Comparision of total dietary fiber content of mushrooms under different growing conditions and between the analytical methods

Abstract

The content of total dietary fiber was compared for Shiitake (Lentinus edodes), Maitake (Grifola frondosa, including those growing wild) and Nameko (Pholiota nameko, in cluding those growing wild) mushrooms, which are produced and consumed in large amounts, that were cultivated on logs and on medium. As a result, the amounts of total dietary fiber and chitin per 100g in terms of the mean and standard deviation of the dry matter for Shiitake cultivated on logs (n=35) were 47.3±3.41% and 5.3±0.91%, while those for Shiitake cultivated on medium (n=24) were 45.1±5.02% and 4.6±0.45%, respectively.
In the case of Maitake, the values for Maitake on growing wild (n=13) and on logs (n=7) were 47.1±3.07% and 3.1±0.23%, and 48.8±5.90% and 3.5±0.38%, respectively, while the values for Maitake cultivated on medium (n=9) were 40.9±3.03% and 2.8±0.29%, respectively.
With respect to Nameko, the values for cultivated on logs (n=7) were 42.0±2.92% and 2.8±0.31%, and the values for Nameko cultivated on medium (n=14) were 38.8±2.67% and 2.2±0.28%. Result by Modified prosky method-2 were 45.0±2.22% on growing wild (n=4), 42.3±1.15% on logs (n=9) and 37.9±3.74% on medium (n=9), respectively.
In each of these cases, mushrooms on growing wild and cultivated on logs demonstrated higher levels of total dietary fiber (TDF) and chitin than mushrooms cultivated on medium.
The levels of TDF and chitin in Kikurage per 100g were 67.7±2.76% and 4.4±1.47% in the case of Auricularia auricura (n=6), 84.7±4.96% and 3.0±0.65% in the case of Auricularia polyricha (n=7), and 67.9±3.76% and 6.3±0.94% in the case of Tremalla fuciformis (n=6). Thus, Kikurage contain high levels of TDF, with Auricularia polyricha in partticular exhibiting a high content TDF. Kikurage are therefore considered to be a good source of dietary fiber.
When the revised Prosky variation for chitin was compared with the 5 th Revised ingredient table manual method used for drafting the 5 th Revised Japan Food Standard Ingredient Table (Modified prosky method-2), analytical values determined with the latter method were found to be higher. It was therefore considered necessary to further study the method used to analyze the content of dietary fiber in mushrooms.