Once you have established a polytunnel garden, one of the challenges that you will have is working out how to store and preserve all the produce that you grow. If your fridge and freezer are crammed full to bursting point, it can be a challenge to work out how to preserve the fresh produce that you cannot eat right away. Dehydrating polytunnel produce is one preservation option that is often overlooked. But it can be a useful method in the attempt to avoid food waste.
Why Dehydrate Polytunnel Grown Produce?
There are a number of reasons why you might wish to consider dehydration as a method for preserving some of the food that you grow in your polytunnel. For example:
- Dehydrated produce can last longer than fresh produce, and be stored without the need for refrigeration or freezing. Drying foods you have grown yourself can be a useful way to preserve some produce for use over the winter months.
- Dehydrated fruits and vegetables can often be stored in a smaller space than fresh produce, taking up less space in your stores.
- Dehydrating fruits and vegetables can often concentrate their sweetness and intensify their flavours.
- Dehydrated fruits and vegetables, with their lower water content, can often be better for use in a range of recipes and baked goods.
- Dehydration (especially solar dehydration) can be a way to preserve food without using non-renewable sources of energy.
What Dehydrating Does To The Nutritional Composition of Food
Dehydrating fruit and vegetables can be a sustainable way to keep certain items to enjoy out of season and can make up part of a healthy vegan diet. However, it is important to know that, unlike the methods mentioned above, drying food does create a change in the nutritional composition of the food.
While by freezing or canning you are pretty much halting the process of nutritional degradation in fresh food, drying changes the food more profoundly, retaining some of the good healthy qualities of the produce, while slightly losing some others.
Dried fruits can still provide you with fibre and antioxidants, but will have lost a small percentage of its vitamin content during the dehydration process. Vitamin C, the B vitamins thiamine and folate and vitamin A become unstable and some of those are lost over time.
Mineral content also goes down somewhat when produce is dried. For example, in a cup of fresh apple you will find 8 mg of calcium, 6mg of magnesium and 14mg of phosphorus, while in an equivalent calories portion of dried apple you will find only 3mg of calcium, 3mg of magnesium and 8mg of phosphorus.
That said, it should be remembered that even with this slight loss, dried fruit and vegetables are still extremely healthy, nutrient dense foods and can be good in moderate quantities as part of a healthy, balanced diet.
Denser dried fruits are higher in calories than fresh fruit, so can be used to increase calorific intake where healthy weight gain is required. Of course this also means that you should be careful of intake of dried fruits if you are trying to lose weight.
Which Crops Can You Dehydrate?
Many of the crops commonly grown in a polytunnel are suitable for dehydration. Some crops that can be dehydrated particularly usefully and effectively include:
- soft fruits (strawberries, raspberries, currants and other berries)
- peppers (both bell peppers and chilli peppers)
You can also make dried crisps for snacking from root vegetables such as carrots and beetroots, and can even dehydrate greens like spinach to rehydrate later in meals. What is more, you could even branch out into dehydrating mushrooms for stocks or rehydration… However, the options mentioned above are a good place to start if you are new to dehydrating produce from your polytunnel, and the results of drying these crops arguably have the largest number of uses.
How To Use Dehydrated Produce
Apples can also be dehydrated to make dried apple snacks, or turned into apple crisps which are another delicious snack. Thin slices of dehydrated apple can also be used in baked goods or in home-made bread. They also work well for breakfast alongside grains and seeds in a home-made muesli or with another breakfast cereal.
Dehydrating plums will allow you to make prunes which are excellent for the digestion. These are also excellent with yoghurt or other ingredients as a breakfast, and can also be widely used in baking, or an an accompaniment to main roast dishes.
Like plums and apples, dried/ partially dehydrated apricots are delicious when included as part of a healthy breakfast. Dried apricots, like prunes, can also be cut up and used in fruit cakes and in other baked goods.
Grapes, of course, are dehydrated to make currants and raisins, which we are familiar with from a wide range of traditional baking recipes. Currants and raisins can also be used in savoury dishes, such as curries, to add a little sweetness to such dishes.
Dehydrating soft fruits like strawberries and raspberries will not only make them store for longer, it also makes it easier to use them in a wider range of baked recipes, such as cakes and muffins.
Dried tomatoes can be rehydrated and used in a range of recipes, or used in their dried form to add some flavour to breads and other bakes. Since they have a lower water content and can have a more concentrated flavour, they can be better for use in yeasted breads such as focaccia or your own signature tomato loaf.
Drying both bell and chill peppers can deepen and intensity their flavours. Dried peppers can be ground to make spices and seasoning mixes, or rehydrated to use in a wide range of recipes. You could also consider adding peppers, like tomatoes, to breads or other savoury baked goods. You could even consider adding dried chillies to a chocolate cake or chocolate muffins, for a bit of a kick and an interesting flavour combination.
Solar Dehydration: Dehydrating Polytunnel Produce Using the Sun
So, how do you go about drying the produce from your polytunnel? Well, this will, of course, depend on the resources you have at your disposal, the weather conditions where you live, and what exactly you are trying to dry. Dehydrating fruits and vegetables without resorting to electric power is easier with a polytunnel, since you will have an undercover area where humidity levels can be controlled, and produce can be stored as it dries. A polytunnel can be much warmer than outside, which can help allow produce to dry.
However, in order to fully take advantage of the power of the sun to dry food effectively, you may wish to consider making a solar dehydrator to use to dry food during sunny periods in the summer months. Use a reclaimed window or another piece of glass and other scrap materials to make a solar dehydrator. That can be used to help store produce that will be grown in your garden in a sustainable way, and can also be made sustainably, using items that may otherwise have been thrown away.
However, while it can be beneficial to have a solar dehydrator, you may find that you need to use an electric dehydrator or your oven in order to effectively dry many of your crops. While solar dehydrators are a fantastic idea in hot or warm climates, here in the UK, humidity can be a problem, and the sun can sometimes seem in short supply. It can also take a lot, lot longer dehydrating food when relying on solar power directly. This can increase the likelihood of problems occurring with your drying crops.
Dehydrating Polytunnel Grown Produce With an Electric Dehydrator or Oven
There are a number of dedicated, specialist electric dehydrators on the market. While dehydrators are more commonly used in other countries, like the US, it is still easy to get your hands on one right here in the UK. You can find budget options for under £50, though you can spend several hundred pounds on better and more sophisticated models. If you have renewable power, using an electric dehydrator could still be an eco-friendly and sustainable choice.
Even if you do not wish to splash out on a dehydrator, or bother with making your own and hoping for sunshine, you can still dehydrate your polytunnel produce using your oven. Produce can be placed on trays and left in your oven overnight on a low heat in order to dry your crops. While this is energy intensive, if you use an electric oven, and use 100% renewable energy, this could still be a green option that will help you make the most of the fruits and vegetables that you grow.
Share your tips and suggestions for dehydrating fruits and vegetables, or using these in recipes, in the comments below.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.