BACKGROUND An interesting approach to improve dried foods nutritional properties, functionality, and sensorial attributes, is by taking advantage of pre-treatments for incorporating components into the food matrix. Based on this, this work studied the incorporation of black carrot anthocyanins in apple tissue by using ethanol (concentrations 0-300 mL L-1) as a pre-treatment to ultrasound-assisted convective drying. Samples were pre-treated in acidified ethanol solutions, with and without anthocyanins, and then dried (50 degrees C, 1 m s(-1)) by convective and ultrasound-assisted convective (21.77 kHz, 20.5 kW m(-3)) drying. Both the drying process improvement and the obtained product properties were studied. RESULTS The anthocyanins did not influence the drying kinetics. In contrast, time reduction was > 50% by using both ethanol pre-treatments and ultrasound. Ethanol pre-treatments decr...

This work studied three emerging approaches to improve the convective drying (50 °C, 0.8 m/s) of celery. Celery slices of 2 mm thick were pretreated for 5 min using ultrasound (32 W/L, 40 kHz), vacuum (75 kPa vacuum pressure) and ethanol (99.8% v/v, as drying accelerator) applied individually or in combination. To evaluate individual effects of ultrasound and vacuum, the treatments were also performed with distilled water or air medium, respectively. Moreover, the cavitational level was characterized in each condition. Drying kinetics was evaluated tending into account the drying time required by each treatment and the Page’s model parameters. In addition, microstructural effects and shrinkage were evaluated. As results, ethanol combined with ultrasound significantly improved drying kinetics reducing drying time by around 38%. However, vacuum pretreatment did not affect drying kinetic...

ABSTRACT Different drying accelerators were studied to improve vegetable drying: acetone (AC), ethanol (ET), isopropanol (ISO) and acetic acid (AA). Pre-treatments were performed by immersion of pumpkin cylinders. Convective drying was performed at 40 °C and air velocity 1 m/s. Different aspects were evaluated: drying kinetics, structural changes (microstructure and macrostructure), thermal profile and viscoelastic and rehydration behaviours. The microstructure was modified by pre-treatments, being more pronounced with AC and AA. Thinner cell walls, changes on turgor and extraction of components and air were reported, affecting the mass transfer. Moreover, the microstructural changes reinforced anisotropy and also affected the macrostructure, changing the viscoelastic behaviour. All pre-treatments resulted in a super-diffusive behaviour, decreasing the drying time from 9% (ISO) to 22% (...

Different drying accelerators were studied to improve vegetable drying: acetone (AC), ethanol (ET), isopropanol (ISO) and acetic acid (AA). Pre-treatments were performed by immersion of pumpkin cylinders. Convective drying was performed at 40 degrees C and air velocity 1 m/s. Different aspects were evaluated: drying kinetics, structural changes (microstructure and macrostructure), thermal profile and viscoelastic and rehydration behaviours. The microstructure was modified by pre-treatments, being more pronounced with AC and AA. Thinner cell walls, changes on turgor and extraction of components and air were reported, affecting the mass transfer. Moreover, the microstructural changes reinforced anisotropy and also affected the macrostructure, changing the viscoelastic behaviour. All pre-treatments resulted in a super-diffusive behaviour, decreasing the drying time from 9% (ISO) to 22% (AC)...

ABSTRACT The residues from agricultural and agroindustrial activities are not adequately valorised and at best they are destined for animal consumption or else they are inadequately disposed of. The objective of the present work was to estimate and highlight the energy (calorific and electric) potential of second-generation bioethanol production using lignocellulosic waste from the most important crops in Peru. In addition, the reduction of CO2 emissions by using bioethanol produced from those lignocellulosic wastes was estimated. The biomass considered in this study was from the harvest and processing of sugarcane, rice, banana, yellow corn, oil palm and asparagus. It was determined that the annual lignocellulosic biomass availability was ~22 million tons, from which, 33.03% correspond to banana waste, 28.56% correspond to sugarcane waste. The potential of bioethanol production and ener...

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This work aimed to evaluate how cut orientation affects mass transfer during the drying and rehydration process. Sweet potato cylinders of 1.90 cm of diameter and 0.50 cm of height were prepared. Three cut orientations were carried out regarding the vascular tissue orientation, preparing longitudinal, transverse and oblique (45°) cuts. In addition, osmotic pretreatment (50°Brix sucrose solution) was also evaluated. Convective drying and rehydration kinetics were evaluated at a constant temperature. As results, cut orientation and osmotic pretreatment did not affect the drying kinetics. However, transverse cut without osmotic pretreatment presented less shrinkage than the other cut orientations. On the other hand, rehydration process was affected by cut orientation, being longitudinal cut the slowest sample absorbing water. In conclusion, both the cut orientation and osmotic dehydra...

ABSTRACT Freezing (-20 °C, 12h) and alkaline (NaOH 8%) pretreatments were applied individually and combined in rice husk (Oryza sativa L.) before their hydrolysis with cellulase (EC: 3.2.1.4.). The effects on structural modifications, lignin content, cellulose, hemicellulose content and glucose production were evaluated. In addition, the glucose production kinetics were described by using the Peleg model. The homogenous rice husk (1 g) with and without pretreatments was hydrolysed with 150 U of Cellulase in 10 ml of acetate for 60 h (37 °C, pH 5.5, 100 rpm). As results, the SEM images evidenced porous microstructures with less agglomeration generated by all pre-treatments, which were intensified by the combined pretreatment. This pre-treatment allowed to obtain higher cellulose (62.51 ± 0.3 %) content. Besides, the glucose content after pretreatments increased. The Peleg model paramet...

ABSTRACT Abstract– The use of edible coverage represents one of the important methods used to preserve the quality of minimally processed products. The aim of this research was to determine the effect of chitosan and essential cinnamon oil coverage in the phenolic content, antioxidant capacity, mould and yeast count, and general acceptability in minimally processed strawberry along 16 days of refrigerated storage at 10 °C, in order to improve the conservation and characteristics of minimally processed strawberry var. aroma. In this experiment a response surface methodology using a Central Composite Rotational Design (CCRD) was carried out; the variable ranges used were 0.7 – 2% (Chitosan) and 0.02 – 0.1% (cinnamon essential oil). As results, it was found that the significant variable (p<0.05) was cinnamon essential oil for both phenols content and antioxidant capacity. For these c...

ABSTRACT This work evaluated the influence of the concentration of NaOH (100, 200 and 300 g/L NaOH) in the mercerization process at 25 °C for 1 h, and of the percentage (15, 20 and 25% m/m) of Mauritia flexuosa fibers on impact resistance in a polyester matrix composite. The polyester matrix composite was obtained by the compression molding process, at a constant pressure of 24 MPa. The obtained plates had a dimension of 130 mm long x 80 mm wide x 3.4 mm thick. Specimens for the impact assay were extracted from the obtained plates under the EN ISO 179-1 standard. Likewise, the fiber-reinforced composites without treatment were also evaluated, all the fibers were characterized before and after the NaOH treatment by means of the chemical characterization of the fiber, absorption percentage, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy ( FT-IR). The result...