sourdough

Guest Blog by Kate Rennie: What am I growing in my kitchen… a gluten free sourdough journey through the eyes of an IPC nurse

girlymicro General, Guest blog , , , , , , , , , ,

I am currently in the middle of secret project, which I hope to announce more about in late August/early September. I’m really excited about it but it’s taking a bunch of my time. I’m hoping that you will be just as excited when I can share more details. The wonderful Dr Claire Walker is helping me deliver my passion project by curating the Girlymicrobiologist blog for a few weeks. This means that I hope you all enjoy getting some great guest blogs from a range of topics. Girlymicrobiologist is a community, and all of the wonderful authors stepping up, sharing their thoughts and projects, to support me in mine means the world. I hope you enjoy this guest blog series. Drop me a line if you too would be interested in joining this community by writing a guest blog.

Dr Walker who is a paid up member of the Dream Team since 2013, token immunologist and occasional defector from the Immunology Mafia. Registered Clinical Scientist in Immunology with a background in genetics (PhD), microbiology and immunology (MSc), biological sciences (mBiolSci), education (PgCert) and indecisiveness (everything else). Now a Senior Lecturer in Immunology at University of Lincoln. She has previously written many great guest blogs for the Girlymicrobiologist, including Microbial Culture: An Immunologist’s Side Project Gone Wild.

This weeks blog post continues this months fungal theme (all things yeast) and is from the absolutely amazing Kate Rennie. Kate is a born microbiologist, even if she was diverted by the world of nursing and has gone on to become a cracking Infection Prevention and Control nurse. Her curiosity and willingness to learn and expand her skill sets, makes it no surprise to me that when she decided to expand her hobbies, she decided to go down a route that touches on all things micro.

Before we get into the sour dough however, let’s start by talking what coeliac disease (the condition that leads to the requirement for gluten free bread) as written for us by Dr Claire Walker, our in-house immunologist:

Coeliac disease is a serious autoimmune condition where eating gluten, a protein in wheat, barley, and rye, triggers the immune system to attack an enzyme in the gut called tissue transglutaminase. This damages the villi, tiny structures in the small intestine that absorb nutrients. The result? Symptoms like bloating, diarrhoea, fatigue, and iron deficiency. But it doesn’t stop at the gut. Some people develop dermatitis herpetiformis, an intensely itchy, blistering skin rash. Others experience neurological symptoms such as brain fog, headaches, and numbness or tingling in the limbs. It’s often misdiagnosed or missed entirely.

Around 1 in 100 people in the UK have coeliac disease, but most remain undiagnosed. Diagnosis usually starts with blood tests (like the tTG-IgA), followed by a small bowel biopsy to confirm intestinal damage. These tests only work if you’re currently eating gluten. So if someone’s already gone gluten-free and are feeling better, they need to reintroduce it for several weeks which can cause symptoms to reappear and puts many people off testing.

There’s no cure and the only treatment is a strict, lifelong gluten-free diet. That means no “cheat days” as even tiny amounts can cause damage. It takes serious commitment: careful label reading, avoiding cross-contamination, and asking awkward questions when eating out. But for most, removing gluten thankfully leads to major improvements in symptoms and overall wellbeing.

Blog by Kate Rennie

What am I growing in my kitchen… a gluten free sourdough journey through the eyes of an IPC nurse

I’m Kate, I’m an infection control nurse at GOSH. I’ve worked in infection control since 2020 (1.5 years in primary care, 9 months in community/mental health and I’ve been at GOSH since April 2022). I was diagnosed with Coeliac disease in 2013 and decided 2025 would be the year of new hobbies and I am bored of gluten free bread that resembles cardboard.

I decided to embark on my sourdough journey (albeit slightly late to the party as I know this was a lockdown thing). I didn’t actually know what I was getting into with making sourdough, I read the first few steps and thought it sounded pretty simple, flour and water in a jar.

My flour and water sat on my kitchen side in a jar for 2 weeks (gross), and I named it Marilyn (Mondough)… I nurtured her and fed her daily, for those who may remember Tamagotchi’s, this is how I can describe it and as a previous Tamagotchi owner, I loved it.

Part of me was obsessed with what have created and look forward to waking up each morning to see how it’s looking (highlight of your late 20s) but the infection control nurse in me is slightly grossed out by it. I’ve read a bit more and learnt a lot, she just needed a little bit of extra love and care (troubleshooting) at a few days old.

HOOCH – I’ve only ever known hooch as this from my late teens/early 20s.

