The alleviation of pear chilling injury by chitosan-based coating during long term refrigeration is related to respiratory path, ethylene biosynthesis, and GABA shunt

Long-term cold storage usually induces chilling injury of pear fruits. This study investigated the effects of CTS/SiO 2 -GABA (Chitosan/Silicon dioxide-γ-Aminobutyric acid) coating on alleviating chilling injury in pears during long-term refrigeration (1 °C). Results showed that GABA significantly improved the mechanical properties of CTS-based films, attributable to amidation, Maillard reaction, and non-covalent crosslinking between CTS and GABA, which offset the undesirable effects of SiO 2 . Specifically, the values of tensile strength and elongation at break of CTS/SiO 2 -GABA film increased to 23.95 MPa and 78.13 %, respectively. These enhanced crosslinked structures also contributed to the water resistance behavior of CTS/SiO 2 -GABA film, that is, the moisture content, water solubility and water vapor permeability reduced to 20.38 %, 25.49 % and 0.86 g·s −1 ·m −1 ·Pa −1 ·10 −7 respectively, and the water contact angle increased to 50.47°. Additionally, CTS/SiO 2 -GABA coating effectively maintained the quality of pears, including weight loss (4.38 %), firmness (6.24 kg·mm −2 ), peel yellowing (1.40 of Δa*), core browning, sugars/acids balance. Mechanistically, CTS/SiO 2 -GABA coating regulated the metabolic flux in respiratory pathways of pears (suppress glycolysis and tricarboxylic acid cycle, enhance pentose phosphate pathway), by inhibiting ethylene biosynthesis and enhancing GABA shunt metabolism. This study provides a novel perspective on the regulatory mechanism of functional coatings to improve postharvest fruit quality.