In this article I will talk about how to determine the quality of grain spawn, how to store it and how it can be defective.
I have an article about what grain spawn is, what grain it is grown on, and why we use it in oyster mushroom production. Read here.
Sections of the article:
There is a photo of such a high-quality spawn below, in the section “How to choose a spawn supplier” ↓
If you see loose grains in the bag and a yellow-brown color of the grain itself, it means that the spawn is not ripe enough. It is better not to buy such packages.
But if this happens and you bought an unripe spawn, put it in a warm, clean place (in no case in an incubator).
At a temperature of 18-22 degrees Celsius, the active mycelium will overgrow and become completely white in literally three to four days.
If during these three days it becomes covered with mold, this means that the infection occurred before delivery, and there is no way you could have infected it.
When can grain spawn become solid?
In this case, it can be broken and kneaded with great difficulty. It often also contains large blobs - saucers of rusty or light brown liquid underneath the film.
This means that the spawn was made two to three months ago and was in the refrigerator - either at your place or at the supplier's.
How do you know if mycelium is bad?
Gelatinous spots of yellow-brown color, mold of pink or all shades of green or black on the grains indicate that the spawn was made or stored in a non-sterile environment.
Even if you remove moldy areas of grain, you cannot be sure that mold hyphae have not grown into areas where spores are not yet visible.
After all, mold mycelium differs little in appearance from oyster mushroom mycelium; it is whitish or light gray.
And only spores have bright multi-colored colors.
Small black dots on the oyster mushroom spawn are also mold spores. If they are on thin hairs, this is one of the types of mucoraceae.
Such material cannot be inoculated.
Read more about mold in mushroom blocks.
If you come across such a lump, do not try to crush it in a container with previously mashed grains prepared for inoculation. Mold is often found in the middle of such conglomerates. Place such a lump in a plastic bag.
The remainder of the grain from this bag can be used for inoculation if it has a normal smell and the grains are uniformly white. Be sure to label the bags seeded from this briquette and watch their development.
As a rule, such mushroom blocks overgrow and bear fruit without any problems.
When you finish inoculating, carefully cut the stuck together grain and look to see if there is a colored coating or fluff in the cavity. If there is, it's mold. It can be green or olive. Less common are orange or pink shades.
Take a photo of a cross-section of the lump with a colored formation and the barcode of this package, contact the supplier and tell him about the problem.
High-quality grain spawn has a very subtle, slightly sweet aroma - it reminds me of the smell of milk.
I read on the Internet that good mycelium smells like wild mushrooms. I don’t know... For me, wild mushrooms smell of freshness, even more like rain, but mycelium does not have such a smell.
Any strong smell - sour, “smelly”, alcohol, antibiotics or ammonia indicates that the development of the mycelium did not proceed correctly; such a smell indicates a defect.
Storage should be in a refrigerator, separate from mushrooms, at a temperature of 0 to 2°C, without light.
It's okay to turn on the lights when you go into the refrigerator, but don't leave them on when you're not there!
If the mycelium is fresh and active, at temperatures above 5 degrees it forms white compactions protruding above the grain surface.
This begins the germination of hyphae, primarily under the filters, where gases are exchanged, oxygen enters from the outside, and the formation of primordia begins.
See the picture on the left.
A short-term decrease (increase) of 2-3 degrees is acceptable.
You cannot freeze grain spawn!
If the mycelium is frozen (stored below minus 2-3°C for a long time), then when it is thawed (defrosted), it loses its activity.
The longer it was stored frozen, the higher the likelihood of not only loss of activity, but also its partial death. Blocks inoculated with it become overgrown, but do not produce a crop.
It happens that after defrosting it not only overgrows well, but also produces a harvest. But why take the risk?
The documentation must indicate the final period of use, after which the supplier is not responsible for its quality.
Shelf life depends on storage conditions.
Some heat-loving varieties cannot be stored in the refrigerator.
Initially, it is advisable to draw up a delivery schedule in order to use only fresh material. However, if you live far from the supplier and have to purchase a large batch for a long time, you need a separate cold storage for storing spawn.
Ask the manufacturer the following questions:
- Does the supplier provide a technological map (passport) for growing strains? Agree, if the supplier is not aware of how the products he grows are used in the future, this is more than strange.
- from which laboratory did the supplier source the source (mother culture) of the variety? Find this laboratory on the Internet. If there is no information about it, think about whether you should trust it.
- Does the supplier keep records of products sold, is there any identification mark, barcode or batch number on the packages.
The use of a barcode indicates that the manufacturer takes its products seriously. This indicates the uniqueness of each package - it is easy to track. Labeling can only be developed for product registration purposes. That is, it does not contain information about the country of production, but only about the batch of goods and the name of the strain. If you buy packages with a barcode, ask the manager what information it contains.
- Are there filters on cellophane? Filters can be round and similar to cotton pads (as in the photo next) or in the form of a tape with notches (as in the photo below).
- Is the package sealed?
If it is simply tied or sealed with tape, if there are no filters through which the oyster mushroom mycelium breathes, it is better not to risk it.
He's definitely spoiled!
The defect could appear both at the company that produces it and at your place. If mold develops near a tear (cut, puncture) of cellophane, it has penetrated into the contents through this hole as a result of improper storage.
When receiving the shipment, carefully inspect each package, as they could have been damaged during transportation. If you find a tear, seal it with tape immediately.
Inoculate it immediately (do not store) and do not mix it with others in the same bowl. You must sign these blocks. If these blocks are poorly overgrown, have green mold or smell bad, it means that contaminant spores have already penetrated through the tear.
If packages are delivered with visible orange, pink, black, green stains, take photographs of them, contact the supplier and demand compensation.
What to do if the packaging is torn?
If it breaks in your hands - it gets caught on the corner of the box, or falls and tears, seal the tear with tape and inoculate it immediately.
If you find torn packaging in the delivered batch, immediately contact the manufacturer and send a photo. Such holes can be sealed and used.
Be sure to label the blocks that were inoculated from these torn packs.
If the cellophane broke a long time ago, or there is a tear between the film and the filter, and fluffy mold has appeared there, throw it away without regret. Otherwise, you will spoil the steamed raw materials and infect the incubator with mold spores. Do you need it?
