What Could Be Wrong With…L-Cysteine?

When is the last time you have seen a harvest? Some of us can think back to last fall’s grape crunch; others can still picture a combine’s quick clearing of a wheat field for Shmurah flour. Most of us, however, could not rapidly identify the last harvest we witnessed. It would surprise many of us to learn that we have all been at a harvest, and the harvested field was us.

If you have not guessed by now, this mysterious farm is your local barbershop, or beauty salon. Did you know that human hair is loaded with valuable amino acids? One of those amino acids, l-cystine, is used as a base for the production of food and pharmaceutical chemicals. Its derivative, l-cysteine, is used as a dough relaxant and as a component in reacted meat flavors. Another derivative, n-acetyl-l-cysteine, is used in treatment of respiratory disorders.

But do not worry. It is probably not your hair that will find its way to relax your next Shabbos challah and grace your table. In this land of throwaway diapers, cutlery, and cameras, there is little interest in barber-shop droppings. But in the frugal Far East, clippings are too valuable to waste. Human hair is collected from area barber shops for extraction of its component amino acids.

So the story goes. Of course, there are other alleged versions of this hairy tale. Some say heads of Asian corpses are shorn before they are interred (or otherwise disposed of). Others say that heads – again, Asian – are shaved in a pagan, idolatrous ritual. These latter versions are denied vehemently by l-cysteine manufacturers.

L-CysteineThe halachic ramifications of the hair-collection method are significant. Although human flesh is prohibited, human hair, collected from the living, is permitted. A corpse’s hair, however, is prohibited (see Mechaber in Yoreh Deah 349:1 and Tosafot in Bava Kamma 10a s.v. she’hashor). Likewise, hair shorn in idolatrous rituals is prohibited. In the course of our research, we did not uncover any evidence to support the allegations of hair gathered for idolatrous rituals or posthumous shearings. Therefore, it is the OU’s position that l-cysteine derived from human hair is acceptable.

It is interesting to note that some manufacturers of l-cysteine will no longer accept human-hair-derived l-cysteine. Although, like the OU, they have investigated, and rejected, the claims of idolatrous and posthumous hair, they are concerned about public opinion and perception. The European Union has moved to draft a regulation prohibiting the use of all human by products in food and pharmaceuticals. Thus, industry is scrambling to provide l-cysteine not sourced from human hair.

L-cysteine need not be isolated from natural sources. Ajinomoto, a large, OU-certified manufacturer of amino acids, produces l-cysteine synthetically. Ajinomoto cannot, however, meet the world’s demand itself. In addition, many industries, such as flavors, require natural chemicals to meet their customers’ demands for clean labels. Food producers, as a group, prefer to list natural flavors, instead of artificial flavors, on their labels. They do not wish to use a flavor that contains synthetic l-cysteine, as this would require them to list artificial flavors. Hence, the need for naturally derived l-cysteine, not sourced from human hair, is growing.

Fortunately, or perhaps unfortunately, there is an abundant supply of natural, non-human material, from which l-cysteine can be derived. The spines of feathers contain many of the same amino acids that are found in human hair. Since feathers are an unavoidable by-product of poultry production, they would seem to be the logical choice for l-cysteine raw material. Once our pillows, comforters, and down jackets are properly stuffed, there should still be an adequate supply of feathers remaining for amino acid production. Feather-derived l-cysteine is natural, it is not affected by any of the halachic concerns discussed earlier, and it will not disturb the sensibilities of even the most squeamish European Union regulator.

Alas, there is an halachic issue concerning the kosher status of feathers that is not easily resolved. Poultry producers have discovered that birds are properly stripped of their feathers only by first soaking them in hot water. Producers are somewhat restrained in the temperature of water they may use; they cannot use water that is too hot, for it will pre-cook the bird. Nevertheless, all seem to agree that the water is in excess of 160 degrees Fahrenheit, a temperature considered yad soledes bo according to almost all opinions.

Soaking a bird in hot water is discussed in Yoreh Deah 68:10,11. The specific case discussed there is a slaughtered bird that has not yet been salted, and still contains blood. In our discussion, we are confronted not only with blood, but also with unslaughtered flesh, which is neveilah.

Like most cases of heat-inspired transfer of taste, the extent of the damage depends on the method of heating employed. Soaking the bird in a kli rishon prohibits the entire bird, pouring kli rishon water on the bird prohibits its skin, and soaking it in a kli sheini does not prohibit it. In our case, the spines of the feathers are only a skin’s-width thick, and therefore would absorb the blood and the neveilah if any kli-rishon water were used. It is our experience that kli rishon water is used, despite some representations to the contrary.

It is interesting to note that Empire Poultry, who does not use hot water to soak the birds, said they dispose of their feathers as waste because the feathers are ruined by their cold water process.

How can kosher l-cysteine be made from neveilah – and blood-laden feathers? This question was pondered by our Poskim and by those of other kashrus agencies. In order to understand the different approaches to this question, it is first necessary to describe some of the details of l-cysteine production.

The spines of the feathers are first dissolved in a 3% hydrochloric acid solution. The l-cystine floats to the top. Residual acid in the l-cystine is neutralized with a caustic soda solution. The l-cystine is then purified and crystallized. The l-cystine is converted to l-cysteine by further reaction and chemical processing.

Some have argued that since the feathers are first dissolved in a strongly acidic solution, all absorbed taste of neveilah and blood would be rendered pagum. As a point of history, a similar argument has been presented, and rejected, for permitting gelatin produced from non-kosher hides and bones. Since, at the end of the process, the gelatin is no longer pagum, we cannot accept its mid-process pegimah as sufficient grounds for permitting it.

Those that have forwarded this argument to permit feather-derived l-cystine distinguish between gelatin and l-cystine. In making gelatin, the hides and bones are processed with the intention of removing the pegimah at the end and transforming them into gelatin. In making l-cystine, however, there is no intention to utilize the absorbed neveilah and blood. The only product of interest is the l-cystine, which is kosher in its own right. Therefore, the mid-process pegimah of the neveilah and the blood is acceptable and the l-cystine is permitted.

Rav Schechter rejected this view. Rav Schechter argues that a mid-process pegimah has lasting validity only if the pegimah is not removed, but rather is rendered ineffective for another reason. For example, if neveilah would be treated with an acid and rendered pagum, and then it would be sweetened with sugar until it would be edible, it would be permitted. But if the acid would be removed, then the neveilah reverts to its original prohibition.

The same logic applies to l-cystine. Even though it is treated with hydrochloric acid, the acid is later neutralized and removed by treatment with caustic soda. Therefore, the mid-process pegimah is not sufficient grounds to permit l-cystine.

Rabbi Genack, however, felt that l-cystine is permissible for a different reason. L-cystine is subjected to multiple purifications before it is crystallized. In the purification process, all, or almost all of the absorbed blood and neveilah will have been removed. Based on this, Rav Schechter ruled that as long as the blood and neveilah will now be batel b’shishim, the l-cystine is permitted. We need not concern ourselves with chanan, because the feathers have the status of a kli, which is not subject to chanan.

Rav Schechter also ruled that since the l-cystine producers would prefer that the feathers not be contaminated with absorptions of blood and neveilah, their use of the feathers is not considered mevatlin issur lechatchila. Therefore, we would be permitted to grant certification to such producers.

The elaborate tale of this seemingly innocuous amino acid proves, once again, that our presumptions about raw materials must be constantly reviewed and scrutinized. Only careful research and the Halachic process can ensure the acceptability of raw materials used in kosher foods.

OU Kosher Staff