Many people are used to putting a few medlar into soup, water and Congee, hoping that they can benefit their health. However, if the color of the goji berries you buy is too rosy, it may be harmful and not beneficial, as such goji berries may have been dyed. So, what are the safety hazards of dyeing goji berries, and how should consumers distinguish them? Professor Liu Shaowei, a member of the expert group of the Shanghai Food Safety Research Association, said in an interview with the China Consumer Daily that there are two main situations people often talk about dyeing goji berries. One is to use coloring agents to enhance the appearance of aged goods, making the appearance of goji berries look bright and attractive; Another method is to fumigate the picked goji berries with sulfur to make their skin dry and bright, which not only prevents insects but also makes it difficult to absorb moisture, thereby extending their shelf life. Liu Shaowei explained that goji berries have a high sugar content, with a total sugar content of over 10 grams in 100 grams of fresh goji berries, which is beneficial for microbial growth and also attractive to insects. In addition, goji berries contain carotenoids and polyphenols, which are prone to enzymatic reactions and browning, affecting the appearance and sales of goji berries. The use of sulfur dioxide for pest control and color protection is the most commonly used method by people. According to the national standard GB2760-2011 "Food Additive Standard Regulations", sulfur dioxide and its sulfites can be used in various types of food such as dried fruits, candied fruits, and dried vegetables, but there are very strict limits on residue levels. Generally speaking, the residual sulfur dioxide in goji berries should not exceed 50 mg/kg or 100 mg/kg. Liu Shaowei pointed out that currently, the main problem with the smoking of goji berries is that some unscrupulous vendors use industrial sulfur, which is strictly prohibited for use in food, and some excessively use sodium metabisulfite, resulting in excessive sulfur dioxide levels. The Joint Expert Committee on International Food Additives (JECFA) and the World Health Organization (WHO) have established a daily safe intake limit of sulfur dioxide per person not exceeding 0.7 milligrams per kilogram (intake per kilogram of body weight). For example, an adult weighing 60 kilograms should not consume more than 42 milligrams per day. If you only eat goji berries as seasoning or side dishes, it may not be a big problem. But if taken as medicine or soaked in water every day, the risk is relatively high. Especially for people who are sensitive to sulfur dioxide, such as asthma patients, the intake of sulfur dioxide may cause symptoms such as nausea, vomiting, abdominal pain, dizziness, and difficulty breathing. Liu Shaowei reminded that natural goji berries are mostly red or slightly dark red in color, as well as darker carrot red. Stained or fumigated goji berries are mostly bright red and relatively uniform. Soak them in clean water for about 20 minutes, and the color of the water will turn red; Good goji berries have a natural and fragrant aroma, while those smoked with sulfur have a more vibrant color and a strong or light pungent smell, which can be sour, bitter, and astringent when eaten. (Lixin News Agency) (Reporter Li Jian)