Value‐added processing of seeds from tomato sauce industry and comparison of extraction solvents on the chemical properties

Abstract

BACKGROUND Tomato seed oil (TSO) was obtained using a combined method of pre‐keeping in solvent and Soxhlet extraction. A considerable oil yield could not be obtained using samples without drying or grinding, with dried or non‐dried seeds, which were not kept in solvent (<2%). For this purpose, oil yield, physicochemical properties, oxidation values, spectrophotometric indices and fatty acid composition of the samples extracted with acetone, ethyl acetate, chloroform and petroleum ether were determined. RESULTS Oils obtained by the extraction of petroleum ether (20.36 meq g O2 kg−1) and ethyl acetate (11.16 meq g O2 kg−1) were found to have very high peroxide values. Besides, a high‐quality edible oil should have an anisidine value (p‐AnV) of less than 10. Samples extracted with chloroform alone had a p‐AnV of 8.86, while slightly higher values were found for other samples (P < 0.05). Chloroform (20.50) and acetone (23.06) both gave the best results and met the expected value, with total oxidation value below 30. Finally, the highest levels of primary fatty acids observed were linoleic acid (32.77–41.95%), palmitic acid (23.75–32.27%), oleic acid (16.17–24.52%), and stearic acid (7.76–12.82%). CONCLUSION This process is applicable to recycling tomato sauce waste and essential oil. The research proved that the seed‐drying process and pre‐keeping in solvent have an important effect on oil yield, quality and fatty acid composition. © 2023 Society of Chemical Industry.