Coffee beans, Humidity and Grind Adjustment??
Hi there CS. I am new here and really value any input in regards to my question. 6 days ago I purchased a Breville BES 900/B and Smart grinder after careful consideration, and reading the entire CS threads associated with this machine. I purchased 2 types of pre roasted coffee beans. One from Toby's Estate (Wooloomooloo Blend 250g) and the other from Belaroma (Octavia Blend 250g). I used the Belaroma first, set up my grinder and have left the BES 900 on the pre factory settings. I am using a sinlge wall, single shot basket. It took me 3 attempts to dial my grinder in before i was getting really nice shots with an extraction time of 27-29 seconds. I was only pouring enough beans into the hopper to make a single shot at a time. The remaining beans were stored in the zip lock bag in a cool dark cupboard until i had used all the beans up. I then opened the Toby's Estate coffee and decided this time to pour the entire contents of the bag into the hopper to learn about what flavour change i could possibly detect over the following days, and what effect temperature change, humidity etc may possibly have. The grinder setting did not need to be altered from the previous blend and was extracting shots at approx 28-31 sec. (Just to clarify, the grinder setting was operating on the 5th last (finest) setting in the espresso range on the BCG). On the third day of using these beans and keeping all the setting the same, the machine choked. I adjusted the grinder, re-evaluated my tamp pressure and dosage. To cut a long story short, I have now adjusted my grinder back towards the courser grind setting by six increments, the shots are now pouring between 40-50 sec. The espresso initially flows nicely and at about the 15 sec mark turns to a slow dribble. The coffee is still drinkable (milk based), however there is some bitterness coming through.
I have not been able to detect any changes to the sound the machine is making during the extraction process. The extraction pressure on the gauge reads 9-10 bar without fluctuation. There is no visible signs of any water leaking etc. The machine appears to be working normally.
The question I have is...can time (48-72hrs) and a 15% variation in humidity over that time effect the beans that much that the grind settings need be adjusted to such a great extent? It appears I still need to dial the machine back further to get the correct extraction flow and time. I am pretty sure the problem is me and not the machine!