This autumn, Monica Berg’s thoughts have turned to infusions – using seasonal raspberries to illustrate.

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Before we start, let’s get the technicalities out of the way. Infusion, maceration, decoction – they are in (almost) every practical sense the same. Yes, there are minor variances and nuances, but let's agree to call them infusions. At least for now.

The main purpose of infusions – meaning to steep or soak something, whether it is a herb, a fruit or a botanical, in a liquid – is to extract flavour. It is often the first advanced technique many of us encounter when we begin our bartender journeys. In my early days working in clubs it was the Martini craze – passion fruit, green apple or rhubarb Martinis being the big hitters. The method was pretty straightforward: infuse whatever ingredient you wanted into vodka, then mix with liqueur, fruit juice and maybe some citrus. Shake, and voila.

Since then, I’ve obviously learned a lot more about technique, layering flavour and being more purposeful in the way I extract flavours, but what remains the same is that this is still one of my favourite ways to capture the true nature of any ingredient.

So let me take you through my thinking and tinkering on the topic of infusions. When tackling infusions, there are three things you simply cannot ignore, and those are time, texture and temperature – because these three factors will deeply impact the end result. More often than not, you will need to utilise all three, and often together, to get the best result.

Time

Let’s start with time. If you want to infuse raspberries into something, the length of time you infuse them will impact how much flavour you get. But this can be manipulated if you change the ratio between raspberries and liquid by adding more raspberries to shorten the time needed to infuse. In reverse, it’s also true that if you have fewer raspberries to liquid, then the time you infuse needs to be longer to achieve a similar result.

You can also influence the process by maximising the surface ratio, for example by cutting the raspberries into smaller pieces to create more surface area, or you can put everything into a blender and purée it – which will create maximum integration between the two ingredients. Though this will obviously add to the prep time as you’ll need to strain it back to clear liquid, while the harshness of the process can also affect the volatile aromatics of the raspberry.

Sometimes if you have a prep that’s not going the direction you want, the best thing to do is to leave it and see how it develops. My shortest infusions often last no longer than a few hours (when using ingredients such as coffee beans or other very potent elements) while other times I can leave ingredients to infuse for months, or even years.

Texture

Moving on to texture, if you infuse raspberries into milk the end result will be different to infusing them in double cream, because the texture of the liquid will react differently to the raspberry and carry over different elements. Similarly, you can say this is the case when we infuse raspberries into alcoholic liquids, as the abv will impact both the texture of the liquid and the flavours extracted in the process. Alcohol and fat are both excellent carriers of flavour, and when you understand how they work, it makes it easier to let them do the hard work for you.

Imagine the fresh raspberry as a 360° image of the flavour profile you want to capture – all of these infusions and preparations we do are different angles or isolated parts of that picture. To achieve the full image, we need to put the puzzle together. This, in a way, is how I look at an ingredient when I taste it and deconstruct it in my mind, in order to know what techniques to use to reassemble it in a finished cocktail.

In practical terms, this means that if you do a raspberry infusion in vodka, gin or any other high(er)-abv product, you will get a one-dimensional picture of what a raspberry looks like, but if you were to also do an infusion in a lower-abv liquid like vermouth or fortified wine – and then combine the two together in your drink – your raspberry universe will start to look a little bit more real and complex.

Temperature

Finally, you have temperature, which is perhaps the most controversial for me. I use infusions mostly to capture what for me is the true essence of an ingredient, and this means I’m always chasing those delicate nuances. If you’ve ever bitten into a perfectly ripe raspberry, it starts off with that juicy brightness, followed by the structured fruity sweetness that lingers almost till the end before it finishes with tartness.

What it doesn’t mean is the more jammy, candy-like flavours you often get when you add heat into the equation – which is why I never do. Obviously, there’s no rule without exception, and I do add heat when working with dried ingredients, spices and seeds, where you want to access the essential oils. But, more often than not, I work in what we might unscientifically call ‘room temperature’.

So as a rule, when working with fresh fruits or vegetables at their natural, seasonal peak, I never use heat. If the fruit is very bruised or damaged, I’d argue that using it for infusion might not be the way to go – perhaps fermentation could be a better option.

I’m always an advocate for less and more, meaning less technique applied but more focus on the raw material, because good ingredients don’t require as much to make them taste delicious.

In the end, there are many techniques you can choose to use when infusing: traditional steeping with or without heat, rapid infusion using iSi, vacuum sealed, sous vide or supersonic – they all have the pros and cons. One of which is cost.

For example, some say it’s time-saving and efficient to use the iSi chargers to rapidly infuse a liquid by using pressure, but in the bigger picture, you’ll need to factor the cost of those cartridges into the final drink, which can make it quite expensive and wasteful. Likewise, with equipment such as a vacuum sealer or a supersonic homogeniser, the initial cost for the machine is quite high and it takes up a lot of space, so you’ll need to factor in how many drinks you’ll need to make to justify the investment.

Which leads me back to the most traditional forms of infusion. If you master the three Ts – time, texture and temperature – it will outshine technological alternatives any day of the week