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discoloration during stability test
hi i’m newly registered in this forum but i’ve been reading a lot of your discussion. some of your tips are very helpful. i signed up so i can also share some of my experience in formulation
btw im currently on my stability test for this lotion and i noticed a very distinct discoloration (from off white to bright yellow) at the elevated temp (45C)formula:cetearyl alcohol 2-5%stearic acid 5-8%polysorbate 20 1.00-3.00%shea butter 0.10-0.50%hyaluronic acid 0.50-1.00%vitamin e 0.50-1.00%sorbitol (70% solution)- 7.00-10.00%xanthan gum- 0.70-1.00%phenoxyethanol- 0.50-0.80%end product pH range is 4-5.what do you think caused the discoloration?thank you for your comments
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7 Replies
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I also faced this problem, It may be due to 2-3 ingredients like Stearic acid, Perfume, Vit. E, orbitol & Xanthan gum also.
1. Stearic acid is available in off white to slight yellow colour which may change colour at accelerated temp. because it is prepared from vegetable fat which tend to change colour.2. Perfume is formulated with many of the ingredients which tend to change colour from off white to yellow at accelerated temp.3. Vit.E is also available in yellow colour which may be threat here.4. Sorbitol tends to change from off white to dark brown at accelerated temp. or long storage because it is prepared from glucose or dextrose which may change colour of it.5. Xanthan is also available in off white to slight yellow colour.You can try following solutions :1. Use suitable anti-oxidant other than Vit. E like Tinoguard range from BASF.2. Try other glycol or triglycerides instead of sorbitol.3. Check colour of your perfume used. -
before I make a comment, I’ve got a couple of questions:
firstly, where are you planning to sell this product?
secondly, does this yellowing also occur at lower temperatures?
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Fragrance/perfume reactions are always my first suspect when something like this happens, but you didn’t list any, so I can only assume you’re unfragranced.After eliminating fragrance, my next suspects are always the natural ingredients. To me, the most likely culprit is actually the shea butter, since I’ve seen old shea butter turn bright yellow by itself. You also have a very high percentage of Vitamin E, which is available in many versions. A natural version is also likely to turn yellow eventually
Sorbitol typically browns with heat, so it would be less likely to go yellow. Everything else is much less likely.
My typical response to an unexpected stability event is to prepare a set of knock-out batches and put them all up on stabilitiy, in order to positively identify the culprit. -
thank you for your replies!
i work in a toll manufacturing so my formulation is based on client’s request, yes she is planning to market this product. they want it to be unscented, so i did not put any fragrance. they want to claim very high moisture lotion so i added a very high percentage of sorbitol, also the client prefer sorbitol as their main moisturizer, so i cannot replace the sorbitol.i have exposed the lotion to room temperature which at my current location is at 30-35C, and my lotion did not turn to bright yellow, it only turned yellow at 45C and the lotion also turned rancid.bobzchemist, i’m currently doing your advice of knock out batches and will check my test after one more week.i will also check what kind of vitamin e versions we have.if the client still want to pursue this formulation, what can you suggest a procedure for stability test without exposing it to 45C? -
I think I would begin by knocking out the hyaluronic acid. The shea is such a small percentage, I doubt that’s the cause.
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Sorbitol is in higher conc. here, it is a biggest suspect, please check colour of sorbitol and try to indent colourless sorbitol from suppliers. Also check possibilities with St.acid also.
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thank you for your comments and suggestions!
its confirmed hyaluronic acid and sorbitol both caused the discoloration…
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