If you have eaten gummy bears, yogurt, marshmallows, popped some pills, used film photography (remember that?), had a vaccination, have worked in forensic ballistics or you’re a synchronized swimmer then you have definitely come across gelatin (or its alternatives).

Gelatin is as substance derived from collagen, which is a natural protein mostly present in skin, bone and connective tissues. It is capable of forming strong gels and flexible films that are tasteless, transparent, soluble in hot water, and easily digested. Its various applications as a stabilizer and gelling and thickening agent make it a hot commodity in a range of industries, including the food industry.

Gelatin production has been around prior to its first patent in the UK in 1754. Almost half of the world production of gelatin is from porcine hide (pig), while the rest is mainly from bovine hide (cow) and bones from cattle. Its kosher status has been debated by halachic authorities for the past couple of centuries. Although the OK, and most other kosher agencies, require gelatin to have a reliable kosher certification, there is a minority that will consider it kosher and pareve even from non-kosher sources.

The halachic rule regarding an accidental mixture of kosher and non-kosher substances is that if the non-kosher substance cannot influence the mixture it will be nullified and the mixture keeps its kosher status. This is the basis for Botul B’shishim, nullification by the ratio of one sixtieth. Our Sages determined that a food’s flavor cannot be tasted in a ratio of one to sixty. Therefore non-kosher food that is less than a sixtieth of a mixture cannot cause the mixture to be non-kosher because it has no influence. (This does not apply to foods that can be tasted in minute quantities like spices.)

However, there are circumstances where it could influence the mixture in ways other than taste, and in those situations the ratio of one sixtieth does not apply. One example is if it helps solidify the mixture, referred to as Davar Hama’amid. If the forbidden substance solidifies the mixture then it can influence at a smaller ratio than one sixtieth; therefore, even a minute quantity can’t be nullified and would render the mixture non-kosher.

An example of a Davar Hama’amid is using rennet to create cheese. Rennet is a complex of enzymes that coagulates milk to turn it into cheese. A source of rennet is from the abomasum (the fourth stomach chamber) of a calf. If rennet from a non-kosher source is used to coagulate kosher milk then the whole mixture would become non-kosher (see Shulchan Oruch Yoreh De’ah 87:11).

As explained earlier, gelatin is used as a stabilizer and thickening agent and is therefore considered a Davar Hama’amid. In that case, gelatin cannot become nullified to the mixture. To understand why some thought to permit non-kosher gelatin, we need to delve into the process of making gelatin.

Gelatin is produced by treating the skin or bones with acid or alkaline (depending on the raw material) to facilitate the release of collagen. Afterward, the skin or bones are dried for preservation if necessary. Then, they sit in hot water at a minimum of temperature of 45°C/113°F to extract the gelatin, which can be done multiple times. Next, the gelatin is strained to remove any traces of fat, and concentrated to remove any water. The gelatin is dried and usually ground into a powder or formed into small thin leaves.

The main reason why some earlier halachic authorities permitted non-kosher gelatin was because the bones or skin were completely dried for preservation, and were not considered food because they were inedible (Achiezer, vol. 3, 33:5). This is based on the Rema’s ruling (Yoreh De’ah 87:10) regarding rennet, which says that if the skin of the calf’s stomach was completely dry then it was permissible to use it as rennet. This is because dried skin is inedible and considered like a piece of wood (there is a dispute if this applies to non-kosher meat, see Pischei Tshuva 21). Similarly we find with regards to bones from a non-kosher animal that are mixed with a kosher mixture, that it will not render the mixture non-kosher if they are “bone” dry (Yoreh De’ah 99:1).

There is an additional reason why some authorities permit gelatin. Since it originally was part of the bone or skin and now has been extracted and dried, it can be considered a new creation (Yabia Omer, Yoreh De’ah 8:11). This is disputed even by lenient opinions because they claim that gelatin has always been there, and now is simply separated from the bone or skin (Rabbi Yechezkel Abramski in the introduction to Tzitz Eliezer Vol. 4).

There are opinions that disregard the above reasons for leniency and forbid gelatin from a non-kosher source. They hold that even though at one point it may not be edible it will eventually become fit for consumption. Since it returns to a food state it will take on the previous non-kosher status at that point (Igros Moshe, Yoreh De’ah 2:23 & 27, Minchas Yitzchok 5:5).

As mentioned above the OK and most kosher agencies take the stricter approach and forbid gelatin from a non-kosher source. An important reason for this is because the lenient opinion is based on the fact that the skin and bones are dried. This process is only for preservation purposes and not integral for producing gelatin. Since there are many applications of gelatin even beyond the food industry, the market for gelatin is massive. Therefore, there isn’t a need to preserve the bones or hide because an immense volume of gelatin is constantly needed, and the leniency of dried gelatin is not applicable.

There is kosher certified bovine gelatin from cows that have been halachically slaughtered. It is considered to be pareve since it is dried and tasteless and therefore comparable to the dried skin from the calf’s stomach that could be used as rennet (see above). In addition to the expense of kosher supervision, kosher bovine gelatin is more expensive because the hide is bought from the slaughter house, unlike the non-kosher version which is bought from scraps from leather factories which is far less expensive.

The most common kosher gelatin which is used is marine gelatin (fish), as the skins and scales of fish contain relatively large amounts of collagen. This is easier from a kosher perspective since fish do not have to be halachically slaughtered. However, kosher fish is not the only source for marine gelatin and the skins of non-kosher fish are also used (e.g. catfish and shark), which is why a kosher certification is necessary for marine gelatin. In addition to the kashrus advantages, marine gelatin is also beneficial as fish skins and scales do not have much use and usually go to waste, unlike cow hide which can become leather.

About 1% of the world gelatin production is from marine gelatin. Gelatin can be produced from both cold-water (e.g. cod and salmon) and warm-water (e.g. tuna and tilapia) fish, though there are differences in their production. Cold-water gelatin tends to have a low bloom and warm-water commonly has a high bloom (bloom refers to the strength of the gelatin, high being strong and low being weak). Warm-water skins are less available in comparison to cold-water fish skins.

The industry does have some challenges as production is a delicate process and the quantity of available raw material is a lot smaller compared to bovine gelatin. Due to continuing research, some of the production difficulties have been overcome, including removing the odor, which initially was difficult. The method has improved so much that now marine gelatin has a less noticeable odor than bovine gelatin.

Kosher consumers purchase many different products containing fish gelatin, and while most are medicines or supplements, the consumer should take note that most kosher marshmallows are made with fish gelatin. It is especially important to be aware of this when roasting marshmallows or serving marshmallow desserts with meat meals.