The tech behind good coffee

There is a lot of tech behind good coffee. All too often we hear that someone bought XYZ coffee machine and it makes crap coffee.

Well, it may not be the machine – there is a lot of tech behind good coffee. In this brief guide, we cover water hardness, bean types (and capsules), cup size and the tech behind good milk coffee – anyone can make a decent cup of black joe.

Now before you question our credentials in talking about the tech behind good coffee, we suggest you click here where you will find nearly 250 articles over the past decade.

The tech behind good coffee

What you make

Obviously, if you are an instant powder coffee lover – Nescafe 43, Moccona, International Roast, Bushels, Robert Timms or heaven forbid home brand, Maxwell House or Pablo and like it – stop reading. You are not drinking real coffee, but coffee extract (freeze or spray-dried) often added to flavoured fillers and chemicals.

How you make it

In the US, dripolator coffee is still by far and away the most popular coffee type. Essentially hot water drips through fine coffee grounds in a filter paper. It produces a decent black coffee, and that is passable with milk – American coffee. There is no tech here – a hotplate and a pot – but the longer coffee sits in the pot on the hotplate – the more bitter it gets as it stews.

Next step up is those Pod machines. Depending on pod price (not so much the pedigree) they will have either coffee grounds (ground beans), coffee extract or even coffee powder and all sort of fillers, flavours and extenders. Coffee Pods are convenient, consistent and hugely expensive. In no way do they make as good a coffee as freshly ground beans. And in no way are Pod machines as complex or powerful as proper coffee makers – pod, hot water, cup and maybe frothed milk.

Italians love using an ‘Express’ coffee pot (percolator). A cup or so of water (depends on the size) goes into a bottom screw off pot, as it boils the steam is forced up through ground coffee and ends up in the top pot. Fresh, strong, aromatic and full of flavour – black coffee.

Plunger coffee is popular. Boiling water is poured into a jug, and a plunger pushes coffee grinds down into it. It can make good coffee but invariably the water is too hot, and it ends up too bitter. Hint – don’t quite boil the water – 80-90°

There are many other types of coffee maker – drip, pressed, french etc.

But the truth is that the tech (call it art and science) behind good coffee really only comes from Barista made coffee and selected coffee machines.

Q: What have you learnt so far?

A: it is pretty easy to make a decent cup of black joe and optionally add low-or-high-fat milk, soy, almond or more to it.

So why do people pay baristas $4 or more, several times a day for real coffee?

Water has a huge impact

If your water supply is ‘wrong’, e.g. too hard, chlorine, calcium, sodium, dissolved solids or pH value, it will make the coffee taste ‘off’.

The perceived acidity of coffee corresponds to the amount of acid extracted from the coffee bean, minus the amount of alkalinity from the water. If you get the water right, it makes the bean’s job easier.

Most coffee makers come with a disposable paper Aquadur strip (pH testing) that reveals ‘pH’. That is only one factor, and even if pH (Alkalinity or Acidity) is spot on there may be other issues that you need to identify.

Baristas and coffee purists need a ‘pool water test kit’ to check for chlorine, calcium and salt as well.

Fortunately, in most Australian capital cities, the water quality is fine. But you probably need an activated charcoal water filter (these last a couple of months of typcial use) or acid/alkalinity tablets (some machines can use Smart disposable filters and tablets) or some form of water pre-treatment like an inline filter to get good coffee – don’t blame the machine.

For the techie types, there is new research from the Coffee Science Education Centre and the University of New South Wales on how to engineer Sydney water to get the most out of a cup of coffee here.

Coffee beans are next

A cheap bean makes a poor cup of coffee. It is rare to find the best bean at a supermarket where the price per kg is the focus. Decent coffee beans start at $40 per kg, and you may easily spend much more to get just what you like. If your family drinks a mix of black and milk coffees, then you need to find an acceptable compromise because a good black coffee bean seldom makes a good milk coffee.

Start with your favourite baristas and ask what beans they use for what coffee types. If you like it buy some and experiment but as most coffee machines have only one grinder go for one that all the users – black or white – will love. Or look for a dual grinder or two-scoop bypass machine if you need a stronger bean or decaf (why bother).

You will often see the term ‘single origin’ – that means the beans come from the same country, not necessarily that they are a single type of bean from a single coffee plantation. These will be more expensive – typically $60 or more per kg.

Then there are blends – usually marketed by strength and include Arabica and Robusta beans from places like Mexico, Brazil and Uganda and who knows where now that real coffee is so popular.

Cups per kg: Remember that 1kg of beans can make between 65 and 200 cups of coffee depending on the strength (from 5-16g per cup). In dollar terms, $50 per kg means from 25-80 cents a cup (plus milk). Dedicated coffee drinkers will look to 12-16g per cup.

Why are beans best?

Sorry Pods are pathetic – yes, really. Inside that aluminium and plastic pod is 5-7g of something. That is coffee, caffeine (or not), carbs, fat, sodium, flavourings, and unspecified extenders. Generic pods cost from 33-70 cents each, so that is from $66 to a massive $140 per kg. No wonder Nespresso can afford George Clooney’s fees.

Pods have one advantage – you can buy a variety to suit different coffee drinkers including faux coffee drinkers that want a flavoured hazelnut, Creme Brulee, etc.

Automatic coffee machines – is the coffee as good as a bought one?

Barista grade machines cost upwards of $10K

Out-of-the-box the majority of coffee machines heat water to between 85-90°. If its any hotter you burn the coffee and any colder you don’t extract the aroma.

The vast majority of lower cost coffee machines are semi-manual or involve some labour. It may be that you need to use a separate coffee grinder (or even buy pre-ground coffee) or a milk frother or a steamer. These all use one boiler, and frankly, it is hard to get a decent milk coffee from any of them.

Manual coffee machine — There are so many brands – look at least for a grinder and steam wand

Then some machines have grind size (fine to coarse), coffee strength (pressure levels applied to the grinds), water levels (for cup size), and delivery temperatures (usually only one level). One thing is for sure – no lower-cost machine with a milk delivery system will give you an option to change the milk temperature.

That is why in the lower-cost arena we recommend a semi-manual machine with a steam wand – at least this way you can technically get the milk to the right temperature.

Milk is the biggest problem for all except two boiler machines.

Milk coffee drinkers will complain of two issues.

First, that the coffee is too watery – typically because the boiler delivers 90° maximum – not hot enough for steam – more a watery mix.

Second, because the coffee is too cold. Most milk coffee is between 180-340ml (less 90ml coffee), and single boiler coffee machines often end up pumping froth instead of hot milk. This results in a reduction overall to 45-50° coffee.

Ideally, stream at 100° heats milk to 55-65° keeping the overall coffee cup temperature to over 65°.

And cup capacity is last

Official cup capacity (if you can call it – and it need not fill to the brim) are

Espresso/single shot (100ml)
Small (280ml)
Medium/regular/double shot (400ml)
Large/triple shot (500ml).

These roughly equate to 8, 12, and 16-ounce standard cups.

Simply put – the larger the cup size you like, the more coffee grounds you must use. Lower cost machines will use the same amount of coffee grounds and simply double the water volume.