Friday 17 February 2012

Oak Barrels...101


The use of oak plays a significant role in winemaking and can have a profound effect on the resulting wine, affecting the colour, flavour, tannin profile and texture of the wine.  Oak can come into contact with wine, in the form of a barrel, during the fermentation or ageing periods. It can be introduced to the wine in the form of free-floating oak chips or as wood staves (or sticks) added to wine in a fermentation vessel like stainless steel. The use of oak barrels can impart other qualities to wine through the processes of evaporation and low level exposure to oxygen.

The use of oak has been prevalent in winemaking for at least two millennia, first coming into widespread use during the Roman Empire.  In time, winemakers discovered that beyond just storage convenience that wine kept in oak barrels took on properties that improved the wine by making it softer and in some cases better-tasting.

The chemical properties of oak itself can have a profound effect on the wine.  Phenols within the wood interact with the wine to produce vanilla type flavours and can give the impression of tea notes or sweetness. The degree of "toast" on the barrel can also impart different properties affecting the tannin levels of the wine as well as the aggressive wood flavours.

Since French oak must be split, only 20% to 25% of the tree can be utilized;
American oak may be serrated, which makes it at least twice as economical. It’s more pronounced oxidation and a quicker release of aromas help wines to loose their astringency and harshness faster; which makes this the wood of choice for shorter maturations - six to ten months. Because of American oak’s modest tannin contribution, the perfect first fill is a wine with abundant tannins and good texture; it allows the fruit to interact harmoniously with the wood, which contributes a wide array of complex aromas and soft, yet very palatable tannins.

French oak, on the other hand, generates silky and transparent tannins, which transmit a sensation of light sweetness combined with fruity flavours that persist in the mouth.  Spices and toasted almond are noteworthy, combined with flavours of ripe red fruit in red wines, and notes of peach, exotic fruits and floral aromas like jasmine and rose in whites, depending on the grape variety employed.

Wine barrels, especially those made of oak, have long been used as containers in which wine is aged. Aging in oak typically imparts desirable vanilla, butter and spice flavours to wine. The size of the barrel plays a large role in determining the effects of oak on the wine by dictating the ratio of surface area to volume of wine with smaller containers having a larger impact. The most common barrels are the Bordeaux barriques style which hold 220 L followed by the Burgundy style barrel which hold 230 L.

New barrels impart more flavours than do previously used barrels. Over time many of the oak properties get "leached" out of the barrel with layers of natural deposits left from the wine building up on the wood to where after 3 to 5 vintages there may be little or no oak flavours imparted on the wine.  The cost of barrels varies due to the supply and demand market economy and can change with different features that a cooperage may offer. In South Africa barrels can cost about R10 000 each.  Due to the expense of barrels, several techniques have been devised in an attempt to save money. One is to shave the inside of used barrels and insert new thin inner staves that have been toasted.

Barrels are constructed in cooperages. The traditional method of European coopers have been to hand-split the oak into staves (or strips) along the grain. After the oak is split, it is allowed to "season" or dry outdoors while exposed to the elements. This process can take anywhere from 10 to 36 months during which time the harshest tannins from the wood are leached out. These tannins are visible as dark gray and black residue left on the ground once the staves are removed. The longer the wood is allowed to season the softer the potential wine stored in the barrels may be but this can add substantially to the cost of the barrel. In some American cooperage the wood is dried in a kiln instead of outdoor seasoning. While this method is much faster, it doesn't soften the tannins quite as much as outdoor seasoning.

The staves are then heated, traditionally over an open fire, and when pliable are bent into the shape of the desired barrel and held together with iron rings. Instead of fire, a cooper may use steam to heat up the staves but this tends to impart less "toastiness" and complexity to the resulting wine. Following the traditional, hand worked style a cooper is typically able to construct one barrel in a day's time. Winemakers can order barrels with the wood on the inside of the barrel having been lightly charred or “toasted” with fire, medium toasted, or heavily toasted. Typically the "lighter" the toasting the more oak flavour and tannins that are imparted. Heavy toast or "charred" which is typical treatment of barrels in Burgundy wine have an added dimension from the char that medium or light toasted barrels do not impart.  Heavy toasting dramatically reduces the coconut note lactones, but create a high carbon content that may reduce the coloring of some wines. The toasting also enhances smokey and spicy notes that in some wines are similar to the aromatics of oil of cloves.

Although oak barrels have long been used by winemakers, many wineries now use oak wood chips for aging wine more quickly and also adding desired woody aromas along with butter and vanilla flavours. Oak chips can be added during fermentation or during aging. In the latter case, they are generally placed into fabric sacks and placed into the aging wine. The diversity of chips available gives winemakers numerous options. Oak chips have the benefit of imparting intense oak flavoring in a matter of weeks while traditional oak barrels would need a year or more to convey similar intensity. Critics claim that the oak flavouring from chips tend to be one-dimensional and skewed towards the vanilla extract with the wines still lacking some of the physical benefits that barrel oak imparts.

The use of oak powder is also less common than chips, although they are a very practical alternative if oak character is to be introduced during fermentation. Oak planks or staves are sometimes used, either during fermentation or aging. Wines made from these barrel alternatives typically do not age as well as wines that are matured in barrels. 

