Lycopene and β-carotene in non-blanched and blanched tomatoes

Tomatoes are an important agricultural commodity worldwide. Tomatoes and tomato-based food products, such as tomato paste, tomato sauce, tomato juice, and tomato soups, are considered as important sources of carotenoids in the human diet. There are many studies showing strong correlations between carotenoid consumption and a reduced risk of cancer and coronary and cardiovascular diseases. The beneficial effects of carotenoids are thought to be due to their role as antioxidants. Lycopene is the predominant carotenoid in tomatoes and exhibits the highest antioxidant activity of known carotenoids. β-carotene is also present in tomatoes, but in a much smaller amount. Lycopene is able to function as an antioxidant and has an activity that is twice as strong as β-carotene, but β-carotene is the major dietary precursor of vitamin A. The waste of tomato processing has been shown to be an excellent and inexpensive source of carotenoids because a large proportion of the carotenoids are discarded along with the peels during the processing of tomatoes into pastes or sauces. Furthermore, some studies indicate that tomato thermal processing (for example, the blanching process) increases carotenoid bioavailability. In the present study, it was established that the best source for purified lycopenes is tomato peels (a by-product of tomato juice production). Data from the present study suggest that the mean lycopene and β-carotene concentrations were higher in the blanched ‘Admiro’ F 1 tomatoes than in the non-blanched tomatoes. The β-carotene concentration in the blanched tomato peels was 24.7 mg/100 g, and there was over 2 times more β-carotene than that in the non-blanched tomato peels. The lycopene concentration in the non-blanched tomato peels was 62.92 mg/100 g, whereas it was 134.04 mg/100 g in the blanched tomato peels. Because a literature review has shown that hexane is the most suitable solvent for extracting carotenoids from the tomato matrix, the stability of lycopene and β-carotene in hexane extracts was evaluated. The samples were stored in the dark at +5°C (±1°C) for 23 days. The all-trans lycopene from the non-blanched tomato peels gradually degraded (by approximately 37% after 23 days), whereas the degradation of the all-trans lycopene from the blanched tomato peels was only approximately 25%. The β-carotene was stable during storage for 23 days. The color of the fresh tomato fruit and after blanching was measured with a portable MiniScan XE Plus spectrophotometer. The intensity of the color was expressed in CIE L*a*b* color coordinates: L* (brightness), a* (redness) and b* (yellowness).