Wine Time

The low­down on wa­ter, sugar, acid, sul­phur diox­ide, (aka Preser­va­tive 220, SO2)

Good - - Contents - Words Joelle Thom­son

The low-down on what's in your glass

“I drink one glass of red wine a day for my health. The rest of the bot­tle is be­cause I like wine.” Anony­mous

What does that glass of vino that you're sip­ping on right now ac­tu­ally con­tain?

The short an­swer is: wa­ter, sug­ars, acids and, pos­si­bly, a lit­tle oak. There will doubt­less be phe­no­lic com­pounds, which give wine its colour, sense of as­trin­gency, bit­ter­ness and even add weight and body to wine.

The wine in your glass right now is more likely than not to con­tain sul­phur diox­ide (aka SO2), but an in­creas­ing num­ber of wines around the world are made with­out the ad­di­tion of it, how­ever, th­ese are still in the mi­nor­ity. Like the vast ma­jor­ity of food that we eat from a packet, most wine con­tains SO2 be­cause it helps to pre­vent it from ox­i­dis­ing.

The lev­els of SO2 used in wine to­day have sig­nif­i­cantly dropped over the past decade and par­tic­u­larly over the last cen­tury.

The main in­gre­di­ents in wine are: wa­ter, sug­ars and acids. We are talk­ing about nat­u­rally oc­cur­ring sug­ars and acids.

Wine does not con­tain added wa­ter. Its ‘juice’ is the prod­uct of freshly har­vested picked grapes which have then been fer­mented, so the liq­uid that you are con­sum­ing is the fer­mented juice of those grapes. This tasty trio of wa­ter, sugar and acids makes up about 99.9 per cent of each grape that is pressed to make wine, ex­cept for that minis­cule 0.1 per cent, which is known as phe­no­lic com­pounds. Th­ese com­pounds are com­mon in na­ture. They con­tain the colour com­pounds known as an­tho­cyanins, which are found in the pulp cells just be­neath the skins of red grapes. An­tho­cyanins are an­tiox­i­dants, so, yes, wine can be good for you.

The wa­ter com­po­nent of wine, ac­counts for about 80 per cent. The grape’s nat­u­ral sug­ars ac­count for about 20 per cent, leav­ing acids with a minis­cule sound­ing but hugely im­por­tant 1 per cent. With­out acid­ity, grapes – and wine – would lack its fresh taste and pre­serv­ing qual­i­ties. The acid also helps to bal­ance the nat­u­ral sweet­ness of grape sugar.

The sul­phur diox­ide ques­tion

Here are some of the ques­tions that read­ers of my news­pa­per col­umns have been ask­ing over the past five years:

· Why does wine con­tain sul­phur diox­ide and which ones can you rec­om­mend that don’t have any?

· Does sul­phur give me a headache when I drink wine? Or is the headache more re­lated to the amount of al­co­hol I drink?

· If most wine is made to be con­sumed within a year, why do wine­mak­ers bother adding sul­phur to it?

· What is SO2 and what does it do?

· Why does wine con­tain a preser­va­tive?

· I think I am al­ler­gic to sul­phur diox­ide ... Why is it added to wine?

Th­ese ques­tions show that there is a lot of con­fu­sion about the use of sul­phur diox­ide in wine, why it is there and what it does.

Sul­phur diox­ide is not only an im­por­tant in­gre­di­ent, it is present nat­u­rally in all wine be­cause it is a by-prod­uct of fer­men­ta­tion.

To be­gin with, let’s look at what sul­phur diox­ide is.

Sul­phur diox­ide

Sul­phur diox­ide is also known as SO2 and as Preser­va­tive 220. It is the most im­por­tant ad­di­tive to wine be­cause it is an­timi­cro­bial, and also helps to re­duce ox­i­da­tion. It can be used as a ster­il­is­ing agent in winer­ies.

Sul­phur diox­ide it­self is not a preser­va­tive but it binds with other chem­i­cals in wine to work as one.

Sul­phur has been used in wine since Ro­man times; both for its preser­va­tive qual­i­ties and to kill bac­te­ria in wine­mak­ing tanks, vats and other con­tain­ers in which wine is fer­mented and aged, such as con­crete tanks and wooden bar­rels.

Small amounts of sul­phur diox­ide are pro­duced via the fer­men­ta­tion process, so there will, tech­ni­cally, al­ways be some sul­phite present in all wine, at least when the wine is first fer­mented.

