Is wine good for your health? Be careful when drinking homemade wine

Autumn is the season when grapes ripen. At this time, many people start to make their own wine. Many people think that their own wine is not only delicious, but also can avoid drinking fake wine. They also heard rumors that drinking wine regularly is good for the body.

It is important to note that although homemade wine is low-cost, is it safe? It is said that drinking alcohol is harmful to health, but is drinking wine harmless? In this article, we will talk about homemade wine.

How is home-made wine made?

Wine is an alcoholic beverage made from fresh grapes or grape juice through partial or complete fermentation. The history of wine is quite long. The oldest evidence of wine comes from western Iran, where a wine jar dating back to 6000 BC was excavated with traces of wine at the bottom. Around 700 BC, wine became a standard drink in Greece. At that time, wine was very strong and needed to be diluted with water before drinking. In 200 BC, Italy began to develop wine culture.

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The history of homemade wine in my country has been more than 3,000 years. Grapes can preserve a large amount of tartaric acid, which most microorganisms cannot metabolize, but is very conducive to the growth of yeast. Therefore, grapes are very suitable for winemaking. First, you need to select and process grapes. Choose ripe, soft, thin-skinned, and elastic grape fruits. Wash them with water, but don't use too much force to avoid breaking the fruits. After washing, control the water. Choose a suitable container for cleaning and disinfection. If it is a glass container, you can disinfect it with boiling water and dry it. Rub and crush the dried grapes to squeeze out the grape juice, because many components in grapes are not evenly distributed, such as phenolic substances, which are mainly present in the peel. After crushing, they can be evenly distributed, making the wine better quality. However, because grape stems contain bitter resins and grape seeds contain tannins, these components will bring unpleasant tastes and increase bitterness, so do not crush them when handling them, and it is best to remove them.

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Put the pressed grape juice and peels and pulp into the container, add sugar, stir evenly and seal, and carry out preliminary fermentation at 25℃ for 5~7 days. This is a key step in homemade wine. Grapes contain a lot of sugar when they are ripe, and there is natural glucose yeast on the surface of the peel (so when washing grapes, do not wash off the white frost), and brewing yeast can also be added artificially. Yeast will convert sugar into alcohol and carbon dioxide, producing a lot of gas, so pay attention to exhaust during this period. After the preliminary fermentation is over, gas production will stop. At this time, use gauze to filter the grape skins and pomace, seal for 10~15 days, then turn the cylinder over to remove the bottom sediment, and seal again. The last step is the aging (maturation) of wine in the container, which can further improve the flavor and taste. Complete the transformation from elegant to fragrant, from refreshing to mellow.

Why is wine delicious?

The reason why many people like wine is because of its unique aroma and taste. Some of the aroma of wine is the taste of the grapes themselves, and some is the aromatic components produced after fermentation. During the fermentation process of wine, brewer's yeast can metabolize and produce a variety of aroma-active compounds, such as alcohols, esters and volatile sulfides, which are the three most important types of aroma substances in wine flavor. It can provide fruity aromas for wine, such as apple, pineapple, grapefruit, passion fruit and boxwood.

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After the alcohol fermentation is completed, the wine will also undergo the process of malic acid-lactic acid fermentation, which can reduce the original sourness in the wine and produce several unique aroma compounds, such as diacetyl with a creamy taste, making the wine taste softer. In the later stage of wine maturation, redox reactions and esterification reactions will occur, making the flavor of mature wine more complete and the taste softer. The tannins and some phenolic compounds in the wine will make people feel astringent. In fact, astringency is not a taste, but a sense of touch. Because tannins react with proteins in saliva to form small aggregates and increase friction, the tongue will feel rough; phenolic compounds have a slightly bitter taste. In addition, succinic acid produced during yeast metabolism can increase the umami taste of wine. The sweetness is due to the fructose and glucose contained in the grapes themselves, as well as the sugar added later.

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What are the problems with home brewing wine?

