Sumatra Boru Batak (Happy Mug), Success!

My previous attempts at roasting Sumatra beans resulted in under-roasted, sour, twangy tasting coffee. Each time there was hardly any first crack and no second crack. This time I roasted at a higher temperature hoping to produce both a better first crack and possibly a second crack.

The first batch started at 400F and increased to 450F at six (6) minutes into the roast. Once first crack ended I backed the temperature down to 375F. This seemed to be a mistake as no second crack occurred.

 The second batch I started at 350F and increased to 400F at four (4) minutes into the roast. When first crack finished at 7:20 I kept the temperature up and even increased it to 500F at eight (8) minutes into the roast. The roaster never quite reached 500F but did get close. This produced a second crack at 9:20 into the roast.
I left the coffee set for 3 days and tried it. It was much better than the first few batches I did of the Sumatra. It still had a slight twang but it was much more pleasant. It was slightly sour but had a nice nutty flavor as well. I really like this coffee and have enjoyed drinking it. I plan on roasting some more with the second batch profile from above.