Does stainless steel affect the flavor of coffee?
Coffee makers are quite often made of stainless steel, especially the small espresso makers. Although most mugs and cups for drinking coffee are made of china, porcelain or paper, stainless steel is sometimes preferred for cups which need to have a lid put on them or cleaned in a particular manner. Although stainless steel has many benefits in that it is extremely durable, tough and easy to clean, many coffee drinkers feel that the use of stainless steel either in the coffee maker or the drinking cup can adversely affect the flavor of the coffee. But is there any truth in this?
From a scientific point of view, stainless steel cannot affect the flavor of the coffee. Steel is a stable and inert compound, and even when formed into a cylinder such as a mug and filled with boiling hot liquid, there are no chemical reactions going on which could mean that the flavor of the coffee is altered. It does not start to break down or corrode, which is exactly why it is such a popular choice for professional kitchens and for environments where hygiene and cleanliness are essential.
However, that’s not the whole story. Steel is porous just like other materials such as plastic or glass used for coffee pots, and china or paper used for cups. This means that tiny particles of oils from fingers or mouths can seep into the surface of the steel and even a thorough cleaning regime won’t remove them. Over time, these oils and other tiny particles start to rot down and when they come into contact with a hot liquid they pass back into it and affect the flavor. This is obviously much more of an issue when dealing with stainless steel coffee mugs than with makers, as the mugs have much more contact with fingers and mouths. To minimize the effects of the stainless steel on the flavor of the coffee, it’s important to ensure that mugs are rinsed out well using hot, soapy water after use. If any sort of build up or residue is noticed on the inside of the cup, this can easily be remedied by filling the mug with household vinegar and leaving it to soak overnight, before rinsing it out. There are special products available which do the same job, but they are often full of harsh chemicals and best avoided for things you are going to drink from afterwards.
When talking about stainless steel coffee mugs, these are usually used for situations such as travel or when working in an environment where it is essential liquids are not spilled or mugs are not easily broken. Lids on the mugs are designed to be tight fitting to avoid drips or spills and as a consequence this cuts off the aroma of the coffee. Smell is a massive part of taste, and not being able to smell the coffee inside the cup can lead many to believe that the flavor has been affected by the container.