On my bookshelf: Adventures in Fermentation + Panettone Negroni recipe

New book by Dr. Johnny Drain, discussion on the importance of enzymes in fermentation, and that holiday drink recipe

Today we are taking a small break from Peru. I will sprinkle in more stories over the next few months as still have a lot to write share; the rest of the Inca trail, the Maras salt mines, Andean herbs, Tocosh (fermented potatoes sometimes called Andean penicillin), and so much more.

We haven’t visited my bookshelf in a while, and some fantastic new books have been added to my shelves this year and the fermentation literature (dare I say?) canon. Are we there yet? I do think that the subject of fermented foods has at least graduated to having a tiny bit of its own shelf space in bookstores.

This month, my friend, Johnny Drain’s book, Adventures in Fermentation landed in the US. Hopefully, you can find it at your local brick-and-mortar bookstore. Johnny and I had an excellent chat a couple of weeks ago at December’s member webinar at The Fermentation School. I am going to share some nerdy highlights about our enzyme chat, and Johnny is sharing a holiday drink recipe from the book.

But first, let’s talk to Johnny

For as ancient as food fermentation is, finding a path that becomes a career in food fermentation is not always clear-cut. Sure, if you are in wine or beer brewing, there are degrees from prestigious universities. To become a cheesemaker, or baker, one could start out in food science and then get hands-on experience with internships, or just go straight to internships, learning by experience. As Johnny pointed out, “There are very few people that you and I know that actually choose a course for the heart of fermentation.”

For Johnny, his work, which has taken him all over this planet to some of the world’s most well-known restaurants, began as a young man who thought chemistry came easy so why not start there.

The Dr. in Johnny’s title is a Ph.D in materials science. Guided more by circumstance and curiosity, Johnny pointed out he was, and still is, interested in many things; he ended up specializing in materials science. While he was interested in gastronomy he never made decisions based on a career in food, he followed what was interesting at the moment. Yet, as he pointed out, there is an intersection between the world of material science and food.

A material scientist asks, what is the stuff in the world made of, and can you make it more useful? Essentially, can you make it better? Similarly, chefs and bartenders look at the food that we have on offer, (wherever we are in the world) and ask, how do we make this delicious? Or, how do we preserve the nutrients in this? Or, how do we make this non-toxic so that humans can eat? So actually, there’s a lot of overlap between the world of material science and the world of food.

The way we think about fermentation and use fermentation is perhaps even more closely aligned with that sort of philosophy of a material scientist asking, you know, how do we use these processes to make nutrients more bioavailable, or make food safe to eat, or more delicious, or change the texture or color, or detoxify things?

Our conversation continued to meander. His book is such a delightful journey through the world of fermented foods from the traditional foods in remote jungles to where we are now. Including looking at fermentation as such an incredible tool for reducing food waste, on both an industrial scale, and in your kitchen. As you will see in the recipe below, which uses a waste bread miso (recipe in Johnny’s book and Kirsten’s sourdough miso recipe can be found in Julia Skinner’s new book Essential Food Preserving out May 2026). Johnny’s book ends with a look at where fermented foods might be going. I remember, when I put it down after reading last spring, I found it left me hopeful for life on earth.

Enzymes are a catalyst

We also talked about enzymes. Enzymes are an important aspect of fermentation that many people don’t think about or don’t fully understand. And to be honest, you don’t have to understand them to make successful ferments. However, if you want to understand more, or be comfortable creating your own ferments without a recipe, or changing one to suit you, then understanding enzymes is super helpful.

Enzymes are examples of what we call catalysts. Catalysts to a chemist, or a biochemist, are just things that make a reaction, or set of reactions that would otherwise happen, happen much more quickly. They speed things up, essentially without taking part in the reaction itself.

In biology, enzymes makes things happen that might otherwise take thousands or millions of years. That’s not an exaggeration. It can make something happen in a matter of seconds or minutes, and it’s basically how all of biology works.

You and I, a cat and a leaf, and a frog store energy, and when we need that energy, we need a key, to quickly unlock that energy. Enzymes are things that allow us to take stores of energy and quickly process them when we need them. We need enzymes to facilitate that kind of relationship with all sorts of other useful things that you or I, or a leaf or a frog, or a cat need to survive.

They also help break things down. So when we’re talking about food, if we stick to that idea of energy, an enzyme might allow the breakdown of a store of energy. So for a carbohydrate, the enzyme will facilitate the breakdown of that carbohydrate into the simple sugars that carbohydrates are made of. Different classes of enzymes might also allow the breakdown of big proteins into simple amino acids, or will break down fat molecules into its component parts. It is these microorganisms that we use, or leverage, when we ferment. They produce these enzymes, and when we ferment, those enzymes break down these larger molecules into smaller molecules.

And that’s useful because sometimes we want to convert things that are carbohydrate into simple sugars, which is why when you allow koji to break down rice in a amazake, you go from something starchy into something sweet. Then you might add yeast that can feed on those sugars and turn them into to alcohol. Similarly, when we make things like miso, a good part of what we want is that breakdown of the protein that is classically in a soybean. The smaller amino acids is where we get glutamates from. Thus we get an umami component to something that started off being quite a bland soybean.

