Carotenoids are a class of phytonutrient present in a variety of fruits and vegetables. Tomatoes (and their products) can be a particularly good source of carotenoids (especially lycopene) and their consumption is correlated with a reduced risk of some cancers (e.g. prostate cancer(Reference Miller, Giovannucci and Erdman1)) and CVD(Reference Rissanen, Voutilainen and Nyyssonen2). Several factors have resulted in an increase in tomato ketchup consumption in the Western world(Reference Ishida and Chapman3) that may be viewed as detrimental, but may also be beneficial to health. At present there is little information on the carotenoid content of ketchups available in the UK.
Lycopene and β-carotene were extracted from fourteen different ketchups (diluted 1 in 10 with distilled water) using dichloromethane then analysed by HPLC with detection at 480 and 460 nm respectively after separation on a C30 column(Reference Muratore, Rizzo and Licciardello4). Antioxidant activity (AA) was assessed on the lipophilic extracts spectrophotometrically using the Trolox equivalent antioxidant capacity assay(Reference Re, Pellegrini and Proteggente5).
SL, supermarket low-price product; SR, supermarket regular-price product; SP, supermarket premium-price product; M, manufacturer's product; O, organic product; ND, no data available.*Values (μg/g) are means for four determinations. †g/100 g finished product. ‡Values (mmol Trolox equivalents/l) are means for three determinations.
A 4-fold variation in lycopene content was observed, with the highest level measured in a supermarket premium product (SP1) and the lowest level measured in a supermarket low-price product (SL1). For β-carotene a manufacturer's own brand contained the highest level with the lowest level observed for a supermarket low-price product (SL2). For AA the SP1 ketchup contained the highest activity whereas a manufacturer's own brand ketchup (M1) possessed the lowest. Both lycopene and β-carotene content correlated with AA (r 0.845 and 0.769 respectively, P<0.001)). Significant correlations were also observed between tomato content and carotenoid concentrations (r 0.749 and 0.608 for lycopene and β-carotene respectively). These results are consistent with data from other studies(Reference Ishida and Chapman3,Reference Markovic, Hruskar and Vahcic6) and taken together with information on ketchup intake indicate that ketchup consumption could contribute to between 8 and 38% of UK lycopene intake.
