Comparative effects of superchilling, refrigeration and freezing on storage quality, lignification and enzymatic browning of Chimonobambusa utilis shoots

Postharvest lignification and enzymatic browning limit the storage quality of Chimonobambusa utilis shoots. This study evaluated whether superchilling storage (−2.0 ± 0.5 °C), selected according to the experimentally determined initial freezing point of shoot tissue, improved quality retention compared with refrigeration (4.0 ± 0.5 °C) and freezing (−18.0 ± 0.5 °C). Appearance, thawing drip loss, soluble constituents, cell-wall components, absorbance-based PAL, PPO and POD activities, microstructure and multivariate quality profiles were analyzed. On day 24, superchilling maintained better visual quality and showed lower thawing drip loss than freezing (4.46 vs. 18.48 g/hg initial mass). Frozen shoots exhibited pronounced post-thaw microstructural disruption, whereas superchilled shoots retained clearer cellular boundaries and a more organized tissue network. Refrigerated shoots showed progressive quality deterioration, with increased lignin and cellulose accumulation and higher lignification-related enzyme activities. Superchilling moderated PAL, PPO and POD activities, maintained relatively stable soluble components, and was associated with reduced lignification- and enzymatic browning-related deterioration and better-preserved tissue structure. Multivariate analyses further showed that superchilled samples remained closer to the initial quality profile than refrigerated samples. Frozen samples should be interpreted as freeze–thaw-treated tissues. Overall, −2.0 °C superchilling improved storage-quality retention under the tested conditions.