When I, Kirsten, explain enzymes in a class and get to the part about how they break things apart, I like to give people a visual: think of them as little snippers, cutting things into their smaller components. Or, maybe it is just that I like to talk with my hands and can let my pointer and middle fingers on both hands become scissors that go wild, snipping at the air. Just like the enzymes, say in a miso, that are breaking down carbohydrates, protein, and fats into deliciousness.

Back to Johnny.

Enzymes always have names that end in -ase; amylase, protease, and lipase, etc. They’re doing all sorts of vital things in fermentation. But what they’re not is alive.

Enzymes are not living organisms; they’re not microbes. They’re just these little chemical compounds that float around. (In his book he calls them chemical chaperones.) And that thing that I mentioned at the beginning, that they don’t take part in the reaction. That’s the really key thing, because it means that as long as you’ve got some enzymes in your ferment, as long as you don’t denature them they will carry on just floating around, catalyzing, making happen these reactions.

For example, heating them up to a temperature that they break apart at, or putting them in an environment that’s too acidic or too alkaline. So as long as you have a small portion of these enzymes, they will do their thing, month on month, year on year. And you will witness the magic of of fermentation, or kind of enzyme catalyzed breakdown of things.

It might just take a bit longer if you have less starting enzymes. And it will happen very quickly if you start off with with lots of them. They’re not living things. They don’t get used up. So you just need to make sure that they’re that they’re there when you start.

Kirsten here again. I bet some of you are asking: How do you know if you have them? In many cases, the microbes produce the enzymes as you ferment. For example, in lactic acid vegetable ferments, the bacteria produce the enzymes to help themselves metabolize the food in the vegetables. In doing so they are creating these chemical helpers. In ferments like amazake or miso, that are based on starchy grains or legumes, something that is enzyme-rich must be added to help the microbes access those smaller components. In this case, it is the filamentous fungus, aspergillus oryzae, or koji that is added to begin the breakdown so that the microbes, like bacteria and yeast, can access the food they need.

Also, enzymes by themselves are not going to multiply on their own, as bacteria or yeast might. However, if you still have microbial metabolism, enzymes will continue to be created by those microbes. If not, you have a set number; you will continue to have that number if they don’t denature. I am thinking about miso again. Let’s say a miso has been aging for years, and in super-simplistic terms, the microbes have consumed all of the food available to them. They die off or go dormant. If the miso hasn’t been treated in a way that would denature the enzymes, then the enzymes are still present, transforming the paste as it ages and continues to undergo enzymatic reactions.

Back to Johnny.

The other critical thing is that they’re quite picky and choosy. They will work much better if they have their ideal environmental conditions. Their sweet spot is the same at which a lot of biology happens. Microbes and enzymes are very happy around the same temperatures as the human body temperature, around 37 to 40°C. Enzymes are most effective, or efficient, a bit warmer at 50 to 60 °C. And if you provide them with those conditions, then they will work very, very quickly and do all of these wonderful things. And they don’t get used up. This is why we want to understand how to best take care of them.

Another way to think about them is the common way of describing enzymes in your average sort of chemistry textbook is that they’re essentially like a key to a lock. And that, that idea, that concept, helps us understand two key things about enzymes. One is that they give you access to things that you wouldn’t otherwise be able to access. As in, if you don’t have the key to a door, you can’t get to the room behind it. But the other crucial point is that they’re very specific. You know, you need a particular key to open a particular lock, and so that’s, again, how biology works.

Panettone Negroni

From Adventures in Fermentation by Dr. Johnny Drain

Panettone, the sweet, yeast-risen, Milanese bread, is now a festive favourite around the world. Simone Sanna, former head bartender at Cub restaurant and one of my favourite collaborators, created this negroni to remind him of his hometown using the bready, caramel notes of our waste bread miso paired with gin infused with cacao husks (another by-product ingredient I started working with at Cub, sourced from London chocolate-maker Phil Landers of Land Chocolate). If you can’t get hold of cocoa husks, dark chocolate works just as well.

Ingredients

For the cocoa husk gin:
250 ml gin
20 g cocoa husks (or 20 g dark chocolate grated)

For the panettone negroni:
20 ml Navy-strength gin
10 ml cocoa husk gin
20 ml Campari
30 ml sweet vermouth
10 ml waste bread miso, replace with any miso

Equipment

Glass jar or bottle (for infusing) Fine-mesh strainer
Funnel
Grater (if using dark chocolate)
Storage bottle for infused gin
Jigger or measuring cups
Mixing glass or cocktail shaker
Bar spoon or long-handled spoon Hawthorne strainer or fine-mesh strainer Rocks glass

Cocktail pick or toothpick (for garnish)

Method

For the cocoa husk gin:

• Mix the cocoa husks or grated dark chocolate with the gin. Let it rest for 20 minutes at room temperature.

• Fine strain it.

• Bottle it and store for up to one year.

  For the drink:

• Combine ingredients and give them a stir.

• Strain into a rocks glass packed with ice.

• Garnish with a cocktail stick threaded with raisins and pieces of candied orange.

Enjoy!

Parting Shot

This week the last of my 2025 garden harvest came indoors and become sauerkraut—about three gallons worth. These Mermaid’s Tail cabbages are so enchanting, they are the last of seeds gifted to me a few years ago, by Petra at Fruition Seeds, when I was in upstate New York for the FLX fermentation festival.