Although wine tastes mellow, home-brewed wine may pose food safety risks. In previous incidents, poisoning due to drinking home-brewed wine is not uncommon. In 2014, Mr. Zhang from Hunan suddenly felt a rapid heartbeat, chest tightness, and blurred vision after drinking home-brewed wine. The doctor said that it was because the methanol in the wine that Mr. Zhang drank exceeded the standard and caused poisoning. In July 2022, Ms. Pan from Chongqing brewed wine by self-study online. After tasting it, her husband experienced dizziness, headache and other poisoning symptoms, so he was sent to the hospital. After analysis, it was not drunkenness but methanol poisoning.

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Therefore, compared with wine produced by regular manufacturers, home-brewed wine still has certain health risks. Mainly in the following four aspects:

1

Methanol content problem

Excessive methanol content is the most common problem in home-brewed wine. Methanol is produced during the winemaking process, which is inevitable. Because grapes contain pectin, which is mainly found in grape skins, pectin will decompose methanol under the action of pectinase or heat energy. Methanol is a neurotoxin. Excessive intake can lead to poisoning, visual impairment and neurological symptoms, and severe cases can lead to blindness or even death. Grape varieties, cleaning conditions, fermentation temperature, yeast strains used, etc. will affect the methanol content. In particular, grape varieties have the greatest impact. Generally speaking, red wine> rosé wine> white wine. The national standard "GB/T15037-2006 Wine" clearly stipulates that the methanol content of red wine must be ≤400mg/L, and the content of white and rosé wines must be ≤250mg/L. Regular manufacturers will test relevant indicators before the wine leaves the factory, but home-brewed wine does not have the conditions for testing, and the methanol content may exceed the standard. In 2015, researchers collected six types of homemade wines and used gas chromatography to detect and analyze the methanol content. The results showed that the methanol content in the six types of homemade wines exceeded the standard, with the highest content exceeding the standard by 1.6 times.

2

Pesticide residues

When choosing grapes, you may choose grapes with more pesticide residues as brewing raw materials. When the grapes are crushed, pesticides will directly contaminate the juice. Although the residual amount of some pesticides will be reduced after fermentation, clarification, filtration and other steps, some pesticides will be metabolized to produce more toxic and harmful components. Residual pesticides will affect the growth and metabolism of yeast during the winemaking process, and will also affect the quality, taste and color of the wine, and may also cause the wine to have an unpleasant odor.

3

Hygiene issues

The sanitation of homemade wine is difficult to control, and there are problems such as poor sanitary conditions and a large number of bacteria. The disinfection of containers and the washing of grapes may not be thorough. This will increase the risk of bacterial contamination during the winemaking process, especially when homemade wine is made in plastic barrels, which will also produce harmful ingredients and endanger health.

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Using plastic barrels to hold alcoholic liquids will allow phthalates to seep into the liquid. Phthalate is a plasticizer and a toxic compound that cannot be found in food. However, the solubility of phthalates in alcohol is much greater than that in water. If plastic containers are used to hold alcoholic liquids, it is easy for phthalates to seep into the wine. The higher the alcohol content, the higher the content. This can contaminate food and harm health.

4

There is a risk of explosion

During the wine brewing process, gas is produced and it needs to be deflated in the middle. If you open the wine and deflate it in the middle, it is easy to be contaminated by bacteria. If you do not deflate it, there may be a risk of the bottle exploding. In addition, the fermentation temperature is not easy to control during the homemade wine making process, which will affect the quality of the wine. Therefore, I advise you not to try to make your own wine. In addition to homemade wine, other homemade and pickled foods should also be vigilant about food safety issues!

Is drinking wine regularly good for your health?

Whether it is homemade wine or wine produced by regular manufacturers, most people will silently comfort themselves when drinking wine: "It's okay to drink more wine, it's good for blood vessels and heart!" Is it really like this? The rumor that drinking wine is good for blood vessels is because a study shows that drinking wine properly can increase high-density lipoprotein cholesterol. This is "good cholesterol", which is good for the health of blood vessels and helps to lower the "bad cholesterol" in blood vessels, that is, low-density lipoprotein cholesterol, thereby reducing the risk of coronary heart disease. However, the "Guidelines for the Prevention and Treatment of Dyslipidemia in Adults in China (Revised Edition 2016)" and the "Guidelines for the Dietary Care of Adults with Hyperlipidemia (2023 Edition)" clearly state that although moderate drinking can increase high-density lipoprotein cholesterol, even a small amount of drinking will further increase the triglyceride level of patients with hypertriglyceridemia, which is not conducive to cardiovascular health.

