That tinned tuna requires proper supervision is not surprising, but why would Kosher SA under the Hechsher of the Beth Din provide two options for tinned Tuna—the so-called “bishul Yisrael – mehadrin” line and “regular” tuna? What is the difference between the two options? In this article I will offer some background to the topic; however, each reader should discuss this with their rabbi as to which tuna they should purchase.

What is the difference between the two products?

There are two potential halachic issues with tinned tuna: 1) The prohibition of Bishul Akum, which restricts eating food cooked by a gentile; and 2) Ascertaining that the tins indeed only contain Kosher-species fish.

1.Bishul Akum

The Gemara in tractate Avoda Zara (38a) teaches that in certain cases it is forbidden to consume food cooked by a gentile—even if the raw ingredient on its own is perfectly kosher—lest by dining with gentiles on food which they prepared it could lead to assimilation with them. 1. This prohibition is known as Bishul Akum, literally, “Gentile Cooking.”

The two criteria for a cooked item to be considered Bishul Akum, and consequently forbidden, is that a) it is a type of food that most people would not eat in its raw state, and that b) it is a type of highly respectable food “fit to be served upon a king’s table.” The reason for the first criterion is that if it were a food normally eaten raw, then the cooking is not really enhancing and changing the status of the food. As for the second criterion, if it were not a highly respectable food to serve, we need not be concerned that eating it could somehow lead to intermingling and assimilation, as a person would not invite people to join them for such a meal. Only if both criteria are met would the food cooked by the gentile become forbidden. If, however, only one of these criteria are met, then the food may be cooked by a gentile and the food may be consumed. Therefore, in order to decide whether tinned tuna must be cooked by Jews (Bishul Yisrael) to prevent Bishul Akum or no such precaution is necessary, we must first understand the process by which tinned tuna is produced.

The process of Tinned tuna In a tuna factory, the fillets are first steamed which causes them to be very slightly cooked. Then, after the tuna is cut and canned, it is retorted (cooked by pressure) again inside the cans which is a regular cooking process.

A reason to say tinned tuna is not subject to Bishul Akum

The prohibition of Bishul Akum includes cooking, roasting, frying and baking. It does not include pickling, salting or cold smoking.2 There is a halachic dispute as to whether steaming is included in the prohibition.3

If we accept the opinion that steaming is not considered cooking,4 then, seemingly, there would not be a problem of Bishul Akum because retort-cooking is done with steam. However, since the tuna is steamed when it is already packaged in the tin, it is not truly steam-cooking because it is not the steam which is directly cooking the tuna but the heated cans! Consequently, this is considered ordinary cooking and would be subject to Bishul Akum. However, there is another way at looking at this. The Gemara there in Avoda Zarah5 teaches that if food is salted (by a Jew or non-Jew) to the point that it is edible as is, then even if a non-Jew subsequently cooks it, we say the food remains acceptable and there is no prohibition of Bishul Akum. Based on this, some authorities maintain that since the tuna is pre-steamed in the factory, in the first stage of the process, before the fish is cut and tinned, it already became edible at that stage and therefore the subsequent cooking inside the tins does not change its status and the food cannot become forbidden under Bishul Akum. This line of reasoning, of course, is only valid according to the opinion that steaming is similar to the effect of salting, which is not subject to Bishul Akum

The Minchas Yitzchak 6 presents this rational and adds another mitigating factor: since this is a situation of cooking in a commercial setting there is no Bishul Akum, as we do not know the identity of the ones who are cooking the food,7 so there would not be an issue of potential intermingling/intermarriage. Though this is not a stand-alone leniency, it can be combined with the first rational for a lenient ruling. Therefore, based on both of these reasons, Minchas Yitzchak rules that one may be lenient with using tinned tuna not actually cooked by a Jew. Note that he is talking only of the issue of Bishul Akum, not with other critical factors of kosher fish, as will be discussed below.

Another reason why tinned tuna does not pose a problem of Bishul Akum: Not oleh al shulchan melachim – it is not fit to be served at a king’s table

Shulchan Aruch,8 based on Avodah Zarah (38a), rules that only a dignified type of food that is oleh al shulchan melachim—“fit to be served at a king’s table”—is subject to Bishul Akum. In practical terms, the definition for this type of food is cooked food that would be served at an important meal to which guests are invited.9 Conversely, Bishul Akum does not apply to food not fit for such a meal, since a person would not invite people over for such a meal and therefore it could not lead to intermingling. Using this rule, some authorities are of the opinion that tinned tuna is exempt from the requirement of bishul Yisroel (cooked by Jew), for while some tuna can be prepared in a way that is fit to be served at “a king’s table,” they argue that tinned tuna is certainly not fit, as when it is in this form it is a very cheap food.10

• An argument that does not (yet) hold water…

Above we mentioned the criteria of “most people would not eat it in its raw state,” which means that only food that people would not eat raw is susceptible to Bishul Akum. If, however, it is a type of food that people do normally eat it raw, then the cooking does not pose any problem of Bishul Akum. Perhaps, you may argue, since nowadays many people eat raw fish in the form of sushi, Bishul Akum categorically does not apply anymore to tuna. Though this is a logically sound argument, we may not rely on this reasoning because although sushi is indeed becoming increasingly popular, it is still difficult to categorize fish as a food that is normally eaten raw.

