Abstract
Different strategies have been developed to increase the concentration of bioactive compounds in tomatoes during post-harvest, with ultraviolet light (UV) and light emitting diodes (LEDs) being interesting tools. The aim of this study was to evaluate the effect of ultraviolet (UVA at 366 nm and UVC at 254 nm) pre-treatment (1 kJ/m2) and red–blue LED light (25.4 µmol/m2/s) on the concentration of carotenoids, (poly)phenols and hydrophilic/lipophilic antioxidant capacity during 7 days of refrigeration storage of green tomatoes (Solanum lycopersicum L.) cultivar “Raf”. In addition, special attention was paid to quality parameters (weight loss, colour, acidity, soluble solids and ripening index). Tomatoes exposed to LED light at 6 °C for 7 days increased up to three times the total carotenoids content (mainly β-carotene and E-lycopene) compared to tomatoes refrigerated in the dark, while UV treatments alone did not significantly affect the carotenoid content. Besides, exposure to LEDs increased the hydrophilic and lipophilic antioxidant capacity of tomatoes by 30%, without affecting phenolic contents. Thus, LED treatments alone during refrigerated storage fostered ripening and improved the nutritional value of tomatoes, without compromising quality parameters. Further studies must be carried out to evaluate the impact on sensory attributes and consumer acceptance.
Highlights
Published: 25 March 2021The tomato (Solanum lycopersicum L.) is one of the most consumed fruits in the world.The Spanish cultivar “Raf” is highly desired by consumers due to its sweet flavour and crunchy and juicy texture
We tested the effect of combined ultraviolet light (UV) (A or C) and red–blue light emitting diodes (LEDs) light treatments on the concentration of carotenoids, total phenolic compounds and antioxidant capacities of mature green tomatoes stored for 7 days under refrigeration conditions
Our results showed that the key condition to increase carotenoid contents and hydrophilic and lipophilic antioxidant capacities was the exposure to continuous LED light, whilst the effect of UV pre-treatments alone was negligible
Summary
Published: 25 March 2021The tomato (Solanum lycopersicum L.) is one of the most consumed fruits in the world.The Spanish cultivar “Raf” is highly desired by consumers due to its sweet flavour and crunchy and juicy texture. Intake of tomato has been inversely related to the incidence of cancer, cardiovascular diseases, ageing and many other health problems [1]. These beneficial effects of tomatoes are associated to their content in bioactive compounds, including antioxidants such as carotenoids (mainly lycopene), ascorbic acid, tocopherol, and phenolic compounds (mainly hydroxycinnamic acid derivatives and flavonols) [2,3]. Since tomato is a climacteric fruit and continues to ripen after harvest, different strategies have been developed to increase the concentration of bioactive compounds during post-harvest storage and to maintain or enhance the quality during the shelf-life. Treatments with ultraviolet light (UV) and light emitting diodes (LEDs)—alone or in combination—have been shown to be successful for this purpose, as light is an important regulator of the expression of carotenoid
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