| Abstract: | Edible and medicinal mushrooms contain many bioactive substances dietary fiber and vitamins, etc., it has many enzyme activities that could degrade phytic acid from the matrix. Inositol is the product of phytic acid after hydrolysis by enzyme, and it has similar function to vitamin B. Inositol can promote the metabolism of fat in the liver, prevent skin aging and hair loss, promote the growth of various bacteria and yeast. Besides, it could be used as an additive in food and feed industry. Recent studies have found that the edible and medicinal mushroom in Grifola frondosa and mushrooms contain phytase, and use the solid-state culture matrix to degrade phytic acid into inositol.
In this study, we selected mushroom fruiting body with higher phytase activity and used liquid and solid fermentation to discuss phytase activity, phytic acid and the transformation of inositol. The research includes fermentation phytase activity, myo-inositol content changes inositol solid culture curve of Grifola frondosa and Cordyceps militaris. The aim of search is suitable medium for improvement of phytase activity and transformation capacity of inositol.
We analyzed the phytase activity based on 24 kinds of mushroom fruiting bodies. The results showed Grifola frondosa has higher phytase activity(1.85µmol /min). Cordyceps militaris has higher phytase activity (2.14 µmol /min) around medicinal mushrooms. In submerged fermentation, the phytase activity increases as the growing days increase. Grifola frondosa has high phytase activity of 2.46 µmol /min at 12th day. Cordyceps militaris has high phytase activity of 2.28 µmol /min at 4th day.
According to Grifola frondosa, the phytic acid content in buckwheat (41.47 μg / mL) and brown rice (35.36 μg / mL) decreased at the 12th and 15th day. Brown rice (31.64 mg/g) has the maximum value of the inositol than buckwheat (6.38 mg/g) in solid state fermentation. On the Cordyceps militaris side, the phytic acid content in brown rice (23.73 µg/mL) and buckwheat (44.99 µg/mL) decreased at the 6th and 3th day.. Besides, the inositol yield increases as the growing days increase. the maximum value of the inositol yield is brown rice (25.24 mg/g) > buckwheat (4.95 mg/g ) in solid state fermentation. Generally, Grifola frondosa contain more inositol contents than Cordyceps militaris.
On anti-oxidative components, the total pheno and flavones content of Grifola frondosa brown rice are high than brown rice, 0.97 mg/g and 1.56 mg/g mg/g, respectively. As for ethanolic extracts from brown rice and Grifola frondos brown rice which antioxidant activity (EC50 value), the reducing power is Grifola frondos brown rice (5.51 mg/mL) > brown rice (7.98 mg/mL), scavenging ability on DPPH is Grifola frondos brown rice (3.39 mg/mL) > brown rice (4.08 mg/mL), and chelating ability on ferrous ions is Grifola frondos (4.20 mg/mL) > brown rice (9.83 mg/mL). In sum, Grifola frondos contains the highest phytase activity, it can promote the function of brown rice. |
