Additives
What you add, and what each one punishes.
43 additives and treatments a home winemaker actually reaches for, from the tartaric that lifts a flabby wine to the copper that is a last resort. Every dose here is a typical range, not a specification, and it defers to a bench trial and the product’s own sheet, the same way every other number on this site defers to the reading you take.
The numbers that are hard facts are the legal limits, and 4 of these carry one. Those are stated with the country that sets them. Where a figure is genuinely uncertain it is described in words rather than dressed up as a measurement, because a made-up dose is worse than an honest fault.
Acids and deacidifiers
7 entries
Moving acidity up with the grape's own tartaric, or bringing a searing wine down with a carbonate. Every addition is bench-trialled, because pH follows the acid by a smaller and far less predictable amount than titratable acidity does.
Tartaric acid
L(+)-tartaric acid
Raises acidity and lowers pH using the acid grapes already contain.
About 1 g/L raises titratable acidity by roughly 1 g/L and drops pH by around 0.1. Bench-trial before treating the batch.
Malic acid
DL-malic acid
Raises acidity with a sharper, greener sourness than tartaric.
Comparable to tartaric by weight; bench-trial. Do not use in a wine that will undergo malolactic fermentation.
Citric acid
Small acid corrections and iron-haze prevention, but microbially unstable.
Kept small, up to roughly 1 g/L; the US limits citric additions. Bench-trial.
Lactic acid
Gentle acidity for fine-tuning, especially after malolactic.
Bench-trial to taste; a soft acid, weaker per gram than tartaric.
Potassium bicarbonate
KHCO3
Deacidifier: lowers titratable acidity and raises pH.
About 0.9 g/L lowers titratable acidity by roughly 1 g/L. Keep the total drop under about 2 g/L.
Calcium carbonate
chalk, CaCO3
Deacidifier for large acid reductions, via the double-salt method.
About 0.67 g/L lowers titratable acidity by roughly 1 g/L; more effective per gram than bicarbonate but slower to stabilise.
Potassium carbonate
K2CO3
Deacidifier, stronger per gram than the bicarbonate.
Bench-trial; more alkaline than potassium bicarbonate, so easier to overshoot.
Sulphite, sorbate and antioxidants
5 entries
The compounds that keep oxygen and stray yeast out of a finished wine. Sulphite is the one everything else leans on, and it is dosed against the wine's pH rather than to a familiar free-SO2 number.
Potassium metabisulphite
KMS, K2S2O5, potassium Campden
The antioxidant and antimicrobial the whole cellar leans on, and the usual source of SO2.
Yields a little over half its weight as SO2 (about 57%). Dose to a molecular-SO2 target for the wine's pH, not to a fixed free-SO2 number.
Sodium metabisulphite
SMS, sodium Campden
An SO2 source like the potassium salt, but one that leaves sodium in the wine.
A similar SO2 yield to the potassium salt; the same molecular-SO2 targeting.
Potassium sorbate
sorbistat, the potassium salt of sorbic acid
Stops surviving yeast refermenting a sweetened wine. A preventer, not a killer.
Roughly 150 to 250 mg/L sorbic acid, which is about 200 to 340 mg/L of potassium sorbate (multiply the sorbic-acid figure by 1.34).
Ascorbic acid
vitamin C
A fast oxygen scavenger for whites, used only alongside sulphite.
Around 50 to 100 mg/L at bottling, with adequate free SO2 already present.
Dimethyl dicarbonate
DMDC, Velcorin
A cold sterilant that kills yeast at bottling and then breaks down.
Up to about 200 mg/L, which is also the US limit. Needs metered dosing equipment.
Antimicrobial and reduction treatment
3 entries
Targeted fixes for one organism or one off-smell. Most are last resorts with a cost of their own, and none is a substitute for the sulphite and sanitation that prevent the problem in the first place.
Lysozyme
An enzyme that suppresses lactic bacteria, delaying or blocking malolactic.
About 250 to 500 mg/L to delay malolactic, toward the top of that to inhibit it.
Chitosan
An antimicrobial fining that targets Brettanomyces and clears haze.
Fungal chitosan around 0.1 to 0.5 g/L; follow the product sheet.
Copper sulphate
CuSO4, copper(II) sulphate pentahydrate
A last-resort treatment for hydrogen sulphide and light mercaptans.
A copper screen sets the trial; the minimum that clears the smell, typically fractions of a mg/L of copper.
Nutrients and enzymes
8 entries
What the yeast needs to finish cleanly, and the enzymes that clear a haze or free an aroma the fruit is holding onto. The nutrient failures are the ones you meet later as hydrogen sulphide.
Diammonium phosphate
DAP
Inorganic nitrogen for the yeast, the direct fix for a starved ferment.
Staged, commonly up to about 1 g/L in total, split across additions rather than dumped in.
Complex yeast nutrient
Fermaid O, Fermaid K, organic nutrient
Nitrogen plus the amino acids, vitamins and sterols the yeast also needs.
Per the product sheet, staged through the first half of fermentation.
Rehydration nutrient
Go-Ferm, inactivated-yeast rehydration protectant
Primes dry yeast with micronutrients before it is pitched.
