Tempeh

Tempeh keeps about 5–7 days refrigerated unopened, or its printed date, and 3–4 days once opened. It freezes well for several months.

Keep it in its sealed package until you use it, then wrap the remainder tightly or store it in an airtight container.

Frozen tempeh is genuinely convenient and loses little quality. Freeze it in usable portions; it thaws in the refrigerator in a few hours and can be sliced while still slightly frozen.

Some cooks steam tempeh for ten minutes before using it, which softens any bitterness. Steamed tempeh should be used or refrigerated promptly.

Vacuum-sealed tempeh keeps longer than loosely wrapped; follow the package date.

Tempeh is unlike anything else in this category because it is a living fermented food, and the mold on it is the product rather than a problem.

Tempeh is made by inoculating cooked soybeans with Rhizopus oligosporus, a mold whose white mycelium grows through the beans and binds them into a firm cake. That white, fuzzy, cottony growth is correct and expected — it is what tempeh is.

Black or gray patches are also normal. As the Rhizopus matures it produces dark spores, most often around the edges, at the corners, or wherever the cake had air contact. This indicates a more mature, stronger-flavored tempeh, not spoilage. Many people find it unsettling, and a great deal of perfectly good tempeh is discarded because of it.

What is not normal is mold in other colors: pink, yellow, blue, or green growth means a different organism has taken hold, and the cake should be discarded.

The other signals are sensory. Good tempeh smells nutty, earthy, and faintly mushroomy. Spoiled tempeh smells strongly ammoniac or sharply sour, which indicates the protein is breaking down past the point of fermentation. Sliminess and a wet, mushy texture are also discard signals — tempeh should be firm and dry to the touch.