Basic Guide To Fermentation

Fermentation is one of the oldest and most basic forms of preserving food. Fruits and vegetables contain natural bacteria that, when deprived of air, can suppress and inhibit the growth of other microbes that would cause spoilage. During the fermentation process, these natural bacteria convert the carbohydrates and sugars in food to an acid which creates an ideal environment for preserving. Lacto-fermentation, a process brought on through the presence of lactobacillus, gives fermented foods and drinks their signature tangy and sour taste, but also creates probiotics that aid digestion.

Due to their health benefits, fermented foods such as kimchi and sauerkraut have become increasingly popular in recent years. Making fermented foods at home is a cheap and healthier alternative to shop bought products and allows you to experiment with new and exciting flavours.

It’s easiest to start your fermenting at home with vegetables you are familiar with such as carrots, green beans and cauliflower florets etc. They will remain crunchy and their colours will stay bright. Salt brine fermenting is always best done with firm vegetables. Some vegetables, such as those that are either soft or very seedy or dark green vegetables such as kale and spinach, are best preserved by other methods.

Things to consider when fermenting:

  • Before starting your recipe ensure that you have thoroughly washed your Kilner glass fermentation jars. Jars are dishwasher safe but lids and airlocks should be hand washed only. Do not pour boiling water directly into the glass jars as this can cause them to break.
  • When filling the Kilner glass fermentation jars, leave 2.5 inch/6.5cm headspace. This allows for any expansion of food/liquid during the fermentation process.
  • Always use filtered water or cooled boiled water.
  • It is recommended to use salt free of iodine and anti-caking agents.
  • Always ensure food inside the Kilner glass fermentation jars is completely submerged under the salt brine. The weights included in the fermentation jars will help to weigh down food and allow the anaerobic fermentation process to take place.
  • The Kilner glass fermentation jars should be kept at 17.8°C to 24°C, this is the ideal temperature for the fermentation process.
  • Once your ferment has reached your desired taste, replace the fermentation lid with the standard lid or transfer into sealed Kilner glass jars. Keep in the refrigerator to slow down the fermentation process and keep fresh. Consume within one month.
  • It is recommend that you check the fermenting food on a regular basis. You may find that some foam has appeared on the top of the food; this is perfectly normal and can be removed using a skimmer or stainless steel spoon.
  • It is also recommend to clean the inside of the top of the jars to remove any food debris or juices. It is important to ensure that all food remains submerged under the salt brine.
  • If mould appears in the ferment, discard the batch and start again.
  • Always ensure the lid is securely fitted onto the top of the jar to create an air tight seal.
  • It is perfectly normal for pieces of shredded cabbage or smaller sized vegetables to float up to the surface when fermenting. It is recommended that you remove any pieces which are floating or protruding above the brine.
  • Cloudy brine and sediment in the bottom of the jar are both signs that the vegetables are culturing well and is not cause for concern.
  • Some vegetables foam more than others when fermenting. Foaming is completely harmless and generally disappears after a few days. You may also notice some bubbling in the jar as gases are formed by the fermentation process, this is also perfectly normal. As long as the ferment smells and tastes pleasant, the culture is doing well.
  • Fermentation is a continual process and flavours will change over time so it is recommended that you taste and smell your fermented vegetables regularly. As an indication, once the vegetable ferment appears gaseous or bubbly and smells sour but pleasing, it is time to taste. If you are happy with the texture and taste then you can move your fermented recipe to the fridge.
  • The presence of mould indicates that there has been some air exposure. If the mould is dark in colour then the batch should be discarded. If there is white coloured mold on the top then this is perfectly safe and you can remove this by using a skimmer. Your fermented vegetables will carry on fermenting in the usual way.

To gain a thorough understanding of the fermentation process and be confident in your fermented food creations, it is a good idea to acquire and expand upon your knowledge with a range of books and lots of practice. We have a range of fermentation books for you to peruse.

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