Welcome to the March edition of the Coffee Mailbag where we take questions submitted about a range of coffee topics and answer them as best we can.

The aim is to help our readers learn a little bit more about coffee! Read on to find out what we covered in this month’s edition.

What’s the difference between cold brew and iced coffee?

Cold brew basically extracts all of the flavour from the bean. This isn’t always a good thing because that means the good flavours as well as the bad are extracted.

Iced coffee on the other hand is brewed hot over ice, so it extracts the bits of the coffee that you want but doesn’t over extract and compromise the good flavours for the bad. Most people would typically equate the good flavours to “chocolate”.

From what I’ve noticed with cafes that do cold brew, it’s usually their worst coffee that they know will be masked with extracting all of the flavour. Then they add a higher price tag because of the labour involved but that’s a discussion for another day!

I have a Gaggia Classic and was wondering if it’s better to steam the milk first or make the espresso?

The Gaggia Classic has a single boiler and with a single boiler, it’s better to steam milk first, as the machine will take too long to heat up enough to steam milk. By this time, the espresso has lost most of its warmth due to the tiny volume of espresso. Note to keep swirling the milk to keep it intact.

Why does my first coffee extraction of the day always look so dull and without crema?

This is a common issue that is usually caused by grind retention from the day before. The bits of ground coffee left the day before will be well oxidised by the time you go to pull your first shot of the day, hence the dull espresso.

Keeping your equipment clean will help but it might be an idea to purge your grinder with a couple of grams of fresh coffee beans first.

Is there an easy formula to follow to make the perfect home coffee?

Sometimes coffees can surprise you. All coffees have a different sweet spot, and it’s your job to find it. You can start with a basic formula but you will learn that there is no “one-size-fits-all” formula. Happy accidents is a delightful part of coffee.

But most follow their taste buds. We just tune in the direction our palate tells us until we find it. And often it strays quite a bit from the standard ratios, extraction times, pressures and temperatures. You basically have to play around a bit. The better you get at it the quicker you can find it too. That is what experience gives you.

I’ve got a Sage Barista Express – is there a reason my shots are pulling for 9 – 10 seconds?

10 seconds is really quick. It’ll be MUCH nicer closer to 30 seconds. I’d go much finer (try 4 numbers, or 6) and see what happens. Just don’t tamp too hard – straight down and firm, but not too hard like you’re leaning into it. That should do the trick.

I recently got the new Rancilio Silvia V6 and my coffees are always sour. Any advice?

Changing to a VST 20g ridge-less basket should sort this issue. I’d get rid of the Rancillio baskets as they’re pretty rubbish. I would grind at 20g at about marker 3. Level then tamp and pull for 25 – 30 sec for a 40ml double. Basically, get a VST basket and tweak your grind and tamp till you hit the spot!

Is there a reason my Sage Barista Express is giving me shots that are dark and burnt?

Here’s some things to look at:

Single baskets are notorious for problems due to uneven bed depth so it’s easier to use a double.

If you’re not sure your beans have been roasted in the past 28 days then you may as well use the dual wall basket until you can get some beans you know are fresh.

Then try reducing your variables; start by weighing your beans before putting them in the grinder (try 18.5-20g if you’re having trouble getting pressure), grind through until the grinder is empty. Keep your tamp consistent, but don’t worry about it too much, as long as your bed is level and the air removed.

Weigh your output, and stop the pump when you reach a 1:2 ratio, so if you’re putting 20g of ground coffee in, then stop the pump at 40g of coffee out. The Barista Express is set up to work on volumes and the defaults shot sizes are too high which might be the problem you’re having.