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Demystifying additives in winemaking and viticulture

Growing awareness of the impact of consumption on both wellbeing and the environment is a step in the right direction. However, there is growing concern over whether it may be problematic to treat all preservatives and additives as unwelcome and harmful. An unfortunate byproduct of growing public concern has been that unscrupulous charlatans are more able to sensationalise harmless additives and capitalise upon unsuspecting consumers. Admittedly there have, in the past, been genuine scandals which created cause for concern, the 1985 diethylene glycol scandal an example of one. With that being said, robust regulatory systems, regular review of the science, and a large amount of data now required pre-approval should give consumers confidence that they are buying wine free of harmful additives. Winemakers are well aware of the stringent regulations they are subject to and have a good track record of compliance. Modern consumers expect to purchase quality products (albeit this is a somewhat subjective measure) which are free of spoilage and have a long shelf-life. In order to achieve a consistent quality product in a commercially viable manner, winemakers have available to them a number of harmless additives. Whilst there may be over 60 additives available to winemakers, the reality is that only a handful are used in often small, measured quantities. In this article, I hope to demystify common additives in winemaking and provide a more nuanced exploration of what these ‘additives’ are, how, why, and in what quantities they are used, and to discuss their harmless nature.

In the vineyard

Not only in viticulture but in agriculture as a whole, fungicides, herbicides and pesticides are a controversial topic, one often discussed in far too much of a binary manner. Fungicides have been used in Europe for close to 150 years to protect wine grapes from powdery and downy mildew. Fungicides are applied at an average rate of p/ha throughout the E.U. with 12 to 15 fungicide applications typically made each season. Sulfur and copper are still widely used and are the fungicides of choice for organic growers. Herbicides, also commonly known as weedkillers, are substances used to control unwanted plants. There are a number of common chemical herbicides used, glyphosate perhaps the most controversial, whilst organic solutions are also available. Pesticides are substances that are meant to control pests, including weeds, and is commonly used interchangeably with insecticides, herbicides, and biopesticides.

There is no doubt that in the past pesticides have been used indiscriminately (and to some extent are today) in excessive quantities. Having faced many challenging decades attempting to fight off problems in the vineyard, vigneron can hardly be condemned for an overenthusiastic approach to pesticide application. Particularly given the immaturity of understanding of long-term impacts regards both soils, and subsequently wine, quality. However, much has changed in the past 25 years, the advent of integrated pest management (IPM) and precision viticulture (PV) have given winemakers the ability to not only more accurately coordinate their spraying protocol but also to reduce it in favour of more environmentally friendly pest management.

Targeted spraying by tractor

This reduction has come about not only due to increased consumer concern but also as winemakers have recognised the mounting evidence that pesticides harm soil quality, biodiversity (specifically the microbiome), and site longevity. Given the large costs associated, alternatives to spraying are also commercially viable. In his book Viticulture, Stephen Skelton MW points toward the University of California’s IPM website as an example of the brilliant work being done around IPM and PV.

As well as ecological concerns, there are also public health and philosophical reasons to be concerned about pesticides when purchasing wine. I am not going to discuss the more philosophically inclined reasoning here (it can be rather tedious) but will address health concerns surrounding pesticide use. Though there have been a number of articles ‘revealing’ pesticide levels in wine, much of this is scaremongering, as Jamie Goode has pointed out. The Pesticide Action Network layout many of their findings online; however, many of the chemicals they find evidence of are not only fairly benign but are also found in incredibly low quantities. Additionally, there has been a great deal of unwarranted noise made around glyphosate as a probable carcinogen; however, one ought to more closely evaluate the evidence before subscribing to this train of thought. Spoiler alert, it most likely isn’t. Winemakers are subject to maximum pesticide residue laws, not only this but the products themselves are subject to stringent testing prior to approval for use. Furthermore, winemakers are in the most part committed to minimising, and even eradicating their use, with Champagne aiming to be herbicides free by 2025.

