As a food additive, sulfur dioxide has many functions. […]
As a food additive, sulfur dioxide has many functions. The most important thing is its reducibility. It can bleach some pigments and inhibit the oxidation of polyphenols to avoid browning. For example, wine, without the color of antioxidants, will gradually become darker; and bamboo shoots, mushrooms, etc., will soon turn black without "protection".
In addition, sulfur dioxide has bactericidal and antiseptic properties. This effect is perfect for the grape juice extraction process, because the grape juice needs to inhibit the growth of the bacteria, and the fermentation needs to kill the yeast. Dried fruits, dried vegetables, seasoning powder and other foods are also often preserved by sulfur dioxide fumigation.
This "multiple art" ability is relatively rare, especially in the wine and fruit wine brewing process, has not found a good alternative.
In addition to sulfur dioxide itself, various compounds capable of producing sulfur dioxide, such as potassium metabisulfite, sodium metabisulfite, sodium sulfite, sodium hydrogen sulfite, sodium hyposulfite, etc., are used in food production. These compounds are added to foods which release sulfur dioxide during processing. National standards put these substances together and manage them, limiting the “residue of sulfur dioxide”. That is to say, regardless of the amount of addition, as long as the final residue is qualified.
In the national standard, there are 25 types of foods that can use the sulfur dioxide produced by these substances as additives, such as dried vegetables and fruits, nuts, flour, vegetable juice, juice, fruit wine and so on.
In addition, the use of sulfur fumigation is also the use of sulfur dioxide, such as dried fruit, candied fruit, dried vegetables, fresh mushrooms and so on. When fumigating, some sulfur dioxide will adhere to the food, and the control standard is also for the residual amount of sulfur dioxide.
Sulfur and sulfur dioxide-producing compounds are not expensive, and the function of sulfur dioxide is “the more used, the better the effect”, so it is often reported that sulfur dioxide is “excessively used”.
In fact, sulfur dioxide is not low for most people, so the safety standards are set more stringent. Mainly some people are allergic to sulfur dioxide, especially in asthma patients. The amount of sensitive symptoms required by different people is not the same. Symptoms of mild nausea, vomiting, severe symptoms may cause dizziness, difficulty breathing, and the most serious may be life-threatening.
The safety standard for sulphur dioxide developed by the Joint Expert Committee on Food Additives (JECFA) is 0.7 mg per kilogram of body weight per day, equivalent to 42 mg per day for a 60 kg adult. The meaning of "safety standards" is that even if you consume so much sulfur dioxide every day, it will not harm your health.
The amount of sulphur dioxide remaining allowed in different foods varies, and the allowable levels of wine and fruit wine are relatively high. The US limit is 350ppm and China is 250ppm. That is to say, from the United States purchasing wine, the sulfur dioxide content may exceed the Chinese national standard and become a non-conforming product.
For "sweet" wines or fruit wines, the Chinese standard has been relaxed to 400ppm. However, the sulfur dioxide content in actual products is generally not so high, and the test results in the United States are about 100 ppm on average. According to this average, 400 ml of wine contains 40 mg of sulfur dioxide, which is basically close to the maximum intake of the human body. If you are reaching a maximum of 400ppm "sweet" wine, you can reach the maximum intake of sulfur dioxide by drinking 100ml.
Residues of sulphur dioxide in other foods are usually less, and the amount consumed is usually less, making the possibility of “exceeding the standard” less than that of wine.
All in all, sulfur dioxide has important value in food processing. As long as it does not exceed the national standard limit, there is no need to worry about harm to health. What needs to be vigilant and opposed is that the excess of sulfur dioxide caused by “over-use” exceeds the standard, rather than panic when it comes to seeing sulfur dioxide.