Melatonin Postharvest Treatment in Leafy ‘Fino’ Lemon Maintains Quality and Bioactive Compounds

Abstract

Spain is a great producer of organic lemon; however, it is necessary to reduce the losses caused by post-harvest diseases. Melatonin (MEL) is a naturally occurring compound with physiological functions in fruit growth and ripening and is able to modulate postharvest ripening and senescence, most of it being concentrated in climacteric fruit. Thus, the aim of this study was to apply MEL to organic lemon fruit with stems and leaves (LEAF) and to organic lemon without those components (LEAFLESS) after harvesting and storage during 21 days at 2 °C to understand the effects of this treatment on the fruit quality. For this purpose, two experiments were carried out. First, MEL was applied at 0.01 mM, 0.1 mM and 1.0 mM by immersion for 15 min on lemon fruits, and the quality parameters and bioactive compounds of the fruit were analysed. Subsequently, a second experiment was carried out where the best concentration (1 mM) was selected and another time (15 and 30 min) was added, with the same quality parameters being analysed. As a result, we observed that all MEL treatments showed positive effects on weight loss reduction, softening (higher fruit firmness), total acidity and lower colour changes. Total phenols increased in MEL-treated lemons, both in peel and juice. For the three concentrations tested, the best efficiency was obtained with MEL at 1.0 mM, while LEAF lemons were the most effective. In conclusion, lemons containing stems and leaves (LEAF) improved preservability by using MEL at 1.0 mM with better organoleptic quality and enhanced phenolic compounds.

A New Ready-to-Eat Product Based on Enzymatically Peeled ‘Hernandina’ Clementine Segments and Citrus Syrup

“…Apart from vitamin C, citrus fruit contains a wide range of other antioxidant bioactive compounds, mainly carotenoids and phenolics, which differ qualitatively and quantitatively depending on the fruit species and cultivars, and collectively are responsible for health beneficial properties [3,36,37]. In 'Fino' lemon fruits, increases in total phenolics content during cold storage have been reported, while decreases were found in ascorbic acid concentration [38,39]. Accordingly, 30% loses in ascorbic acid have been reported in 'Satsuma' mandarin fruit after 35 days of storage at 4 • C [40], and 25% loses were reported in manually obtained segments after 9 days of cold storage in low density polyethylene bags [41].…”

Polypropylene/Poly(butylene adipate-co-terephthalate) Breathing Film for Inhibiting Pseudomonas and Maintaining Microbial Communities and Postharvest Quality of Allium mongolicum Regel during Storage

“…Generally, the postharvest quality loss in fresh fruit and vegetables is controlled by many physical, chemical, and biological treatments, such as cold storage [ 5 ], ozone [ 12 ], melatonin [ 13 ], and antimicrobial coating treatments [ 6 , 7 ], etc. However, most of these have high costs or toxic residues, which are difficult to popularize.…”