Impact of pulsed light and mild thermal treatments on fungal decay and optical properties of strawberries

CONTIGIANI, EUNICE; JARAMILLO-SANCHEZ, GABRIELA; GÓMEZ, PAULA; ALZAMORA, STELLA M.

Las Vegas

Congreso; IFT Annual Meeting 2017; 2017

Institute of Food Technologists

Fungal development limits the storage life of strawberries and can cause great economical losses. The postharvest use of fungicides is restricted in most countries, thus there is a need for alternative preservation strategies.This work investigated the effect of pulsed light (PL) and mild thermal treatments (TT), applied as single factors or in combination, on fungal spoilage and color of strawberries stored at refrigeration temperatures. Strawberries (Fragaria x Ananassa Duch cv. Albion) were exposed to irradiation for 10 s at 10 cm from the lamp (fluence: 11.9 J/cm2) in a Xenon RS-3000B Steripulse-XL system. For heat treatments, fruits were immersed in sterile water at 46 ± 1 ºC and maintained under stirring for 2.5 or 5 min. Combined treatments were performed by applying the thermal treatments followed by the PL treatment. Treated fruits were compared to non-treated ones throughout 12 days of storage at 5 ± 1 ºC. The presence of macroscopic fungal growth was daily visually inspected and the results were expressed as percentage of decayed fruit. Color measurements were made at selected intervals during storage period. Thermal treatments were more effective than PL treatment to reduce fungal incidence during refrigerated storage. After 10 days of storage, the percentage of infected fruits was about 97.5 % for control, 87.5 % for PL-treated samples, 67.5 % for samples treated at 46 ºC -2.5 min and 25 % for fruits exposed at 46 ºC -5 min. Combined treatments did not allow a significant higher reduction in the number of infected fruits. Thermal treated fruits (2.5 and 5 min) and 46 ºC -5min+PL treated fruits showed slight changes in color, reflected by a significant decrease in a* and b* parameters when compared to control.Mild thermal treatment at 46 ºC -5 min was the most effective strategy evaluated to reduce fungal decay in strawberries during refrigerated storage without affecting greatly the color properties.