Did you know that any metal surfaces that coffee oils contact during espresso brewing will contribute rancid flavors in the cup if you do not take steps to keep them clean.
Check out some of the following distributors of coffee machine cleaning products.
Urnex Brands Coffee and Espresso Equipment Cleaners
Coffee & espresso equipment cleaners since 1936. Liquids, tablets, and powders. Detergents and descalers. Six NSF certifications and OMRI organics listing.
[...] Coffee Roasting Equipment (7) Commercial Espresso & Capuccino Machines (57) Coffee Cups & Sleeves (3) Commercial Coffee Grinders (17) Coffee Syrups & Flavorings (2) Espresso Machine Parts (1) , Coffee and Espresso Machine Cleaner [...]