Characterization of tomato processing by-product for use as a potential functional food ingredient: nutritional composition, antioxidant activity and bioactive compounds.

Tomato pomace, a by-product generated during tomato processing, was collected at a large tomato processing industry. The by-product was mainly constituted of tomato skin (61.5%), and presented high moisture content (66.58 g.100g-1 wet basis). Among the nutrients, the highest content was of dietary fibre, followed by proteins and fat (50.74, 20.91, 14.14 g.100g-1 d.w., respectively). The pomace has high in vitro antioxidation capacity, especially when measured with the TEAC assay (224.81 µmol Trolox equivalent 100g-1 d.w.). This is due especially to the high amount of lycopene remaining in the by-product after processing (446.9 µg.g-1 d.w). The waste was fractioned into skin and seed fractions by sedimentation, resulting in the increase of lycopene yield by 55%, when using skin fraction as the source material in place of the whole pomace. This by-product shows great potential for being used as a source of the ingredients of high nutritional value, especially dietary fibre and lycopene.

Sustainable approach for lycopene extraction from tomato processing by-product using hydrophobic eutectic solvents.

Lycopene, a non-polar antioxidant compound with important effects on human health and wide commercial applications, was extracted from tomato processing wastes using innovative hydrophobic eutectic mixtures (HEMs) replacing traditional organic solvents. HEMs were prepared using DL-menthol as hydrogen-bond acceptor (HBA) and lactic acid as hydrogen-bond donor (HBD), and the ultrasound-assisted extraction (UAE) was optimized using a Box-Behnken design to evaluate extraction conditions: extraction temperature (°C), molar ratio of eutectic mixture (moles HBA: mol HBD), solvent to sample ratio (volume to mass, mL/g), and extraction time (min), with lycopene extraction yield (µg/g d.w.) as the response variable. Optimization of parameters was performed using response surface methodology, and the optimized extraction conditions were determined to be 70 °C, 8:1 mol HBA/mol HBD, 120 mL/g solvent: sample, and 10 min. The experimental optimal yield was 1446.6 µg/g, in agreement with the predicted optimal yield, indicating the validity of the model. This new technique for lycopene extraction, using a HEM as extraction solvent in replacement of hazardous organic solvents, and tomato pomace as source material, represents a viable and more sustainable approach for obtaining a high value-added bioactive compound, and can contribute towards the development of greener extraction processes.