The joke goes that on Pesach there is nothing to eat, and on Sukkot there is nowhere to eat. On Shavuot we are too tired to eat, on Purim we are too drunk to eat and on Chanukah the food is much too oily and fattening to be able to eat.
On Rosh Hashana there is no time to eat, while on Yom Kippur we’re not allowed to eat. Finally, we reach Tu B’shvat and all the fruits are much too dry to eat.
Well, that is fine for the humor, but what about on a regular weekday? We are all familiar with the delicious variety of options the Sushi selection offers us, but are they all perfectly Kosher to eat?
The one ingredient Sushi needs and without it won’t be able to be called Sushi is the seaweed, well known as Nuri.
Nuri (the explanation is meant for those who live under a rock and don’t know) is a flattened edible seaweed, that is used to wrap the rice in the Sushi rolls.
One concern about the Sushi is the artificial flavoring added to the Nuri. According to the Chicago Kashrut Agency CRC, some companies add non-Kosher flavors such as Shrimp flavoring. This raises concern not only for those Nuri sheets, but also for unflavored Nuri sheets which are made on the same equipment. Although the Nuri producer is obligated to write this on the ingredient list; realistically, many times they do not.
Secondly and more alarming, Nuri is a vegetable that grows in the ocean, the ocean has all types of creatures which can attach themselves to the Nuri. For example, it is very common to have small seahorses, shrimp, and scorpions. Unlike other leaves like lettuce, etc. which can easily be inspected by a good light, Nuri sheets are much harder to check because they are pressed in layers, one on top of the other, making the insects harder to find since they can be lost between the sheets.
The infestation on the seaweed is considered common (בדיקת המזון לרב משה ויא עמוד 233) and therefore one wouldn’t be able to eat it without making sure it is clean.
According to Rabbi Revach (ספר תולעת שני ח״ב עמוד קמג), after thoroughly checking and investigating, even Nuri marked with a Kashrut supervision, doesn’t guarantee that it’s clean since the infestation is so hard to find.
If the Nuri would have been 12 months old, we could have relied on the Halacha that a dead insect after that period of time disintegrates and is thus permitted (חולין נח,א), but since the Nuri also has a shelf life it’s likely that it’s sold prior to that date (תולעת שני שם).
Moreover, some Poskim say that if the product is sealed as is the case with the Nuri, the twelve months expiration period doesn’t apply (ש״ע סי’ פד ס״ק יב).
Bitul doesn’t apply as well since the insect is visible to the eye, even though they are hard to find; but once found, they are very clear.
The good news is that companies have created an electronic laser to detect insects, but even those lasers aren’t able to completely clear the seaweed and many times may miss the insects. (תולעת שני שם)
So what can we rely on?
Well, that is a good question, probably better than the answer. But since this is such a common food, we must try to see what Kosher agencies can rely on.
Some feel that if there is a professional Mashgiach who learned how to check the sheets and indeed makes sure to check each one thoroughly it can be cleaned. Those who permit it without checking rely on few leniencies.
First, there is a Halacha in Shulchan Aruch (סי’ פד סעיף יז) that permits eating a burnt insect if needed as medicine, and since the way Nuri is made is that after it’s soaked, they take the layers and press them with a hot iron press to dry and flatten it, in the process burning the insect as well, we could have permitted it. However, since we don’t eat Sushi as a medicine, we need to look for further leniencies.
Chochmat Adam (בבינת אדם שער או״ה אות לו) writes that this that the Shulchan Aruch permitted the consumption of burnt insects for medicinal purposes, is only if one intends to consume the insect. But if one doesn’t intend to eat the insect, but it is merely in his food, one is allowed to eat the food which has the burnt bug.
Still, most Poskim would not consider the press as a form of burning since the insect doesn’t disintegrate completely like ashes (חכמת אדם כלל לח סט״ו).
There are some Poskim who were lenient with burning the vegetables on a low heat of 200 , relying on partial burning. (אבן ישראל לרב פישר ח״ז סל״א).
There are also those who rule that if the insect was dead for 6 months it’s sufficient time to permit it (פר״ח סי’ פד ס״ק מג, שאילת יעב״ץ ח״ב סי’ קכד).