Whilst I am certainly not an advocate of chemical pesticides, I would encourage a more nuanced discussion on the topic and a more considerate approach by consumers given current constraints for many winemakers, who whilst committed to reduction cannot immediately halt use. If for either ecological or philosophical reasons you are looking to buy wine low in, or free of, pesticides there are a few simple ways to do this more easily. Renowned consultant and author of ‘Viticulture’, Stephen Skelton MW, has been a voice of reason on this topic from whom I have learned a great deal. In a brief exchange, Stephen points toward the trade-offs involved in viticulture as opposed to the planting of annual crops.

Grapes showing powdery mildew damage

Take any major winegrowing region, and the chances are that the major varieties have been the same for hundreds of years. These varieties have been, and remain, at the pinnacle of fine wine production. Their genes haven’t been tinkered with either by genetic modification, gene-editing, or even cross-breeding. New vines supplied by nurseries may have been selected by clone for certain beneficial traits, but they are only marginally different from their forebears. This means that most of the world’s major vine varieties have very little resistance to the major maladies and thus need a fair deal of chemical assistance.In the latter half of the1800s, pépiniéristes started crossing wild, and resistant, American vines with Vitis Vinifera vines to produce hybrids which didn’t succumb to mildew and which could be grown on their own roots largely immune to the damage done by phylloxera. ‘The problem was that the wine quality wasn’t high enough, and instead, cheap and cheerful copper and sulphur controlled the mildews in most years’ Stephen adds. 

Vine hybridisers and geneticists didn’t give up, Skelton talks of an ‘underground group’ interested in developing disease and pest resistant varieties which can be grown without the use of any chemical inputs. Since the 1970s, modern interspecific crosses produced from multi-generational crossings of vine species from all over the world, but having at their heart Vinifera wine quality, have been developed.  As this example, and hundreds of others like it worldwide show, pesticides, even copper and sulphur, the chemicals of choice for organic and biodynamic producers, are not required to be used in a vineyard, except if you want to grow varieties that are susceptible to disease. Which happen to be the varieties producing the most alluring of wine.  ‘Pesticides could be banned in vineyards, or at least very severely restricted … but of course, that would change for all time the economics of wine production and many of the appellations we know and love today would struggle to survive’ notes Skelton. 

Stephen adds a similarly fair and rational position on herbicides, acknowledging their advantages whilst recognising their flaws. ‘If you believe that all herbicides are poisonous, that they all do irreversible harm to the soil … this is not a route you can contemplate’ he tells me. However, he also explains that many farmers and growers believe where correctly handled and applied, herbicides can be used without any long-term harm to the soil or its inhabitants or the environment. Before any product is allowed to be used in a vineyard it has to be tested and  for the most part we assume them to be safe if correctly used. ‘Rather perversely, one of the few things we consume which of course we know not to be safe at all, is alcohol’ notes Skelton. 

The problem with using herbicides has as much to do with perception as reality. Lots of things are dangerous if used incorrectly, herbicides, alcohol, medicines. Many people seem to think that they ‘poison’ the soil, but without being able to explain or measure what that means. Rather candidly, Stephen tells me ‘I accept that in these ‘woke’ days, we must look after the environment … herbicides will be around for many decades and they will continue to be used in many different areas, but in viticulture, their days are numbered

Yeast, enyzmes and bacteria

The transformation of grapes by alcoholic fermentation is made possible by yeast. Whilst ambient yeast (of varying genus) present on both the grapes and in the winery itself can, and often do, complete alcohol fermentation this is not always the case. In many cases, for a number of reasons, winemakers opt to inoculate the juice in order to kickstart or undergo fermentation. These inoculations are often undertaken with yeast which is either chosen for its particular properties (extraction, alcohol resilience, cleanliness of ferment etc.) or cultured from ambient yeast in the winery, a growing trend. Whilst fermentation can be completed spontaneously there are a great deal more complications associated with this, not to say good winemakers cannot manage these. For this reason, many winemakers opt to innoculate for the sake of consistency and less challenging fermentations. Inoculating fermentations is commonplace across both the food and drink industry, from bread to beer, cultured yeast is used to provide consistency, stable return on investment and a safety net for producers small and large. To expect winemakers to take unnecessary risks, rejecting tools available to them, on the basis of ones philosophical inclination is somewhat selfish. If you’ve no problem with cultured yeast in bread, keep on sipping.


