After drinking freshly roasted coffee for about a month, I tried two store-bought coffees: 1) Dunkin’ Donuts and 2) Marketplace Coffee from Giant Eagle.
The Dunkin’ Donuts coffee was on sale for about $5.50 for a 12 oz. bag. After making a mugful in my French press, I took it on the bus on my way to work. I found my stomach was upset. Since it was on sale, I chocked it up to old beans, hence the sale.
This past weekend I got the La Prima’s Coffee Roaster too late on Sunday afternoon to replenish my green bean supply. So I went to Giant Eagle to get some coffee, especially since my father-in-law was coming to work on my basement. I decided that for the price at approximately $6.50 a 1b. I filled up a bag with whole Sumatra beans. It looked dark roasted, with the oils shining on the surface of the beans. I made a pot with my Cuisinart Grind ‘n Brew. It wasn’t bad. The next morning I made a mugful with my French press with the same beans. I took that on the bus on my way to work. Just like the Dunkin Donuts, my stomach was upset.
Hmm. What’s up with these store-bought coffees? In the past I’ve always attributed the upset stomach to the caffeine content. But during the month I drank my fresh roasted coffee, I never had this problem. Actually, I really looked forward to my bus rides with my mug in hand. I found the best cup of coffee was made with beans half from Kenya and the other half from Brazil. The Brazilian beans give the coffee a very sweet taste that becomes more and more chocolaty and nutty as the cup cools. The Kenyan beans makes the cup bright in flavor – tantalizes the taste buds – when first sipping the brew. As the coffee worked its way down to the gut, there was a warm comfortable feeling, especially on cold mornings in the teens and twenties.
So what do I think? I think the upset stomach is from the oils in the roasted coffee beans going rancid. I’m a chemist working in a lab analyzing proteins being studied by biologists and medical doctors. Just by being exposed to air proteins readily oxidize and hydrolyze – both being chemical processes that take place when things decompose.
I’ve heard that the rule of thumb for roasted coffee beans is that they are good for two weeks. Anything longer than that – they are going bad. So how long do beans sit on the shelves or coffee bins at Giant Eagle? It’s hard to believe it would be less than two weeks.
Are all coffees sold at supermarkets rancid or at least starting to go rancid?
