Fruit must be an essential part of our diet. Experts recommend eating at least five servings of fruit and vegetables a day. However, the reality is quite different, since we are witnessing a gradual decline in consumption, especially among children. This is one of the reasons that made a team of Valencian researchers develop new products that could promote fruit consumption.
The main drawback affecting the stability and useful life of fruit is its high water content. So the scientists studied the best way to obtain more durable products that conserve most of its properties. For this they applied the techniques of lyophilisation, also called freeze-drying, and spray drying.
Grapefruit, kiwi and strawberries are the first fruits the researchers have turned into powder ready to sprinkle on other foods or as a functional ingredient in juices, purees, milk or tea. Another product they have presented is dried fruit slices that are perfect for a healthy snack. This is a new way to enjoy fruit with all its natural taste without losing its nutritional benefits.
According to Nuria Martínez Navarrete, researcher at the CUINA group from the Universitat Politècnica de València, fruit consumption is so low because fresh fruit only lasts a few days and this clashes with our current lifestyle that in many occasions prevents us from shopping daily, and because of this we consume more processed products that are long-lasting and easy to prepare. This tendency could change thanks to projects such as this one, as soon as the results are transferred to food companies.
"We are working with grapefruits, kiwis and strawberries. Grapefruit is a citrus fruit with great nutritional and functional value but its consumption is very small because, among other reasons, it is very bitter. Meanwhile, strawberries are a seasonal fruit. In powder, however, would open more markets" says Nuria Martínez. "We chose kiwis because of its high vitamin C content, an especially labile component that has enabled us to strengthen the result for the study of the impact of the technologies applied in the functional value of fruit."
The research results show that freeze-drying conserves the bioactive compounds that are responsible for the beneficial effects that grapefruit has on our health and also maintains its antioxidant property. According to the researchers, per 100 grams of fresh grapefruit, between 10 and 15 grams of powdered grapefruit are obtained. Half of this dose could flavour a serving of salad, for example, or if we add 85 millilitres of water we would be drinking the juice of half a grapefruit.
Another product the Universitat Politècnica de València is working on is dried fruit snacks, mainly of grapefruit and 'lulo', a typical fruit from Colombia whose acidity prevents consuming fresh. As part of a cooperation project with a Colombian University, the researchers plan to apply their discoveries to other Colombian typical products. The project also includes a part of nutrition information to help improve the diet of the local population.
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