Enological enzymes are a group of enzymes used by winemakers to aid in extraction, to enhance aromas, and to block malolactic fermentation. Enzymes make up a large category of compounds that are essential to life. Originally used in the production of fruit juice in the 1950s, to increase juice yield and improve clarification, commercial enzymes were adopted by the wine industry worldwide in the 1970s. Today these enzymes serve a number of practical and useful functions in winemaking, from saving time and space to increasing yield. Enzymes help winemakers (primarily those more commercial in nature) liberate aromatic compounds, block lactic acid, break down pectins for faster release of colour and tannin, and to speed up the process of settling the must. Again, as is the case with cultured yeast, there are no health concerns associated with enzymes and any objection is likely to be grounded in philosophical objection to additives in winemaking opposed to any objective reasoning. SevenFiftyDaily has written in detail about enzymes in winemaking here.

The role of sulphur dioxide

Sulfur Dioxide (SO?) is the most common chemical compound used in winemaking and is also present naturally, on grapes and as a byproduct of fermentation. Despite this, as Jamie Goode points out, it is often the most misunderstood. Its preservative and anti-bacterial qualities were discovered thousands of years ago, and because it is non-toxic it has been used in foods and wine since antiquity. Historians believe that sulphur dioxide has been used in winemaking since the Roman era, and Pliny the Elder described using the “vapour of sulphur” as an improving agent.

For many years producing and storing wine was a constant battle against the ill effects of oxidation and spoilage. SO? has made it possible for winemakers to produce and distribute fault-free wine around the globe, greatly increasing the likelihood of consumer satisfaction. First and foremost, SO? guards wine against oxidation throughout the winemaking process and into the bottle. Second, it serves as an antimicrobial agent preventing the growth of unwanted spoilage. SO? is effective in relatively small quantities, for example, the EU has set a legal limit for total SO? of 150 mg/litre in red wines and 200 mg/litre in white wines. With that being said, many wines have quantities much lower, usually well below 100mg/l (100ppm). To put this in context, a serving of French Fries is likely to have over 1850ppm and a serving of dried fruit up to 3000ppm.

Comparison of sulfites in foodstuffs

Although rare (1 in 100 according to the FDA) and with symptoms ranging from severe to life-threatening, there are those who suffer from sulphite sensitivity (sulphites consist of a group of sulphur-based chemicals, including sulphur dioxide). So, should the average consumer be worried about sulphites? Unless you’ve established that you suffer from the aforementioned sulphite sensitivity with a medical practitioner, there is little to suggest you should be at all concerned about sulphites in wine when it comes to your health. In recent decades there has been a general shift toward a more conscious consumer (despite a fairly broad lack of scientific understand) which has given product likes Good Clean Wine the opportunity to make disingenuous claims about sulphites exacerbating the effect of hangovers and causing headaches (a claim not so uncommon). Despite these spurious claims, there is a distinct lack of credible evidence to suggest sulphites are the cause of either hangovers or headaches, it is much more likely that both of these are direct effects of alcohol consumption. For those not scientifically literate, SO? and any other chemical formula for that matter, appear immediately concerning, the Dihydrogen monoxide parody is a brilliant example of this. The reality is, for most people, SO? is harmless, as is DHMO, otherwise known as water.

As is the case with almost every aspect of wine, there are those who make philosophical arguments centred around the use of sulphur dioxide. Many natural wine advocates and winemakers see SO? as the final frontier to wine truly free of intervention. There are those who claim that SO? mutes a wines characteristic and that wine free of SO? shows more purity of fruit. These claims are purely anecdotal and from my own tasting experience simply don’t stand up in the long-run, particularly given a general shift toward less SO? by the majority of winemakers. In reality, making fault-free wine without SO? is extremely difficult and requires a great deal of additional effort, even with these efforts guaranteeing fault-free wine is somewhat impossible. If I were to be controversial, I am almost certain there are winemakers who accept faults as a stamp of authenticity, a note to their natural credentials. I do not buy wine to be greeted by faults or spoilage (consider the difficulties of shipping sulphur-free wine) and so see no practical benefit to arguing against the use of SO?.

