The Mixture of Ozone and 1-Methylcyclopropene Prevents Post-Harvest Discoloration in Nectarines

Nectarine (Prunus persica L. Batsch, var. Nectarine, Rosaceae family) is a fruit rich in fibers, polyphenols, vitamin C, amino acids, and carotenoids, making it a very healthy food. The color of the pulp and pericarp are critical characteristics that impact consumer acceptance. Anthocyanins, secondary metabolites, are responsible for the desirable red color in ripe nectarines. They mainly include compounds like cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside, giving the fruit pulp nutraceutical properties. Additionally, anthocyanins structurally consist of compounds with various hydroxyl-phenolic groups that exhibit significant antioxidant effects. In plants, they also act as protectors against abiotic and biotic stress. The role of ethyleneThe biosynthesis and stability of anthocyanins are modulated by various factors, with the plant hormone ethylene being a crucial regulator. In the late stages of fruit ripening, several irreversible changes occur, including pulp color and an increase in the respiration rate, where ethylene production plays a significant role. This can lead to over-ripening and post-harvest fruit deterioration, reducing its shelf life. Recent studies have estimated that the harmful impact of ethylene on fruits and vegetables is responsible for between 10% and 80% of product losses. Therefore, the application of inhibitors and scavengers of this hormone in the ripening process can play a vital role in maintaining the quality of stored fruit. Counteracting ethylene without affecting appearanceThe application of 1-methylcyclopropene (1-MCP) in vegetables and fruits is a way to counteract ethylene responses by inhibiting its action through receptor blocking. In recent decades, it has been widely used to delay ripening and senescence, thus maintaining the post-harvest storage qualities of bulbs, flowers, vegetables, and fruits. However, studies have shown that fruit treated with 1-methylcyclopropene reduces the biosynthesis of anthocyanins, resulting in a deficient appearance and nutritional properties. The use of external absorbents shows promise in extending the post-harvest life of fruit. For example, crystalline or powdered potassium permanganate (KMnO4) removes ethylene from the storage environment through absorption and oxidation, producing water and carbon dioxide (CO2). Ozone's potentialOzone (O3) is another substance used in fruit treatment due to its potent oxidative power on ethylene, in addition to having broad-spectrum germicidal properties. Scientists have demonstrated that ozone treatment reduces respiration and also suppresses the expression of the genes AdACO1 and AdACS1, while reducing the activity of the enzymes aminocyclopropane-1-carboxylic acid oxidase (ACO) and 1-aminocyclopropane-1-carboxylic acid synthase (ACS). All of these are elements involved in ethylene biosynthesis. Furthermore, a recent study has shown that ozone treatment (O3) in some fruits promotes the accumulation of anthocyanins and proanthocyanidins by positively regulating the genes involved in the biosynthesis of these metabolites. Positive effects of the combined application of 1-MCP and O3Scientists investigated the effects of the combined treatment of 1-methylcyclopropene and ozone on anthocyanin biosynthesis in nectarines stored at 0?C. The results showed that this mixture effectively inhibits respiration and ethylene release while increasing anthocyanin biosynthesis due to the positive regulation of enzymatic activities, genes, and transcription factors involved in the phenylpropanoid pathway, the precursors of anthocyanins. These findings may shed new light on how to improve the quality and color development in post-harvest nectarine preservation. SourcesZheng, Y.; Duan, L.; Jiang, Y.; Yang, X.; Wang, H.; Li, W.; Pan, N.; Wang, X.; Liang, F.; Pan, Y.; Chen, L.; Li, X.; Jia, X. (2023). Ozone mitigates the flesh discoloration in response to 1-methylcyclopropene by promoting anthocyanin biosynthesis in post-harvest nectarines. Scientia Horticulturae, 321:112253. Minas, I. S.; Vicente, A. R.; Dhanapal, A. P.; Manganaris, G. A.; Goulas, V.; Vasilakakis, M.; Crisosto, C. H.; Molassiotis, A. (2014). Ozone-induced kiwifruit ripening delay is mediated by ethylene biosynthesis inhibition and cell wall dismantling regulation. Plant Science, 229:76-85. ImageLink to the image Accessed on 10/18/2023.