By Rabbi Yair Hoffman


Last month a kashrus alert was issued regarding quinoa. It seems that quinoa sold in the Northeastern United States was found to be infested with bugs due to issues in the distribution chain and storage. The Star-K reported that the issue is more widespread than previously thought, and that affected batches were found in markets from New York to Maryland. Book lice and mites are the most common insects being found in quinoa, according to the alert.

Does halachah require that quinoa be checked with the lightbox method? If someone is serving you quinoa, are you required to avoid it if you think it was not checked properly?

Of course, each person should ask his or her own posek. This article will discuss the operative term that we all need to know, miut ha’matzui. It will also discuss the different views among the poskim about miut ha’matzui as well as other relevant aspects of quinoa.

Miut Ha’Matzui

Miut Ha’matzui is a term that is applied to quinoa, shatnez, missing husbands, and chickens. The parameters of this term determine many, many things other than quinoa. May we buy and immediately wear Uggs? May we eat that quinoa or brown rice presentation at the wedding we are attending? Is the chicken that Uncle Feivel buys kosher enough for his nephew Yoeli in Monroe on account of the somewhat prevalent tzumas ha’giddin problem (ripped veins in the back of the chicken’s knees)?

The translation of miut ha’matzui means “a prevalent minority.” The Gemara in Chullin (11a) tells us that by Torah law we may (and do) follow the majority. There are, however, some exceptions.


One such exception (according to most poskim and the Shulchan Aruch) is when there is a prevalent enough minority. Some examples are:

A husband falls off a ship in deep never-ending waters. The body is not found. Can the wife remarry based upon an assumption that no one survives such a fall? No, states Tosfos (Niddah 44b “Dakim” and Yevamos 36a “ha”), because a prevalent minority do survive.

A man was on his deathbed. This was witnessed, but they did not actually see him die. May his wife remarry? No, says the very same Tosfos. There is a prevalent minority of those who get up from what seemed to have been their deathbed.


The Rema in Yoreh Deah 84:8 writes that in regard to checking vegetables for bug infestation, it is insufficient just to check one out of a pack when there is a miut ha’matzui, a prevalent enough minority. The Rema’s ruling is based upon a responsum of Rabbi Shlomo ben Aderet (1235–1310) also known as the Rashba. He writes (Vol. I #274) that even if the vegetable is not muchzak b’tolaim, known to be infested, if there is a significant or prevalent minority, it still must be checked.

Another question is whether or not the obligation to be concerned for a prevalent minority is a Torah law or a rabbinic law. This is a debate in the poskim and it is discussed in the Pri Megadim 384:28. It seems from the Shach (Y.D. 39:8 and the Pri Megadim in Sifsei Da’as 39:3) that the halachah is that it is rabbinic in origin. The Pri To’ar seems to learn that it is a biblical requirement.

What Is Considered Prevalent?

What percentage must we be concerned about in order to necessitate an examination for something forbidden? There are at least seven different approaches in the poskim as to how to calculate “prevalence,” if it can even be calculated at all.

(1) Rav Yitzchok ben Sheshet Perfet (1326–1408), otherwise known as the Rivash, writes in a responsum (#191) that it is close to 50 percent. There are two possible understandings of this Rivash:

  • It could be that he means that up until 49% it is still considered a non-prevalent minority. This is the classical understanding of the Rivash, but it is problematic in that this is a plain ordinary minority. What benefit is there to a non-prevalent minority over a regular ordinary minority?
  • The second possible reading of the Rivash is that he means 26%. How so? Well, 25%, is considered a quarter, not a half, so 26% would be considered closer to half. This is how Rav Scheinberg, zt’l, reads this Rivash (see HaRav v’Rosh Yeshiva by R’ Elchanan Peretz p. 118). It is also explained in this manner by the Sichas Chullin as cited in Toras HaOf (page 165).