Throughout history other wood types, including chestnut, pine, redwood, and acacia, have been used in crafting winemaking vessels, particularly large fermentation vats. However none of these wood types possess the compatibility with wine that oak has demonstrated in combining its water tight, yet slightly porous, storage capabilities with the unique flavour and texture characteristic that it can impart to the wine that it is in contact with.

Chestnut is very high in tannins and is too porous as a storage barrel and must be coated with paraffin to prevent excessive wine loss through evaporation. Redwood is too rigid to bend into the smaller barrel shapes and imparts an unpleasant flavour. Acacia imparts a yellow tint to the wine. Other hardwoods like apple and cherry wood have an off putting smell.

Fauna and Flora on our doorstep

We are very excited that the tarring of the Hemel en Aarde road is starting this year.
New emphasis has been put on the rich wildlife in our area and how the roadworks will affect them.  I am happy to report that a large project has been initiated to preserve the wildlife while roadworks are in progress. 

The largest carnivorous plant in the world is called roridula or vlieëbos in Afrikaans. Dr Anina Lee, chairperson of Whale Coast Conservation says this plant grows right here on our doorstep, but the exact location is a closely guarded secret as it is so rare and endangered.
This plant can get up to two meters tall and its leaves are covered in hairs with sticky droplets with which they capture insects and even small birds.

But, surprisingly, the plants have no digestive enzymes to digest their prey, so why do they catch them? It was found that small bugs live on roridula in great abundance. The bugs hold their bodies away from the traps and, with specially adapted feet, they run at great speed over what would be a death trap for any other insect. These bugs roam the plants in search of food – insect food. When an insect is found, struggling helplessly against the stickiness, the bugs approach cautiously. The bugs probe with their probisci looking for a weak spot in the exoskeleton of the prey.
Each time the prey moves, the bug retreats, only to probe again and again. With each probe, a tiny amount of venom is injected and soon the prey succumbs and dies. Within half an hour black bugs fly in from close by and a massive seething scrum develops, vying for a place at the carcass, using their hind legs to lash out at rivals that get too close.

Soon the prey is reduced to a dry husk and the bloated bugs slowly disperse. But before they disperse, they defecate on leaves of roridula. The nitrogenrich faeces are fertilizer for roridula which can absorb the nitrogen straight through their leaves. So roridula does not need digestive enzymes – it has an army of living organisms to do the job of digestion.
Dr Lee says: “For more interesting facts about our weird and wonderful indigenous species, visit the Hermanus Flower and Eco Fair at the Fernkloof Nature Reserve in September.

Thursday 16 February 2012

Fire Hot Hermanus

The last thing you need is a fire on your farm just before harvest time!

Thick clouds of smoke enveloped Stanford and Hermanus over the first weekend in February 2012 as a massive bush fire raged out of control on the Klein River Mountains
The fire, which started in Tesselaarsdal, was fanned by strong winds and dry fynbos and quickly spread from farm to farm.

Residents and volunteers from as far afield as Caledon and Hermanus raced around the hamlet trying to keep the fire from consuming any houses.

Reinard Geldenhuys, head of Fire and Rescue in the Overberg, said several firefighters and a helicopter battled to quell the flames.

By midnight on the Saturday an ominous orange glow filled the night sky on the mountains above Stanford. By the Sunday morning the fire was raging on the Sir Robert Stanford wine estate and quickly spread to neighbouring farms.

Farmers from the district and dozens of volunteers pitched in to keep the fire from spreading to the vineyards.
Jan and Madré Malan, owners of Sir Robert Stanford, said they were overwhelmed by the amount of support they received.

“Everyone, neighbours and strangers, pitched in to help save the vines. We are planning on starting the harvest in the new week, and we are so grateful for all the help we received,” Madré said.
Charlie and Julie Crowther, owners of the Glen Oakes farm, said two of their pigs were caught in the fire. “Their skin was burned off. The one burned to death, and we had to shoot the other,” Charlie said.
Riaan Jacobs, head of Overstrand Fire and Rescue, said he suspects the fire started after a homeowner burned the grass around his house to clear it. The wind picked up, and the fire could not be stopped.
The Crowthers said it was like an avalanche coming down, with nowhere to run. “The fire burned 80% of our farm. Even though we lost two pigs, we are very thankful to all involved in coming to our rescue to prevent a very ferocious fire from destroying our home, the rest of our livestock, irrigation systems and infrastructure.”
CapeNature, Working on Fire, Overstrand Fire and Rescue, Overberg Fire and Rescue, farmers, their workers and members of the public worked non-stop for four days to bring the fire under control.
Some six fire trucks, a helicopter, 30 members of Fire and Rescue and countless members of the public fought against the fire.
Reinhard Odendaal, winemaker at Walker Bay Vineyards and Birkenhead Brewery, said his eyes were still red, and he still smelled like a barbecue after helping to fight the fire continuously for more than 24 hours.
Approximately 15000 hectares of fynbos were destroyed, but thankfully no structures or lives were lost.

Janine van der Riet and De Waal Steyn
Source: Hermanus Times