The opinion of those who maintain that it does constitute Bishul Akum

A. Other authorities disagree with reasoning of the Minchas Yitzchak, mentioned above. These authorities maintain that when the tuna is pre-steamed, before it is placed in the tin, it does not yet become ready-to-eat as is. The reality is that the tuna at this stage is only “edible” in a dire situation and is therefore analogous to the case taught by the Rashba11 —that if one salts a large fish it is still prone to Bishul Akum (as opposed to small fish which becomes edible through the salting process) because it can only be eaten in a dire situation and the subsequent cooking by the non-Jew has a major effect on the fish.12

B. These other authorities also disagree with the premise that tinned tuna is not oleh al shulchan melachim—i.e., not fit to be served at a king’s table, and consequently not susceptible to Bishul Akum. They point out a ruling of the 17th century commentator Sifsei Cohen13 regarding the cooking of the stomach of a kosher animal: People would not normally eat a stomach and it is certainly not fit for a kings table, yet since meat, in general, is fit to be served at an important meal, we extend the prohibition of Bishul Akum to undesirable cuts of meat as well. The same reasoning would apply to tuna since some types of tuna can be served at an important meal.14

Conclusion for part I: Since the prohibition against Bishul Akum is not of Biblical but of Rabbinic origin and there are many authorities to rely on, we have strong grounds to be lenient on the issue of Bishul Akum vis-à-vis tinned tuna.

2.Kosher Fish

Not all species of fish are kosher. In order for a fish to be considered kosher, it must possess snapir vekaskeses—both fins and scales. Furthermore, those scales must be easily removable without tearing the skin of the fish.15 Since every fishing net inevitably catches a small amount of “other” fish varieties in addition to the main catch, there must be times when non-kosher fish might be mixed in the same nets as a kosher variety. How are we to know that only kosher fish (in our case, tuna) end up in our tinned cans of tuna? The simple answer is that it is standard practice throughout the fish industry to hand sort the catch several times to remove all foreign fish from the main catch. This sorting is intended to ensure that only the desired variety of fish is sent to the plant before the processing begins.

• Is the fishing company’s self-sorting process sufficient to assume all the fish that reach the plant is of the kosher species?

Despite the existence of this sorting system, some poskim take the position that there must be a rabbi continuously present—a mashgiach temidi—to supervise the entire processing, to confirm that non-kosher varieties of fish do not enter the manufacturing facility. These poskim point to the Rambam and the Chinuch’s position that it is a positive commandment to check each fish before consumption in order to confirm its kosher status.16 Also, once fish have been filleted, or skinned and canned, they no longer bear signs of kosher. It is evident from the rulings of Shulchan Aruch (YD 83:8) that under such circumstances the fish may not be eaten unless it is readily recognizable as being of a kosher species through other telltale signs.17 Indeed, Rav Moshe Feinstein zt”l18 writes against identifying skinned fish with a mere tevias ayin (familiar eye). Fish must possess simanim (identifying characteristics) to confirm that it is from a kosher variety. Therefore, when it comes to tuna simply saying “it looks like tuna” will not do.

• A reason why we may rely on the company that only kosher fish is being used: “A tradesman will not ruin his reputation”—uman lo maura umnaseih

Tradesmen ride on their reputation and are usually careful to avoid any practice that could ruin that reputation. This reality is reflected in tractate Menachos 19 which teaches that if a person buys strings for tzitzis from a non-Jewish merchant, we may assume the strings are “kosher” and fit for tzitzis, as we say the merchant would not risk ruining his reputation. This principal is known as: uman lo maura umnaseih—“A tradesman will not ruin his reputation.”

Magen Avraham 20 states that this principle of uman lo maura umnaseih applies not only with regard to possible tampering with materials or food products offered for sale, but even with regard to the intrinsic species which he offers for sale—provided that such substitution would destroy his credibility not only in the eyes of Jews but in the eyes of his non-Jewish clientele as well. Thus, the testimony of a non-Jewish tradesman may not be accepted in order to verify that an animal has been slaughtered in the prescribed manner since this is not a matter of concern to non-Jews and hence a falsehood would not damage his reputation in their eyes.

Rabbi Mordechai Yaakov Breisch in his responsa Chelkas Yaakov 21 cites this Magen Avraham and posits that since it is against the law of the land to substitute one species of fish for another, a non-Jewish processor would not dare substitute any type of fish for what the can is labeled as containing. This is so because if his substitution were to be detected by others, it would ruin his reputation in the eyes of non-Jews as well. Accordingly, his statement with regard to the contents of the can may be relied upon.

However, as Chelkas Yaakov himself notes, Magen Avraham’s position is rejected by Noda bi-Yehuda22 who maintains that although we may assume that a tradesman will not establish his business on the basis of fraud, a tradesman is nevertheless suspected of being ready to profit from the substitution of one species for another when an inferior product has somehow come into his possession. This is true even when, if detected, his reputation would be damaged in the eyes of non-Jews. It would emerge, then, that according to Noda bi-Yehuda tinned tuna processed without constant kashruth supervision would be an issue.

