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Pucking fresh coffee.

Freshly roasted coffee is good. No complaints there, we don’t want to drink stale coffee. But for me, there are times where I need to use a freshly roasted coffee. It sucks even more when its for espresso, for example, for QC,  baristas receiving their competition coffee, but its fresh and are itching to taste it, or you only have freshly roasted coffee at home. 

It doesn’t sound like a dilemma of some sort, but trying to dial in, and pulling great tasting shots; out of super fresh coffee is quite challenging.

There always seems to be a certain flavour that’s present when you make an espresso using a fresh coffee, and its quite hard to get rid of. What can you do? Well, you can’t force the coffee to degas and settle, and opening a bag or not sealing them to let it degas quicker is a bad idea. When CO2 is released from the porous walls of roasted coffee, so does the many volatile compounds that make up the lovely aromas. Also, adsorption of oxygen and moisture increases the rate of oxidation, thus, ‘damaging’ the quality of the cup. 

With the frustration I had, I wanted to think of a way to use fresh coffee but not by compromising on quality. I think I found a way, but please note that this method isn’t suitable for a cafe, needing to go through 5kg of fresh coffee. 

All you need is an Aeropress filter. 

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It seems that when I place a aero press filter on the bottom of the basket, then dose and tamp like you normally would, then extract the coffee, you yield an espresso which is clean and sweet, unlike the harsh, roasty finish you get from freshly roasted coffee.

It seems that the aero press filter removes the bitter qualities in the cup, and what’s noticeable is the colour of the crema. Filtered espresso is way lighter, and it seems that the paper filter restrained fines ending up in the cup. Fines and crema tastes awful, by removing these, it seems like the espresso was free from the bitter and roasty aftertaste. 

I wanted to know how the filter affect the overall extraction of coffee. So by using the same amount of dose, time, temperature, I pulled 5 shots each of non filtered espresso and filtered espresso, and measured their EXT% and TDS%. 

Here are the parameters:

Dose: 17.5g

Time: 28sec

Machine: Synesso Hydra

Temp: 94C

Basket: 20g VST 

Coffee: Square Mile RED BRICK Roasted on 28th Jan

Regular espresso shots:

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 So, except for shot number 3 , they are pretty consistent. They tasted quite nice, fruity with creamy body, but had this bitter, roasty notes on the after taste.

Espresso shots with aero press filter:

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It showed that with the aero press filter in the basket, with no change in grind setting or dose, it produces shots with bigger mass. What’s more interesting is that, eventhough shots are bigger, and extraction % higher, the TDS% were similar to shots without filters, which pulled shorter shots. 

The filtered espresso tasted slightly cleaner, had more complexity and balance. I really don’t know why this is happening. I don’t know whether the psychological affect of ‘This is going to taste better because its filtered’ is kicking in and playing with my palate, or the aeropress filter is altering the extraction in some way. It’s interesting that, Shot number 3 from regular espresso has 2% difference in TDS compared to a similar shot (in mass) in filtered espresso.

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Definite thing is that, visually, the shots pours differently, the filtered shot is much more streaky, and the viscosity of the shot is lower than the normal shots. 

5 shots each might not be enough data to justify anything, but,I would love to hear from others what they think!

 

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Watch your head space.

I’ve realised that, when I talk about coffee, what I say isn’t backed based on a data that’s been proven or experienced myself. This frustration has lead me to actually experiment on few things, rather than pondering and hypnotising myself that my pocket science (very little of it) is correct.

One subject that I always wanted to, but had no commitment to experiment, was the importance (if there is any) of headspace between the shower screen of espresso machines and the coffee bed.

In my perfect little world, I always believed that it did, that having some head space produced higher percentage of consistent shots, without any data to back my opinion on. I started to have firm believe because of several reasons, firstly, I got so frustrated when, even though I have the same dose, grind setting, extraction time and temperature of the machine in each shot, sometimes the results fluctuated quite abit. I started to dissect and see what variables I could control and those I couldn’t, I didn’t even bother about the uncontrollable variables, but I’ve realised that I’ve never accounted head space as a variable.

Those of you who use the Nuova Simoneli Aurelia ,would know that each group head has a brass dispersion block. Which disperses the hot water into 8 different holes for even distribution of water from the group head to the coffee bed.

                         

Now this brass block comes in 2 different thickness, 3mm and 5mm ones. I first thought 2mm difference would only make a minute difference but the results below proved me wrong.

