Quality determination of avocado fruit immersed in a pyridoxal 5′-phosphate solution

Abstract

Vitamin B6 plays a crucial role in plant metabolism. It acts as a cofactor in over 140 reactions and has a potent antioxidant function, as described in plant growth and development related to root and leaf tissues, but not yet in fruit ripening. Here, we aimed to explore simple practices to improve endogenous content of vitamin B6 in avocados, measured by high-performance liquid chromatography (HPLC), and to evaluate to what extent and through which mechanisms pyridoxal-5′-phosphate (PLP) treatment influences fruit quality during postharvest ripening and cold storage. Emphasis was put on evaluating a possible link between vitamin B6 and phytohormones by performing hormonal profiling analyses using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). We hypothesized that PLP could improve quality parameters and prolong the shelf life of fruit. Results showed that Bacon avocados had a low vitamin B6 content compared to Hass and other varieties. However, basic techniques like short-term cold storage increased the vitamin B6 content 2.5 fold. Exogenous application of vitamin B6 slightly delayed avocado ripening at room temperature and caused reduced softening in the mesocarp, which was related to a hormonal response that was most likely mediated by cytokinins. In long-term cold-stored avocados, PLP treatment triggered γ-tocotrienol and plastochromanol-8 accumulation, which improved the tocochromanol composition in the fruit. In conclusion, the vitamin B6 content of Bacon avocados can be improved through simple practices. Exogenous applications of PLP can be used either to delay ripening of avocados at room temperatures or to increase tocochromanol content in cold-stored fruit.