Wine preservatives

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Wine preservatives
Preservatives-in-wine.jpg
TypeAdditive
ColourPurple/transparent colour
FlavourMost are tasteless and a few, such as tannins, have a bitter taste
Related productsFood preservative

Wine preservatives are used to preserve the quality and shelf life of bottled wine without affecting its taste. Specifically, they are used to prevent oxidation and bacterial spoilage by inhibiting microbial activity. [1]

Contents

Wine contains natural preservatives such as tannin, sugar and alcohol, [2] and can be preserved through physical preservation methods, such as storage at an appropriate temperature. [3] However, bacterial growth is still possible, so chemical preservatives are added to most wines. [1] [4] Typical chemical preservatives include sulfur dioxide and its related chemicals, such as sulfites. [2]

The use of preservatives in wine has been shown to cause health problems in some consumers.

Deterioration

Despite the alcohol in wine, growth of bacteria is possible, even when completely fermented. [2] Wine is made from the fermentation of grape juice, which contains sugar. [4] During the fermentation process, yeast will convert sugar into alcohol. [5] If the fermentation is not complete, the wine will contain residual sugar content. The sugar acts as nutrient needed for the growth of bacteria, which can deteriorate the wine or even turn it into grape vinegar. [5] Because the alcohol content of wine is relatively low, the alcohol cannot completely inhibit the proliferation of bacteria. Long-term improper storage may accelerate deterioration. [4]

During the brewing process, microbial spoilage can lead to the deterioration of wine quality and taste, making it unhygienic and unacceptable to consumers. [5] The main bacterial groups are yeast, candida and Hanseniaspora. [5] In addition, microbial diseases of wine are mainly caused by yeast, lactobacillus and acetic acid bacteria. [6] This is because yeast may re-ferment a wine with high sugar content, making it cloudy and impure. [1] Lactic acid bacteria can cause acid spoilage in dry wine with low acidity and lactic acid bacteria disease in sweet wine with low acidity. [2] Acetic acid bacteria may cause the increase of volatile acid in wine, resulting in an undesirable sour vinegar taste. [2] These fungi are all bad for the safety and flavor of wine. [2]

Preservatives

Anything that extends the shelf life of red wine is considered a preservative. Preservatives are mainly divided into natural preservatives and chemical preservatives. [3]

Natural preservatives

Tannins

Tannins, also known as polyphenols, are found in the xylem, bark, leaves, fruits and roots of plants. [3] Tannin molecules undergo polymerization to join into longer molecules [7] and turn it into a "protective colloids" that prevents or limits aggregation, flocculation and step haze formation and precipitation. [6] At the same time, tannins are also one of the main sources of bitterness and astringency in wines. [1] Its content and quality are one of the important factors in evaluating the quality of red wine.

Sugar

Just as people use sugar or salt when making preserved foods, sugar is also a preservative for wine. [4] The sugar lowers the water activity of the food, meaning that less water is available for the bacteria, stunting its growth. [2] Salt is used as a preservative in the same way. [8]

Alcohol

Alcohol is used as a preservative especially in spirits such as sherry. [3] Because common alcohol can have the same problems as acid when used as preservatives, the lack of acidity does not play a role of maintaining quality. [4]

Chemical preservatives

Acid

Acid is widely used as a preservative. In red wine, Sulfurous anhydride or sulfur dioxide (SO2), in particular, is the most frequently used source. [4] Acid protects wine from bacteria by regulating the pH value, which affects the growth and vitality of yeast during fermentation. [2] Acidity also directly affects color, balance and taste. [2]

For example, sulfur dioxide, the most widely used preservative by wine merchants, has been used as a cleaning agent for centuries. [9] Sulphur dioxide has a pungent taste that people dislike, and its use has been controversial because of its disease-causing properties [10] (see section on the controversy).

