MARE - Marine and Environmental Sciences Centre

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Assessment of thermosonication as postharvest treatment applied on whole tomato fruits: optimization and validation

Publication . Pinheiro, Joaquina; Ganhão, Rui; Gonçalves, Elsa M.; Silva, Cristina L. M.

Tomatoes are a popular and rich fruit due to their nutritional and bioactive composition as vitamins, antioxidants, and phenolics contributing to the promotion of consumer health. For this reason, emerging postharvest technologies need to be evaluated to achieve the maintenance of sensorial and quality-related characteristics, like color and texture, while aiding to fruit decontamination. Optimization of thermosonication as postharvest treatments on whole, mature-green tomatoes (cv. “Zinac”) to improve quality (color, texture, total phenolic content, and weight loss) was performed by response surface methodology. Temperature (32–48 °C), treatment time (13–47 min), and storage period at 10 °C (1–15 days) at constant ultrasound frequency (45 kHz; 80% power level), were the independent variables. In general, thermosonication delayed tomato color changes while achieving total phenolic content increase and good overall quality. Three optimal thermosonication conditions were selected and validated (32 °C-13 min, 35 °C-20 min and 40 °C-30 min). The most suitable thermosonication condition that promoted a longer storage while keeping a high-quality standard was at 40 °C during 30 min. This study demonstrated that thermosonication provides an effective alternative methodology to guarantee tomato quality without significant change during the expected postharvest period.

2019Journal article

Open access

Sargassum muticum and Osmundea pinnatifida enzymatic extracts: chemical, structural, and cytotoxic characterization

Publication . Rodrigues, Dina; Costa-Pinto, Ana R.; Sousa, Sérgio; Vasconcelos, Marta W.; Pintado, Manuela M.; Pereira, Leonel; Rocha-Santos, Teresa A. P.; Costa, João P. da; Silva, Artur M. S.; Duarte, Armando C.; Gomes, Ana M. P.; Freitas, Ana C.

Seaweeds, which have been widely used for human consumption, are considered a potential source of biological compounds, where enzyme-assisted extraction can be an efficient method to obtain multifunctional extracts. Chemical characterization of Sargassum muticum and Osmundea pinnatifida extracts obtained by Alcalase and Viscozyme assisted extraction, respectively, showed an increment of macro/micro elements in comparison to the corresponding dry seaweeds, while the ratio of Na/K decreased in both extracts. Galactose, mannose, xylose, fucose, and glucuronic acid were the main monosaccharides (3.2–27.3 mg/glyophilized extract) present in variable molar ratios, whereas low free amino acids content and diversity (1.4–2.7 g/100gprotein) characterized both extracts. FTIR-ATR and 1H NMR spectra confirmed the presence of important polysaccharide structures in the extracts, namely fucoidans from S. muticum or agarans as sulfated polysaccharides from O. pinnatifida. No cytotoxicity against normal mammalian cells was observed from 0 to 4 mglyophilized extract/mL for both extracts. The comprehensive characterization of the composition and safety of these two extracts fulfils an important step towards their authorized application for nutritional and/or nutraceutical purposes.

2019Journal article

Open access