and livestock health, sales and transport.
Their newsletter had very an interesting article.

There has been an outbreak of  the Ikeda variant of Theileriosis (bovine anaemia) on the south coast.
This disease is caused by Theileria orientalis a vector borne blood parasite.
Bush ticks, among other biting insects, are believed to be a common transmitter of the disease.
Calves are very susceptible succumbing from between 6 and 16 weeks of age.
Most the symptoms listed were noticed in our calves including the sudden death of apparently healthy ones.
There is no treatment.
Prevention is the cure.
Keeping the animals healthy by drenching for fluke and worms as well as feed supplements is one way.
Pour on insecticides/repellents during the tick season is another.
We will be ready next season.

Wednesday, February 06, 2013

Vintage 2013 / Harvest Gets Closer

We have been busy testing the grapes for ripeness.
Ripeness can mean a number of things. To most, sugar ripeness is the criteria. This means when the sugar level gets to a certain stage that produces a wine with suitable alcohol content then it's ready.
To others there is flavour ripeness to also consider. That is when the grape is exhibiting its typical varietal characteristics. To get both these happening at the same time is the goal.
My first ripeness runs are simple ie. walks around the rows with sample tastings from a selection of berries from random bunches. It's easy to tell when the sugar level is not quite there. There are 'green' flavour characteristics with a distinct malic acidity showing through.
During follow up walks, I look at the stalk of the bunch for colour change (brownish rather than green) and during a taste for sweetness look at the seeds for maturation (again dark rather than green), then I test the juice which I squeeze onto a hydrometer.

This gives me the sugar level in Baume' (a degree of density) which in turn gives me an indication of the final alcohol content of the wine ie. 13 deg Be' should be around 13% alcohol.
We look for a level between 13.0 and 14.0 deg Be' with the exception of Semillon when around 11.5 deg Be' suits the wine style we like to make.
This is a good indication when a final test should be made.
The final test is more exhaustive. We take a larger representative sample ie. grape berries from the top, bottom, outside and inside of many bunches, crush them and let the juice settle before testing.
We usually find that at harvest the Be reading is always about 1.0 deg below that of the test.
Some think pH (acidity) is also a critical test.
In warm climates like ours, pH will always be high ie. outside the required range for wine making.
We can adjust that with acid addition (allowed in Australia) during the wine making process.
So it looks like we will be harvesting the Tempranillo, Semillon and Pinot Noir in the next week or two.
The Cabernet has a long way to go. It will be late March, I suspect, before it is ready.