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Low-dose x-ray irradiation was used on vacuum skin-packaged fresh-cut asparagus to extend its shelf life and improve its microbial safety. Freshly imported Peruvian asparagus (Asparagus officinalis L.) spears were obtained from a local source, cleaned, trimmed, and sanitized and then vacuum skin-packaged (VSP) in a tray pack system. A breathable lid film was vacuum-sealed to protect the product from contamination and allow for gas exchange. Asparagus were packaged in VSP, which modified the package atmosphere, and exposed to a target dose of 1.0 kGy or left untreated. Asparagus were also placed in low-density polyethylene (LDPE) bags as a control. All samples were then stored at 4 °C for 24 days. To determine the effectiveness of the irradiation treatment, sample packages were periodically removed from storage and several measurements were used to evaluate the product, including headspace gas content, microbial growth, water soluble sugar content, and enzyme activity. A dose of 1.0 kGy reduced initial microbial population up to 3.8 log colony-forming units (cfu)/g and maintained 20% more of the initial sugar content relative to the non-irradiated VSP asparagus. Phenylalanine ammonia-lyase (PAL) activity in VSP asparagus was lower than in the control package (LDPE bag) regardless of irradiation treatment (P < 0.05). However, x-ray treatment increased the PAL activity of asparagus in VSP up to Day 8 (P < 0.05).
The United States is the world's largest producer of blueberries and strawberries. Successful marketing for both of them requires fruit of the highest quality and appearance. However, these fruits have a relatively short postharvest life, mostly due to the incidence of molds such as Colletrotrichum acutatum, Alternaria alternata, and Botrytis cinerea. At present, several natural occurring plant volatiles have been shown to be effective against fungal growth, but, even so, those compounds could not be maintained at constant concentration during the whole postharvest period due to their volatility. In this work, two naturally occurring aldehydes (acetaldehyde and hexanal) were tested and compared against the growth of the above mentioned fungi at 23 °C. After that, the most effective antifungal compound for each fungus was encapsulated in ß-cyclodextrins (ß-CD) and tested during storage period. Both aldehydes were effective in reducing and avoiding fungal proliferation depending on concentration. Fungal proliferation depended on daily, and not initial, volatile concentrations. Volatiles encapsulated in ß-CD showed higher antifungal activity compared to that obtained using the pure volatile during storage. Tested volatiles showed both fungicidal and fungistatic capacities after storage of fungal cultures in air. Results suggested ß-CD-acetaldehyde and ß-CD-hexanal complexes can be used as a new technology to release a naturally occurring antifungal compound during storage against several fungal diseases.