To compare and note the difference between the 2 different sizes of the dispersion block, I wanted to gather 2 different sets of data. First being consistency, and second, rate of flow/rate of espresso extraction.

So firstly, consistency:

I wanted to see the consistency of espresso produced in grams, with different size of dispersion block, when other variables become constant. (Impossible but I’ve tried my best!)

Machine used: Aurelia T3

Temperature: 94C

Time: 28 seconds

Basket: 18g VST

Dose: 19g

Coffee used: Jirmiwachu, Ethiopia SOE

result:

If we ignore the fact that, 3mm block produced big shots that wouldn’t normally cut the mark, it is apparent from the data that, 3mm block produces fairly consistent shot in terms of weight , you have to remember that I’m just looking for consistency in weight of espresso produced.

In the other hand, the 5mm block shows that the shots produced are not even, it fluctuates rapidly after shot 4, it produces some values which could be considered as an outlier, and its hard to produce a mean value.

I’m no scientist, and I think people cleverer than me could give me a better answer, but here’s an educated guess. If we think of the shower screen as a perfume, and surface of our clothes as the coffee bed, applying perfume from a distance will cover broader surface area of your clothes evenly. On the other hand, spraying your perfume in close range will highly saturate a specific area. If we want the water to be evenly distributed amongst the coffee bed, it makes sense to me to have a gap between the surface of the coffee bed. I mean, we are talking about 93~94C water under 9bars of pressure, 2mm difference in my opinion, gives the water some space to actually distribute the water evenly.

                                 

*Note that spent coffee bed from 5mm leaves clear mark of the screw, where 3mm does not.



Lastly, I wanted to record the rate which the espresso was being extracted, by plotting a time/espresso weight graph. The reason why I wanted to obtain this data was to observe the pattern in which the flow of water through coffee bed was affected by the head space.

The result is quite interesting:

Now this graph was plotted using average values from 5 different set of shots, you can see from the result that, 5mm block produces espresso faster than the 3mm block; and that flow is maintained until 17 seconds, where the 3mm block actually overtakes 5mm block and produces more espresso at the end.

Now why does this happen? why does the flow rate gain momentum from 17 seconds on the 3mm block? Here’s my guess, the reason why 3mm block took longer to produce any espresso initially, is because the water starts to fill the basket and slowly, and saturates most of the coffee bed before extraction occurs.

Where as the 5mm block (this is just my opinion), the coffee bed is mostly pushed up against the shower screen, and when the extraction occurs, the water isn’t able to fully saturate the the coffee bed evenly and finds a path which allows extraction to occur without full saturation.

With my shallow knowledge, I wanted to know why there is an increase in flow from 17 seconds with 3mm block, and I came up with this.

Darcy’s law states that, flow rate of fluid increases as pressure increases, until it reaches a certain pressure (correct me if I’m wrong), so it would mean that there are less resistance created by the coffee bed than the 5mm block, allowing the water to flow through the coffee bed at an increasing rate, which means full saturation at the start of the extraction loosens up the coffee bed, and allows the water to flow through  evenly, which also benefits even extraction throughout the coffee bed?

I really enjoyed the shots coming out form the 3mm block, not saying the 5mm block didn’t produce any good shots, but 3mm block hands down delivered the consistency, and I think we all need that in our lives.   

The pocket science rant above could be all wrong, but having the data gives me boost of confidence in what I believe in, and I would love to hear other peoples thought on this. I would also love to be proven wrong, if anyone has better explanation please please comment!!

** For those of you without an Aurelia where you don’t have any interchangeable dispersion screen maybe try playing with different basket size, but keeping the dose same.


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Tasty stale coffee.

One of the many joys working in the coffee industry, is trying endless amount of different coffees, in season being offered. For a year, I was subscribed to weekly and monthly coffee subscription from 2 of my favorite roastery. I’ve learnt so much by tasting different coffees itself, but what I was left with was countless amount of bags of half finished or even some unopened bags. I’m sure we all had this, but I want to focus on our customers, who buy these freshly roasted coffees from our shops.

Recently there has been substantial interest in manual filter brewing method from the customers, and beans have been flying off the shelves. If the beans were roasted on 1st of February, if FedEX does there jobs properly, it could be on the shop shelves on the 3rd of February. Now, we say that coffees taste the best when its ‘fresh’, where generally it is between 2nd day of roasting to 14th day of roasting. Now, I’m not saying it will suddenly taste horrible after 14 days, it will have so much factors affecting this, such as type of coffee, level of roast and also storage. Don’t we all agree that you can drink milk 2~3 days after its best before by dates if they are refrigerated well? Same goes for eggs and many other product.

