Valorization of Tomato Residues by Supercritical Fluid Extraction

Abstract

Tomato processing leads to the production of considerable amounts of residues, mainly in the form of tomato skins, seeds and vascular tissues, which still contain bioactive molecules of interest for food, pharmaceutical and nutraceutical industries. These include carotenoids, such as lycopene and β-carotene, tocopherols and sitosterols, among others. Supercritical fluid extraction is well positioned for the valorization of tomato residues prior to disposal, because it remains an environmentally safe extraction process, especially when using carbon dioxide as the solvent. In this article, we provide an extensive literature overview of the research on the supercritical fluid extraction of tomato residues. We start by identifying the most relevant extractables present in tomatoes (e.g., lycopene) and their main bioactivities. Then, the main aspects affecting the extraction performance are covered, starting with the differences between tomato matrixes (e.g., seeds, skins and pulp) and possible pretreatments to enhance extraction (e.g., milling, drying and enzymatic digestion). Finally, the effects of extraction conditions, such as pressure, temperature, cosolvent, flow rate and time, are discussed.

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“…Due to decreased use of organic and synthetic chemicals, decreased operating durations, and increased yield and extract value, non-traditional methods have emerged over the past 50 years that are more ecologically friendly (Azmir et al 2013). The production and specificity of bioactive components from material from plants should be increased by ultrasound (Ghafoor et al 2009;Lee and Yoon 2023;Villamil-Galindo et al 2023), pulsed electric field (Fincan et al 2004;Toepfl et al 2006), enzyme digestion (Gaur et al 2007;Yan et al 2018;Marathe et al 2021), extrusion (Lusas and Watkins 1988), microwave heating (Kaufmann and Christen 2002;Barrios et al 2022;Liang et al 2023), ohmic heating (Torgbo et al 2022;Sharifi et al 2022;Goksu et al 2022), supercritical fluids (Mira et al 1999;Berna et al 2000;Comim et al 2010;Aniceto et al 2021), andaccelerated solvents (Smith 2002). These methods are believed to be non-conventional methods.…”

Sustainable Drying and Green Deep Eutectic Extraction of Carotenoids from Tomato Pomace

“…This technique is increasingly used, thanks to its versatility that allows one to fine-tune the solvent; this can be done by modifying its polarity, e.g., with ethanol, according to the polarity of the target compounds. Moreover, when using CO 2 , since it is volatile at ambient conditions, it can be easily separated from the extract, with benefits for health and the environment [51]. The use of supercritical CO 2 can successfully extract thermolabile compounds (generally at temperatures around 60 • C), such as carotenoids, considering the inert characteristics of this solvent, namely non-explosive and non-toxic characteristics [51].…”

“…Moreover, when using CO 2 , since it is volatile at ambient conditions, it can be easily separated from the extract, with benefits for health and the environment [51]. The use of supercritical CO 2 can successfully extract thermolabile compounds (generally at temperatures around 60 • C), such as carotenoids, considering the inert characteristics of this solvent, namely non-explosive and non-toxic characteristics [51]. Technologies such as supercritical fluid extraction require particular equipment that is comprehensive of pumps, stainless steel extraction vessels, pipes, etc., and therefore upscaling of this technology would be very expensive.…”

Valorization of Tomato Seed By-Products as a Source of Fatty Acids and Bioactive Compounds by Using Advanced Extraction Techniques

“…Carbon dioxide is one of the most common solvents used in SFE, due to its low critical temperature and pressure, avoiding thermolabile compounds degradation. Moreover, CO 2 is environmentally friendly, highly available, non-toxic, easy to remove and generally recognized as safe by the FDA, which makes it especially useful for food and natural product applications [ 19 , 20 ]. Due to its low polarity, SC-CO 2 has been used for lipophilic substances extraction, such as fatty acids, lipids, and carotenoids; however, co-solvents such as ethanol, methanol or acetonitrile could be added to favor highly polar compounds extraction.…”