Making umami powder from your own leftover harvest
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Grow for a few months and you inevitably get a problem that is a luxury problem: too many mushrooms at once, and too many trimmings of the wrong shape. The solution most often on our shelf is a jar of brown powder. Mushroom powder, ground from dried harvest, is the most concentrated seasoning you can get from your own growing, and it replaces the stock cube in almost every dish. Here is how to make it.
What is umami, and why is it in mushrooms?
Umami is the fifth taste, alongside sweet, sour, salty and bitter: the savoury, full flavour of broth, aged cheese and seared meat. It comes from glutamate and from a group of related compounds, the nucleotides, which amplify the taste of glutamate many times over. Mushrooms are full of both. Dried shiitake is even one of the richest natural sources of guanylate, the nucleotide the food industry uses as a flavour enhancer. Dry and grind mushrooms and you are effectively making your own flavour enhancer, with nothing added.
Which mushrooms do you use?
Anything that can be dried, which is almost everything. The base is dried shiitake, which brings the depth. Into that we mix oyster, nameko, wood ear and lion's mane, in whatever proportions happen to be left over. Trimmings, stems, over-mature specimens with curled edges, the thin caps not pretty enough to eat fresh: all powder material. Only mushrooms that smell bad or show mould stay out; those go in the bin.
How to make it
- Dry. As in the drying piece: in the oven at 50 to 60 degrees, on a rack, door ajar, until everything snaps when bent. Trimmings dry faster than whole caps, usually in two to four hours. They must be truly dry, otherwise the powder clumps and goes mouldy.
- Grind. In a coffee grinder, blender or mortar to a fine powder. A coffee grinder works best. Do it in small batches and grind briefly, otherwise it heats up and packs together.
- Sieve. Through a fine sieve; whatever stays behind gets ground again. The result should have the fineness of ground coffee.
- Store. In an airtight jar, dark and dry. It keeps for a year that way. To keep it longer, add a small sachet of rice against moisture.
How do you use it?
As a spice, not an ingredient. A teaspoon of powder through a pan of mince, a soup, a sauce, a stew or a risotto does what a cube promises, without the salt and the greasy taste. In tomato sauce it deepens the flavour without anyone tasting mushroom. Half a teaspoon in a dressing or mayonnaise. Stirred into butter it becomes a spread for bread or a steak. And in a barbecue rub, with salt, paprika and a little sugar, it replaces the flavour enhancer found in most ready-made rubs. Start cautiously: it is stronger than it looks, and a tablespoon where a teaspoon was meant turns a dish bitter.
A few blends we make ourselves
Pure shiitake: the strongest, the smokiest, for Asian dishes and broths. Shiitake and oyster half and half: milder, rounder, the all-purpose jar for everything. Shiitake with lion's mane and a pinch of sea salt: sweet and full, surprisingly good with fish and cream sauces. And anyone whose wine cap harvest got too big grinds that separately: earthy, almost like potato powder, lovely in a gratin.
Why this is the best ending for a harvest
Because nothing is lost and the result outlasts everything else. A block that gave four flushes and a log that suddenly delivered a kilo in October end up in a jar that improves every meal for a year. Once you have a jar of your own powder in the cupboard, you never buy a stock cube again, and that may be the best reason to grow that we know.