Consumer watchdog reveals nutritional benefits and safety concerns in popular Chinese soup ingredients
Hong Kong’s Consumer Council has released a comprehensive study on 28 pre-packaged dried edible fungus samples, revealing that while all products contained trace heavy metals, only two snow fungus items raised pesticide-related concerns. The findings, published in the council’s Choice magazine issue 556, offer consumers both reassurance and practical guidance.
Study Methodology and Scope
Between August and September 2022, researchers collected samples from supermarkets, department stores, and specialty food shops across Hong Kong. The study examined 10 varieties of black fungus (黑木耳), 9 varieties of white-back wood ear (白背木耳), and 9 varieties of snow fungus (雪耳). Each sample underwent rigorous testing for soluble and insoluble fiber content, three mineral types (calcium, iron, and potassium), six metal contaminants (including arsenic, cadmium, chromium, lead, mercury, and antimony), pesticide residues, and two preservatives (benzoic acid and sulfur dioxide).
Nutritional Findings: Fiber and Mineral Content
Fiber Content Highlights
Snow fungus emerged as the leader in water-soluble fiber, with every sample meeting the “high” classification. The average content reached 11.1 grams per 100 grams of dried product. The “Organic Dried Snow Fungus” from Green Dot (點點綠) topped the category with 18.4 grams. In contrast, white-back wood ear averaged 5.6 grams, while black fungus contained only 3.4 grams.
A single 10-gram serving of dried snow fungus provides 1.1 grams of soluble fiber and 4.8 grams of insoluble fiber—equivalent to 24 percent of an adult’s daily recommended fiber intake.
All samples demonstrated high levels of insoluble fiber, ranging from 40.9 to 68.6 grams per 100 grams. The “Eu Yan Sang White-Back Black Fungus” (余仁生 白背黑木耳) led this category. A 10-gram serving of white-back wood ear delivers 6.5 grams of insoluble fiber and 0.6 grams of soluble fiber, meeting 28 percent of daily fiber requirements.
Mineral Content Comparison
Black fungus proved richest in calcium, containing 443 milligrams per 100 grams—3.6 times more than white-back wood ear and 10 times more than snow fungus. The “Hang Hing Hong Single Leaf Cloud Ear” (恒興行 單葉雲耳) ranked highest with 662 milligrams per 100 grams.
Iron content followed a similar pattern, with black fungus averaging 16.2 milligrams per 100 grams, compared to 4.6 milligrams for white-back wood ear and just 0.2 milligrams for snow fungus. “Jing Yun Wild Black Fungus” (菁雲 野生黑木耳) led the iron category at 42.1 milligrams per 100 grams.
Snow fungus dominated potassium levels, averaging 2,908 milligrams per 100 grams. The “Zhen Dian Gutian Snow Fungus” (珍殿 古田雪耳) sample contained 3,270 milligrams per 100 grams. Black fungus and white-back wood ear contained only 898 milligrams and 450 milligrams, respectively.
Safety Assessment: Pesticides and Heavy Metals
Pesticide Residue Concerns
The council detected at least one pesticide in over 40 percent of samples (12 products). Two snow fungus items raised particular concern:
The “Green Dot Organic Snow Fungus” contained four pesticide residues, including abamectin B1a at 0.29 milligrams per kilogram, reaching Hong Kong’s maximum residue limit under the Pesticides Ordinance. For context, a 4-year-old child weighing 17 kilograms would need to consume over 59 grams (approximately six cooked bowls) daily, while a 60-kilogram adult would require 207 grams (about 21 cooked bowls) to face potential health risks.
The “Yan Yee Tong Selected Snow Fungus” (仁御堂 精選銀耳) tested positive for two pesticides, with propargite levels at 0.28 milligrams per kilogram, exceeding European Union limits. A child would need to eat 607 grams (61 bowls) and an adult 2.1 kilograms (214 bowls) daily for visible health effects.
Heavy Metal Contamination
All 28 samples contained detectable levels of metal contaminants, including total arsenic, cadmium, chromium, lead, and total mercury. However, the council emphasized that concentrations remained well below safety thresholds, posing no health risk under normal consumption patterns.
Practical Consumer Guidance
Soaking and Storage Recommendations
The council warns against prolonged soaking, recommending no more than two hours to prevent bongkrekic acid poisoning. Contaminated fungus can cause abdominal pain, vomiting, and in severe cases, liver dysfunction or death. For overnight soaking, refrigerate the fungus immediately. Leftover cooked fungus should be refrigerated at 4 degrees Celsius or below within two hours of cooking.
Price Does Not Equal Quality
Sample prices ranged from HK$12 to HK$99 per package, with per-100-gram costs varying between HK$7.9 and HK$130.3. Notably, the cheapest black fungus and white-back wood ear samples achieved 4.5 to 5-star ratings in overall assessments, demonstrating that affordable options can deliver excellent quality.
Top-Rated Products
5-Star Overall Rating (per 100g price)
- Black Fungus: Green Saint (綠の聖) – HK$37.7
- White-Back Wood Ear: Hong Kong Qi Tai (香港啟泰) – HK$26.7; Shang Pin (尚品) – HK$15.0; Tong Xin Tang (同心堂) – HK$14.7; Golden Imperial (金御膳) – HK$11.0; On Kee Dried Seafood (安記海味) – HK$9.3; Nam Pei Hong (南北行) – HK$18.7; Sheung Sheung (老上環) – HK$7.9
- Snow Fungus: Yu Wan Jia (御萬家) – HK$27.8
4.5-Star Overall Rating (per 100g price)
- Black Fungus: Yu Pin Huang (御品皇) – HK$30.8; Hua Run Tang (華潤堂) – HK$23.3; Hang Hing Hong (恒興行) – HK$72.5; Mei Wei Zhan (美味棧) – HK$25.0; Dai Zhan (大棧) – HK$32.4; Tai Sang Dried Seafood (大生海味) – HK$24.0; Wai Yuen Tong (位元堂) – HK$60.0
- White-Back Wood Ear: Guang Da (光大) – HK$10.5; Eu Yan Sang (余仁生) – HK$30.9
- Snow Fungus: Zan Ji (盞記) – HK$45.0; Guan Yan Zhan (官燕棧) – HK$46.0; Sheung Sheung (樓上) – HK$130.3
Looking Forward
Consumers can confidently include these nutritious fungus varieties in their diets while following proper preparation practices. The council advises checking product labels and purchasing from reputable sources. For those monitoring pesticide intake, selecting top-rated products provides an additional safety margin. As dietary preferences shift toward plant-based nutrition, these findings help Hong Kong families make informed choices about affordable, fiber-rich ingredients.