Edible flowers of wild allium species: Bioactive compounds, functional activity and future prospect as biopreservatives.

Edible flowers are rich in phenolic compounds with antioxidant and antimicrobial properties. Fresh flower extracts of four wild underutilized allium species (i.e., Allium narcissiflorum Vill., Allium schoenoprasum L., Allium sphaerocephalon L., and Allium ursinum L.) were analyzed to assess their potential applications in the food industry. Allium narcissiflorum exhibited the highest total phenolic content, together with A. schoenoprasum, the highest anthocyanin content, and the highest antioxidant activity. Conversely, A. ursinum generally showed the lowest values. The analysis of specific phenolic compounds, including cinnamic acids, benzoic acids, flavonols, and flavanols, and vitamin C further differentiated the allium species. Allium narcissiflorum showed high content of coumaric and ferulic acid. Allium schoenoprasum was the richest in quercetrin and epicatechin, and showed a high content of quercetin and coumaric acid. Allium sphaerocephalon was the richest in ellagic acid and showed a high content of quercetin. Allium ursinum was the richest in hyperoside and rutin and showed a high content of ferulic acid; moreover, this species was the only one in which gallic acid was detected. Antibacterial properties were tested against two ubiquitous bacteria strains associated with food spoilage (i.e., Bacillus cereus and Bacillus subtilis). While A. sphaerocephalon was totally ineffective, the other three species showed a similar antibacterial activity against both strains. Allium flower extracts inhibited B. cereus less than the synthetic antibiotic chloramphenicol, and A. narcissiflorum and A. ursinum were effective against B. subtilis as much as chloramphenicol. The results revealed the potential of fresh edible allium flowers to be used as functional food and biopreservatives.