Is it permissible to work as a food quality and safety consultant in restaurants that serve alcoholic beverages, bearing in mind that this work is not the sole source of income?

Your work is permissible and not forbidden, provided it does not involve evaluating the quality of alcoholic beverages. You must strive to forbid evil to the best of your ability. However, if you leave it out of piety, it is more cautious and absolves you of blame.