The old expression, slow and steady wins the race, is not applicable when it comes to espresso. Sure, when you first start out, take your time to get shots ready and take your time to steam milk just right. Speed in those areas come later and with more experience. For now, just focus on doing it right. But there are some areas of making espresso that have very strict time tables.
First, there is the shot. When pulling a shot it should never take less than 15 seconds, otherwise it will not be strong enough and there will not be enough crema to ensure a good taste. It should, however, also not take more than 20 seconds. This is vital because as a shot pulls, after the 20 second mark, the bitter tannins in the espresso beans begin to be released. Essentially, you want to get your shot time as close to 20 seconds as possible, ensuring maximum crema, without crossing the 20 second mark.
After pulling a shot, things get much more rushed. Once your shot ends pulling, you have literally 10 seconds before the natural espresso bean sugars that are in the crema disintegrate completely. There are two ways of stopping this process. The first is to have your milk steamed ahead of time, so that once your shot is done, you can pour it directly into the milk, which will stop the disintegration process. The other option is to add ice or water, which will have the same affect as the steamed milk. Worst case scenario, if you have neither ready, you can always save a shot with a splash of milk or cream in a cup.
A similar countdown exists when it comes to steamed milk. When milk is steamed, the lactose in the milk converts to sucrose because of the heat. However, once the milk is done steaming, the sucrose in the milk begins to convert to a starch. This can ruin the taste of a drink, so the process has to be slowed as well. This is done by adding the shots of espresso. They stop the sugar and calcium from making the starchy taste. Essentially this process needs to be stopped before the milk cools down below 140 degrees F. However, as with all things espresso, the sooner you can stop the process the better.
After a drink has been made, all these processes of conversion and chemical change have only been stalled. That is why old espresso never taste quite as good. Best espresso machine with milk frother should always be served immediately after being made, and should be enjoyed as soon as possible. By following these simple time tables in regards to espresso making, you can ensure to get the best quality out of your espresso machine.