Research on the Cultivation of Edible Fungi Using Yellow Ginger Residue

Yellow ginger (Dioscorea zingiberensis) is the main raw material for industrial extraction of saponin. Yellow ginger residue is the waste left after saponin extraction by yellow ginger processing enterprises. Most of this residue is discharged directly into the natural environment by processing enterprises without any treatment, causing environmental pollution. In order to effectively utilize this abundant resource of yellow ginger residue and turn waste into treasure, edible fungi were chosen as the carrier, and through the development of the edible fungi industry, a large amount of yellow ginger residue can be effectively converted and utilized, reducing environmental pollution, developing a circular economy, and promoting the harmonious development of the economy and the environment.

1 Nutritional Analysis of Yellow Ginger Residue

According to the nutritional requirements of edible fungi for the cultivation substrate during their growth and development, it is first necessary to detect and analyze the nutritional components in yellow ginger residue and compare them with the commonly used cultivation material, mixed wood chips, to clarify the differences in nutritional composition between yellow ginger residue and mixed wood chips, laying the foundation for medium formulation. In accordance with the GB/TS009.5-2003 standard, items such as crude protein, crude fiber, crude fat, soluble carbohydrates, and ash in yellow ginger residue were tested, and the comparison with the nutritional components of mixed wood chips is as follows:

Through testing and comparative analysis, it was found that yellow ginger residue has the following physicochemical characteristics:

① The protein content is relatively high; the contents of crude protein and crude fat reach 4.6% and 3.11%, which is 3 times that of mixed wood chips, while the contents of crude fiber and soluble carbohydrates are 17.2% and 24.7% lower than those of mixed wood chips.

② Poor hydrophilicity, strong water absorption.

③ Light specific gravity; generally, dry material is 60% lighter than mixed wood chips.

④ The fibers are fine and small, resulting in poor air permeability after bagging.

⑤ It tends to shrink when heated.

From this, it can be seen that yellow ginger residue is rich in nitrogen sources but insufficient in carbon sources and other inorganic salts. If raw materials with higher carbon content are added to yellow ginger residue to meet the requirements of the C/N ratio and other nutritional elements of the cultivation substrate during the growth and development of edible fungi, the waste yellow ginger residue can be fully reused.

2 Selection of Cultivation Varieties

Based on the nutritional composition analysis of yellow ginger residue, edible fungus varieties of both wood-rotting and straw-rotting types were selected. In terms of variety combination, conventional varieties were combined with rare varieties, and varieties with higher nitrogen source requirements were preferentially selected for cultivation trials, so as to screen out suitable medium formulas for different edible fungus varieties and lay the foundation for promotion and application.

3 Design of Culture Medium Formulas

3.1 Design of Culture Medium Formulas

Because the contents of crude protein and crude fat in yellow ginger residue are relatively high, while the contents of soluble carbohydrates and crude fiber are relatively low, the main consideration in formula design was to balance the C/N ratio of the medium. Combined with the nutritional requirements of various edible fungus varieties during their growth and development, the following three formulas were formed through screening and calculation, and cultivation comparison was carried out with the traditional edible fungus cultivation medium formula (Formula 4).

3.2 Design of Experimental Treatments

A total of 4 culture medium formulas and 3 edible fungus varieties were set up, with 12 treatments in total. Each treatment had 500 bags, for a total of 6,000 finished experimental bags.

·

4 Cultivation Experiment

In the cultivation experiment, all steps such as bag making, sterilization, inoculation, mycelial growth, and fruiting management were carried out according to conventional edible fungus cultivation techniques.

4.1 Comparison of Mycelial Growth

During the mycelial growth stage, the four formulas showed relatively large differences in mycelial growth rate and growth vigor across the varieties, with Formula 2 performing best on each variety. The specific data are shown in Table 4:

4.2 Yield Comparison

Yield performance at the fruiting stage: different culture medium formulas had little effect on the yield of oyster mushroom (Pleurotus ostreatus), and the yields of the various formulas were comparable; they had a relatively large effect on the yields of king oyster mushroom (Pleurotus eryngii) and Hypsizygus marmoreus. Comparing the yield of king oyster mushroom, Formula 2 performed best, with biological efficiency 25.6% higher than Formula 1 and 36.7% higher than the control Formula 4. This indicates that using pure yellow ginger residue or pure mixed wood chips as a single cultivation substrate is not conducive to increasing the yield of the rare edible fungus king oyster mushroom.

5 Experimental Conclusions

The experimental results show that a culture medium substrate formulated with 50% yellow ginger residue, 38.5% mixed wood chips, 10% wheat bran, 1% gypsum powder, and 0.5% quicklime, plus, calculated on a dry material basis, 0.15 ml of Gushusu and 0.65 g of Kemeijing per kilogram, is suitable for the cultivation of king oyster mushroom, oyster mushroom, and Hypsizygus marmoreus, and is especially suitable for the cultivation of the rare edible fungus king oyster mushroom, which has higher nitrogen source requirements. Using yellow ginger residue to cultivate the rare edible fungus variety king oyster mushroom can not only reduce the amount of wheat bran and mixed wood chips used and save production costs, but compared with the traditional formula (78% mixed wood chips + 20% wheat bran), the yield is also increased by 36.7%. At the same time, it also solves the difficulty faced by yellow ginger processing enterprises in disposing of yellow ginger residue, enables waste reuse, and promotes the development of a circular economy.