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Home > How to > The Heat is On – Optimizing Fermentation in High Temperatures

The Heat is On – Optimizing Fermentation in High Temperatures

Summertime! The days are long, the sun is warm, and vacations are in full swing. We’re all about soaking up the sunshine and enjoying delicious treats – but what about our beloved fermentation projects? This post guides you through the issues, keeping your fermented goodies safe and delicious all season long!

Heat may be tricky for milk and water kefir

While it can speed up fermentation time, it can also cause overfermentation and make your kefir too sour or weirdly flavoured. This is because the heat upsets the balance between friendly bacteria and yeast in the kefir. On top of that, warm and humid weather can lead to mould, so make sure your kefir is well-covered and clean to keep it safe during these hot months.
  • The optimal temperature range for water kefir: 20-25°C (68-77°F).
  • The optimal temperature range for milk kefir: 22-24°C (72-75°F).

Is it too hot for kefir cheese?

The heat speeds things up, which sounds good at first, but it can make the cheese grainy or separated instead of nice and smooth. On top of that, the warm weather can lead to stronger flavours that you might not enjoy. Also, your kefir cheese might not last as long in the heat, so make sure you store it extra carefully during these hot months!

The optimal temperature range for kefir cheese: 22-24°C (72-75°F).

Isn’t kombucha a summer drink?

In warmer environments kombucha ferments faster, making it too sour, and the heat favours yeast growth. You might end up with a more alcoholic brew with lots of floating strings (yeast) instead of your refreshing drink. Keep your kombucha cool and watch the SCOBY for a delicious summer ferment!

The optimal temperature range for kombucha: 22-27°C (72-80°F).

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Fruit and Vegetables don’t enjoy the warmth

Both vegetables and fruits ferment faster in the heat, which can be great for impatient fermenters. However, the rush can lead to some unwanted changes. Vegetables might turn mushy or slimy, while fruits could become overly sweet or alcoholic. The heat can also disrupt the delicate flavour balance, creating strong, pungent flavours in vegetables or encouraging unwanted mould and yeast growth in fruits. Most importantly, uncontrolled fermentation at high temperatures can increase the risk of harmful bacteria growth, so keeping your ferments cool is crucial for safe and delicious ferments!

The optimal temperature range for fruit and vegetables: 21-22°C (70-72°F).

Who bakes bread in the summer?

Despite the heat created by the oven being turned on, do you insist on freshly baked sourdough bread? The heat can hinder the preparation of the dough. The warmth speeds up yeast activity, making the dough rise too quickly. This can lead to collapsed loaves, a dense crumb with less air, and less time for the complex flavours to develop – you might miss that signature sourdough tang.

The optimal temperature for proofing sourdough: 21-27°C (70-80°F).

When can high temperature be a good thing?

  • Higher temperatures can speed up the fermentation process in lactic acid fermentation. For example, sauerkraut and kimchi can ferment more quickly at higher temperatures, resulting in faster production of lactic acid, which helps preserve the food and develop the desired tangy flavour.
  • When first activating a sourdough starter from scratch, warmer temperatures (around 75-80°F or 24-27°C) can help encourage the growth of wild yeast and beneficial bacteria, speeding up the process.
  • Tempeh requires a warm environment (86-90°F or 30-32°C) for the Rhizopus mould to grow and ferment the soybeans properly. This higher temperature range is essential for successful fermentation.
  • Yoghurt fermentation typically occurs at higher temperatures (around 110°F or 43°C). This environment is ideal for the growth of yoghurt cultures, resulting in the proper texture and tangy flavour.
But when we’re nearing 30 °C it’s also important to ask ourselves if this is the environment we can have a quality life in. If it is separated from our living quarters this can still be possible. Again we are returning to the main conclusion of this post that fermentation requires a controlled temperature and we need to strive to achieve this.

Some tips to ensure the right temperature:

  • Monitor: use thermometers for the fermenters where possible.
  • Separation: ferment in separate cupboards, rooms, and chambers where it’s dark and the place does not heat up.
  • Accessories: use heating pads or cooling jackets.
  • Refrigerate: second ferment and store the ferments safely in the refrigerator, in some cases, you can easily do the primary fermentation in the fridge too.

In summary, while high temperatures can present challenges, they can also be advantageous for specific fermentation processes or stages. Knowing and enabling the perfect temperature for each ferment helps you use summer warmth to your advantage and enjoy delicious ferments all season!

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