Advances in the Application of Amino Acids in the Preservation of Postharvest Fruits and Vegetables

Postharvest loss of fruits and vegetables remains a significant global challenge, while concerns over chemical residues, energy consumption, and storage-induced physiological disorders have accelerated the search for safe and eco-friendly preservation strategies. As key plant metabolites and signaling molecules, amino acids are gaining more attention for their roles in postharvest biology. This article reviews the primary postharvest issues of fruits and vegetables, the functional roles of representative amino acids, including γ-aminobutyric acid (GABA), glutamate (Glu), arginine (Arg), cysteine (Cys), proline (Pro), and phenylalanine (Phe), with emphasis on the postharvest applications and mechanisms of action of amino acids. Increasing evidence suggests that amino acids can improve postharvest performance mainly by mitigating oxidative stress, enhancing ROS scavenging capacity, retaining cellular membrane integrity, regulating osmotic and energy metabolism, activating phenylpropanoid-mediated defense, and modulating respiration–ethylene processes. These responses contribute to reducing chilling injury, decay, browning, softening, and senescence, thereby helping maintain color, texture, nutritional value, and storage quality. However, the effectiveness of amino acid treatments varies depending on the product types and conditions, and is influenced by concentration, application method, storage environment, and combined preservation strategies. The information in this review provides a systematic foundation for understanding amino acid-mediated modulation mechanisms of postharvest horticultural crops and for developing more environmentally friendly postharvest preservation technologies, while highlighting the need for treatment standardization, mechanistic validation, and commercial-scale evaluation.