Preserving the future of food: Drying technologies for sustainable and nutritious fruit and vegetables
Scientists at the National Prepared Consumer Foods Centre (NPCFC) in Teagasc Ashtown, managed by Shay Hannon, are investigating various drying processes using state of the art drying systems that can extract and create valuable ingredients from fruits and vegetables.
The aim
Drying is one of the oldest methods of food preservation, but can be a complex process and affects the texture, chemical composition, nutrition and sensory properties of foods in different ways. Scientists at the National Prepared Consumer Foods Centre (NPCFC) in Teagasc Ashtown, managed by Shay Hannon, are currently investigating various drying processes using state of the art drying systems that can extract and create valuable ingredients from a wide range of fruits and vegetables. They’re finding ways to enhance snack foods and other food products to give us nutritional benefits. This will also reduce environmental impact and contribute to a sustainable food system.
Air drying
Using a recently installed air-drying system, high quality drying results can be achieved in short times utilising gentle drying at low temperatures. The unique design of the system ensures the drying process is very efficient and doesn’t waste energy. For effective drying, the air should be hot, dry and moving and these three factors are all interrelated. For drying vegetables such as spinach, the optimum drying conditions have been determined to make sure as many nutrients as possible are retained. The dried samples are tested in the in the Centre’s nutritional laboratory. Based on the results, the most efficient method of drying the product can be worked out. Food safety is also a key concern, and each product is tested to ensure it is safe to eat.
Freeze drying
The NPCFC also offers food businesses access to freeze drying technology. The basic principal of freeze drying is the removal of water from a product while the water is in its solid state of ice. This is a process known as sublimation, which is the transition of water directly from its solid state to its vapour state without first passing through an intermediate liquid phase. The equipment lowers the temperature of product to as low as -40°C and then a high-pressure vacuum is applied to take out the water in the form of vapour. The advantage of freeze drying foods and liquids is that they can be dried at low temperatures without damaging a product’s physical and chemical structure. Freeze-dried foods can be stored with an extremely long shelf life if stored properly.
Strawberries
We have carried out trials on drying whole and sliced strawberries to work out the fastest method of drying while keeping the overall structure of the strawberry intact. These finely chopped freeze dried strawberries can be used in breakfast cereals or ready-to-eat snacks. We can also produce strawberry powder which can be used in a variety of other snack products.
To learn more about food processing, register for 'Sustainable, Nutritious and Delicious - What’s New in Fruit and Veg?' on Thursday, November 11th at 11am. This online event is part of Teagasc’s Festival of Farming and Food for Science Week 2021.
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