SummaryIn this work, the antioxidant and antimicrobial activities of Brassica oleracea var. capitata extracts obtained through ultrasound-assisted extraction are evaluated. The extracts obtained using the best extraction conditions were subjected to diff erent hydrolysis conditions before their use in the biological tests. The crude and hydrolysed extracts were characterized using gas chromatography coupled with a mass detector. The use of ultrasound at 30 °C with 60 % (by volume) solvent enabled obtaining a richer extract. All extracts had antioxidant activities against DPPH (13.0-80.0 %), superoxide (35.2-63.2 %) and peroxyl (89.3-99.5 %) radicals, but the use of hydrolysed extracts considerably improved the antioxidant activities. Antimicrobial activities only of the hydrolysed extracts of Brassica oleracea var. capitata were detected. It was confi rmed that antioxidant activity of vegetable extracts can be considerably increased when hydrolysis is applied as a pretreatment to their extraction.
This study aimed to optimize ultrasound-assisted palm oil-in-water nanoemulsions. The influence of hydrophilic-lipophilic balance (HLB), oil and surfactants concentrations, ultrasound intensity and processing time were investigated by means of two experimental designs. Desirability profiles were applied to detect the optimal conditions for preparing the nanoemulsion. Stable nanoemulsions with small droplet size and polydispersity index (PDI) were obtained at an HLB of 6.5, oil and surfactant concentrations of 2.8 wt%, ultrasound intensity of 200 W.cm-2 and processing time of 15 minutes. The nanoemulsion presented stability for 30 days at three different temperatures (4°C, 25°C and 40°C), which makes it suitable for application in the food and cosmetic industries. Ultrasound was shown to be a promising technology to produce nanoemulsions containing palm oil.
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