Characterization of oleoresin extracted from tomato waste using carbon dioxide in sub and supercritical conditions

Introduction The food industry is characterized by a high number of wastes, nowadays they are used for agriculture or animal feed; in particular, in Italy, the tomato processing industry produces around 150 thousand tons of wastes each year (2-6% of the raw material). Tomato waste is characterized by high amounts of bioactive compounds such as carotenoids, polyphenols, vitamin E and essential fatty acids. In this work oil extracts from skins and tomato waste were produced using carbon dioxide in sub and supercritical conditions. Compositions of the oils were analyzed and compared to the composition of oil obtained by means of solvent. Method Skins and tomato waste were dried at 60°C and ground to get particle size of 1 mm. Skins and tomato waste were separately submitted to extraction by supercritical carbon dioxide, liquid carbon dioxide and hexanedichloromethane mixture solvent. Supercritical and liquid CO2 were carried out also using ethanol 10%. Carotenoids and tocopherols were determined in the extracts by means of high-performance liquid chromatography and spectrophotometry. Total polyphenols were determined via HPLC Diode Array/MS detector and using FolinCiocalteau method. The antioxidant capacity was measured via the DPPH method. Results / Discussion / Conclusion The best extraction parameters with subcritical CO2 were pressure 150 bar, temperature 20°C and flow 5 ml/min, while for the extraction with supercritical carbon dioxide parameters were 340 bar, 60°C and 10 ml / min. Extraction from waste with CO2 supercritical conditions with ethanol provided the highest yields in oleoresin (12.7- 12.9%), while the extracts obtained from skins with supercritical carbon dioxide without ethanol had the highest quantities of lycopene (205.7 mg/100g oil), ß-carotene (75.1 mg/100g oil), a and γ tocopherols (800.2 and 5756.0 mg/kg oil respectively). The highest quantity of polyphenols (93 mg GAE/g oil) was found in oil from skin by supercritical carbon dioxide with ethanol. The oleoresin extracts from skins and tomato waste using carbon dioxide in sub and supercritical conditions showed a great value in its antioxidant capacity (+780%) due to the presence of carotenoids, polyphenols, and tocopherols compared to the extracts obtained with solvent.