Saturday, March 21, 2015

Growing wood ear (木耳) at Shi Fang (什邡)

I went to Shi Fang in Sichuan to learn how to grow wood ear (木耳).  It starts with the mixing of nutrient into fine wood chips or coarse saw dust to form the growth medium for wood ear, and the packing of the medium into a cylindrical plastic bag. 

The bags are then packed into a steamer to be sterilised.  

The small mountain of bags is covered, and coal is burnt underneath the steamer to steam the bags for 24 hours.  The steamer is obviously a very old design.  It does not contain the steam very well.  The bags are packed too tightly, so the steaming process is not efficient and takes a long time.  There is no quantitative measurement of how successful the process is.  

The wood ear spores are then implanted into the sterilized bags of growth medium.  The process has to be carried out inside a box, which is filled with a chemical vapour to ensure that the bags are not contaminated in the process.  The process is hazardous for the workers, even though the workers stay outside and put only their hands inside the box, because the boxes are not completely airtight.  

The bags are then stacked in a darkened room to wait for the wood ear spores to sprout.  

If the sterilization is not done properly, or the environment is not clean (which obviously it is not), the bag can get infected at any stage, and it has to be thrown away.  If the infected area is small, it is cut away, to savage the rest of the bag, to cut down on the lost.  But the infection can also spread if not excised properly.  

After sprouting, the bags are transported to a growth shed, to give room for the wood ear to grow.  The shed is semi-darkened.  The appoint of light, temperature and humidity have to be just right.  Hence moisturization and ventilation are important.

The wood ear grows out of the bags.  When they are ready, they are cut from the bags, and dried under the sun.  For better quality and better price, they have to be cleaned with water, and then dried in a clean environment.  For this part of Sichuan, sunny days are rare.  Under a bright sun, the wood ear can dry in a day or two.  When it is cloudy or raining, it won’t dry even in one week.  It can even get mouldy, then the whole crop can be ruined. 

The whole cycle takes about a year.  There are many points where the process can fail, a whole crop ruined, and tens of thousands of dollars of investment going down the drain.  I now have a much better appreciation of how complex the process is, and how challenging the life of a wood ear farmer can be. 

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