Too many variables

mininova

I would love some advice in setting up my machine/grinder to help perfect my espresso making ability.

My dilemma is understanding the cause/effect relationship between grinder and machine. I am using a single group Wega MiniNova semi-auto machine and Ibertal grinder (which has a worm drive allowing infinite adjustment) and always use the double filter holder filling the basket to the top with coffee, levelling and then tamping.

With regards to grinding/dosing I am not one to get out the scales and weigh the correct amount of coffee, tamp to 30lbs and run for 28 secs and measure the precise amount of espresso in the cup. Instead I have let the quality of the "pour" guide me to let me know if the grind is too course/fine or the tamp too light /heavy. What I look for is a nice thin golden brown stream that tapers towards the cup turning off just when I notice a slight change in colour. Usually I observe "tiger striping" and the "Guinness effect" but am not sure if these are indications of correct method or just type of beans used?  

I have also adjusted with the pressurestat to see what difference that has on the extraction (dropped from 1.25 bar to 1.1bar) and noticed due to the reduced temprature the crema becoming much lighter than the usual chocolaty brown colour (almost as wheat/straw colour) using Genovese Super Brazil beans.

Does anyone have any suggestions or proven methods to correctly calibrate machine and grinder as I still think there is still room for improvement but unfortunately I have fallen into a rut and am not sure what next to change to achieve true espresso greatness.

Thanks all.
Doug.

dcbc

tiger stripping is usually the result of a blended coffee, whereas a single origin will be more consistent.

FreshCoffee2

Hi Mininova, a) for a guide to the "how to" of making a decent espresso, go to the Trade Section of this Forum, select page 2, and scroll down to the topic called something like "A question for Ristretto, Fresh coffee & the Like"...Open it and read on... b) What you are asking, after you have the gist of the principles, becomes a bit of a black art in terms of "fiddling" (pardon the choice of adjective) the technique or the equipment in order to achieve a certain result in your espresso, and this is dependent on the blend or type of coffee you use, and may change accordingly and require re working if you change the type of coffee used due to the change in the density/ oil content. c) Maybe I have misread your post but I am wondering whether your decription of the colour of your crema indicates you are over-extracting....so that when you pulled the boiler pressure back a little and the crema became lighter in colour, you may have mistaken a great looking golden crema for an under-extraction. This is usually the trouble if you are trying to set your grind with a stopwatch (ie by going with the 18 to 26 second rule as written in sundry "manuals") rather than by "feel and touch" for the type of coffee used... In addition I am not familiar with Genovese's Super Brazil blend but note that good quality Brazilian coffee in general is lighter in density and therefore has less body than many other coffees. It is therefore easily "upset" (ie overextracted) if you tend to follow the text book method of brewing rather than going by the aforementioned black art of "feel and touch". Sorry I cant be of more help but you really need to "be there" to help in the best possible way. If at any time you are going to be in the Canberra area I will be happy to run through it with you as long as you give me some notice. Good luck, FC. PS this is only a personal opinion but I like to set machines to run at a lower pressure / temperature and usually set things up, dependent on the individual machine, to run at a pressure of between 1 and 1.1 bars at max. I believe 1.25 bars is too high and is usually a compromise to deliver a greater capacity of steam. Unfortunately it has the effect of running hotter water through your grinds.

mininova

Ok thanks, that kinda makes sense. I guess each variety of bean will react differently when exposed to a specific water temp hence the "tiger striping" effect witnessed during extraction. :P It appears is there so much focus on using the correct grind and tamp and so little on the correct temperature adjustment of pressurestat for a perfect extraction. I have spoken to roasters asking them what they suggest I set my pressurestat to for their particular roast/blend and mostly get a ballpark 1-1.5bar should be fine which in my opinion is just not optimal as even a difference of 0.2bar can turn a great espresso into a bad one. Regards Doug.

Reschsmooth

FC, you didn't mention how to get a CONSISTANTLY good espresso - hahaha. Just kidding, I know how much that grates for you P

mininova

Thanks for your suggestions FC. As you say I guess it is just familiarity of your machine and the particular beans you are using. The hard part for me is being in a domestic environment I find myself experimenting different brands (mostly local from Melbourne) quite regularly so do not get to chew through 5-10 kg of the same coffee each day to set my machine for optimal results. Thanks Doug.

FreshCoffee2

Doug, re your second last post. The thing is, when you 'fiddle" one thing, you get some kind of reaction and have to fiddle something else to compensate. It's the old, every action has a re-action thing. That's why I refer to it as a black art. I prefer lower pressure therefore less chance of burning the grounds / wet coffee, and compensate by using the greatest possible volume of coffee in the filter (which actually happens to be the "right" dose, because the right dose IS TO FILL the filter for a particular grind and tamping pressure), with  perhaps a slightly finer grind. This makes for SMOOTHER but VERY FULL BODIED coffee rather than just 'orrible strong but not really full bodied coffee, and is my preference (the smootherfullbodiedone). Just remember that in addition to the type of coffee being used, this is all also dependent on the type of machine being used. They are like motor vehicles. They all do the same job, but they do it to different levels of satisfaction, convenience and ability. Re your last post: If you keep changing your coffee supply you have to keep fiddling the system! Good luck. Patrick, when are you coming to visit? FC.