Use of time-resolved spectroscopy as a method to monitor carotenoids present in tomato extract obtained using ultrasound treatment.
BACKGROUND
Compounds exhibiting antioxidant activity have received much interest in the food industry because of their potential health benefits. Carotenoids such as lycopene, which in the human diet mainly derives from tomatoes (Solanum lycopersicum), have attracted much attention in this aspect and the study of their extraction, processing and storage procedures is of importance. Optical techniques potentially offer advantageous non-invasive and specific methods to monitor them.


OBJECTIVE
To obtain both fluorescence and Raman information to ascertain if ultrasound assisted extraction from tomato pulp has a detrimental effect on lycopene.


METHODS
Use of time-resolved fluorescence spectroscopy to monitor carotenoids in a hexane extract obtained from tomato pulp with application of ultrasound treatment (583 kHz). The resultant spectra were a combination of scattering and fluorescence. Because of their different timescales, decay associated spectra could be used to separate fluorescence and Raman information. This simultaneous acquisition of two complementary techniques was coupled with a very high time-resolution fluorescence lifetime measurement of the lycopene.


RESULTS
Spectroscopic data showed the presence of phytofluene and chlorophyll in addition to lycopene in the tomato extract. The time-resolved spectral measurement containing both fluorescence and Raman data, coupled with high resolution time-resolved measurements, where a lifetime of ~5 ps was attributed to lycopene, indicated lycopene appeared unaltered by ultrasound treatment. Detrimental changes were, however, observed in both chlorophyll and phytofluene contributions.


CONCLUSIONS
Extracted lycopene appeared unaffected by ultrasound treatment, while other constituents (chlorophyll and phytofluene) were degraded.
Department of Food Science, University of Udine, Via Sondrio 2/A, 33100, Udine, Italy.
Francesca
F
Bot
Department of Food Science, University of Udine, Via Sondrio 2/A, 33100, Udine, Italy.
Monica
M
Anese
Food and Life Sciences, School of Science, Engineering and Technology, University of Abertay Dundee, Bell Street, Dundee, DD1 1HG, UK.
M Adília
MA
Lemos
HORIBA Jobin Yvon IBH, 133 Finnieston Street, Glasgow, G3 8HB, UK.
Graham
G
Hungerford
D002338:Carotenoids / Q000032:analysis* / Q000737:chemistry; D002734:Chlorophyll / Q000032:analysis / Q000737:chemistry; D006586:Hexanes / Q000737:chemistry; D000077276:Lycopene; D018551:Solanum lycopersicum / Q000737:chemistry*; D010936:Plant Extracts / Q000032:analysis* / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods; D014465:Ultrasonics / Q000379:methods*
D006586:Hexanes; D010936:Plant Extracts; D002734:Chlorophyll; D002338:Carotenoids; C003140:phytofluene; D000077276:Lycopene
Chlorophyll; Raman; fluorescence lifetime; lycopene; phytofluene; ultrasound assisted extraction