Sorbic acid, which acts like sulfites, has recently been approved for use in European Community countries, but only under very limited conditions. [10] It must be effective in wines with an alcohol concentration of 12%. [11]

Apart from sulfur dioxide, which is used most frequently, other chemicals such as benzoic acid, diethyl pyrocarbonate, parabens, pimaricin and sorbic acid are also used as preservatives in wine, but the potential threat or side effects of these chemicals are still to be investigated, so they are not permitted to be used in large quantities for the time being. [10]

Weak acid

Compared with other preservatives, weak acids are characterized by their antiseptic effect by slowing down the growth and reproduction cycle of microorganisms rather than killing them. [12] Weak acids inhibit microbial growth by dissociating protons from cells. [12] Although the chemical formula of different weak acids is different, they all play a more obvious inhibitory effect in the environment with a low pH value; that is, the more acidic the environment, the greater the inhibitory effect. [12] This practice was first discovered by John Evelyn in 1670, who used sulfur dioxide from burning sulfur to preserve cider. [12]

Tartaric acid

In hot climates, tartaric acid is added when grapes become too ripe for natural acidity. [7] Most people agree that grapes should be picked when there is a balance between optimum ripeness and acidity, and there are many factors that can reduce the acidity of the wine-making process. [9] Acidification is widespread in Argentina, Australia, California, Washington, Italy and South Africa. [9] It is not common in northern France, Germany, Austria, Oregon and New Zealand. [4]

Calcium carbonate

In contrast to tartaric acid, if the grapes are too acidic, calcium carbonate is used to bring them down to the level needed to make wine. [10]

In addition, many also use oak, oak slices, fermentation agents, tutu, and more, according to the quality of grapes and the different styles of wine. The need for additives and the amount used depends on the winemaker, as different winemakers make different choices. [7]

The basic principle of preservatives against oxidation

Wine has different preservatives from other drinks such as milk, juice and beer. Its preservatives work primarily by inhibiting the growth of microorganisms through oxidation. [3] However, because different kinds of wine have different aromas, colors and flavors, they should not use the same preservatives. [3] For example, the preservatives added to white wine are mainly ascorbic acid (vitamin C) and sorbic acid. [13] Ascorbic acid is used as an antioxidant, while sorbic acid is used to inhibit the growth of yeast in white wine. [3] Sorbic acid cannot be used in red wine because it can cause pollution. Sulfites, or small molecules of sulfur dioxide (SO2) and hydrogen disulfide (H2O2), are commonly used as preservatives in wine and even other fruit drinks. [7] Their principle is basically to make microbial protein coagulation or denaturation, thereby interfering with their growth and reproduction. [7] Sulfites are mainly in the form of sulfur dioxide at different pH concentrations. [10] Experiments show that only the sulfur dioxide molecule has an antibacterial effect. [14] That's the active ingredient in preservatives. Sulfur dioxide inactivates by combining with compounds derived from wine. [14] Because of the nature of sulfur dioxide, it is more effective at lower pH concentrations and at higher ethanol concentrations, [15] finally achieving the function of anti-corrosion.

Preservatives controversy

Allergy to preservatives has aroused people's concern. [4] Studies have shown that a possible cause of allergy in wine ingredients is an adverse reaction to sulfur dioxide by asthma patients. Sulfur dioxide allergy was the cause of 1.7% of asthma patients. [4] It is not precisely a true statement that a person is allergic to preservatives, but rather, the person may be allergic to preservatives that contain sulfur dioxide. [13] The controversy over preservatives has not entirely disappeared, [4] but sulfur dioxide is still the most widely used preservative in wine at this stage because it is effective and no alternative chemical additive has been found. [10]

People are concerned about their health and have higher requirements for food quality. [16] Because of the controversy, disease-causing preservatives have been used as sparingly as possible [16] or clearly labeled on wine bottles to make it easier for people with the disease to stay informed. [4] Meanwhile, people are increasingly looking for safe and healthy wine preservatives. [4]

