Do we need to mention E501 acidity regulator on back of pack?

We make all natural cocoa roll. our cocoa powder will contain 7% acidity regulator E501.Do we need to mention this on back of pack?

Any one help me.

regards

Where are you selling the product?
That will potentially have a significant impact on labelling requirements.

Uk and EU

Ok, so the primary point of reference for you will be Article 20(b)(i) of Regulation (EU) 1169/2011:

Without prejudice to Article 21, the following constituents of a food shall not be required to be included in the list of ingredients:...

(b)food additives and food enzymes:

(i) whose presence in a given food is solely due to the fact that they were contained in one or more ingredients of that food, in accordance with the carry-over principle referred to in points (a) and (b) of Article 18(1) of Regulation (EC) No 1333/2008, provided that they serve no technological function in the finished product.

If I've understood correctly that the Potassium carbonate (E501(i)) and/or Potassium bicarbonate (E501(ii)) are present in your raw material then these may exempt from labelling in the final product, subject to whether it/they do or don't serve a purpose in the final product - if they are in effect still acting as acidity regulators then you would need to list them in the ingredients.

Also just to note regarding the "natural" status, you may want to check how you're labelling that and what the expectations are in the particular countries where you will sell the product - unfortunately this isn't harmonised at EU level IIRC, but for the UK specifically you will need to be cautious with the wording around this given that you've got at least one additive there. See page 10-12 of the attached for reference (the document is now well over ten years old but I don't recall seeing anything more recent!).