In general, one checks the yolks of raw eggs for blood spots before using them. However, is it strictly necessary to do this with eggs that have a hechsher on the box? Please provide an authoritative source.
First of all raw eggs do not need a hechsher according to CRC, Denver Vaad HaKashrut and others. The presence of a hechsher on the box does not appear to be a factor in two major treatments of the topic.
In a discussion on blood in eggs, the OU explains that, due to modern production methods, any blood spot found in eggs will never develop into an embryo and according to R Moshe Feinstein do not present a fundamental kashrut problem. As a result, the entire egg is never assur and mei’ikar hadin removal of the blood spot would suffice. However Rav Moshe writes that it is a proper practice to dispose of the entire egg even today, as eggs are not expensive and a person does not incur any significant loss. Therefore, the requirement to check each egg remains in effect, as does the requirement to dispose of eggs containing actual blood spots.
On the practicalities, the OU writes that
- The accepted practice is to check each individual egg prior to use.
- If checking is overly difficult, such as at night on a camping trip, for example, where there is no available good light, one may eat eggs without checking.
- There is no problem with eating eggs cooked in the shell (boiled or roasted), even though these cannot be checked.
- If one is in doubt whether the eggs have been checked, it is permitted to eat the food.
One does not have to check eggs to see if they have blood spot, as one relies on the fact that most eggs do not; nonetheless, people have the custom to be strict and check the eggs for blood spots when cooking during the day.
The crucial question is whether the halachic custom to check eggs must still be observed or whether it is possible to be lenient on this matter and simply not check any eggs generally. The answer to this question is not simple. It might be that one does not have to check eggs for blood spots, but when one is seen, it is still required to remove it according to Jewish law, and thus, it is prudent to check the eggs before placing them in a situation where it is difficult to remove the blood spot.
It is possible to conclude that Jewish law does not require that one check eggs for blood spots prior to their use if one purchases grade A or AA eggs from a supermarket in America, although there is a minhag to check eggs, and one who checks for such eggs is in the category of Hamachmir tavo alav bracha, (pious conduct for which one is blessed for being strict). No less than six different reasons can be provided to justify the practice of not checking eggs prior to using them:
- The United States Department of Agriculture already requires that all eggs be checked for blood spots before they can be sold in a supermarket as grade A or AA eggs. There was never a custom to check twice for blood spots.
- There are virtually never blood spots found in eggs sold in supermarkets in America that are a result of fertilization; thus no biblical violation is ever present even if there is a blood spot in the egg. The custom to check all eggs was limited to a society where not checking might lead to a Torah violation.
- There never was a custom to check for blood spots when all eggs derive from hens raised alone, in which case some authorities rule that even the blood spot itself can be eaten.
- The incidence of blood spots in Grade A or AA eggs sold in the supermarket is less than one in a thousand, and generally one does not have to check for very infrequent rabbinic prohibitions.
- Halacha never required that one check for blood spots; it was a custom, and the custom itself did not apply when it was difficult to check, such as at night. Nowadays, given the way we cook, checking is more difficult in a variety of settings.
- If there is a blood spot in the egg, one will generally see it even after the egg has been opened, and one can remove the blood spot then.
Even though halacha does not require that one check every grade A or AA egg purchased in a supermarket prior to using it, there might be prudent reasons why a person might choose to do so, and this explains the common practice of checking eggs found in many Ashkenazi homes. Most significantly, if one sees a blood spot, one must remove it, and it is easier to remove a blood spot prior to adding the egg to food than afterwards.
So, too, a person who purchases brown eggs, free range eggs, organic eggs, or eggs sold at a farmers' market, has to check those eggs, and thus it might simply be easier to check all eggs than to monitor what type of egg one is using at any given time.
As always CYLOR for a practical ruling.