Changes in lipid oxidation stability and antioxidant properties of avocado in response to 1-MCP and low oxygen treatment under low-temperature storage

Avocado (Persea americana Mill.) pulp is rich in unsaturated fatty acids, including oleic, linoleic, and palmitoleic acids, which tend to oxidize during storage. Oxidation of avocado oil in pulp can lead to the formation of volatile compounds responsible for off-flavors and to nutritional losses. Antioxidant systems in cells inhibit lipid oxidation and thus may contribute to protection against oxidative deterioration of fatty acids. The aim of this study was to determine the fatty acid profile of avocado pulp and to evaluate the extent of lipid oxidation and antioxidant properties of avocado pulp resulting from treatment with 1-methylcyclopropane (1-MCP) prior to low O2 treatment under low-temperature storage conditions. The avocado (cv. Fuerte) fruit was treated with 1 μL L-1 1-MCP for 24 h at 20oC, stored at 5oC for 21 days under a low O2 atmosphere (3.5% O2 and 96.5% N2), and then stored at 20oC for 14 days to simulate shelf storage conditions. We found that combined treatment of avocados with 1-MCP and low O2 and under low-temperature storage conditions lowered peroxide levels and increased iodine levels, which effectively controlled lipid oxidation and ripening. In the sensory evaluation test, off-flavors were not identified in either the treated or control avocado pulp at the early stages of ripening but were identified in the control at the over-ripe stage. Avocado fruit treated with 1-MCP and low O2 had higher saturated fatty acid (palmitic acid) and lower mono-unsaturated fatty acid (oleic acid and palmitoleic acid) than controls. In control fruit, total antioxidant activity, SOD activity, and α-tocopherol content decreased under low-temperature and room temperature storage conditions. Under the same conditions, fruit treated with 1-MCP and low O2 had increased total antioxidant activity, SOD activity, and α-tocopherol content. Taken together, these results show that pre-storage treatment of avocado fruit with a combination of 1-MCP and a low O2 atmosphere effectively reduces lipid oxidation by enhancing the antioxidant activity of avocado pulp.