That lovely soft packet of bagels or rolls you just bought at the supermarket may well have been softened by something very very soft. If the packet mentions the dough conditioner, l-cysteine, that soft stuff is most likely to be asian hair, poultry feathers or hog hair.You may have seen the ingredient l-cysteine listed on the packets of pre-made baked goods like bread rolls, bagels and pizza bases. L-cysteine is a non-essential amino acid (L-2-amino-3-mercaptopropanoic acid - C3H7O2NS) that is used to condition and strengthen dough and improve its manageability during the cooking phases. Essentially, it stops the dough from retracting once stretched out. (It isn't used in wholemeal cooking.)L-cysteine is also used to make beef, chicken and meat flavours, so you will see it in things like chicken stock cubes.Most of the commercial l-cysteine is produced in China and while a great deal of it comes from human hair, it also comes from duck feathers and even pig hair. Essentially, hair or feathers are gathered and dissolved in hydrochloric acid to separate the l-cysteine protein.Around 10 percent of l-cysteine is derived from non animal sources, and this number is growing with increasing demand for vegetable based product.L-cysteine is considered generally to be safe to eat. Read the label and if you are fine with a bit of feather and hair, go ahead and eat the product. If you are vegan or not fine with feathered bagels, choose a fresh product, eat wholemeal, bake your own bread or make your own stock!Image: Volodymyr Goinyk/Shutterstock