Per the product sheet, stirred into the rehydration water, not the must.
Thiamine
vitamin B1
A micronutrient that helps a ferment finish and lowers SO2 binding.
Small, per the product sheet; often already present in a complex nutrient.
Yeast hulls
yeast ghosts, inactivated yeast cell walls
Detoxify a stuck ferment and give the yeast a surface to work from.
Around 0.2 to 0.5 g/L when restarting a stuck wine.
Pectic enzyme
pectinase
Breaks down pectin to clear haze and free juice and colour.
Per the product sheet, a fraction of a gram per litre of must.
Glucanase
beta-glucanase
Breaks down Botrytis glucans and speeds lees ageing and filtration.
Per the product sheet, on affected or lees-aged wine.
Beta-glucosidase
aroma-release enzyme, glycosidase
Frees the bound aroma compounds locked up in aromatic white grapes.
Per the product sheet, on aromatic whites.
Fining and clarification
11 entries
Agents that pull one class of thing out of the wine, a protein, a tannin, a brown colour, a taint, and settle out with it. Almost all are bench-trialled, because the right dose clarifies and too much strips the wine bare. Several are animal-derived, which is what decides whether a wine is vegan.
Bentonite
sodium or calcium montmorillonite clay
Adsorbs unstable protein to prevent haze in whites and roses.
Bench-trial, usually 0.25 to 1 g/L for whites and more for very unstable juice. Confirm with a heat test.
Isinglass
Fish-derived collagen that polishes whites to brilliance at a tiny dose.
Very low, around 5 to 25 mg/L; overfining coarsens rather than clears.
Gelatin
Collagen that strips harsh tannin and astringency from reds.
Bench-trial, roughly 30 to 100 mg/L, usually paired with a silica sol.
Egg white
albumen, fresh or powdered
The traditional, gentle softener of barrel-aged red tannin.
Roughly one to three whites per barrel, about 30 to 100 mg/L of albumen.
Casein
potassium caseinate, milk protein
Treats browning and light oxidation or taint in whites.
Bench-trial, roughly 0.1 to 0.5 g/L.
PVPP
polyvinylpolypyrrolidone, Polyclar
A synthetic that removes browning, pinking and bitter phenols.
Bench-trial, roughly 0.1 to 0.75 g/L.
Kieselsol
silica sol, silicon dioxide
A negatively charged fining, paired with gelatin for a compact lees.
Per the product sheet, dosed together with a protein fining such as gelatin.
Sparkolloid
A polysaccharide clarifier for stubborn hazes that resist other finings.
Per the product sheet; the hot-mix form is prepared and added warm.
Activated carbon
activated charcoal, decolorising carbon
A blunt last resort that strips colour and off-odours together.
Bench-trial and use the least that works, roughly 0.1 to 1 g/L.
Plant protein fining
pea protein, potato protein
A vegan substitute for gelatin and isinglass.
Per the product sheet, in the range of the animal finings it replaces.
Diatomaceous earth
DE, kieselguhr, filter aid
A filter aid, rather than a fining, for wines too cloudy to filter.
As a filter pre-coat and body feed per the equipment, not added to remain in the wine.
Tannin, oak and mouthfeel
4 entries
Additions that build structure and texture rather than remove a fault: grape and oak tannin for grip and colour stability, oak for flavour, and colloids for a rounder palate.
Oenological tannin
grape, skin or seed tannin, condensed tannin
Adds structure, stabilises colour and mops up oxygen.
Fermentation tannins roughly 0.1 to 0.4 g/L; finishing tannins less, bench-trialled.
Oak tannin
ellagitannin, hydrolysable tannin
Adds firmness and oxidation resistance, with a faint oak signature.
Small, bench-trialled, a fraction of a gram per litre.
Gum arabic
acacia gum
A colloid that rounds mouthfeel and holds colour, added at the very end.
Per the product sheet, at bottling.
Oak chips, cubes and staves
oak alternatives, inserts
Flavour and structure from oak without the cost or over-oaking of a barrel.
By taste; cubes over months, chips over a fortnight. Taste weekly and pull them when the oak is right.
Tartrate and colloidal stabilisers
5 entries
Ways to stop a wine throwing tartrate crystals in the bottle without cold-stabilising them out, from a cheap temporary coat to durable additions that last the life of the wine.
Metatartaric acid
A cheap, temporary block on tartrate crystallisation.
Around 100 mg/L, at bottling.
Carboxymethylcellulose
CMC, cellulose gum
A durable tartrate stabiliser for whites and sparkling.
Per the product sheet, at bottling into a filtered white.
Mannoproteins
Yeast-derived colloids that steady tartrate and protein and add texture.
Per the product sheet, on a finished wine before bottling.
Potassium polyaspartate
KPA, the potassium salt of polyaspartic acid
A newer tartrate stabiliser that also works in red wine.
Per the product sheet, at bottling.
Bitartrate seeding
cream of tartar, KHT contact process
Seeds cold stabilisation so tartrate drops faster and more completely.
Around 4 g/L of cream of tartar stirred into cold wine as seed crystals.