In addition to traditional preservation methods that do not require preservatives, such as cryopreservation, [17] it is evident that there are many new technologies, such as high hydrostatic pressure (HHP) and pulsed electric fields (PFF) that can also play a beneficial role in food preservation. [13] Whether these new technologies can replace chemical preservatives is worth considering. [13] In addition, researchers have targeted potential biological preservatives, such as antimicrobial peptides and bacteriolytic enzymes. [5] There is still a lot of research space for biological preservatives, which is relatively safe and has certain benefits. [5]

Known health effects due to preservatives

It has been reported that many food preservatives, including sorbitan, hydrogen peroxide, benzoic acid and sodium benzoate, can cause health problems, especially in high doses. [16] In addition, as mentioned in the controversy section, the adverse effects of sulfites on asthma patients also confirmed the health threat of preservatives containing this substance. [18] In the meantime, sulfite accumulates can decompose sulfur dioxide and also have certain stimulation to lungs. [19] Therefore, some people are urging that sulfur dioxide be banned as a preservative and food additive, in wine and other food and beverages. [10]

Propionic acid, which is also used as a preservative, has also been shown to be carcinogenic in rodents. [8] However, there are currently only two ways to minimize the health threat of sulfur dioxide. [10] One is to try to reduce the dose of sulfur dioxide, which is already happening. [10] The second is to study the chemical structure and characteristics of sulfur dioxide, looking for alternative chemical preservatives. [10] This requires a lot of scientific research efforts and has not seen effective results in a short time. [10]

Experts studying wine preservatives have discovered that a specific type of wine yeast can be made [17] using the substances secreted by yeast during fermentation as new biological preservatives may reduce the threat of wine preservatives to life and health. [17] But the possibility of adding antibacterial compounds to the manufacturing process may prevent the risk from being completely avoided, so the study is ongoing. [20]

See also

Related Research Articles

<span class="mw-page-title-main">Food preservation</span> Inhibition of microbial growth in food

Food preservation includes processes that make food more resistant to microorganism growth and slow the oxidation of fats. This slows down the decomposition and rancidification process. Food preservation may also include processes that inhibit visual deterioration, such as the enzymatic browning reaction in apples after they are cut during food preparation. By preserving food, food waste can be reduced, which is an important way to decrease production costs and increase the efficiency of food systems, improve food security and nutrition and contribute towards environmental sustainability. For instance, it can reduce the environmental impact of food production.

Acetic acid bacteria (AAB) are a group of Gram-negative bacteria which oxidize sugars or ethanol and produce acetic acid during fermentation. The acetic acid bacteria consist of 10 genera in the family Acetobacteraceae. Several species of acetic acid bacteria are used in industry for production of certain foods and chemicals.

<span class="mw-page-title-main">Winemaking</span> Production of wine

Winemaking, wine-making, or vinification is the production of wine, starting with the selection of the fruit, its fermentation into alcohol, and the bottling of the finished liquid. The history of wine-making stretches over millennia. There is evidence that suggests that the earliest wine production took place in Georgia and Iran around 6000 to 5000 B.C. The science of wine and winemaking is known as oenology. A winemaker may also be called a vintner. The growing of grapes is viticulture and there are many varieties of grapes.

<span class="mw-page-title-main">Sulfite</span> Oxyanion with a central atom of sulfur surrounded by 3 oxygen atoms

Sulfites or sulphites are compounds that contain the sulfite ion, SO2−
3. The sulfite ion is the conjugate base of bisulfite. Although its acid is elusive, its salts are widely used.

<span class="mw-page-title-main">Red wine</span> Wine made from dark-colored grape varieties

Red wine is a type of wine made from dark-colored grape varieties. The color of the wine can range from intense violet, typical of young wines, through to brick red for mature wines and brown for older red wines. The juice from most purple grapes is greenish-white, the red color coming from anthocyan pigments present in the skin of the grape. Much of the red wine production process involves extraction of color and flavor components from the grape skin.

<span class="mw-page-title-main">White wine</span> Wine fermented without skin contact

White wine is a wine that is fermented without skin contact. The colour can be straw-yellow, yellow-green, or yellow-gold. It is produced by the alcoholic fermentation of the non-coloured pulp of grapes, which may have a skin of any colour. White wine has existed for at least 4,000 years.

