Does pH level affect the cleaning ability of soap, detergent or stain remover?If so, please give the reason and resources

pH is a measure of the acidity of a substance.  More
specifically, it measures the proton concentration via the following equation:
pH=-log[H+].  The pH level will absolutely affect the effectiveness of soaps,
detergents, and stain removers.  Many stain removers and detergents contain enzymes to
help break down stains.  Enzymes are proteins and consist of long chains of amino
acids.  Proteins are designed to operate most efficiently at a particular pH.  If the
pH of their environment is changed too much, the protein will denature and lose its
shape, thereby losing it's ability to function (in this case breaking down stains and
soils).  Soap itself is made under highly basic conditions, meaning a very high pH.  As
such the polar part of soap is in salt form.  Using soap under highly acidic conditions
can affect this salt and therefore the effectiveness of the soap's cleaning
abilities.