Fast forward to my late 20s, this is a sign that your sourdough starter is hungry, it’s eaten all its nutrients, and you must feed it more frequently. I was reluctant to throw her away and start fresh so I added teff flour in the hope she would perk up and SHE DID.

But she smelt disgusting… A familiar reminder of my 16 year old, pre-nurse self, having my long acrylic nails removed in the salon. ACETONE?? Apparently, it’s a byproduct of fermentation…

So, I wondered if this was actually safe to have something fermenting in my kitchen with absolutely 0 knowledge and thinking I’m probably going to poison myself. After a bit of research, I learnt this is normal and how to fix it, yet again, she’s hungry and I’m a rubbish mother.

Whatever is happening inside that jar is creating its own yeast to make it grow which is quite cool! I’m not sure how many people have actually gone this deep into the thought of a sourdough starter, but my IPC brain is fascinated yet disgusted and I want to know more. Do I want to culture it in the lab? Probably not. Am I going to eat it? Most definitely.

Fast forward 2 weeks… My sourdough journey ended abruptly after my first loaf. I felt disheartened that it didn’t turn out like the GF loaves I’d spent too much time obsessing over on Tik Tok.
The perfectionist I am wanted the perfect loaf to happen first time, so I abandoned sourdough and ventured into making non-sourdough gluten free bread. I popped Marilyn in the fridge for when I decided to revisit sourdough making and there she stayed for a good 3 months. Apparently, this puts it to sleep, and you can later revive it… but after pulling it out the fridge and seeing a layer of black liquid on top of the starter, my IPC brain got the better of me and I decided with my limited knowledge of sourdough and fermentation at home, it probably was best that I didn’t consume this and decided to throw it in the bin and I spared a brief thought for what Marilyn was and could have been if I had more patience.

I’d hoped this would be a success story about my gluten free sourdough rather than a failure but basically, sourdough isn’t easy and gluten free sourdough, really isn’t easy. It truly is a science.

Gluten free bread making in general is a delicate science because it lacks the key protein—gluten—that gives traditional bread its structure, elasticity, and chew. In wheat-based breads, gluten forms a stretchy network that traps gas bubbles from yeast, allowing the dough to rise and hold its shape. Without gluten, you have to rely on a blend of alternative flours—like rice, sorghum, or buckwheat—each contributing unique properties such as starch, protein, or flavour. Binding agents like psyllium husk are also essential to mimic gluten’s elasticity. No single gluten-free flour can replicate all the functions of wheat flour, which is why crafting a successful gluten-free loaf requires a carefully balanced mix rather than just throwing in a single substitute flour and hoping for the best.

I have been successful on a few occasions in making non-sourdough gluten free bread which has still been a real insight into science in everyday life.

To all life’s problems there are solutions if only we are curious and passionate enough to see them and change direction in order to maximise our successes. It appears Kates’ experience with sour dough as part of her coeliac journey is no different.

All opinions in this blog are my own

Guest Blog by Dr Claire Walker: Microbial Culture – An Immunologist’s Side Project Gone Wild

girlymicro Guest blog, Science Communication , , , , , , , , ,

I am currently in the middle of secret project, which I hope to announce more about in late August/early September. I’m really excited about it but it’s taking a bunch of my time. I’m hoping that you will be just as excited when I can share more details. The wonderful Dr Claire Walker is helping me deliver my passion project by curating the Girlymicrobiologist blog for a few weeks. This means that I hope you all enjoy getting some great guest blogs from a range of topics. Girlymicrobiologist is a community, and all of the wonderful authors stepping up, sharing their thoughts and projects, to support me in mine means the world. I hope you enjoy this guest blog series. Drop me a line if you too would be interested in joining this community by writing a guest blog.

Previous mycology posts have covered how fungal mycotoxins can cause us harm, and how the new yeast on the block, C. auris, is causing problems in healthcare, but the next two posts will talk about how beneficial fungi can be in our every day lives.

Guest Blog by Dr Sam Watkins: The wild world of mycotoxins, maybe not such a fun-gi
Candidozyma auris the New Kid on the Fungal Block: What is it and why should we care?

The blog posts will look at how certain yeasts can be used in something that brings me a lot of joy, bread. Many of you will know I’m dairy free, and although I know I should cut down on carbs, you can take my bread from my cold dead hands. It’s one of the few things I can eat without fear and makes me happy. In celebration of this oft overlooked area of microbiology we shall be talking all things baking over the next two weeks.

