Authors: SLAVEN JURIC, KRISTINA VLAHOVICEK-KAHLINA, BORIS DURALIJA, LUNA MASLOV BANDIC, PETRA NEKIC, MARKO VINCEKOVIC
Abstract: An innovative approach to stimulate the production of plant secondary metabolites (PSM) is the use of encapsulated bioactive agents. Zinc-alginate microparticles [microspheres (ALG/Zn) and microcapsules (CS/ALG/Zn)] were applied near the root zone of soilless cultivated strawberries (Fragaria × ananassa Duchesne) to ensure a constant supply of an essential micronutrient zinc ions throughout the whole period of maturation. Both, ALG/Zn and CS/ALG/Zn had a positive effect on PSM (total polyphenols, total flavonoids, total anthocyanins, and flavan-3-ols) synthesis and increased antioxidant activity in two strawberry varieties (Albion and San Andreas). Treatments with Zn-alginate microparticles resulted in no visible damages on the plant and fruits. A two-year study revealed an increase of ~34% in total polyphenolic compounds and ~23% in total flavonoids in the San Andreas variety. The highest increase in antioxidant activity [ABTS (~37%) and DPPH (~38%)] was observed in the San Andreas variety treated with CS/ALG/Zn. Respectively high increase in anthocyanins was observed in both varieties (~54% and ~61%, respectively) treated with CS/ALG/Zn. Treatments with zinc-alginate microparticles resulted in a successful stimulation of PSM synthesis and increased strawberries' nutritive value. Encapsulation of zinc ions proved to be simple, sustainable, and environmentally favorable to produce strawberries fortified with important bioactive compounds.
Keywords: Zinc-alginate microparticles, encapsulation, soilless cultivation, strawberries, plant secondary metabolites, antioxidants
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