Effect of ultrasound treatment on microbial inhibition and quality maintenance of green asparagus during cold storage.

The study focused on inhibiting microorganism and improving preservation of green asparagus (Asparagus officinalis L.) during cold storage. Green asparagus is treated with ultrasound (US), acetic acid and gibberellin acid (AG) separately as well as combination (US + AG) and then stored at 4 °C for 20 days. Microorganism, physicochemical qualities and sensory characteristics were monitored at regular intervals. Results showed that the US treatment significantly (p < 0.05) reduced the total number of colonies, mold and yeast merely in the 12th and 16th day of storage, while the US + AG treatment not only achieved an effective decontamination (up to 2 log reduction) of green asparagus throughout the storage, but also retained the physicochemical characteristics to a higher level in comparison to other treatments. The US + AG treatment exhibited lower weight loss, higher levels of total soluble solid (TSS), ascorbic acid, chlorophyll content and total phenolic content (TPC), as well as kept better sensory attributes. Moreover, the US + AG treatment significantly inhibited the activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD) (p < 0.05), suppressing the biosynthesis of lignin. These results suggested that the US + AG treatment could be a potential strategy to preserve quality of green asparagus during cold storage.