Slower melting rate for ice cream with freeze dried fruit powder
Research carried out by the Agricultural Research Service in the USA has proved that freeze-dried fruit powders including strawberries, blackberries and raspberries improve the taste and structure of ice cream and other frozen desserts.
Freeze dried fruit powders provide a raw fruit alternative to traditional stabilisers such as xantham gum or sodium alginate. With a rise in consumer demand for natural ingredients driving new food markets, food processors can benefit from using raw ingredients in sweet products, according to Diana Morris, country manager UK from European Freeze Dry.
Morris said: “This research allows ice cream producers and makers to revisit the stabilisers that they use in their products and move to a raw fruit alternative that is more attractive to consumers.
“While different varieties of fruit powders were tested as part of the research, strawberry powder was found to be the most effective as a stabiliser, with raspberry powder also having a positive effect.”
The powders, which are created by a gentle freeze-drying process which removes all water content, absorb the liquid from the ice cream as it rises in temperature, which rehydrates the powder rather than causing the product to melt. The powders also reduce the formation of ice crystals during the ice cream making process, while giving the product a creamier taste.
The research added 3.5% of freeze-dried strawberry, raspberry, blackberry and blueberry powder to ice cream. This equated to roughly 20 grams of powder per litre of ice cream. Strawberry powder was found to act as the most effective stabiliser, completely preventing melt-down, followed by raspberry and blackberry. Blueberry powder was found to have a minimal effect.
At European Freeze Dry, all products for freeze drying start as frozen raw materials and undergo a process known as sublimation under specifically designed programmes.
During the freeze drying process, a deep vacuum is applied, and under these conditions neither ice or water can exist. The pressure from the vacuum, with a controlled amount of heat applied, causes the ice to leave the product as a vapour trail which is then captured on an ice condenser within the freeze drier, upon which the vapour forms again as ice.
The process takes a day to complete on average, carried out in a set of chambers which can be controlled at various temperatures and time schedules depending on specific product requirements.
The reduction in water in the final freeze dried product means there is a reduced potential for microorganisms existing in such low amounts of water, leading to a shelf life of up to two years at room temperature.