RESUMO

An in vitro digestibility protocol was used to elucidate the role of different emulsifying polysaccharides particles on the lipid digestion rate of oil-in-water Pickering emulsions. Emulsions stabilized by cellulose crystals (CCrys), cellulose nanofibers (CNFs), chitosan particles and a conventional emulsifier (Tween 80) were evaluated concerning microstructure, droplet size, zeta potential and free fatty acids released during digestion. After gastric step, the high positive charge of chitosan-stabilized emulsions favored the droplets disaggregation resulting in a mild effect of bridging flocculation by particles sharing and displacement of the size curve distribution toward lower size. After passing through the intestinal condition, these emulsions presented few droplets and chitosan aggregates with a monomodal size distribution and high mean droplet size (D4,3 = 197 ±â€¯8 µm). On the other hand, Tween 80, CCrys and CNFs were able to inhibit lipid digestion and no changes on mean droplet size were observed following intestinal step. CNFs-stabilized emulsion showed the lowest lipid digestion, whereas the strong adherence of the CCrys particles onto the droplet interface became them resistant to displacement by surface-active components (i.e. bile salts and lipase enzyme). On the other hand, a slow lipid hydrolysis could be observed in chitosan-stabilized emulsions promoted by competition between chitosan aggregates and intestinal fluids by the oil droplet interface. Studying the emulsions stabilized using different polysaccharides particles on gastrointestinal conditions we could elucidate important features for their potential application as control systems of lipid digestion rate, as well as, as delivery systems of lipophilic compounds.

Assuntos

RESUMO

Cellulose nanofibers (CNFs) from banana peels was evaluated as promising stabilizer for oil-in-water emulsions. CNFs were treated using ultrasound and high-pressure homogenizer. Changes on the size, crystallinity index and zeta potential of CNFs were associated with the intense effects of cavitation phenomenon and shear forces promoted by mechanical treatments. CNFs-stabilized emulsions were produced under the same process conditions as the particles. Coalescence phenomenon was observed in the emulsions produced using high-pressure homogenizer, whereas droplets flocculation occurred in emulsions processed by ultrasound. In the latter, coalescence stability was associated with effects of cavitation forces acting on the CNFs breakup. Thus, smaller droplets created during the ultrasonication process could be recovered by particles that acted as an effective barrier against droplets coalescence. Our results improved understanding about the relationship between the choice of emulsification process and their effects on the CNFs properties influencing the potential application of CNFs as a food emulsifier.

RESUMO

The aim of this study was to verify the viability of lignocellulosic substrates to obtain renewable energy source, through characterization of the cellulolytic complex, which was obtained by solid state fermentation using Trichoderma viride. Enzymatic activity of the cellulosic complex was measured during saccharification of substrates filter paper, eucalyptus sawdust, and corncob, and compared with the activity of commercial cellulase. The characterization of the enzymes was performed by a 2(2) Full Factorial Design, where the pH and temperature were the variables of study. Enzymatic saccharification of different substrates appearedviable until 12 to be viable until 12 h; after this period the activity decreased for both enzymatic forms (cellulolytic complex and commercial cellulase). The enzymatic activity of the commercial cellulase was favored with the use of corncob as substrate, while the cellulolytic complex does not show any difference in its specificity by the substrates studied. The largest activities of both enzymes were obtained in the temperature and pH range between 40°C and 50°C and 4.8 and 5.2, respectively. The cellulolytic complex obtained appeared to be viable for the saccharification of lignocellulosic residues compared with the commercial cellulase.

Assuntos