Impact of Local Preservatives (Salt, Lemon Juice and Oil) on the Physicochemical and Antinutritional Composition of Artisanal Tomato Paste

Abstract

Tomato (Solanum lycopersicum L.) is widely consumed in Côte d’Ivoire, but its high perishability and the cost of industrially processed tomato products create interest in accessible artisanal preservation methods. This study assessed the effects of three locally available preservatives—salt, lemon juice and oil—on the physicochemical, mineral and antinutritional characteristics of artisanal tomato paste. Fresh tomato paste was divided into four formulations: no preservative (TPNP), salt-preserved (TPSP), lemon-juice-preserved (TPLP) and oil-preserved (TPOP). Standard analytical procedures were used to determine pH, titratable acidity, colour parameters, mineral composition, phytate, oxalate and condensed tannins. The formulations differed in pH and titratable acidity, with pH values ranging from 3.57 to 4.18. Potassium was the predominant mineral, ranging from 712.32 to 1024.01 mg/100 g, while phosphorus, magnesium, calcium and sodium also varied among formulations. TPOP had the lowest condensed tannin and phytate contents, at 0.49 and 35.11 mg/100 g, respectively, whereas TPLP had the lowest oxalate content, at 21.18 mg/100 g. Colour parameters also varied among treatments, although hue values did not differ significantly. Overall, the results show that salt, lemon juice and oil were associated with differences in the physicochemical, mineral and antinutritional composition of artisanal tomato paste, with the direction of change depending on the preservative used.