Using Powdered Ingredients Past Expiration Date

Regarding the use of powdered ingredients a few weeks past their expiration date, the previous response from cosmeceutical7 provides a good perspective.

Generally, for stable powdered ingredients, the actual shelf life can often be longer than the expiration date stated by the manufacturer. Manufacturers often set conservative expiration dates to limit their liability. Some manufacturers even use "retest dates" instead of expiration dates, indicating when the ingredient should be re-evaluated for quality.

However, from a professional standpoint, it is recommended to discard ingredients once they have passed their stated expiration date. This is because there is no guarantee that the ingredient still maintains its full efficacy, purity, or stability after that date. While it might still be usable, its performance could be compromised, or there could be unforeseen changes. Therefore, to ensure the quality and safety of your final product, adhering to the expiration date is the standard professional practice.