
Coffee tastes bitter with minty aftertaste
I am new to coffee brewing. I am using chestnut c3s for grinding(20 clicks), aeropress inverted 1:30 steep and 30s press until the first air hiss comes. I am using about 100deg water. My beans are dark roast and I got a 4 month old sealed pack. However the coffee is turning out bitter and more importantly has a minty aftertaste. Am I doing something wrong or is it just the old beans?
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