You may remember from Lesson 1.2 that HTST pasteurisation protocols require milk to be held at or above 72°C for at least 15 seconds. This temperature exceeds the normal serving temperature of milk drinks. Beverages above 70°C will scald the tongue; a comfortable serving temperature is between 55°C and 60°C. This discrepancy in temperature targets for hygiene and for comfort means that it is essential for a barista to maintain rigorous hygiene standards during the milk-steaming process. Most baristas do not usually bring milk to a temperature high enough to deactivate pathogens.
The cloth that the barista uses to wipe the steam wand is a particular source of potential contamination. Depending on the guidance of the food hygiene authority in your country, we tend to advise cafes to use a colour-coding system to ensure steam wand cloth is not used for any purpose other than wiping the steam wand. The steam wand cloth must not be stored on the top of the machine or on the drip tray. It is best positioned on its own hygienic tray away from any possible contaminants.
In addition to the steam wand cloth, you will want three other clean cloths each day. You need one specifically for wiping away drips from the drip tray to prevent the bases of cups from being marked. This can rest on the drip tray so long as it is not put to any other purpose. It is convenient to keep another colour of cloth on the work surface at the base of the machine to mop up any spills that may occur here. Then you will have a towel dedicated to wiping portafilters and filter baskets. Keep this towel dry; have it positioned near your grinder. The key is to keep all these cloths separate from each other.