How does espresso-based coffee compare to instant coffee?

Question

When I buy coffee from outside, from whatever popular brand outside, and drink it, I feel a bit elevated. Especially one with higher caffeine content.

However, when I drink the one I make my own I feel a bit more neutral/ have a headache depending on how much instant coffee powder I use. I am so confused on this because to my understanding, both the restaurant and I are using more or less the same ingredient: Coffee beans. So why does one lead me to be elated while the other gives me a headache?

Here is my preparation currently: Powder and sugar in cup, hot milk in, mix to serve. Definitely not the most sophisticated kind of preparation but I think the chemical composition of the ultimate product should be comparable, hence the effect of drinking.

I'm aware of Why are Costa or Starbucks lattes so good?, though that question is aimed at improving coffee at home. In this question, I'm interested in a comparison of instant coffee and espresso-based coffee.

Answer 1

Instant coffee is coffee that has already been brewed then cooled and underwent a process that leaves only the solids.

Instant coffee is usually made of cheaper robusta beans (high quality robusta beans also used in Italian espresso blends to give specific flavors). Robusta also has more caffeine content than Arabica, but instant coffee has less caffeine than a coffee brewed from the same beans using other methods.

Espresso yields a brew that will be more complex and a more satisfactory sensatory experience (how can you resist the smell of a espresso being brewed, that alone has more kick that the caffeine itself!). Instant coffee on the other hand is practical and quick to prepare, espresso forces you to focus on the preparation process and let's you try different parameters (grind size, amount of coffee, temperature, extraction pressure and time) to get your ideal brew.