(2) Rabbi Yaakov Minkowski (1780–1844), a student of Rav Chaim Volozhin, writes in his Mishkenos Yaakov (#17) that the parameter of “prevalent” is ten percent or more. The Mishkenos Yaakov brings a proof to his position from the Mishnah in Gittin 31a that one should check wine three times each year since it is liable to turn to vinegar. Without checking, one may not take off the gifts of terumos and ma’asros from the wines, and one is not permitted to rely on an assumption that the wines have not spoiled. Elsewhere in the Talmud (Bava Basra 93b), the Mishkenos Yaakov points out the percentages of spoiled wine in regard to sales is listed as generally being ten percent. [Those who disagree with the Mishkenos Yaakov state that “bad wine” is different than vinegar.]

(3) The Beis Ephraim (Y.D. #6) argues with the Mishkenos Yaakov and writes that one is only obligated to check for a prevalent minority when it is certain that the minority is extant there somewhere. If there is a doubt about it then there is no obligation.

(4) Rav Vosner, zt’l (Shevet HaLevi 4:81 and 8:180), distinguishes between two different types of minorities. He writes that when the minority is always accompanying the majority, then the concern for it is even when it is less than ten percent. However, whenever the minority appears as mere chance, then one is not to be concerned for it.

(5) Rav Chaim Pinchas Scheinberg, zt’l, and, lbc’l, Rav Pesach Eliyahu Falk (cited in Madrich l’Bedikas Tolaim, p. 10) are both of the opinion that it is not a hard and fast percentage but rather dependent upon whether a person is surprised or perplexed that it exists. According to this understanding, even if it is a low percentage, a person may not be shocked that it is infested.

(6) Rav Elyashiv, zt’l, is quoted by Rav Moshe Vaya as holding that seven percent or above is considered a prevalent minority and that one should be stringent at 5%. This is also cited as the view of Rav Chaim Kanievsky, shlita (Hilchos Orlah in Sefer Levushei Yosef).

(7) Rav Shlomo Zalman Auerbach, zt’l, suggests using the figure of the Mishkenos Yaakov in Minchas Shlomo (Vol. II #61:1). It is unclear to this author whether this is just a recommendation or a psak halachah. Rav Meir Brandsdorfer, zt’l (1934–2009), author of the Knei Bosem, also rules (Vol. I #49) like the Mishkenos Yaakov. Rav Yitzchok Yosef, on the other hand, rules (Issur v’Heter Vol. II Siman 84 p. 212) like the Rivash. It also seems that he holds of the 49% reading of the Rivash and not the 26% reading.

Percentage of What?

For argument’s sake, let’s assume we take the Mishkenos Yaakov’s figure of ten percent—but ten percent of what? For big-ticket “items” such as people and chickens, the ten percent figure makes sense. But what if we are discussing quinoa? Is it ten percent of each seed? Is it ten percent of each bag? Is it ten percent of each recommended serving? What are the parameters here of what we are examining?

In Bedikas HaMazon K’Halachah (4:73), the author, Rav Moshe Vaya, cites a ruling from Rav Elyashiv, zt’l, that it is the general unit that is purchased, and when one is eating it is the general portion that is being consumed.


Now that we know the different opinions about miut ha’matzui, how prevalent is the quinoa infestation? Rabbi Dovid Goldstein of Boro Park is one of the leading bug infestation experts in the country. Rav Moshe Vaya trusts him implicitly. He says that the infestation levels of what he has examined are between 20% and 30%. So let’s go through each of the aforementioned opinions.

  • According to the first reading of the Rivash, one does not have to check quinoa. According to all opinions it is less than 49%. The second reading holds that a miut ha’matzui is 26%, so according to the second reading, it may require checking. According to the Mishkenos Yaakov it should be checked since it is more than 10%.
  • According to the Beis Ephraim and Rav Vosner, one does not need to check in this case.
  • According to Rav Scheinberg and Rav Falk, it should be checked because it is now common knowledge and not surprising at all that quinoa can be infested. Non-Jews posted videos about it four years ago.
  • According to Rav Elyashiv, zt’l, and, ylc’t, Rav Chaim Kanievsky, shlita, it should be checked because it is more than 5%.
  • According to Rav Yitzchok Yosef, it need not be checked because he relies on the first reading of the Rivash.

This author’s own conclusion is slightly nuanced. Generally speaking, it should not be eaten unless it was checked, but each person should consult with his or her own posek.

The author can be reached at


Please enter your comment!
Please enter your name here