Obviously these questions are dependent on the local situation, weather, harvest specs, etc. but just hoping for some general advice which may shorten my learning curve.
1. What is the best indication of complete fermentation for a box of forastero beans? (Drop in temperature below 45C? Purple/brown color inside? Absence of acid smell? Time in box?). Assume we are looking to acheive 90% or more. Is some remaining acid after fermentation good? Would it reduce if I lengthened drying time by transferring beans to the drying beds at night?
2. Generally speaking, How easy is it to over-ferment beans? Can this happen if beans are left for an extra 0-12hrs? 12-24hrs? or does it require more like 48-72hrs? I have read that longer fermentation time is generally correlated with better fermentation rate, but I've also read that fermenting up to 100% can cause a vinegar taste and formation of bad bacteria.
Our beans are all smallholder sourced, mostly forastero. Farmers cut pods themselves and deliver 'fresh beans' to us same day as harvest. There is a lot of mucilage so we stack the beans on pallets in pp bags for 2 days before putting them in hard wood boxes 3'x3'x3' covered with banana leaves. We shift boxes every 48hrs. We are experimenting with soaking/washing the beans after fermentation. Beans are sun-dried on raised beds for 5-7days.
For this recent batch, I have found that by day 6 the beans are still quite warm in the center >45C with an acid/alcohol smell to them. When cut open many are dark purple with brown juice others pale. (see attached @ 2 days on pallets + 6 days in boxes).