By coffee harvesting machines, all coffee berries are collected at the same time, so those berries are the mixed at all conditions as ripe and unripe / big and small sizes / berries and peaberries and so on. Surely, the major proportion of coffee beans are from ripe berries at regular size, but the mixture of other beans will create different coffee flavors.
Moreover, major brands are generally purchasing their green beans from more than one region in a country. Therefore, the coffee is good in quality, but not the best, since if small beans are roasted good, big beans will be raw at the same roasting time; on the other hand, if big beans are roasted good; small beans will be over roast at the same roasting time. Therefore, the coffee taste is good but unstable, and this is really the balancing between cash and quality.
