X-ray irradiation delayed the browning development of fresh-cut bulbs of Lanzhou Lily (Lilium davidii) during room temperature storage

Abstract

Lanzhou lily (Lilium davidii var. willmottiae) are known for its medicinal and culinary attributes and has gained popularity among consumers due to its distinct regional characteristics. However, the bulbs of Lanzhou lily are prone to browning during storage at room temperature, thus adversely affecting their quality and value. X-ray irradiation, a chemical residue-free, and energy-efficient physical technology, emerges as a promising solution for preserving freshly harvested the bulbs of Lanzhou lily. In this study, different doses of X-ray irradiation (0–400 Gy) were applied to the bulbs of freshly harvested Lanzhou lily stored at room temperature, aiming to explore the impact of irradiation on browning development, total phenolic content, and the activity of related antioxidases. The results revealed that X-ray irradiation, especially at the dose of 50 Gy, can effectively maintain the appearance and reduce the browning index (BI) of freshly harvested Lanzhou lily bulbs during storage. The 50 Gy X-ray treatment is found to significantly suppress the activity of polyphenol oxidase (PPO) and peroxidase (POD) in the bulbs of freshly harvested Lanzhou lily, thereby reducing enzymatic browning. Additionally, the X-ray irradiation can elevate the activity of phenylalanine ammonia-lyase (PAL), superoxide dismutase (SOD) and catalase (CAT) while decreasing the accumulation of malondialdehyde (MDA). This led to the preservation of cell membrane integrity, mitigation of lipid peroxidation (LOP), and a delay in browning process. These findings suggested that treating with 50 Gy X-ray irradiation can effectively slow down the color changes of Lanzhou lily bulbs during the storage under the room temperature, which is beneficial to extend the shelf-life of freshly harvested Lanzhou lily bulbs.