keratin safe for cats?

i have been using this hair keratin for about a year or so, i wash my hair and always spray it in my hair after a shower, my cat is obsessed with smelling it and and i let her smell it after i put it in because i've read that keratin is good for cats and she loves it. today i took a shower and sprayed the spray and let my cat smell it and she started rubbing up on my hair and playing with it and was biting my hair a bit, and i'm wondering if this is harmful to her? i just saw that it has red 40 in it for god knows why, but i am so worried if it can hurt her