Coffee beans much like all other plants have various types that vary in size, color shape, and the percentage of caffeine they contain. The strength of the beans are determined by their caffeine content. Although some varieties contain as little as 0.5%, some others go as high as 1.42% percent. Don't let these little figures confuse you. Beans that contain higher than 1.3% caffeine are the stuff that would keep eyes wide open and you running all night long.
The color and the roast of the bean is also important. Darker beans require more roasting time than lighter beans. Which translates to more caffeine being burnt up. Lighter beans don’t need to be roasted as long or with as much heat and tend to contain more caffeine.
Some examples of beans with high caffeine content include:
Robusta beans originate from Western sub-Saharan Africa. they have a caffeine content of 2.7% placing it at number one in the coffee strength charts. They contain less sugar compared to other varieties and are the second most popular coffee in the world. The first is Arabica coffee beans which are supposed to be the creme de la creme of coffee beans but does not contain so much caffeine.
This variety has a caffeine content of about 1.42% making it one of the strongest varieties in the market. They are grown in the Mbeya region of south-western Tanzania. They are lightly roasted helping them to retain a high caffeine percentage even after processing.
This variety is grown in Southwest India, Karnataka state. They have a caffeine content of 1.37% and very low acidity. They are a rich, medium, light roast bean with an excellent flavor. It has a medium acidity and is the most popular Indian coffee.