So customers have generally, 10~12days window to enjoy their coffee whilst its fresh, if its a 250g bag thats around 21g~ 25g of coffee being consumed every day to enjoy them whilst its fresh. Presonally, if you don’t drink coffee every morning, I reckon you won’t be able to finish the bag in time, or you’ll get another subscription coffee and the old coffees are long forgotten.

So, people spend an average of £6 to £13 on bags of coffee, and most likely, they will have around 100g~150g of coffee still in the bag after 2~3 weeks, so what do you do with them? Well, there are lots of things on internet like using old coffees to use as compost, leaving them in fridge and even face pack! I wanted to find out if there are any guide lines, outlining what they can do to make decent cup of coffee using beans over 3 weeks old, rather than throwing it away. Even on the coffee bags, it states, ‘enjoy within 4weeks of roast’. So should people use the same method of brewing for all those 4 weeks? Should they be put off brewing with coffee 3 weeks or 4 weeks old?

-This isn’t a definitive guide to brew good coffee using old coffee, I firmly believe in using fresh coffee will deliver the best result in the cup!

- I will outline the changes you make to your recipe using old coffee from using fresh.

- its an experiment, and I’m not saying it will work for every coffee, as I’ve said before, there are lots of variables to take on board. - If anyone finds something other than what I state below, please comment!

- PLEASE remember, I’m NOT saying you can make the same QUALITY as fresh coffee but something you can enjoy without spitting them out, and actually drinking it rather than putting them in your fridge or your face.

So I wanted to experiment with a coffee I was familiar to, so I chose El Salvador Finca La Illusion roasted by Has Bean, because its on our shops brew menu as well as the espresso, so I know this coffee pretty well. Also luckily, I had an unopened bag of La Illusion which is 5 month old, one which is 4 weeks old and one which is 3 days old. So, I will brew these coffees, with extact amount of dose and water, time and temperature may vary. After brewing, tasting them and mojoing them, then make several changes to find that spot where the old coffees can produce ‘acceptable’ cup.

Firstly, I cupped these 3 coffees, and rated them with scale of 0~10, within different categories.

You can see from the cupping scores that 5month old coffee didn’t do so well, expected really, but surprisingly had the best body from those 3 coffees.

What really surprised me was, how pleasant 4 weeks old coffee tasted like, the only major difference between 3 day roast coffee was lack in overall complexity, but in terms of acidity, it was bright and lively.

So, I decided to brew these coffees as V60 pourover, I know I can’t brew these coffees consistently, but I tried to keep everything the same and mojo the  result which is below.

The result showed that with same dose, water, similar time and technique, as the beans that I used got older, more I extracted from the coffee. This has a correlation to the perceived bitterness I tasted from the cupping result.

With this result, I decided that it wasn’t really worth experimenting further with 5 month old beans, as they didn’t really taste good as V60, very stale, boring and bitter. These were worth going into the fridge and faces.

However, 4 weeks old coffee looked promising, it was bright, some sweetness with nice light body but had unpleasant bitterness coming through. Lacked in the complexity, exciting acidity, sweetness and the body compared to 3days old roast, but I wanted to change how I brewed the 4 weeks old roast to make it taste better and acceptable.

So this is what I’ve changed.

So, the dose was increased by 1g (6.25% increase from original dose) and amount of water reduced by 15g( 6.25% decrease from original dose).

Surprisingly, using the 6.25% increase and decrease method, When I slightly underextracted the brew, I’ve made myself a cup of coffee which was substantially better than one I made before, ok, it still wasn’t good as 3 days old roast, but there was increase in that sparkling acidity and complexity, though sweetness and body was still missing- it was an acceptable cup.

I would be interested to see if anyone experiments with 6.25% increase and decrease method I used with different coffee and brewing method, using old coffees to see if they get a positive result like me.

I know for the experienced coffee professionals, you guys don’t have to read this blog to figure out how to brew decent cup with stale coffee, again, this post is to help(hopefully) home brewers and having fun and learning myself. And please don’t  think I’m weird telling people to try stale coffee, but If you can make yourself a half decent cup of coffee when you have no fresh coffee at home; using 4~6weeks old coffee, and doing some experiments and having fun whilst doing so, I don’t see why people should be trying it. 

In this industry, you learn so much by tasting, tasting is believing!

Comments are welcome!