Ethylene treatment induces changes in folate profiles in climacteric fruit during postharvest ripening

• Folate profiles change distinctly during postharvest ripening in climacteric fruits.
• Ethylene treatment (ET) affects fruit folate levels in a species-specific manner.
• ET increases folates in postharvest ripened banana and tomato fruits.
• ET decreases folates in postharvest ripened papaya fruit.

Avocados, bananas, papayas, and tomatoes are typical climacteric fruits that are usually harvested at the mature green stage. Their ripening is later triggered by exogenous ethylene as a common postharvest practice; however, the effect of ethylene on the folate content of fruit has not been studied. Folates are part of the vitamin B complex and their consumption is essential for proper human development. In this work, changes in folate profiles and contents during postharvest ripening, both with and without ethylene treatment, were evaluated in four climacteric fruits: papaya, tomato, banana, and avocado. Non-induced postharvest ripening increased folates in ripe papaya fruit, while it did not affect total folate contents in avocados. Significant fluctuations in total folate in tomatoes and bananas were observed throughout ripening; however, total folates in ripe fruit returned to their initial mature green values. Ethylene treatment also affected the folate pools in the fruit differently, causing a 24% and 51% increase in ripe tomatoes and bananas, respectively, a 26% decrease in papayas, and no change in avocados compared to non-treated ripe controls. Ethylene treatment affected the accumulation of 5-CH3-THF in all fruits; this folate derivative is involved in ethylene biosynthesis. This work shows that ethylene treatment and postharvest ripening affect fruit folate levels and derivatives in a species-specific manner. This knowledge shows that postharvest treatments can help improve the folate accumulation in plant foods for fresh consumption.

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