‘I can’t control the weather, Monica’

Unique amongst agricultural products, the vintage variation of grapes intended for wine is not only acknowledged but oftentimes revered. Winemakers have only one opportunity each year to get things right. Whilst their work in the vineyard can, to some extent, mitigate troubling factors in a growing season, there are occasions where the weather of any given year is firmly against the production of a suitable, balanced, pleasing wine. The notion that a winery ought to labour the entire growing season, presiding over a crop, a crop in which their livelihood rests, to accept a substandard wine due to factors out of their control when safe, sustainable and reasonable tools are available to them is absurd, particularly when made on philosophical grounds.

As grapes ripen, sugars in the grapes rise progressively as acid levels, through respiration, fall. Grapes grown in particularly hot climates, such as Australia or California, may experience such prolonged heat that they lack the necessary acidity to provide adequate structure and balance. This problem is easily rectified through a process known as acidification. Following an initial tasting, and dependent upon availability a lab analysis, winemakers will usually add tartaric acid prior to fermentation. Tartaric acid is the naturally occurring acid of grapes, and whilst citric acid is cheaper and readily available it can be converted into acetic acid (resulting in unpleasant aromas) and so is often avoided. Acidification is a simple process; the acid is weighed out, dissolved in juice, added to the must and stirred.

Atacama Desert vineyards

Conversely in particularly cool climates, grapes may struggle to ripen with acid levels on the high side at harvest. For this reason, deacidification is permitted almost everywhere in Europe with the exception of zone Ciii (the hottest zone). Although simple on paper, the process of removing acid is more complex than adding it. This is because acids cannot simply be removed from juice, they must be neutralised, they are also not a monolith and instead constitute a mixture of different acids. In order to reduce acidity winemakers add a carbonate such as calcium carbonate (chalk) or potassium bicarbonate (a substitute for baking soda) in order to neutralise the acids in the must. Adding calcium carbonate primarily removes tartaric acid; however, in doing so calcium tartrate crystals are produced, resulting in the challenge of how to remove them. In the face of a changing climate and given the resource-intensive process required, deacidification is in general fairly uncommon.

Furthermore, in cool climates, the natural sugar content of the grape may not be sufficient at the time of harvest to yield adequate levels of alcohol in a finished wine. Through a process known as enrichment (or chaptalisation) concentrated, unfermented grape juice can be added to the must in order to boost a wine’s alcohol level. Dependent upon the region, cane sugar may be the most common type of sugar added, although some winemakers prefer beet sugar or corn syrup. Whatever your attitude may be toward your personal consumption of sugar, it is crucial to acknowledge here that added sugar, whatever form it may take, does not increase the overall sweetness of a wine, nor will this sugar be present, instead it is fermented by the yeast to produce more alcohol.

Important to note is that none of these processes presents any health concern to the general public in and of themselves. Each uses small amounts of harmless additives used commonly in food processing and in some cases appearing naturally in grapes. It’s also worth noting that none of this is done under a cloak of invisibility, each of the aforementioned processes is managed on a region by region basis and for the most part, are controlled strictly by law. Neither are winemakers of the inclination to start off with the idea in mind that they hope to adjust their wine, quite the contrary. For both qualitative and economic reasons, winemakers seek to mitigate the impact of vintage variation in the vineyard to what extent they can, opposed to simply relying on the aforementioned. Again, concerns here are more philosophically and qualitatively concerned, opposed to presenting any concern for the average consumer simply wanting to drink wine

Clarification and stabilisation

Wine is a natural product, though more often than not it presents itself as a clear, attractive liquid on the shelf, things are quite different during the winemaking process. The juice may include dead yeast cells, bacteria, tartrates, proteins, pectins, various tannins and other phenolic compounds, as well as pieces of grape skin, pulp, stems and gums. This is, of course, quite different from that which is desired by the majority consumers and producers for both aesthetic and qualitative reasons. In order to remove these suspended particles, winemakers opt to clarify the must via the practices of fining and filtration, the latter removing spoilage yeasts and some bacteria and the form reducing the overall turbidity of the must.