<span class="mw-page-title-main">Malolactic fermentation</span> Process in winemaking

Malolactic conversion is a process in winemaking in which tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. Malolactic fermentation is most often performed as a secondary fermentation shortly after the end of the primary fermentation, but can sometimes run concurrently with it. The process is standard for most red wine production and common for some white grape varieties such as Chardonnay, where it can impart a "buttery" flavor from diacetyl, a byproduct of the reaction.

<span class="mw-page-title-main">Potassium metabisulfite</span> Chemical compound

Potassium metabisulfite, K2S2O5, also known as potassium pyrosulfite, is a white crystalline powder with a pungent odour. It is mainly used as an antioxidant or chemical sterilant. As a disulfite, it is chemically very similar to sodium metabisulfite, with which it is sometimes used interchangeably. Potassium metabisulfite has a monoclinic crystal structure.

<span class="mw-page-title-main">Potassium sorbate</span> Chemical compound

Potassium sorbate is the potassium salt of sorbic acid, chemical formula CH3CH=CH−CH=CH−CO2K. It is a white salt that is very soluble in water (58.2% at 20 °C). It is primarily used as a food preservative (E number 202). Potassium sorbate is effective in a variety of applications including food, wine, and personal-care products. While sorbic acid occurs naturally in rowan and hippophae berries, virtually all of the world's supply of sorbic acid, from which potassium sorbate is derived, is manufactured synthetically.

A wine fault is a sensory-associated (organoleptic) characteristic of a wine that is unpleasant, and may include elements of taste, smell, or appearance, elements that may arise from a "chemical or a microbial origin", where particular sensory experiences might arise from more than one wine fault. Wine faults may result from poor winemaking practices or storage conditions that lead to wine spoilage.

<i>Zygosaccharomyces bailii</i> Species of fungus

Zygosaccharomyces bailii is a species in the genus Zygosaccharomyces. It was initially described as Saccharomyces bailii by Lindner in 1895, but in 1983 it was reclassified as Zygosaccharomyces bailii in the work by Barnett et al.

<span class="mw-page-title-main">Fermentation</span> Metabolic process producing energy in the absence of oxygen

Fermentation is a metabolic process that produces chemical changes in organic substances through the action of enzymes. In biochemistry, fermentation is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen, while in food production, it may more broadly refer to any process in which the activity of microorganisms brings about a desirable change to a foodstuff or beverage. The science of fermentation is known as zymology.

<span class="mw-page-title-main">Fermentation in winemaking</span> Wine making process

The process of fermentation in winemaking turns grape juice into an alcoholic beverage. During fermentation, yeasts transform sugars present in the juice into ethanol and carbon dioxide. In winemaking, the temperature and speed of fermentation are important considerations as well as the levels of oxygen present in the must at the start of the fermentation. The risk of stuck fermentation and the development of several wine faults can also occur during this stage, which can last anywhere from 5 to 14 days for primary fermentation and potentially another 5 to 10 days for a secondary fermentation. Fermentation may be done in stainless steel tanks, which is common with many white wines like Riesling, in an open wooden vat, inside a wine barrel and inside the wine bottle itself as in the production of many sparkling wines.

<span class="mw-page-title-main">Acids in wine</span>

The acids in wine are an important component in both winemaking and the finished product of wine. They are present in both grapes and wine, having direct influences on the color, balance and taste of the wine as well as the growth and vitality of yeast during fermentation and protecting the wine from bacteria. The measure of the amount of acidity in wine is known as the “titratable acidity” or “total acidity”, which refers to the test that yields the total of all acids present, while strength of acidity is measured according to pH, with most wines having a pH between 2.9 and 3.9. Generally, the lower the pH, the higher the acidity in the wine. There is no direct connection between total acidity and pH. In wine tasting, the term “acidity” refers to the fresh, tart and sour attributes of the wine which are evaluated in relation to how well the acidity balances out the sweetness and bitter components of the wine such as tannins. Three primary acids are found in wine grapes: tartaric, malic, and citric acids. During the course of winemaking and in the finished wines, acetic, butyric, lactic, and succinic acids can play significant roles. Most of the acids involved with wine are fixed acids with the notable exception of acetic acid, mostly found in vinegar, which is volatile and can contribute to the wine fault known as volatile acidity. Sometimes, additional acids, such as ascorbic, sorbic and sulfurous acids, are used in winemaking.