Wine is also alcohol, and drinking it can also threaten the cardiovascular system.

The "Guidelines for the Prevention and Treatment of Dyslipidemia in Chinese Adults (2016 Revised Edition)" states that moderate drinking is 20-30 grams of ethanol per day for men and 10-20 grams of ethanol per day for women. Taking 13% VOL wine as an example, this ethanol content is equivalent to 153-230 ml for men and 76-153 ml for women. Many people drink far more than this amount!

Some people also say that wine contains resveratrol, which is a polyphenol compound with antioxidant properties. It has the functions of protecting cells from damage, preventing diabetes, reducing the risk of cancer, and protecting the heart. Most of the research on resveratrol is limited to animal experiments. There is less data in human experiments, and the optimal dose of resveratrol has not yet been determined in human studies. Some studies mentioned that the effective dose of resveratrol for animals is extrapolated to humans, and the effective dose for humans is 1 gram/day. In the production process of wine, the content of resveratrol will be affected by various factors, including temperature, pH value and other factors. Data show that the resveratrol concentration of red wine is 0.361~1.972 mg/L. Judging from this data, if you want to meet the daily intake of 1 gram of resveratrol by drinking red wine, you need to drink hundreds of bottles of red wine.

It can be clearly stated that this amount is extremely unhealthy and cannot be consumed! Besides, resveratrol is found in grapes, apples, blueberries, plums, and peanuts, so there is no need to drink wine.

In addition, a 2018 Lancet Global Alcohol Health Burden Assessment showed that there is no safe amount of alcohol, and not drinking a drop of alcohol is the lowest health risk. In summary: Wine is indeed delicious, but homemade wine may have health risks, so be cautious. For health, it is important to control the amount of alcohol you drink, and it is best not to drink it. Don't lose the big picture for the so-called "health benefits".

References

[1] Harold Mackey, Food and Cooking. Pasta, Sauces, Desserts, Beverages. Beijing Fine Arts Photography Publishing House. August 2013.

[2] Huang Shengjun. Method and technology of home brewing red wine[J]. Gansu Agriculture, 2006(01):208.DOI:10.15979/j.cnki.cn62-1104/f.2006.01.213.

[3] Zhao Shanshan, Li Minmin, Chen Jieyin, Tian Jian, Kong Zhiqiang, Dai Xiaofeng. Research progress on the changes of pesticide residues and their interference with flavor quality during winemaking[J]. Food Science, 2022, 43(01): 223-231.

[4] Wang Yuhong, Li Meijuan, Sun Ruilin, Yang Huihui, Zheng Qiliang. Study on the methanol content in home-brewed wine[J]. Freshness and Processing, 2018, 18(05): 107-111.

[5] Zhang Guangfang, Zeng Guifeng, Zeng Lingwen. Detection and analysis of methanol and miscellaneous alcohols in home-brewed wine[J]. China Food Additives, 2016(05):141-146.

[6] Liu Xiufeng, Chen Dongwan, Lü Jinchang, Gao Peng, Li Yongjin, Yang Dajin. Detection of 18 phthalate plasticizers in some commercially available liquors in Beijing[J]. Chinese Journal of Health Laboratory Technology, 2016, 26(03): 347-349.

[7] Chen Tongqiang, Li Can, Guo Jincai, Xiang Jun, Xu Wenyang, Yi Shoufu, Li Kailong. Study on the control of methanol content in home-brewed wine during brewing[J]. China Brewing, 2021, 40(02): 193-197.

[8]SabineWeiskirchen,RalfWeiskirchen,Resveratrol:HowMuchWineDoYouHavetoDrinktoStayHealthy?, AdvancesinNutrition,Volume7,Issue4,July2016,Pages706–718, https://doi.org/10.3945/an.115.011627

Author: Xue Qingxin, one of the first nutrition instructors of the National Health Commission, and a registered nutritionist in China

Review丨Zhang Na, PhD Supervisor, Associate Researcher, Peking University School of Public Health