Sul­phur diox­ide is of­ten used by wine­mak­ers to kill wild yeasts that are present on freshly har­vested grapes so that th­ese yeasts do not start the fer­men­ta­tion process in an un­de­sir­able way. A low dose of sul­phur diox­ide at this stage may se­lec­tively re­duce th­ese un­de­sir­able yeasts, al­low­ing more suitable wild (or cul­tured) yeasts to take over the fer­men­ta­tion.

Sul­phur diox­ide is fre­quently used at sev­eral dif­fer­ent stages of the wine­mak­ing process but some wine­mak­ers add it to their wines only at the end when the wine is be­ing bot­tled.

The use of sul­phur diox­ide in wine to­day has be­come con­tro­ver­sial be­cause grow­ing num­bers of peo­ple are ques­tion­ing the va­lid­ity of ad­di­tives in all of the food and bev­er­ages that we con­sume.

Like all al­ler­gies, sul­phite al­ler­gies need to be tested to ver­ify that they are the cause of the prob­lem.

The amount of sul­phur diox­ide used in wine pro­duc­tion to­day has de­clined sig­nif­i­cantly over the past cen­tury; The

Ox­ford Com­pan­ion to Wine records that in 1910 the max­i­mum lev­els of sul­phur diox­ide that were legally al­lowed to be used in wine were up to 500 parts per mil­lion and that ' they were well un­der half this limit for dry wines by the early 1990s. (Sweet wines need higher lev­els of sul­phur diox­ide to in­hibit pos­si­ble fer­men­ta­tion of the resid­ual sugar.)

Sul­phur use has re­duced

“The level of sul­phur diox­ide in wine th­ese days is far lower than it used to be. Ev­ery wine­maker has ways of re­duc­ing the amount that they need to use and grapes are likely to be in bet­ter con­di­tion when they come into the win­ery than in the past,” says Neu­dorf founder and wine­maker Tim Finn.

“If you look at the sul­phur diox­ide found in wine to­day, a care­ful wine­maker doesn’t get any­where near the lev­els that can legally be used.”

Finn says that the use of in­ert gases such as car­bon diox­ide, ar­gon and ni­tro­gen, help to re­duce the up­take of oxy­gen dur­ing wine­mak­ing and bot­tling. Also re­frig­er­a­tion helps pre­vent mi­cro­bial spoilage, al­low­ing the wine a chance to clear nat­u­rally. Both of th­ese prac­tices re­duce the amount of sul­phur diox­ide needed to preserve wine qual­ity. In some wines, par­tic­u­larly reds un­der good con­di­tions, sul­phur diox­ide may be able to be dis­pensed with al­to­gether.

Un­der­stand­ing sul­phur diox­ide in wine and food

North Can­ter­bury wine­maker Theo Coles from Nat­u­ral Wine So­lu­tions talks about the use of sul­phur diox­ide in wine and food to­day.

What is an ex­am­ple of a wine that does need large doses of sul­phur diox­ide?

“A low-priced red from a warm cli­mate that has been fer­mented at a warm tem­per­a­ture and con­tains resid­ual sugar when bot­tled def­i­nitely needs sul­phur diox­ide. To stop it from refer­ment­ing in the bot­tle. That's a big risk. No­body wants to open a bot­tle of un­sta­ble, stinky, refer­ment­ing wine."

How can wine­mak­ers use lower amounts of sul­phur diox­ide?

“Get­ting grapes to op­ti­mum health in the vine­yard is the big one. For small pro­duc­tion wines and in very dry cli­mates, this is not too hard to achieve."

What is an­other way?

“I mea­sure dis­solved oxy­gen in my wine af­ter fer­men­ta­tion and, de­pend­ing on the lev­els that I find, I sparge the tank of wine with ei­ther ni­tro­gen or car­bon diox­ide (CO²) so that I can keep sul­phur diox­ide lev­els low.”

Would you ever con­sider adding no sul­phur diox­ide at all?

“When­ever I con­sider adding no sul­phur to a wine, I take that wine home and leave it on the bench for five days and if it’s still tast­ing great, then I don’t need to add any sul­phur. That never hap­pens.”

Theo Coles makes wines for sev­eral pro­duc­ers in Can­ter­bury and Cen­tral Otago, in­clud­ing his own range, The Her­mit Ram.

Ex­tracted from The Lit­tle Black Book of Wine, By Joelle Thom­son, Chap­ter 2.

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