<span class="mw-page-title-main">Cider</span> Fermented alcoholic beverage from apple juice

Cider is an alcoholic beverage made from the fermented juice of apples. Cider is widely available in the United Kingdom and Ireland. The UK has the world's highest per capita consumption, as well as the largest cider-producing companies. Ciders from the South West of England are generally higher in alcoholic content. Cider is also popular in many Commonwealth countries, such as India, South Africa, Canada, Australia, New Zealand, and New England. As well as the UK and its former colonies, cider is popular in Portugal, France, Friuli, and northern Spain. Germany also has its own types of cider with Rhineland-Palatinate and Hesse producing a particularly tart version known as Apfelwein. In the U.S. and Canada, varieties of alcoholic cider are often called hard cider to distinguish it from non-alcoholic apple cider or "sweet cider", also made from apples. In Canada, cider cannot contain less than 2.5% or over 13% absolute alcohol by volume.

This glossary of winemaking terms lists some of terms and definitions involved in making wine, fruit wine, and mead.

<span class="mw-page-title-main">Clarification and stabilization of wine</span> Wine clarification and stabilisation

In winemaking, clarification and stabilization are the processes by which insoluble matter suspended in the wine is removed before bottling. This matter may include dead yeast cells (lees), bacteria, tartrates, proteins, pectins, various tannins and other phenolic compounds, as well as pieces of grape skin, pulp, stems and gums. Clarification and stabilization may involve fining, filtration, centrifugation, flotation, refrigeration, pasteurization, and/or barrel maturation and racking.

<span class="mw-page-title-main">Wine chemistry</span> Chemistry of wine

Wine is a complex mixture of chemical compounds in a hydro-alcoholic solution with a pH around 4. The chemistry of wine and its resultant quality depend on achieving a balance between three aspects of the berries used to make the wine: their sugar content, acidity and the presence of secondary compounds. Vines store sugar in grapes through photosynthesis, and acids break down as grapes ripen. Secondary compounds are also stored in the course of the season. Anthocyanins give grapes a red color and protection against ultraviolet light. Tannins add bitterness and astringency which acts to defend vines against pests and grazing animals.

<span class="mw-page-title-main">Yeast in winemaking</span> Yeasts used for alcoholic fermentation of wine

The role of yeast in winemaking is the most important element that distinguishes wine from fruit juice. In the absence of oxygen, yeast converts the sugars of the fruit into alcohol and carbon dioxide through the process of fermentation. The more sugars in the grapes, the higher the potential alcohol level of the wine if the yeast are allowed to carry out fermentation to dryness. Sometimes winemakers will stop fermentation early in order to leave some residual sugars and sweetness in the wine such as with dessert wines. This can be achieved by dropping fermentation temperatures to the point where the yeast are inactive, sterile filtering the wine to remove the yeast or fortification with brandy or neutral spirits to kill off the yeast cells. If fermentation is unintentionally stopped, such as when the yeasts become exhausted of available nutrients and the wine has not yet reached dryness, this is considered a stuck fermentation.

The topic of sulfite food and beverage additives covers the application of sulfites in food chemistry. "Sulfite" is jargon that encompasses a variety of materials that are commonly used as preservatives or food additive in the production of diverse foods and beverages. Although sulfite salts are relatively nontoxic, their use has led to controversy, resulting in extensive regulations. Sulfites are a source of sulfur dioxide (SO2), a bactericide.

References

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