| Carotenoids are a group of pigments, yellow to red in colour, which are widely distributed in the vegetal and animal kingdoms, namely in fungi, algae, carrots, tomatoes, crustaceans, insects and fishes. The importance of these natural pigments has increased as colouring and antioxidant agents in the food, and pharmaceutical industries, due to governmental restrictions in the use of the synthetic ones.
Beta-carotene and lycopene are well known carotenoids with important nutritional and biological properties. Lycopene consumption is strongly recommended, because this compound has high antioxidant activity, reducing the risk of atherosclerosis and coronary heart disease. Moreover, epidemiological studies have related the intake of lycopene with a lower risk of the incidence of certain types of cancers. Beta-carotene has an important role in human dietary, because of its pro-vitamin A activity.
Lycopene is the major carotenoid in tomato and it can represent approximately 80- 85% of the carotenoids content, which include beta-carotene and some xanthophylls. Tomato skins contain about five times more lycopene than the tomato pulp. Since the tomato processing companies produce large amounts of solid wastes (mainly skins and seeds) the recovery of carotenoids (namely lycopene) could be considered a good alternative for the valorisation of these by-products.
The objective of that type of studies is to carry out supercritical fluid extraction of carotenoids from tomato industrial wastes (mixture of skins and seeds) with CO2 and assess the influence of the moisture content of the tomato paste on the extraction yield and recovery. Also, the influence of the particle size and the flow-rate can be evaluated.
Table 29: Composition of the fresh and dried tomato paste (Soxhlet extraction)
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