Fining is the process of adding a substance, commonly referred to as a fining agent, to a wine in order to create an adsorbent, enzymatic or ionic bond with the suspended particles. This bond produces larger molecules and particles that will ‘fall’ out of the wine more readily. This process helps produce a clear, appealing wine free of particulates. Unlike filtration, fining removes soluble substances such as polymerized tannins, colouring phenols and proteins, some of which can cause haziness in wines exposed to high temperatures after bottling. A number of substances have historically been used as fining agents; however, today, there are generally two types of fining agents, namely organic compounds and solid/mineral materials.Organic compounds used as fining agents are generally animal-based (a possible cause of concern to vegans) The most of these organic compounds includes egg whites, casein derived from milk, gelatin and isinglass obtained from the bladders of fish. Pulverised minerals and solid materials can also be used, with bentonite clay being one of the most common. Activated carbon from charcoal is used to remove some phenols that contribute to browning as well as some particles that produce “off-odors” in the wine.

Some countries, such as Australia and New Zealand, have wine labelling laws that require the use of fining agents (additives in winemaking) that may be an allergenic substance to appear on the wine label. However, it is worth noting that a study conducted by UC Davis Department of Viticulture and Enology found that no detectable amount of inorganic fining agents, and only trace quantities of proteinaceous agents, are left in the wine. Again, we ought to conclude on the topic of fining that unless you have dietary or philosophical concerns about additives in winemaking, this process presents no harm to the general consumer nor do fining agents remain in a finished wine.

While fining clarifies wine by binding to suspended particles and precipitating out as larger particles, filtration works by passing the wine through a filter medium that captures particles larger than the medium’s holes. Many white wines require the removal of all potentially active yeast and/or lactic acid bacteria if they are to remain reliably stable in the bottle, and this is usually now achieved by fine filtration and acts a quality control process. During the process of filtration, nothing is added to the wine, more so the wine is passed through or over a membrane or filter, for that reason I am not going to detail the process given it does not relate directly to additives in winemaking.

A call for nuance

Outside of pesticides and herbicides, for which there is genuine cause for ecological concern (the public health concern is much less grounded), additives in winemaking have been irrationally demonised by opportunistic marketers and unscrupulous brands. These people have capitalised on a general lack of awareness and transparency amidst a growing public trend toward concerns around food manufacturing and health. Whilst it is pleasing to see the general public becoming more aware of what they consume, we must be careful this does not result in hysteria, panic or worry about any and all additives before any attempt to understand are made. The wine industry can, of course, combat this by improving transparency and attempting to educate consumers as to what additives in winemaking actually are. Whilst the number of additives available to winemaking may sit around 60, the number used is much lower. Outside of those with specific allergies, additives in winemaking are harmless and outside of pesticides present no considerable risk to the environment.

Instead, these additives give winemakers the tools required to produce viable, quality crops year on year. They are mostly natural or organic products (given they are sometimes synthesised) opposed to ‘scary’ chemicals seen elsewhere in food production and industry. Unless one is philosophically inclined to oppose additives, which the vast majority are not, there is little to no cause for concern when buying wine, particularly in settings such as independent wine retailers where choices can be informed by professional staff. I would encourage a level of nuance when it comes to additives in winemaking, it is unreasonable to suggest that based on the poor form of shoddy brands that hard-working farmers the world over be expected to reject mostly harmless tools, tools which help pay their bills and have done for many years. Whilst the industry makes a shift toward improved transparency we ought to take a second to consider what really constitutes an additive worthy of panic prior to absorbing the rhetoric of those profiteering off of genuine concern.

This Post Has 2 Comments

  1. Josh

    Nicely done Josh – Gr8 Sunday morning read

  2. Larry

    Josh, thank you for an objective and concise review of this subject. Clearly, celebrity status allows exploitation of Mr. Barnum’s assertion.

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