Blood Spots in Eggs

You crack an egg and there is a spot of blood in it. The answer to what you do has genuinely changed — not because the halacha changed, but because egg farming did.

Why it used to mean discarding the egg

Eggs were commonly fertilised. Roosters were kept with the hens, because that was how laying was stimulated.

A blood spot therefore raised a real possibility that it was the beginning of an embryo. Where that was in doubt, the whole egg had to be discarded, on the understanding that once an embryo has begun it spreads through the entire egg rather than remaining localised.

This is the origin of a practice many people know without knowing why: boiling three eggs at a time. If one turned out to have a blood spot, the other two — and the pot — remained permitted, because the doubtful item was outnumbered by the same kind of food.

Where the spot sits

Location carried information. The chalaza — the string-like structure connecting the white to the yolk at top and bottom — is the significant place. A blood spot there indicated a developing embryo. A spot elsewhere did not necessarily indicate anything of the sort.

What changed

Modern laying hens are stimulated by feed rather than by roosters, and roosters are kept out of egg farms. Commercial eggs are not fertilised.

That removes the basis of the old concern. Today there is no viable possibility that a blood spot in a commercial egg represents a fertilised embryo.

What a spot actually is, in the ordinary case, is blood — and it has a mundane explanation. As the egg leaves the ovary it breaks through a membrane, and that membrane sometimes carries a blood vessel large enough to leave a trace behind.

What you do now

Remove the blood. Blood is prohibited in its own right, so the spot comes out — but the egg itself is not the problem it once was.

The practice of boiling three eggs together belongs to the older situation. Many keep it anyway, which is a perfectly reasonable thing to do with an inherited practice.

Note the shape of this: the halacha did not move. What moved was a fact about the world that the halacha was responding to, and the conclusion followed the fact. That is worth understanding, because it is also why you check whether reasoning like this applies to your eggs — eggs from a small flock with a rooster are a different case from a supermarket carton.

If you are unsure what you are dealing with, ask your rav.