HONG KONG – A comprehensive safety and nutritional analysis of common dried edible fungi varieties by the Hong Kong Consumer Council (CC) has revealed concerning levels of pesticide residues in two snow fungus samples, alongside widespread detection of heavy metals across all tested products. The investigation, conducted between August and September 2022, scrutinized 28 pre-packaged samples of black fungus, white-back fungus, and snow fungus, staples in traditional Chinese cuisine, to assess their quality, nutritional profile, and safety compliance.
The CC’s findings highlight potential safety lapses in specific snow fungus products, while simultaneously offering consumers valuable insights into the nutritional benefits—particularly high fiber and mineral content—of these dietary fungi. Though the concentration of contaminants poses low immediate risk under typical consumption patterns, the report emphasizes the need for careful sourcing and proper food preparation to mitigate long-term health concerns.
Safety Concerns Raised Over Snow Fungus Contamination
The safety assessment focused on critical risks, including six types of heavy metal contaminants, pesticide residues, and two preservatives (benzoic acid and sulfur dioxide). While all 28 samples contained detectable levels of heavy metals such as lead, cadmium, and total arsenic, the concentrations remained significantly below regulatory limits, leading the CC to conclude they pose negligible health risks under normal consumption.
However, the CC detected residues of at least one pesticide in over 40% (12) of the samples. Two snow fungus products specifically exceeded established maximum residue limits (MRLs).
One product, “Dot-Dot-Green Organic Silver Ear,” was found to contain four types of pesticide residues. Its level of Abamectin B1a reached 0.29 mg/kg, meeting the maximum residual limit stipulated under Hong Kong’s Pesticides Regulation for edible fungi. The council noted that a child weighing 17kg would need to consume 59 grams daily (approximately six bowls cooked) and an adult (60kg) 207 grams (about 21 bowls cooked) for this level to potentially pose a health risk.
Another product, “Yan Yu Tong Selected Silver Ear,” detected Propargite at 0.28 mg/kg, exceeding the maximum permitted limits set by the European Union. The report indicated that for this product to pose a risk, a child would need to eat over 607 grams daily (61 cooked bowls), or an adult 2.1 kilograms (214 cooked bowls). The CC cautioned that because these fungi are dried, the lack of moisture naturally concentrates these substances.
Nutritional Powerhouses: Fiber and Minerals
Beyond safety, the study confirmed the substantial nutritional value of dried fungi, particularly their high levels of dietary fiber and essential minerals (calcium, iron, and potassium).
Snow fungus emerged as the superior source of soluble fiber, with all samples meeting the definition of “high-fiber” food. The average soluble fiber content was 11.1 grams per 100 grams, providing significant digestive benefits.
In terms of minerals:
- Black Fungus contained the highest levels of calcium (average 443 mg/100g) and iron (average 16.2 mg/100g). A 10-gram serving of dry black fungus contributes roughly 44 mg of calcium, critical for bone health.
- Snow Fungus was the highest in potassium, averaging 2,908 mg per 100 grams, a key mineral for managing blood pressure.
Consumer Advice and Preparation Safety
The Consumer Council emphasized that the quality of these products does not always correlate with price. Several black fungi and white-back fungi samples with the lowest per 100-gram prices received excellent overall ratings (4.5 to 5 stars) in safety and quality assessments.
Crucially, the CC issued a stern warning regarding proper soaking techniques to prevent food poisoning, specifically Bongkrekic acid (米酵菌酸) toxicity, which can result from bacterial contamination if the fungi are left at room temperature for too long.
Key Safety Takeaways for Consumers:
- Soaking Time: Do not soak dried fungi for more than two hours at room temperature.
- Overnight Soaking: If prolonged soaking is necessary, the fungi must be kept refrigerated at 4°C or below.
- Leftovers: Store cooked leftovers in the refrigerator within two hours of preparation to minimize bacterial growth and the formation of nitrates.
The publication of the full results, including a list of five-star rated products such as “Green’s Best Black Fungus” and “Eu Yan Sang White-Back Fungus,” provides an actionable resource for consumers seeking safe and high-quality dried edible fungi options in the Hong Kong market.