Limitations of the Megazyme YBGL Kit for Measuring β-Glucans in Medicinal Mushrooms
β-Glucans are an important class of natural bioactive polysaccharides mainly found in fungi, mushrooms, yeast, and cereal grains such as oats. β-Glucans from different sources vary in molecular weight, molecular structure, branching positions, and glycosidic bond types, leading to substantial differences in their physiological activities and bioavailability. Mushroom β-glucans, with their complex structures, exhibit pronounced bioactivities, including immune modulation, antimicrobial and anti-inflammatory effects, regulation of glucose and lipid metabolism, antioxidant activity and so on.
In the mushroom industry, β-glucan content is commonly determined using the YBGL assay kit developed by Megazyme in 2016. This method determines total glucan and α-glucan levels, with β-glucan content calculated as the difference between total glucan and α-glucan. Because α-glucan content in fruiting body products of medicinal mushrooms (e.g., powders or extracts) is typically below 5%, this kit is often used to identify the addition of dextrin, starch or mycelium powder. However, after years of use, we have found that the YBGL assay kit has certain limitations, which are summarized as follows.
1.The YBGL kit is capable of measuring β-glucans from both yeast and mushrooms; however, it does not differentiate their biological origins. β-Glucans from yeast are generally insoluble in water, whereas those from mushroom extracts exhibit higher water solubility.
2.When measuring the same mushroom species with the YBGL kit, β-glucan content in whole mushroom powders often appears significantly higher than in extracts. This is mainly because powders contain large amounts of water-insoluble β-glucans, which are poorly absorbed, whereas the water-soluble β-glucans in mushroom extracts are more easily absorbed by our body.
3.The YBGL kit is not able to identify potential interference from some added ingredients. For instance, adding synthetic polydextrose can make the β-glucan content appear much higher. Polydextrose is a water-soluble dietary fiber made from glucose, sorbitol, and citric acid through heating and polymerization. Its presence can cause the YBGL kit to give misleadingly high β-glucan readings.
4. The YBGL kit is not universally applicable for the determination of β-glucan in all mushroom products. For example, when the updated 2023 YBGL assay kit was used to test products such as Cordyceps militaris and Grifola frondosa (commonly known as Maitake mushroom), the measured β‑glucan values were unexpectedly low, and in some cases, such as the maitake extract, the results were even negative. This is inconsistent with the literature, which reports that β‑glucan is the main active polysaccharide in maitake. From another perspective, if this kit produces a high β‑glucan result for a maitake extract, it may instead indicate the presence of non‑mushroom-derived components in the product rather than authentic mushroom derived β‑glucan.
On November 28, 2025, Mr. Baojun Yu, China Regional Manager of Megazyme (a product line of Neogen), visited our company together with a market expert and a technical specialist. During the visit，both parties engaged in a constructive discussion regarding the observed limitations of the YBGL kit in testing mushroom products. Mr. Yu expressed his appreciation for Biosan’s long‑term trust in and continued use of Megazyme products, and stated that the issues raised would be reported to Megazyme’s headquarters in Ireland for further investigation and optimization.
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