The first of these posts is written by Dr Walker who is a paid up member of the Dream Team since 2013, token immunologist and occasional defector from the Immunology Mafia. Registered Clinical Scientist in Immunology with a background in genetics (PhD), microbiology and immunology (MSc), biological sciences (mBiolSci), education (PgCert) and indecisiveness (everything else). Now a Senior Lecturer in Immunology at University of Lincoln. She has previously written many great guest blogs for the Girlymicrobiologist, including Exome Sequencing and the Hunt for New Genetic Diseases.

Before I hand over to Claire though, I thought I would talk a little about baking and fermentation. About 50% of all the PhD students I speak to have dreamt at some point of throwing their research out the window, running away and starting a bakery. This may be because baking has a surprising amount of science within it when compared to some other forms of cooking, hence the need to closely align to a recipe. A lot of this is actually because you are working with yeast, a living organism, hence the fact that we are talking about this on the Girlymicro blog, as micro is just cool in so many ways

Fermentation is an anaerobic (occurs without the presence of oxygen) process where microorganisms, like bacteria and yeast, convert sugars into energy and various byproducts, like acids, gases, or alcohol. In baking, it causes yeast and bacteria to convert sugars into carbon dioxide, among other things. This is what causes the dough to rise, as well as adding flavour, and is therefore essential to all things yummy and bread related. The most commonly used yeast is Saccharomyces cerevisiae, and this is one of the reason baking can behave so variably on times of the day or seasons, as both temperature and pH can impact on how well the fermentation process works. It can also mean, if you are impatient like me, you add water at far too high a temperature and effectively kill off your yeast so it doesn’t work at all. Fermentation, and its use in food production, is one of the many examples of how microbiology and microbes impact our every day lives, and of how much poorer our lives would be without them. So I hope you’ll enjoy the next couple of blogs about how baking has both microbiological and immunological links.

Blog by Dr Claire Walker

As I’ve confessed on this blog before,I am, what I like to call, a ‘failed microbiologist’. Many moons ago I completed a master’s qualification in environmental microbiology and dreamed of a career tracking pathogens through our water systems guaranteeing safe water for all. However, I graduated during a recession and started applying for any job that would have me. As luck would have it, I ended up on the immunology clinical scientist training scheme (the story of that fateful application I will save for a later date), and the rest is history. However, I’ve always loved a bit of microbiology and my fascination with all things fermented has taken me on many adventures. Including baking afternoon tea for a GirlyMicro special event!

My treat for finishing my marking this year was a fermentation course at the Welbeck School of Artisanal food learning all about the transformation of food by microorganisms. The word fermentation comes from the Latin fervere meaning ‘to boil’ after Romans watched the bubbles forming when they fermented grapes into wine. Name a scientist who doesn’t love a bit of Latin?  There are several biological processes occurring when we ferment foods like grapes, but essentially it is a process by which large chains of molecules are broken down by enzymes into their smaller, tastier, more nutritious, and more easily digestible parts.

The area of fermentation about which I am really passionate is sourdough. Yes, I lived in East London for many years, and yes, I owned a banneton before it was cool. Sourdough doesn’t just indulge my microbiology side project; it became unexpectedly personal. After picking up a particularly unpleasant microbe while travelling in India, I developed amoebic dysentery, and my gut never fully bounced back. I couldn’t tolerate shop-bought bread or much of anything, really. It wasn’t until I began incorporating fermented foods, especially sourdough, into my diet that I noticed slow but steady improvement. (Though let me be clear: this is my experience, not medical advice – if you’re unwell, definitely speak to your clinician!)

For the uninitiated, a sourdough mother, or starter, is a living culture of wild yeast and lactic acid bacteria that needs regular feeding with flour and water to stay active. As a failed microbiologist, I found something oddly fulfilling about sustaining a microbial ecosystem especially one that produces bread with real health benefits. What’s not to love about a culture that feeds you back?

Of course, I’m a dyed in the wool clinical immunologist so I can’t finish up this post without waxing lyrical about the immunology of sourdough. What makes sourdough really special, from an immunologists perspective, is how it supports our gut, which is home to about 70% of our immune cells. By encouraging a healthy mix of gut bacteria, sourdough helps produce bioactive compounds that keep our immune system balanced, strengthening our defenses without overreacting. This means it can help protect us from infections while calming down low-grade chronic inflammation that might otherwise cause problems. So, sourdough isn’t just tasty, it’s a simple, natural way to support a well-regulated immune response. Of course, sourdough isn’t for everyone, especially not for coeliacs. After all, even the most dedicated immunologist moonlighting as a microbiologist hasn’t yet figured out how to turn gluten into something completely safe. Guess some mysteries are still off the menu!

All opinions in this blog are my own