, I would like to ask the Shari ruling on the use of L-cysteine which is widely used in Bakery products. When checking the ingredient list of the bakery products it either lists it as L-Cysteine or E920.

But it does not mention from which source it is derived from ?

According to limited research, i have found that the cheapest Industrial source of obtaining L-Cysteine is from Human Hair.

What is the ruling if the companies do not list the source of the L-Cysteine used in their bakery products ?

Praise be to Allah

There is nothing wrong with eating foods that contain L-cysteine
(E920) no matter what its source is, even if it is from pigs or animal or
human hair, because it does not remain in its original condition; rather it
is transformed into another substance, therefore it becomes pure and lawful.

But if it is proven that harm is caused by that, then it is
not allowed to use it, because of the harm it causes.

If we assume that this substance is taken from an impure
source such as pigs, and is not transformed into another substance, then if
it was in a very small amount that is absorbed (into other ingredients),
there is nothing wrong with eating the food that contains it.

This has been explained previously in fatwa no.
102749.

In Fataawa al-Majlis al-Urubbi li’l-Ifta’ wa’l-Buhooth
(fatwa no. 34) it says:

In the list of ingredients of some foods there appears the
letter E followed by a number. It is said that this means that it contains a
substance manufactured from pork fat or pig bones. If that is proven, what
is the Islamic ruling on those foods?

Answer:

What is referred to by the letter E followed by a number are
additives of which there are more than 350. They are either preservatives,
colourings, flavour enhancers, sweeteners, or other things.

They are divided, according to their origins, into four
categories:

1. 

Ingredients of
an artificial chemical origin

2. 

Ingredients of
plant origin

3. 

Ingredients of
animal origin

4. 

Ingredients that
are dissolved in alcohol

The ruling thereon is that they do not have any impact on the
permissibility of the food or drink, for the following reasons:

With regard to the first and second categories, that is
because they come from a permissible source and there is no harm caused by
using them.

With regard to the third category, it does not remain in the
same state as when it was taken from its animal source; rather it has been
subjected to a chemical process that has changed its nature completely, as
it has been transformed into a new, pure substance. This change affects the
Islamic ruling on that substance. If it was itself prohibited or impure,
then its transformation into a new substance means that it comes under a new
ruling, as in the case of alcohol, if it is turned into vinegar, then it
becomes good and pure, and as a result of this transformation the ruling on
alcohol no longer applies to it.

With regard to the fourth category, in most cases this refers
to colourings, which are usually used in very small quantities, so that they
are absorbed into the final products, and this is overlooked.

So whatever foods and drinks contain any of these substances
in their list of ingredients remain permissible as they originally were, and
there is nothing wrong with the Muslim consuming them.

Our religion is easy, and it forbids us to overburden
ourselves; making excessive enquiries into such matters is not something
that Allah, may He be exalted, or His Messenger have enjoined upon us. End
quote. From Fiqh an-Nawaazil by Dr Muhammad al-Jeezaani (4/263-267).

It says in the recommendations of the Ninth Medical Fiqh
Council:

Additives in food and medicine that come from impure or
prohibited sources become Islamically permissible in one of two ways:

1. 

Istihaalah
(process of transformation)

2. 

Istihlaak
(process of absorption).

That occurs when the prohibited or impure substance is mixed
with another substance that is usually pure and lawful, to such an extent
that the characteristic of impurity and impermissibility is removed from it,
from a shar‘i point of view. That is when the substance that is mixed and
overwhelmed loses its characteristics of taste, colour and scent, so that
the substance that is overwhelmed is absorbed into the dominant substance,
and the ruling applies to the dominant one.

Examples of that include the following:

1. 

Additives that
are used in a form that is diluted in alcohol, and used in very small
quantities in the food or medicine, such as colourings, preservatives and
emulsifiers.

2. 

L-cysteine and
cholesterol, which are derived from impure sources without undergoing a
process of transformation (istihaalah). It is permissible to use them in
food and medicine in very small amounts that are absorbed into the dominant
mixture that is lawful and pure.

3. 

Porcine enzymes
such as pepsin and all other digestive enzymes and the like, that are used
in negligible amounts that are absorbed into food and medicine.

End quote from Majallat al-Majma‘ al-Fiqh al-Islami
(10/1431)

And Allah knows best.