Effect of freeze‐drying on the antioxidant and the cytotoxic properties of Allium roseum L. and its application in stabilizing food emulsions

Allium roseum is a wild edible plant in North Africa. In the present study, the effect of freeze‐drying on the phenolic profile, the antioxidant, and the cytotoxic properties of this plant is investigated for the first time. Furthermore, this is the first research that studies its ability to preserve the stability of emulsions. We found that water extract prepared from freeze‐dried leaves (FDL) contains higher amount of phenolic compounds than the extract prepared from fresh leaves (FL) and therefore the most important antioxidant power. FDL extract is more cytotoxic on K562, MCF‐7, and Caco‐2 cancer cells. Chromatographic analyses identified kæmpferol and luteolin‐7‐o‐glucoside as the major phenolic compounds. Finally, water extract prepared from FDL preserved the physical stability of W/O emulsion at 4°C and room temperature over 30 days. It also protects those emulsions from the production of free radicals at the same temperatures and during the whole storage period. Practical applications Allium roseum is an edible and medicinal plant highly used in the North African kitchen. However, the plant is not available during all the year. The leaves of this plant could be dried for conservation. The present study shows that freeze‐drying the leaves of A .  roseum preserved their phenolic composition and enhanced their antioxidant power and their cytotoxicity on breast, colorectal, and leukemia cancer cells. Water extract prepared from freeze‐dried leaves preserved the physical and chemical stability of emulsions. Such properties are of great interest for food and pharmaceutical industries.