Extraction of phytochemicals from tomato leaf waste using subcritical carbon dioxide

There is an increasing global trend towards efficiently utilizing agricultural biomass. Tomato leaf waste is an unexploited source of bioactive molecules, and we aimed develop methods for extracting compounds of high commercial value. In particular, tomato leaf represents a rich source of phylloquinone (vitamin K1), which has a variety of agricultural and health applications. Phylloquinone was efficiently recovered from tomato leaf waste (29.17 ± 0.96 μg g−1) by a solvent-free process that employed high pressure CO2 at 180 bar pressure and room temperature. This recovery rate for vitamin K1 is higher than traditional extraction processes that involve using organic solvents. Tomato leaf also contained phenolics (240 mg (GAE) g−1) and flavonoids (184 mg Qe g−1). A high level of protein (24.47 ± 0.38%) could be recovered from tomato leaf, with aspartic acid, glutamic acid, and leucine being the dominant free amino acids (13 ± 0.1, 15.1 ± 0.2, 12.8 ± 0.1 mg g−1 dry weight). In summary, tomato biomass is a low cost source of high-value compounds that can be purified for the production of nutritional foods and nutraceuticals. •Tomato leaf waste represents a rich source of phylloquinone (vitamin K1).•This material is also rich in phenolics and flavonoids.•Supercritical CO2 is a method for high-efficiency solvent-free extraction.•High value compounds have applications in nutraceuticals and food fortification.