Recovery of Antioxidants from Tomato Seed Industrial Wastes by Microwave-Assisted and Ultrasound-Assisted Extraction

Abstract

Tomato seed (TS) wastes are obtained in large amounts from the tomato processing industry. In this work, microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) of antioxidant compounds from TS were optimized by using response surface methodology. The effect of MAE and UAE main extraction parameters was studied on total phenolic content (TPC) and antioxidant activity (DPPH) responses. Antioxidant, structural, morphological, and thermal properties of MAE and UAE extracts were evaluated. A great influence of ethanol concentration was observed in both extraction methods. Optimal MAE conditions were determined as 15 min, 80 °C, 63% ethanol and 80 mL, with a desirability value of 0.914, whereas 15 min, 61% ethanol and 85% amplitude (desirability = 0.952) were found as optimal conditions for UAE. MAE extracts exhibited higher TPC and antioxidant activity values compared to UAE (1.72 ± 0.04 and 1.61 ± 0.03 mg GAE g TS−1 for MAE and UAE, respectively). Thermogravimetric analysis (TGA) results suggested the presence of some high molecular weight compounds in UAE extracts. Chlorogenic acid, rutin and naringenin were identified and quantified by HPLC-DAD-MS as the main polyphenols found by MAE and UAE, showing MAE extracts higher individual phenolics content (1.11–2.99 mg 100 g TS−1). MAE and UAE have shown as effective green techniques for extracting bioactive molecules with high antioxidant activity from TS with high potential to be scaled-up for valorizing of TS industrial wastes.

Extraction of natural bioactive compounds using clean label technologies and their application as muscle food preservatives

“…Patra et al (2021) developed a process to extract bioactive compounds from cashew apple bagasse and observed that a 1:30 bagasse to solvent (1%citric acid)ratio, 110 s treatment time, and 560 W microwave power was the optimum MAE condition for extraction of bioactive. A similar study was conducted by Solaberrieta et al (2022) on tomato seed and reported that as compared to UAE, the antioxidant activity and total phenolic content were higher for MAE extract. Recently, Boli et al (2022) reported that the temperature and solvents play a significant role in the extraction of bioactive compounds from olive leaves using MAE.…”

Ultrasound‐assisted extraction of oilseeds—sustainability processes to obtain traditional and non‐traditional food ingredients: A review

“…US application can additionally have some chemical effects on the different oilseed compounds that could affect product quality, such as free radical and hydrogen peroxide formation (Mwaurah et al., 2020), protein structural changes (Du et al., 2021; Liang et al., 2022; Naik et al., 2022), and antioxidant compounds degradation (Rojas et al., 2021). However, there are studies that have demonstrated the maintaining of oil quality (Hernández‐Santos et al., 2016; Mohammadpour et al., 2019; Samaram et al., 2014; Senrayan & Venkatachalam, 2020), a high antioxidant activity of extracts (Mahindrakar & Rathod, 2020; Savic & Gajic, 2021; Solaberrieta et al., 2022), and the improvement of some functional properties of proteins (Du et al., 2022; Flores‐Jiménez et al., 2019; Naik et al., 2022) when US has been applied. More details on these aspects are described in the following sections.…”

“…Since US parameters could have an effect in the potential degradation of thermolabile compounds such as those with antioxidant capacity (Mohammadpour et al., 2019; Rojas et al., 2021), it is essential to optimize them in order to achieve high extraction yields while also reducing the degradation of compounds extracted. Most of the studies related to UAE in seeds evaluate the US parameters and verify the presence of antioxidant compounds by HPLC in the optimized condition of solvent, time, power, temperature, and frequency; however, they do not usually evaluate the degradation kinetics of this kind of compounds using US (Ismail et al., 2019; Mahindrakar & Rathod, 2020; Savic & Gajic, 2021; Solaberrieta et al., 2022). Some studies in other vegetable materials have demonstrated that degradation of phenolic compounds, such as gallic acid and catechin, can be achieved under the combination of different US parameters (Rojas et al., 2021; Zhang et al., 2015; Zhu et al., 2018).…”

Tomato seed extract promotes health of the gut microbiota and demonstrates a potential new way to valorize tomato waste

“…Substantial valorization efforts that previously focused on tomato seeds and the extraction of tomato seed oil and fatty acids, isolation of polyphenolic compounds with antioxidant activities, and generation of tomato seed meal with nutraceutical properties are well investigated [ 7 , 16 , 17 ]. These tomato seed fractions have been proposed for use in food products as a supplemental source of protein, and oil and fat for prepared foods [ 16 , 18 , 19 ].…”