Lycopene in tomato

Isomerization of lycopene in tomato oleoresin increased at 75 and 100°C, reaching the formation of eight unidentified lycopene geometrical isomers in tomato oleoresin stored at 100°C. The k of 0.2597/min was higher, whereas the (11.7 kcal/mol) was lower than that observed for lycopene standard heated in safflower oil at 75°C. 

Hackett, M.M. et al., Thermal stability and isomerization of lycopene in tomato oleoresins from different varieties, J. Food ScL, 69, C536, 2004. 

Khachik, F., H. Pfander, and B. Traber. 1998. Proposed mechanisms for the formation of the synthetic and naturally occuring metabolites of lycopene in tomato products and human serum. J Agric Food Chem 46 4885 1890. 

Shi J and Le Maguer M. 2000. Lycopene in tomatoes chemical and physical properties affected by food processing. Crit Rev Food Sci Nutr 40(1) 1—42. 

Ollanketo M, Hartonen K, Riekkola ML, Holm Y and Hiltunen R. 2001. Supercritical carbon dioxide extraction of lycopene in tomato skins. Eur Food Res Technol 212(5) 561-565. 

Kubota C and Thomson CA. 2006. Controlled environments for production of value-added food crops with high phytochemical concentrations lycopene in tomato as an example. Hortscience 41(3) 522—525. 

We were able to identify five geometrical isomers of lycopene in tomato peel extracts (all-E1, 9-Z, 13-Z, 9,13-ZZ and 9,13 -ZZ lycopenes) by recording LC-NMR spectra. In human serum, we have identified three of these isomers (all-E, 9-Z and 13-Z lycopenes). In comparison to the nutritional source (tomato), the two identified lycopene Z-isomers are enriched in the human serum sample, which indicates a specific role of these geometrical isomers within human organisms. 

The bioavailability of lycopene in tomato-based foods vs. that in fresh tomatoes increases even further when lycopene is consumed with oil. In studies by Stahl and Sies (1992, 1996), ingestion of tomato juice cooked in an oil medium resulted in a two- to threefold increase in lycopene serum concentrations 1 day after ingestion. An equivalent consumption of unprocessed tomato juice caused no rise in lycopene plasma concentration. This indicates that thermal pretreatment and an oil medium were beneficial for extracting lycopene into the lipophilic phase. Solubilization of lycopene in a lipophilic matrix is expected to considerably enhance its availability and its bioactivity. This is likely to boost its effectiveness as an antioxidant. However, this higher reactivity also renders lycopene more vulnerable to the detrimental effects of factors such as air, temperature and interactions with other components of the food. 

Retention of Total Lycopene in Tomato Powder Stored under Different Atmospheres for Different Periods of Time... 

Sharma, S.K. and Le Maguer, M. 1996. Lycopene in tomatoes and tomato pulp fractions. Inti. J. Food Sci. 2 107-113. 

Figure 2. (A) SFE-LC-UV system utilizing a monolithic column both for trapping and analysis and (B) determination of lycopene in tomatoes with the...

Literature is scarce on the effects of controlled atmosphere (CA) and modified atmosphere (MA) storage on carotenoid content and colonr retention in yellow and red vegetables. Sozzi et al. (1999), reported a lower content in total carotenoids and lycopene in tomatoes, which had been stored in 3% O2 or 20% CO2 than after storage in air (control). No differences were fonnd after storage in low O2 and high CO2. When the samples were transferred to air, the total carotenoid and lycopene contents were lower in the tomatoes, which were subjected to different storage treatments from those stored in air all the time. 

Not all carotenoids are vitamin A precursors - they comprise 90% of carotenoids, nevertheless they are excellent free radical scavengers. Examples are lycopene (in tomatoes) and astaxanthin (Fig. 51.2). The latter is enjoying a reputation as a nutriceutical it is pink and found in aquatic animals, e.g. salmon, shrimp and lobster, and in the alga, Haematococcus pluvialis, from which it is commercially extracted. 

Shi and Le Maguer (2000) recently showed that the main causes of tomato lycopene degradation during processing are isomerization and oxidation. Thermal processing generally causes some loss of lycopene in tomato-based foods. In general, dehydrated and powdered tomatoes have poor lycopene... 

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