Present of antioxidants in
strawberry fruits and its possible relation to improved quality and extension of
shelf-life
Collaborators: Claire Hébert &
Louis Gauthier
Botrytis cinerea, a major
fruit pathogen, is limiting strawberry preservation. Grey mold causes extensive losses and
alternative means to pesticides are requested. Fruit antioxydants protect tissues against
stresses and participate to disease resistance. However, they cannot be used on their own
as indicators of postharvest preservation: postharvest disease resistance can also be
induced by specific antifungal molecules, e.g. phenolic compounds such as phytoalexins and
proanthocyanidins. Strawberry proanthocyanidins (flavan-3-ol dimers and
oligomers) may act
both as antifungal chemicals to extend shelf-life, and as antioxidants to enhance quality
preservation. The present study aims at determining whether proanthocyanidins may serve as
biochemical markers of resistance to gray mold, and whether their contents correlate with
maintenance of quality and extension of shelf life of strawberries. Proanthocyanidins (PA)
were extracted from eight strawberry cultivars and assessed for their ability to control
germination and growth of Botrytis. Mycelium growth was determined on Potato
Dextrose Agar (PDA). Germination was evaluated in Potato Dextrose Broth
(PDB) enriched
with PA. A panel evaluated shelf-life (first mold appearance) and quality of the cultivars
after 14 days of storage at 2°C. Strawberry proanthocyanidin extract inhibited Botrytis
development. Radial growth of the mycelium on PDA enriched with PA was significantly
reduced (as much as 75% inhibition) and showed significant correlation with preservation
of the cultivars. Germination and germ tube elongation were reduced in PA enriched PDB and
multiple branching of hypha was observed. This research will offer a screening test to
predict fungistatic and preservation potential of strawberry cultivars. This research will
add new selection criteria for strawberry selections toward improved quality and extension
of shelf-life.
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