Freeze-drying strawberries keeps all their Vitamin C and polyphenols and 92% of their antioxidants, saving more nutrients than by chilling which can lose over 80% of antioxidant concentrations.
It is well known that heat destroys most of the antioxidant potential of berries, making canned and juicing that involve friction and heat a poor choice to maximize their antioxidant potential.
The same is true for refrigeration. It appears that whenever fruit experiences temperature variants from its original state, antioxidant potential is affected, that is unless it is freeze dried.
Researchers at Sheffield Hallam University, UK measured Vitamin C, total antioxidant capacity (TAC), and total phenolic content (TPC) in fresh, chilled and freeze-dried strawberries.
Freeze-drying had no significant impact on nutrient content, but refrigerated fruit experienced large losses.
Researchers at the Ohio State University Comprehensive Cancer Center examined the effect of freeze-dried black raspberries on genes altered by a chemical carcinogen in an animal model of esophageal cancer.
The carcinogen affected the activity of some 2,200 genes in the animals’ esophagus in only one week, but 460 of those genes were restored to normal activity in animals that consumed freeze-dried black raspberry powder as part of their diet during the exposure.
“Freeze drying the berries concentrates these elements about ten times, giving us a power pack of chemoprevention agents that can influence the different signaling pathways that are deregulated in cancer,” said principal investigator Gary D. Stoner, a professor of pathology, human nutrition and medicine who studies dietary agents for the prevention of esophageal cancer.