Deconstruction of banana peel for carbohydrate fractionation.

The deconstruction of banana peel for carbohydrate recovery was performed by sequential treatment (acid, alkaline, and enzymatic). The pretreatment with citric acid promoted the extraction of pectin, resulting in a yield of 8%. In addition, xylose and XOS, 348.5 and 17.3 mg/g xylan, respectively, were also quantified in acidic liquor as a result of partial depolymerization of hemicellulose. The spent solid was pretreated with alkaline solution (NaOH or KOH) for delignification and release of residual carbohydrates from the hemicellulose. The yields of xylose and arabinose (225.2 and 174.0 mg/g hemicellulose) were approximately 40% higher in the pretreatment with KOH, while pretreatment with NaOH promoted higher delignification (67%), XOS yield (32.6 mg/g xylan), and preservation of cellulosic fraction. Finally, the spent alkaline solid, rich in cellulose (76%), was treated enzymatically to release glucose, reaching the final concentration of 28.2 g/L. The mass balance showed that through sequential treatment, 9.9 g of xylose, 0.5 g of XOS, and 8.2 g of glucose were obtained from 100 g of raw banana peels, representing 65.8% and 46.5% conversion of hemicellulose and cellulose, respectively. The study of the fractionation of carbohydrates in banana peel proved to be a useful tool for valorization, mainly of the hemicellulose fraction for the production of XOS and xylose with high value applications in the food industry.

Hydrothermal treatment on depolymerization of hemicellulose of mango seed shell for the production of xylooligosaccharides.

Hydrothermal processing is an interesting biorefinery technology for converting lignocellulosic biomass into biofuels and biocompounds. This process is based on the selective solubilization and depolymerization of hemicellulose fraction (xylan) and may be considered beneficial, due to the possibility of obtaining xylooligosaccharides (XOS) with a degree of polymerization (DP) suitable for prebiotic applications. This study evaluated the effect of pressure (2.5 and 10 MPa) in a kinetic study (30 min) of hydrothermal treatment (180 °C) to optimize the extraction of XOS from mango seed shell. Total reducing sugars (TRS) values were close to the maximum in 15 min showing a slower rate for both pressures after this time, but at 10 MPa the value was 20 % lower than at 2.5 MPa. Based on these results, a new extraction was performed at 2.5 MPa and 15 min, and the extracted XOS were quantified, yielding 393.44 mg XOS/g xylan. XOS with a degree of polymerization between X2-X6 corresponded to 82.24 mg/g and XOS with X > 6 (or soluble xylan) corresponded to 311.20 mg/g. A low amount of xylose (8.81 mg/g xylan) was released, resulting in a hemicellulose conversion of 40.2 %. In general, approximately 8.1 kg of total XOS was produced from 100 kg of dried mango seed shell (X2-X6-1.7 kg and X > 6-6.4 kg).

Encapsulation of eugenyl acetate in PHBV using SEDS technique and in vitro release evaluation.

Eugenyl acetate obtained via enzymatic esterification using Lipozyme TL IM enzyme was encapsulated in biopolymer poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) through solution-enhanced dispersion by supercritical fluids (SEDS). Produced particles were characterized by SEM and confocal microscopy techniques and in addition in vitro release assays were performed in isopropanol and ethyl acetate. Experimental micronization conditions comprised 8 and 10 MPa, 308 and 313 K and eugenyl acetate concentration ranging from 5 to 20 mg mL-1, keeping PHBV concentration constant (20 mg mL-1 in dichloromethane). The maximum encapsulation efficiency was 58.0 % for 5 mg mL-1of eugenyl acetate at 8 MPa and 308 K. The morphology of the encapsulated particles for most of the trials was spherical, with particle size ranging from 0.061 to 0.276 µm. Regarding the release in ethyl acetate and isopropanol solvents the higher the affinity of the encapsulated ester of these solvents, the faster the release was observed. These results demonstrate the importance of essential clove oil esterification reaction and encapsulation of the ester by SEDS method so that this encapsulated ester can be used in different industrial applications.

Lipozyme TL IM as Catalyst for the Synthesis of Eugenyl Acetate in Solvent-Free Acetylation.

The ability of commercial immobilized lipase from Thermomyces lanuginosus (Lipozyme TL IM) to catalyze the acetylation of essential clove oil with acetic anhydride in a solvent-free system was studied, and the antimicrobial activity of the ester formed was evaluated as well. Experimental design based on two variables (eugenol to acetic anhydride molar ratio and temperature) was employed to evaluate the experimental conditions of eugenyl acetate ester production. The maximum conversion yield (92.86 %) was obtained using Lipozyme TL IM (5 wt%, based on the total amount of substrates), with eugenol to acetic anhydride molar ratio of 1:5 at 70 °C. The chemical structure of the eugenyl acetate ester obtained at the optimized condition, and purified, was confirmed by the proton nuclear magnetic resonance ((1)H-NMR) analysis. The antimicrobial activity of eugenyl acetate ester was proven effective on Gram-positive and Gram-negative bacteria, with means of 16.62 and 17.55 mm of inhibition halo.