Storage quality of strawberry fruit treated by pulsed light: Fungal decay, water loss and mechanical properties

Abstract

The effect of different pulsed light (PL) doses (2.4-47.8 J/cm2) on water loss, fungal spoilage, mechanical properties and structure of strawberries stored for up to 8 days at 6 °C was studied. Incidence of postharvest molds on strawberry fruits was reduced by over 16-42% with PL application. There were no significant differences in maximal rupture force (FR), mechanical work (W) and deformability modulus (Ed) values between treated and untreated fruits immediately after treatments. After 8 days storage at 6 °C, untreated strawberries showed a pronounced softening (≈ 48% reduction in FR), but stored strawberries exposed for 10 s and 40 s to PL presented slight or not significant changes in the mechanical parameters regarding day 0, while FR and W values of 20 s-PL treated samples were increased by 35% and 88% compared to those at 0 day storage. Micro and ultrastructure changes evaluated by LM and TEM images demonstrated ITW cell wall strengthening and a major integrity of walls of hypodermis cells induced by PL stress, while cell wall disassembly and reduction of cell-to-cell contact were detected in stored untreated fruit. There were no significant differences in weight loss among untreated and PL treated fruits after storage, excepting at the highest PL dose. PL technique would be able to simultaneously provide disinfection and delete softening of the tissues along cold storage. Present results make this non-thermal, residue-free alternative promising for extending shelf-life of traditional and organic strawberry production. Industrial relevance The present results demonstrated that pulsed light (PL) treatment is a promising alternative for extending the shelf-life of strawberries. A decrease in fungal incidence and a depletion of softening, important factors which limit the strawberry postharvest storage life, were achieved by the application of PL.