Metabolic profiling and quality assessment during the postharvest of two tangor varieties subjected to heat treatments

Citrus growth and export are one of the most important agroeconomical activities in regions with Mediterranean-like climates. Among them, tangors in particular are appreciated by their sweet taste and delicate palatability. The current study describes the analysis of the metabolome of two tangor (Citrus reticulata × C. sinensis) cultivars, Murcott and Ellendale, broadly cultivated in Argentina and other countries, after heat treatment and postharvest storage. This investigation intended to shed light on the biochemistry behind some observed differences in the fruit of both cultivars, such as a distinctive response to cold storage. The differential response to heat treatments and their effectiveness for preventing fungal infection was also evaluated. Metabolite profiling carried out using several chromatographic techniques and differential methods allowed to comprehensively compare the levels of sugars, organic acids, amino acids, polyalcohols, phenylpropanoids and phospholipids among varieties. It was found that Ellendale possess lower content of turanose and melibiose, higher levels of putrescine, unsaturated fatty acids, ribonic and propionic acids, as well as a remarkably higher level of hesperidin than Murcott. After heat treatment, Ellendale was less prone to pathogen development during storage than Murcott. The results, analyzed in terms of the differential metabolome response between the two varieties, hint at a better competence, boosted by heat treatment, of Ellendale to withstand biotic and abiotic stress conditions.