Soap In Laundry Detergents
Yes, Persil has soap, but then again so do many other detergents on both sides of the pond. Was reading the MSDS for the new Tide "Pro-Line" detergent,and it lists soap as well.
Wouldn't get too excited about laundry detergents having soap, Savon de Marseille, etc; the amount is very low in most cases, <5%. Long chained soaps are used more for foam control than anything else.
Reason why Persil, Tide Pro-Line, some versions of Ariel (EU and UK), and others leave laundry feeling softer, has more to do with product formulation than pure soap.
The new buzz word in commercial laundry circles, and has trickled down to TOL domestic laundry products is "encrustation" and how to prevent it.
Encrustation is the rpcess where by calcium and other minerals becomes trapped and builds up in textiles. This causes items to have a rough feel and a dingy tattle-tale grey appearance. Phosphates are good for preventing and removing encrustation, but now that they have been pretty much banned, and or laundry products are moving to non-phosphate versions to be seen as more "green", other substances had to be found.
High pH levels in the wash bath also contribute to encrustation. High pH levels are great for cleaning very soiled laundry because it causes textile fibers to swell, and release soils. However if those fibers are not closed back down, the fabric will feel coarse and rough. In addition calcium and other minerals in the laundry bath can become trapped in textile fibers, thus adding to the problem. In the past the solution was to add a "sour" to the final rinse bath. However souring laundry requires careful monitoring of the pH level to get right.
What modern TOL detergents have done is to clean without raising the pH level above neutral to only slightly alkaline, or even slightly acidic. Keeping pH levels down means no encrustation, hence no worries about grey and rough feeling textiles.
If one compares Persil, and many other TOL European detergents, you will see they contain less washing soda, than say Arm&Hammer or other MOL and BOL laundry products. Liquid laundry detergents also leave laundry feeling softer due to the fact they do not contain washing soda in any amount.