New World Winemaker Blog

The European Union might want to ban wine in which hen’s eggs or dairy products have been used, as some people can be allergic to these products. Alternatively the new law might just insist on labelling the wine as containing these products. The prevalence of allergic reactions to milk and egg products has been reported to be 1% of the adult population. Clinical trials have been inconclusive, and although wine has no history of causing allergic reactions as a result of the protein fining agents used, the possibility still exists.

Eggnog is a traditional drink at Christmas in the USA, and was developed in Europe by combining eggs and alcoholic drinks to let the eggs last longer. The drink was apparently first called “egg-and-grog”, and it has been known to cause allergic reactions in individuals. This seems to be the basis of the fear of egg allergens in wine.

Although HACCP is widely practised in the winemaking industry, almost all of the CCPs (critical control points) have a quality influence. There is only one commonly established real CCP and that is at bottling, to prevent glass from entering the bottles which could be harmful to people who swallow it. Another critical control point was once established to be grapes infected by Ochratoxin A, which is formed by moulds on grapes, but that is not very common.

The allergen law requires wine that contain these products to be labelled, but if there are no residues, who will be the wiser? The naughty compounds in eggs are the proteins that can easily be removed, although milk might leave residues of lactose. The ELISA tests that are used to test for residues cannot test down to zero, but the limits of detection have been found to be good enough to establish risk. There are also people with the view that if a product has been used, if it is still present or not, it must be stated.

There have been companies peddling plant alternative proteins that can apparently perform the same tasks as egg and milk proteins, but I have not had the pleasure to test these.

The new allergen labelling laws were originally intended to be implemented in 2005, but the deadline has now been extended to 30 June 2012, to assess possible exemption of these products. Let’s see what happens.

We are all taught how important pH is in winemaking. A low pH makes SO₂ perform better by having a larger percentage of molecular SO₂, it makes bentonite settle better, it keeps bad bugs at bay, and generally is something to brag about when you are gathered around a barrel at the end of the day. All this has to do with hydrogen ions, iso-electric points, pH tolerances and lots of other stuff we have long forgotten about since learning about it.

The concept of pH was first described by the Danish chemist Søren Peder Lauritz Sørensen in 1909. The notation given by him was at first p_H, with the subscript H, being derived from hydrogen, but the exact definition of the P is a subject of speculation to this day.

When I was studying the importance of pH was drilled into us, and ‘till this day everybody will tell you how important it is, but besides keeping it as low as possible, tell me, what on earth can you do about it? It is like worrying about your own death.

If we follow good practices like adjusting juice acidity early, adjusting acidity after fermentation and malo, what can you do about pH? Why do we keep analysing something, and wasting money doing it, when the purpose of acidification is so broadly linked to pH and not linear at all.  We can just as well stop analysing for it.

I want to ask you how often have you seen lab sheets where people fill in the analysis they have done, and only ask for total acid? If you have the pH, what can you do with it? Be philosophical, brag to your mates about your low pH, worry about it?

When people ask Loftie Ellis (a South African winemaking consultant) what the pH of a wine is, he often answers, “it is enough”. To him the microbial condition of a wine is much more important than the pH.

I have heard of winemakers who do pH adjustments, with legal acids as they should, and then deacidify closer to bottling. This is however an extreme, when you have to take into account that the wine will not win a double gold because of your efforts to fight high pH, but because you have good grapes foremost.

Besides good practice which should always strive to keep the pH of the wine as low as possible, while keeping the affect of acid on taste foremost in mind, you do not need to have the pH of a wine analysed.

I remember reading and hearing about the next big thing, ascorbic acid when I was just starting out winemaking. It was going to revolutionize white winemaking and everybody who did not know about it was simply out of the loop. Since then, very little has happened, and the practice is not widely employed. I wonder about things that people propagate as fact, simply why it is not used by everyone, it just seems to be so obvious, you would think. Now the next big thing might be gluthathione (GSH). Yes, did I pronounce that correctly?

When you look at all the chemicals in wine that can act as anti-oxidants, SO₂ is not very high up in the chain, and is much less effective relative to other compounds. The series from “worst” to best would be something like, SO₂, ascorbic acid (Vit C), vitamin E, gluthathione (GSH) and then tannin. In white wine there is not a lot of tannin, so the next best thing would be GSH. Many of the flavourful compounds in wines have thiol groups, and when they oxidise, they lose their flavour. This is where GSH can save some flavour, because the source of its power is its thiol groups, which will take a bullet for the flavour compounds.

GSH gets used by yeast during fermentation, so if you want to add this lovely compound you have to add it after two thirds of the fermentation has been completed, because then the yeast will not assimilate it. GSH can be added in the form of yeast derived products.

Recently someone suggested that the use of ascorbic acid can lower the amount of SO₂ needed, but what would be much truer, is that low oxygen pickup can lower the SO₂ needed, since this is actually what is combated by SO₂. When you are evaluating practices and trying to compare two different wineries, you are dealing with different grapes, lots of different micro components, different bottling practices, never mind different ascorbic acid regimes.

Ascorbic acid started as the thing to do, but practical experiments and lots of anecdotal evidence suggest that it is not as powerful as first suggested. The grapes seem to have a much bigger influence than anything else, and ascorbic is not the silver bullet that it was first touted to be. In a few more years we must look back and see what GSH accomplished.

For  technical article on glutathione click here.

Louis Nel is the owner and winemaker of Louis wines in South Africa.

In these times we are all becoming more aware of our impact on the environment and the scarcity of natural resources, and going green is the only way to go. Only 20% of the weight of the barrel is used to improve wine quality while the other 80% is used for structural integrity, so maybe it is time for the “plastic” barrel to make a comeback.

Stanley Kubrick’s 1971 movie “A Clockwork Orange”, got its name from the fact that nothing can be as artificial as a clockwork orange, and similarly more than ten years ago there was a very eco friendly barrel on the market, that I called the plastic barrel. At the time there was nothing I could consider more artificial.

Only the inside of the staves were made from oak, while the outer part was made from cheap wood, and the barrel was covered in oak veneer. The barrel was toasted with infra red light and every second stave had a heating element, so that the barrel could be heated to speed up aging, or to stimulate malolactic fermentation. The barrel could be hooked up to the transformer that supplied the electricity to the elements, and a thermometer would be fitted through the bung to monitor and regulate the temperature inside of the barrel.

Wine only enters the first 5mm or so of a barrel and the rest of the oak is wasted, so conserving this natural resource could be highly beneficial. Besides that only 4% of the wood of an oak tree is good enough to be used for making barrels, so you will be saving a lot of trees, while wood that is more plentiful can be used for the structural integrity of the barrel.

At the time I was part of a huge contingent that thought such a barrel is the biggest load of fakery around, but if it lived on we could have had a lot more manufacturers, who could have improved on the concept.

When using staves, a much larger percentage of the oak tree can be used for making staves and the staves have a smaller carbon footprint when transported, because you are not transporting so much French or American air. All the oak is used and none is wasted to keep a barrel from collapsing.

Maybe it is time to revisit the plastic barrel, and look at ways where this “artificial” product can, like screwcaps, low carbon footprint plastic bottles, and staves be used to protect natural resources and hopefully save the planet.