Which of the following practices should be avoided during grinding?

Tapping the portafilter side with the tamper is a practice that should be avoided during grinding because it can lead to an uneven distribution of coffee grounds. This action can create inconsistencies in the packing of the coffee, leading to channeling during extraction. Channeling occurs when the water finds a path of least resistance through the coffee, resulting in under-extraction (where some grounds are not fully saturated and extracted) and over-extraction (where water flows too quickly or unevenly through the coffee).

Maintaining an even and consistent grind, rotating evenly to distribute the grounds, and using the appropriate grind setting are all practices that promote consistency and quality in the espresso extraction process. These methods help ensure that the coffee bed is uniform, which leads to an optimal flow of water through the coffee during brewing. By avoiding the practice of tapping the portafilter, baristas can achieve better extraction results and ultimately enhance the flavor profile of the coffee.