Research suggests that the inclusion of carotenoids in the diet may be associated with a reduced risk of human chronic degenerative diseases(Reference Maiani, Periago and Catasta1). Foods such as tomatoes have been promoted for consumption because of their abundant source of carotenoids, i.e. lycopene, β-carotene and lutein. Thus, the objectives of the present study were to: first, analyse the carotenoid content of different tomato varieties, i.e. cherry, plum, round and high-lycopene round on the vine (round HLB); second, determine carotenoid bioaccessibility from these foods. Carotenoid bioaccessibility, which is defined as the amounts of carotenoid(s) that are available for absorption in the gut after digestion, is a good indicator of carotenoid bioavailability(Reference O'Sullivan, Ryan and Aherne2, Reference Garrett, Failla and Sarama3).
The tomatoes were Irish grown and purchased from a local supermarket chain. All work was performed under amber light to minimise carotenoid photodecomposition. Each food was weighed (2 g), homogenised and subjected to an in vitro digestion procedure(Reference O'Sullivan, Ryan and Aherne2, Reference Garrett, Failla and Sarama3). Micelle fractions were isolated from digested samples using ultracentrifugation. Both undigested and digested samples were extracted twice using a solvent mixture of hexane–acetone–ethanol (2:1:1, by vol.) and the carotenoid content of the samples was quantified by HPLC, as previously described(Reference O'Sullivan, Ryan and Aherne2). Bioaccessibility is defined as the proportion of carotenoids present in the micelles compared with that contained in the original food (expressed as a percentage).
Values are means for four independent experiments.
a,b,c,d Means with unlike superscript letters were significantly different (one-way ANOVA, followed by Tukey's multiple comparison test; P<0.05).
Lycopene content was higher in the round HLB (P<0.05) tomatoes as well as the cherry and plum tomatoes compared with the normal round variety. On the other hand, β-carotene content was greater in both cherry and plum tomatoes (P<0.05) as well as the round variety when compared with round HLB tomatoes. Lycopene was more bioaccessible from round tomatoes compared with cherry and round HLB varieties; however, bioaccessibility of lycopene from all the tomatoes was relatively low. β-Carotene bioaccessibility was greater from cherry tomatoes (P<0.05) when compared with the round HLB variety. In conclusion, varietal differences were seen in the content and bioaccessibility of lycopene and β-carotene from tomatoes. Bioaccessibility of β-carotene was generally higher than that of lycopene.
This work was supported by Science Foundation Ireland (PI Award 04/IN3/B509).
