Influence of the Techniques and Degrees of Ripeness on the Nutritional Qualities and Carotenoid Profiles of Tomatoes (Solanum lycopersicum).

Abstract

Abstract Tomato is a significant vegetable crop with numerous health benefits derived from its carotenoids, flavonoids and other phytonutrients contents. This work studies the nutritional qualities and carotenoids contents of five different cultivars of tomatoes (San Marz, Nasmata, Roma VF, Ogbomoso local and 4-lobes). The variations of pH, titratable acidity, reducing sugar, total solid, lycopene and beta-carotene contents of these tomatoes were investigated under ambient temperature and field ripening techniques and the mean values of these parameters investigated at different ripening stages and techniques were compared. Lycopene contents were significantly higher (p < 0.05) in tomatoes subjected to field ripening compared with those ripened under ambient temperature. The highest lycopene content (17.18 μg/g) was observed in Roma VF cultivar at fully-ripe stage under field ripening technique while the lowest value (0.64 μg/g) was in 4-lobes cultivar at semi-ripe stage under ambient temperature ripening. Similar trend was observed in the variation of betacarotene (a pro-Vitamin A index) among the tomato cultivars. The evaluated reducing sugar contents (ranging from 1.84 to 5.23 μg/g) were significantly higher (p < 0.05) in fully-ripe tomatoes compared to semi-ripe ones under field ripening and the trend was reversed for some cultivars under ambient temperature ripening. The titratable acidities of the tomatoes were significantly higher at the semi-ripe stage (0.24 to 0.38 %) under field ripening than those obtained under ambient temperature ripening (0.15 to 0.25 %). The pH of the tomatoes ranged from 3.58 to 4.07 and 3.46 to 5.40 under field and ambient temperature ripening, respectively, and the higher pH values obtained under ambient temperature ripening condition could make such tomatoes unsuitable in tomato processing plants. Consumption of tomatoes for the purpose of dietary antioxidant lycopene and pro-Vitamin A could maximally be achieved at fully-ripe stage under field ripening condition.