This is what ChatGPT has to say
What you’re seeing is fairly typical peptide behavior and is usually not degradation.
Why MOTS-C + BAC goes cloudy in the fridge
Temperature effect: MOTS-C has limited solubility at lower temperatures. Cooling can cause temporary peptide aggregation or micro-precipitation, which looks cloudy.
BAC interaction: Benzyl alcohol slightly alters peptide solubility. When cold, this effect is more noticeable.
Physical stress: Moving or vibrating the vial in the fridge can encourage these tiny aggregates to form.
Why it clears at room temperature
As the solution warms, the peptide re-dissolves, restoring clarity.
This indicates reversible precipitation, not chemical breakdown.
When it is a problem Cloudiness is concerning only if:
It does not clear after reaching room temperature
You see flakes, strings, or sediment that won’t dissolve
The solution turns yellow/brown
There’s a persistent smell change
Best practices
Let the vial warm to room temp before use
Avoid shaking—gentle rolling only
Store consistently (don’t repeatedly chill and warm if possible)
Use sterile technique to avoid contamination
Bottom line:
If it clouds in the fridge but clears completely at room temperature, your MOTS-C is very likely still fine.