Sulfur smoked star anise contains 16 times more sulfur dioxide than the standard. Can we still eat it safely?

Star anise is a common condiment in our homes, and it is indispensable for making all kinds of delicious dishes. However, a recent media report said that a market in Guangxi used sulfur to smoke star anise, resulting in sulfur dioxide residues reaching 500mg/kg, more than 16 times the standard.

Why is star anise smoked with sulfur? Can we still eat star anise safely?

01

Sulfur dioxide is also found naturally in food

When it comes to sulfur dioxide, many people first think of it as a toxic gas. But in fact, sulfur dioxide is naturally present in many foods we eat, and star anise is no exception.

During the growth of star anise, sulfur dioxide in the atmosphere will enter the plant through the stomata on the leaves, and other bound sulfur dioxide in the soil or water will also enter the plant through the plant's absorption. The incoming sulfur dioxide easily reacts with aldehydes and ketones in the plant, especially sugar compounds, to generate bound sulfurous acid.

Therefore, there is a certain amount of free and bound sulfur dioxide in plants, and its content is related to the degree of air pollution.

In addition, differences in varieties, cultivation methods and growth environments will also cause differences in the sulfur dioxide content in the body, which we call the background value.

The background value of sulfur dioxide in common foods shows that sulfur dioxide is present in many foods.

Many foods contain background levels of sulfur dioxide. According to current data, the background levels of sulfur dioxide in wheat flour and sugar are relatively high. The background level of sulfur dioxide in star anise is estimated to be about 0.079 g/kg, and is generally between 0.01-0.16 g/kg.

02

Sulfur dioxide is a commonly used food additive

In addition to natural existence, most people are concerned about the artificial addition of sulfur dioxide. In fact, sulfur dioxide is also a food additive in the food industry and is widely used.

As early as the 16th century, the Dutch discovered that during the brewing and storage of wine, sulfur fumigation or the addition of a small amount of sulfur could effectively prevent oxidation and sourness, thereby ensuring the stability of the wine quality and a fresh taste.

Sulfur dioxide can be used in many foods. For example, in the preservation or peeling, cutting and other processing methods of fruits, edible fungi, bamboo shoots, yam and other vegetables, it is used for its antiseptic, sterilization and preservation. Sulfur dioxide can also be used to protect the color of dried fruits and vegetables. After sulfur fumigation, the appearance of colored dried fruits and vegetables can be bright. Thanks to the bleaching of sulfur dioxide, we can eat white sugar.

03

Can sulfur dioxide be used in star anise?

Star anise is easy to attract insects and mold. Therefore, during production and transportation, we must pay attention to insect prevention and color protection. Fumigation with sulfur can prevent corrosion and insects, which is why merchants do this.

Previously, if businesses used sulfur fumigation for preservation, it was illegal. But on May 20, 2019, the National Health Commission issued the "Announcement on 24 "Three New Foods" Including Lactobacillus curvatus (No. 2 of 2019)", which expanded the scope of application of sulfur as a preservative and added star anise. (However, this standard has not been implemented in many places.)

Announcement on 24 “Three New Foods” Including Lactobacillus curvatus (No. 2 of 2019)

According to this announcement, sulfur can be used to fumigate star anise, but the residual sulfur dioxide is 0.15g/kg, or 150mg/kg. According to news reports, the residual sulfur dioxide in the sulfur star anise sent for inspection reached 500mg/kg. From various standards, the residual sulfur dioxide exceeded the standard, and the merchant violated the regulations.

04

Can I still eat star anise with confidence?

A study in my country analyzed the residual risk of sulfur dioxide in 27 common foods. The results showed that pickled vegetables, canned vegetables (limited to bamboo shoots and sauerkraut), dried fruits and edible starch are the four types of food that we consume the most sulfur dioxide, and the residual levels are also relatively high, but the overall risk is still within the acceptable range for the human body.

We usually eat very little star anise. It is usually used as a seasoning, and only a few are used. Moreover, sulfur dioxide evaporates easily, so when star anise is used to cook dishes, there is basically no residue.

In daily life, it is recommended that you purchase products produced by regular manufacturers through regular supermarkets or e-commerce platforms, and avoid buying star anise in bulk.

References:

[1]. Zhu Yutian, Peng Jianfei, Chen Shiyu, et al. Research progress on background values ​​of endogenous chemical pollutants in food[J]. Chinese Food Additives, 2015, (8): 149-153.

[2]. Gu Yuxiang, Wang Dinglin, Chen Yufei. A review of naturally occurring food additives in food[J]. Journal of Food Safety and Quality, 2017, 8(6): 2312-2317.

[3]. Du Yegang, Li Bifang, Deng Wujian, et al. Analysis of background values ​​of naturally occurring chemical pollutants in food[J]. Chinese Food Additives, 2013, (2): 165-168.

[4]. Guo Xuguang, Yin Yuyun, Ren Mengke. Determination of sulfur dioxide background value in three spices by titration[J]. Chinese Journal of Food Hygiene, 2019, 31(3): 246-249.

[5]. Liao Yanhua, Liu Zhanhua, Chen Kun, et al. Analysis of sulfur dioxide residue detection results in star anise in Guangxi Province and discussion on health standards [J]. Chinese Journal of Food Hygiene, 2014, 26(5): 486-488.

[6] Announcement on 24 “Three New Foods” including Lactobacillus curvatus (No. 2 of 2019)

[7]. Hu Guixian, Lai Aiping, Yuan Yuwei, et al. Cumulative risk assessment of sulfur dioxide residues in consumers' diets[J]. Chinese Agricultural Science, 2017, 50(7): 1317-1325.