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I'm a bit paranoid about eating dirt, so I probably cut away fruit/vegetable/potato peels/skins more than most people do (and rinse the final surface more than most people do).

What about truffles? truffle

I'm concerned about the grey "maze edges" in the truffle's core. What are these?

One source makes me think these are lines of dirt which remain in the nooks and crannies after filamentous growth:

When the spore germinates its forms a singular filamentous cellular structure called a hyphae, this hyphae grows outward branching, forming mycelium. Once it finds another strand of sexually compatible mycelium it exchanges genetic material forming diploid cells and searches for a compatible root structure.

Mushrooms grow in air, not soil, and therefore look safer. Potatoes, though they grow in soil, grow like a balloon and therefore also look safer. Do truffles really grow filamentously incorporating the dirt, or do they grow like a balloon pushing out the dirt?

Should I always cook as if there are microbes and bacteria (or any other contaminants) inside a truffle? Do restaurants usually therefore only serve truffle items which have seen high heat? Has a typical bottle of gourmet truffle oil from a grocery store seen high heat already?

bobuhito
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2 Answers2

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You seem to confuse the mycelium and the fruiting body of the truffles.

The part your quote talks about is the mycelium, which (not overly precise, but for this question close enough) can be compared to the roots of other plants. The mycelium is the actual fungus that can survive for a long time and become quite large. At some point, some fungi develop fruiting bodies (sporocarps) (what we colloquially call mushrooms and forage or buy in stores), which contain the spores for reproduction.

We humans and other animals typically consume the fruiting bodies but leave the mycelium alone, not unlike eating the apples, but not gnawing on roots and branches.

When a fruiting body develops, it typically starts from a small point and then expands, often in some closed form to protect the spores while they ripen. If you turn over a champignon, you can see the gills, which is where the spores are. (You could even leave the hat gill-side down on a piece of paper for a few hours and observe the pattern of the released spores.) The underside of an champignon is closed while the mushroom is small and young, only opening up later when it matures. Other mushrooms form some form of sphere that releases the spores at a later time, puffballs are a good example. Truffles are the extreme form of protecting the spores inside the fruiting body. They don’t have the release mechanism, instead they rely upon animals to dig them up and disperse them after consuming the truffles.

This should also allay any fears of eating dirt: Truffles (in the sense of the culinary term, so the dark lumps) will at no point have exposed their inside to the surrounding soil. The only point of contact is the outer skin. The pattern you see in the cross section is the combination of carrier substance and spores.

Restaurants typically scrub the truffles to remove dirt (but cleaning is also done before sale, because buyers are not willing to pay a premium truffle price for adhering dirt), and often will serve truffles raw, shaving them over dishes to preserve their delicate flavor and maximize the taste experience. For your truffle oil, other rules apply, because oil-with-something-in-it needs special measures to prevent botulism, heat treatment is one option.

Stephie
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You seem to be asking two related questions, one on food safety and one more general question

Raw truffle is considered about as safe as, say, blue cheese

Truffles are safe to eat, raw, for people with a normal immune system and there is no reason to worry about them on those grounds unless you're a pregnant woman, or immunocompromised in some way, due to a presumed possibility of toxoplasmosis contamination in the soil they grow in. In this they are similar to other foods, such as blue cheese, which are fine for people in normal circumstances but carry a very, very low risk of harm to people under certain circumstances, and I cannot find a single food safety agency that advises against the consumption of raw truffles in general. Indeed, raw truffle is routinely used as an ingredient in many restaurants without issue.

This should not be taken as meaning that they can be safely made into oils or incorporated into other products that are intended to be stored. Commercial truffle oils, if they are not simply made with synthetic flavourings, are typically pasteurised to ensure they are safe to eat.

The interior of truffles is inhabited by a variety of microbes

The interior of truffles is home to a variety of bacterial species and these bacteria are believed to be necessary for the production of the characteristic odour of truffles. Like the overwhelming majority of bacteria and microbes found on Earth and in our food, it is likely that these bacteria are completely harmless to humans. There is no health benefit to consuming food that is utterly sterilised and it may even have negative health effects to completely avoid normal exposure to microbes and bacteria, especially in children.