Improved functional and nutritional properties of tomato fruit during cold storage

Abstract

The use of synthetic antioxidants has been associated with serious concerns for human and environmental health. During ripening stages, tomato fruit is exposed to different abiotic stresses which not only influence its nutritional, mechanical, and functional properties at harvest, but also affect the quality and shelf life of the fruit during storage. This study investigated the pattern of changes in dietary antioxidants during various ripening stages of tomato fruit (cv. Red Rose) and their impact on storage behavior of the fruit during cold storage. Tomato fruits were harvested at mature green, breaker, turning, pink, light-red and red stages of maturity. Then, they were analysed for flesh firmness, soluble solids content, titratable acidity, total sugars, pH, dry matter content, lipophilic (lycopene, β-carotene, and total carotenoids), and hydrophilic (ascorbic acid, phenolic and flavonoids) antioxidants. Additional fruits were harvested at each maturity stage and divided into three equal lots, then were subjected to low-temperature (10 ± 1 °C) storage with 80 ± 5% RH, for 7, 14, and 21 days. Flesh firmness, and the levels of dietary antioxidants were analysed following the subsequent storage periods. The results revealed that the peak of hydrophilic antioxidants such as ascorbic acid, phenolic compounds, and flavonoids was between the 'pink' and the 'light-red' stages of fruit maturity. Whereas tomatoes harvested at the 'red' stage of maturity had the highest levels of lycopene and β-carotene. Both the stage of fruit maturity at harvest and duration of cold storage influenced flesh firmness, organoleptic and functional properties of 'Red Rose' tomato fruit. In conclusion, the results of the current investigation have practical implications in formulating foods with improved functional properties at processing industries.

Keywords: Ascorbic acid; Flavonoids; Functional foods; Oxidative stress; Solanum lycopersicum L; Texture.

Fig. 1

Changes in flesh firmness of ‘Red Rose’ tomatoes as affected by the stages of fruit maturity at harvest. MG, BK, TG, PK, LR, and RD represent the mature green, breaker, turning, pink, light-red, and red stages of fruit maturity, respectively. Vertical bars represent mean values ± SE of 4 replicates (r = 4).

Fig. 2

Changes in lycopene and total carotenoid contents in ‘Red Rose’ tomatoes as affected by the stages of fruit maturity at harvest. MG, BK, TG, PK, LR, and RD represent the mature green, breaker, turning, pink, light-red, and red stages of fruit maturity, respectively, Lyco = lycopene, TCC = total carotenoid content, fm = fresh mass, Vertical bars represent means ± SE of 4 replicates (r = 4).

Fig. 3

Changes in total phenolic and flavonoid contents in ‘Red Rose’ tomatoes as affected by the stages of fruit maturity at harvest. MG, BK, TG, PK, LR, and RD represent the mature green, breaker, turning, pink, light-red, and red stages of fruit maturity, respectively, TFC = total flavonoid content, TPC = total phenolic content,. Vertical bars represent mean values ± SE of 4 replicates (r = 4).

Fig. 4

Changes in β-carotene (a) and ascorbic acid (b) contents in ‘Red Rose’ tomatoes as affected by the stages of fruit maturity at harvest. MG, BK, TG, PK, LR, and RD represent the mature green, breaker, turning, pink, light-red, and red stages of fruit maturity, respectively. Vertical bars represent mean values ± SE of 4 replicates (r = 4).