Ultrasound-assisted hydrolysis of sugarcane bagasse using cellulolytic enzymes by direct and indirect sonication

Hydrolysis of macauba kernel oil: ultrasound application in the substrates pre-emulsion step and effect of the process variables

The main goal of the present work was to evaluate the application of ultrasound as a previous step to promote the substrates pre-emulsion in the hydrolysis reaction of macauba kernel oil (MKO). The ultrasound effect on the substrates pre-emulsion was evaluated on the free fatty acid (FFA) content, as well as the process variables (reaction time, percentage of catalyst Lipozyme® RM IM, and buffer solution). Reactions carried out with the substrates pre-emulsion presented higher FFA production, up to a 40 wt% increase in 1 hour of reaction, yielding 80 wt% of FFAs in 8 hours. The use of catalyst in the reaction medium, from 5 to 15 wt%, favored the FFAs production in 2 hours of reaction. Addition of 25 to 100 wt% of buffer solution led to 86 wt% of FFAs in 4 hours of reaction. Enzyme recycling resulted in a slight decrease in the FFA content, although the catalyst had maintained 85% of its initial activity after 30 h of use. Therefore, the ultrasound pre-emulsion previous step allowed a more efficient hydrolysis reaction of MKO, leading to an increase of up to 40 wt% on the FFA content, when compared to the hydrolysis without such step.

Changes in structure and antioxidant activity of β-lactoglobulin by ultrasound and enzymatic treatment

Effects of ultrasound (20-40% amplitudes at 45-55 °C) and enzymatic (pepsin and trypsin) treatment on structure and antioxidant activity of β-lactoglobulin were studied. Changes in structure of β-lactoglobulin were investigated using spectroscopy techniques and changes in antioxidant activity were measured by chemical and cellular-based assays. Ultrasound treatment had considerable impact on the structure of β-lactoglobulin and increased the susceptibility of β-lactoglobulin to both pepsin and trypsin proteolysis. Intrinsic fluorescence intensity of β-lactoglobulin was increased by ultrasound and then decreased after following enzymatic treatment. Compared with control, the β-lactoglobulin after ultrasound and enzymatic treatments showed significantly higher oxygen scavenging activities in Caco-2 cells models, ABTS (2, 2'-Azinobis-3-ethylbenzthiazoline-6-sulphonate) radical scavenging activity and oxygen radical absorbance capacity (p < 0.05). Results indicated that ultrasound treatment increased the proteolysis of β-lactoglobulin by both pepsin and trypsin and improved the antioxidant activity of the protein and its proteolytic products.