Steensma Priscille, Shapiguzov Alexey, Annala Leevi, Vainonen Julia P, Mikkonen Kirsi S, Kangasjärvi Saijaliisa
Department of Food and Nutrition, University of Helsinki, Helsinki, Finland.
Production Systems, Natural Resources Institute Finland (Luke), Turku, Finland.
Physiol Plant. 2025 Jul-Aug;177(4):e70433. doi: 10.1111/ppl.70433.
Increasing the availability of fresh vegetables and reducing food waste are essential for healthy and sustainable production. However, fresh-cut vegetables such as lettuce (Lactuca sativa L.) often experience rapid quality loss after harvest and processing. To maintain freshness in retail, modified atmosphere packaging (MAP) with low oxygen (O) and high carbon dioxide (CO) concentrations, combined with refrigeration, is commonly used. Packaged leaves are then displayed under dark or low-light conditions. The postharvest physiology of lettuce under these conditions (including changes in energy metabolism, photosynthesis, senescence progression, and light-dependent metabolic alterations) remains poorly understood, limiting the development of strategies to extend shelf life. Using spectroscopic and biochemical approaches, we investigated the physiological changes in fresh-cut lettuce stored in MAP under refrigeration in either darkness or constant low light. Our analysis revealed distinct light-dependent and light-independent adjustments in photosynthesis. MAP triggered rapid and dramatic changes in photosynthetic light reactions, detectable within 1 h of packaging, as observed by pulse amplitude modulated (PAM) and OJIP kinetics assays. These changes were likely associated with compromised electron sink strength in the photosynthetic electron transfer chain and altered dynamics of the energy component of nonphotochemical quenching (qE-NPQ). Notably, these functional alterations coincided with only minor modifications in photosynthetic supercomplexes, as determined by blue native gel electrophoresis. The MAP-induced changes in photosynthesis deteriorated during storage in darkness but were reversed by storage under low light, likely due to photosynthetic gas exchange. Our findings provide new insights into photosynthesis of packaged lettuce and highlight promising physiological readouts for assessing lettuce quality in retail settings.
增加新鲜蔬菜的供应量和减少食物浪费对于健康和可持续生产至关重要。然而，生菜（Lactuca sativa L.）等鲜切蔬菜在收获和加工后往往会迅速失去品质。为了在零售中保持新鲜度，通常采用低氧（O）和高二氧化碳（CO）浓度的气调包装（MAP）并结合冷藏。然后将包装好的叶片在黑暗或弱光条件下展示。在这些条件下生菜的采后生理学（包括能量代谢、光合作用、衰老进程和光依赖代谢改变）仍知之甚少，限制了延长货架期策略的发展。我们使用光谱和生化方法，研究了在黑暗或恒定弱光下冷藏于MAP中的鲜切生菜的生理变化。我们的分析揭示了光合作用中明显的光依赖和光不依赖调节。MAP引发了光合光反应的快速而显著变化，在包装后1小时内即可检测到，这通过脉冲幅度调制（PAM）和OJIP动力学分析观察到。这些变化可能与光合电子传递链中电子汇强度受损以及非光化学猝灭（qE-NPQ）能量成分的动力学改变有关。值得注意的是，这些功能改变仅伴随着光合超复合物的微小变化，这通过蓝色天然凝胶电泳确定。MAP诱导的光合作用变化在黑暗储存期间恶化，但在弱光下储存会逆转，这可能是由于光合气体交换。我们的研究结果为包装生菜的光合作用提供了新见解，并突出了用于评估零售环境中生菜品质的有前景的生理读数。