Nevertheless, argues Chelkas Yaakov, even the Noda bi-Yehuda would concede that a tradesman’s declaration may be relied upon when his declaration can be independently verified—even if such verification can be accomplished only with some difficulty.

Applying this principle to canned tuna, Chelkas Yaakov argues that the manufacturer’s labeling (which is the equivalent of a tradesman’s word) may be relied upon because the identity of the species within the can be confirmed by “experts.”

In support of this position he cites Avodah Zarah23 which states that a certain fish known as chilak24 may be purchased from a non-jewish fish expert but not from other non-Jews. Rashi there explains that this is a small fish of a kosher species which only develop fins and scales when they mature. Now, there is a similar, and not readily distinguishable, type of fish of a non-kosher species that is frequently caught with them in the same net. This Gemara shows that a tradesman who has the expertise to distinguish between diverse species may be relied upon to remove non-kosher fish caught in the net together with kosher fish.

Some poskim offer yet another rational to explain why the fish in tinned tuna does not require continuous kashruth supervision, as follows: The Beis Yosef25 quotes Tosafos Rid26 who maintains that when there is a strong chazaka (pre-existing halachic presumption) that a fisherman deals exclusively with a kosher variety of fish, it is permissible to purchase fish from that source—even without simanim (the standard signs of fins and scales). These poskim maintain that the several meticulous hand-sorting processes create a chazaka which ensures that all by-catch is removed.

Nevertheless, Igros Moshe,27 Rav Henkin and the Teshuvos Vehanagos28 all say you that we may not rely on the concept of uman lo maura umnaseih, that “a tradesman will not ruin his reputation,” for when it comes to fish, only the signs that are mentioned in the Torah count, and it is not a matter of demonstrating logically that a given fish is from a kosher species or. Indeed, as mentioned above, the Rambam rules that it is a mitzvah to actually check each fish before consumption in order to confirm its kosher status.29 As for the opinion of Tosafos Rid cited in the previous paragraph, we see that Shulchan Aruch does not agree with that ruling as he does not mention it in his work.

Conclusion for part II: Since this is a serious disagreement amongst the authorities regarding eating non-kosher fish, which is a prohibition of Torah/Biblical origin, its meritorious to be stringent on this matter as the Mehadrin line actually checks the species of the fish as well.

Now that we have explored the background to this very complex topic, we are in a better position to understand why the Beth Din provides two lines of tinned tuna. As for the practical application of this discussion, and which type of tinned tuna should be purchased, we recommend that each individual consult their own rabbi for guidance.


  1. Tosafos (38a) and Rambam. Rashi (there) and Tosafos present another reason: lest the gentile come to feed you food which is non-kosher. Taz (1) understands that the main reason is because of intermingling.
  2. Shulchan Aruch 113:13.
  3. Darchei Teshuva Yoreh Deah 113:14 and Beis Meir 87:60 and Prisha rule leniently, Shevet Halevi (vol. VI siman 108) rule that steaming is the same as cooking on the fire, see vol. VIII 156. See also Teshuvs Vehanhagos vol. III siman 247, citing Harav Chaim Ozer Grodzinski.
  4. As according to the Minchas Yitzchak if it is in a factory we may be lenient.
  5. 38b.
  6. The logic of factories, the Iggros Moshe writes its only bedieved and the Michat Yitchok is only lenient with a combination with other reasons.
  7. We can say the Rashba agrees to the Ra’ah by factories since its not to a specific person.
  8. Yoreh Dei’ah 113:1.
  9. Minchas Asher – Devarim 5:8.
  10. Responsa Cheshev Ephod vol. 3, siman 29, even though raw tuna is served at a royal dinner.
  11. The Medieval authority Rabbi Shlomo ben Avraham ibn Aderet (1235 – 1310)
  12. Shulchan Aruch Yoreh Deah 113:12.
  13. Issur V’Heter Ha’Aruch 43:2.
  14. Responsa Shevet Kehati vol. VI siman 274 and Aruch Hashulchan paragraph 10.
  15. See Rema, Yoreh Deah 83:1.
  16. Sefer Hamitzvos, Rambam, Asin [152]
  17. Thus, the Shulchan Aruch there records a prohibition against purchasing fish roe unless the intestines possess certain characteristics associated only with kosher species (e.g., the eggs are round at one end and pointed at the other) and the seller confirms that they are the eggs of a kosher fish.
  18. Iggeros Moshe, Yoreh De’ah, III, no. 8.
  19. 43b.
  20. OC 20:1
  21. YD 31.
  22. Responsa OC II, section 72
  23. 34b.
  24. Tosafas Rid learns that this fish is actually referring to tuna.
  25. YD 83.
  26. Tosafos Rid to Avoda Zarah 40a.
  27. Iggros Moshe IIII, no. 1.
  28. Rav Henkin – siman 33, shana 40. Igross Moshe vol. IV:1, Teshuvos VeHanhagos vol. II 382.
  29. Siman 33.