User:Vocalrovezitis/sandbox

Wine and preservatives
For more types of preservatives,Wine preservatives are used to prevent oxidation and bacterial spoilage by inhibiting microbial activity. Although alcohol itself is a natural preservative, most wines are made with extra preservatives to ensure quality. There are two main categories of preservatives, natural and chemical. Among them, the most common natural preservatives are tannin, sugar and alcohol. The typical representative of chemical preservatives is sulfur dioxide and its related chemicals.

Red wine can be embalmed through physical preservatives, such as storage at an appropriate temperature. But the more effective and common method is the chemical method, the preservative additive.

In addition to extending the shelf life of red wine, these chemicals can also cause health problems. For example, people who are allergic to preservatives may be allergic to asthma patients with some complications. There have been reported that propionic acid is a carcinogen, and this has been proved in performances on rodents.

The main function of wine preservatives is to preserve and prolong the flavor of wine without affecting its taste and quality. Many people think that wine is so alcoholic that bacteria can't grow in it, and they shouldn't need preservatives. In fact, wine can spoil, also need to use preservatives.Wine is made from the fermentation of grape juice, which contains a lot of sugar. During the fermentation process, yeast will convert them into alcohol. Generally speaking, the more the fermentation, the more complete the transformation. But there is still sugar in wine, especially if the process conditions are not controlled properly in the process of making wine, such as incomplete fermentation and high residual sugar content, it will provide nutrients needed for the growth of miscellaneous bacteria, which can further deteriorate the wine and even turn into grape vinegar.

And even when fermented into wine, the bacteria can still grow. Because the alcohol content of wine is usually low, and can not inhibit the proliferation of bacteria, if long-term improper storage may accelerate deterioration. So, adding preservatives is a necessary step.As wine reaches a wider and wider audience, the study of wine preservatives is essential.

Preservatives are commonly used in wine
During the brewing process, microbial spoilage can lead to the deterioration of wine quality and taste, making it unhygienic and unacceptable to consumers. The main bacterial groups are yeast, candida, Hanseniaspora and so on. In addition, microbial diseases of wine are mainly caused by yeast, lactobacillus and acetic acid bacteria. This is because yeast may re-ferment a wine with high sugar content, making it cloudy and impure. Lactic acid bacteria can cause acid spoilage in dry wine with low acidity and lactic acid bacteria disease in sweet wine with low acidity. Acetic acid bacteria may cause the increase of volatile acid in wine, resulting in an undesirable sour vinegar taste. These fungi are all bad for the safety and flavor of wine. Anything that extends the shelf life of red wine is considered a preservative. Preservatives are mainly divided into natural preservatives and chemical preservatives.

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

Sugar
Just as people use a lot of sugar or salt when making preserved foods, sugar is also a better choice as a preservative for wine. The sugar enters the food liquid to produce the concentration difference, because osmosis causes the food to dehydrate, forms the environment which the bacterium is not easy to grow, achieves the anticorrosive goal. Salt is used as a preservative in the same way.

Alcohol
Alcohol used as a preservative especially in spirits such as sherry. Because common alcohol can have the problem that is mentioned in the acid part, the lack of acidity does not play the role of maintaining quality.

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. Acid protects wine from bacteria by regulating the ph value, which affects the growth and vitality of yeast during fermentation. Acidity also directly affects color, balance and taste.

For example, sulfur dioxide, the most widely used preservative by wine merchants, has been used as a cleaning agent for centuries. Sulphur dioxide has a pungent taste that people dislike, and its use has been controversial because of its disease-causing properties (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. It must be effective in wines with an alcohol concentration of 12%.

Apart from sulfur dioxide, which is used most frequently, other chemicals such as benzoic acid, diethyl pyrocarbonate, parabens, pimaricin andsorbic 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 difficult to be used in large quantities for the time being.

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. Weak acids inhibit microbial growth by dissociating protons from cells. And 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. This practice was first discovered by John Evelyn in 1670, who used sulfur dioxide from burning sulfur to preserve cider.

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

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.

In addition, may also use oak, oak slices, fermentation agents, tutu, and so on, according to the quality of grapes and the different styles of wine, the need for additives and the amount of different, at the same time different winemakers make different choices.

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. Also, because different kinds of wine have different aromas, colors, and flavors, they should not use the same preservatives. For example, the preservatives added to white wine are mainly ascorbic acid (vitamin C) and sorbic acid. Ascorbic acid is used as an antioxidant, while sorbic acid is used to inhibit the growth of yeast in white wine. 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. Their principle is basically to make microbial protein coagulation or denaturation, thereby interfering with their growth and reproduction. Sulfites are mainly in the form of sulfur dioxide at different PH concentrations. And experiments show that only the sulfur dioxide molecule has antibacterial effect. That's the active ingredient in preservatives. Sulfur dioxide inactivates by combining with compounds derived from wine. Because of the nature of sulfur dioxide, it is more effective at lower PH concentrations and at higher ethanol concentrations. Finally achieving the function of anticorrosion.

Preservatives controversy
Allergy to preservatives has aroused people's concern. Studies have shown that a possible cause of allergy in wine ingredients is an adverse reaction of sulphur dioxide to asthma patients. Sulfur dioxide allergy was the cause of 1.7% of asthma patients. So it's not a very precise statement to say that you are allergic to preservatives, but rather that you are allergic to preservatives that contain sulfur dioxide. But the controversy over preservatives has not entirely disappeared. Because sulfur dioxide is still the most widely used preservative in wine at this stage, it is effective and no alternative chemical additive has been found.

People are concerned about their health and have higher and higher requirements on food quality. Because of the controversy, disease-causing preservatives have been used as sparingly as possible. Or clearly labeled on the outside of the wine to make it easier for people with the disease to find out. Meanwhile, People are increasingly looking for safe and healthy wine preservatives.

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

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. 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. In the meantime, sulfite accumulates can decompose sulfur dioxide, also have certain stimulation to lung .Therefore, some people are urging that sulfur dioxide be banned as a preservative, food additive, in wine and other food and beverages .Propionic acid, which is also used as a preservative, has also been shown to be carcinogenic in rodents .However, there are currently only two ways to minimize the health threat of sulfur dioxide. One is to try to reduce the dose of sulphur dioxide, which is already happening. The second is to study the chemical structure and characteristics of sulfur dioxide, looking for alternative chemical preservatives. This requires a lot of scientific research efforts and has not seen effective results in a short time.

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