Carlos E. Orrego

Encapsulation of antioxidant phenolic compounds extracted from spent coffee grounds by freeze-drying and spray-drying using different coating materials

Freeze-drying and spray-drying techniques were evaluated for encapsulation of phenolic compounds (PC) extracted from spent coffee grounds. Additionally, the use of maltodextrin, gum arabic and a mixture of these components (ratio 1:1) as wall material to retain the PC and preserve their antioxidant activity was also assessed. The contents of PC and flavonoids (FLA), as well as the antioxidant activity of the encapsulated samples were determined in order to verify the efficiency of each studied condition. Additional analyses for characterization of the samples were also performed. Both the technique and the coating material greatly influenced the encapsulation of antioxidant PC. The best results were achieved when PC were encapsulated by freeze-drying using maltodextrin as wall material. Under these conditions, the amount of PC and FLA retained in the encapsulated sample corresponded to 62% and 73%, respectively, and 73-86% of the antioxidant activity present in the original extract was preserved.

Chemical and sensory comparison of fresh and dried lulo (Solanum quitoense Lam.) fruit aroma

The odour-active volatile compounds of lulo fruit (Solanum quitoense Lam.) were isolated by solvent extraction followed by solvent-assisted flavour evaporation (SAFE). GC-O and GCMS analyses as well as quantitation by internal standard method showed that (Z)-3-hexenal, ethyl butanoate, 3-sulphanylhexyl acetate, and ethyl hexanoate were key aroma compounds in this fruit. Other odorants with relevance because their contribution (high OAVs) to the overall aroma were 4-hydroxy-2,5-dimethyl-3(2H)-furanone, methyl benzoate, (E)-2-hexenal, and hexanal. Lulo fruit pulp in presence of maltodextrin DE-20 was dried by using four different types of drying methods: hot air-drying (HD), spray drying (SD), lyophilisation (LD), and ultrasonic convective hot air-drying (HUD). LD sample exhibited the highest sensory rank (lulo-like) in comparison with fresh fruit pulp. Hot-air drying processes (HD and HUD) changed adversely the aroma of lulo fruit pulp.

Optimization of freezing parameters for freeze-drying mango (Mangifera indica L.) slices

ABSTRACT Today, there is an increasing trend toward consuming healthful food products, and dried fruits are one option for obtaining desirable nutrition in dehydrated products. Proper drying method selection is important for minimizing quality losses. Lyophilization (freeze-drying), a technique that removes water by sublimation at low temperature, can produce excellent dried products. Fast vacuum induction during freezing has been proposed as a way to control ice nucleation and to obtain enhanced lyophilized pharmaceutical products. However, this technique has not yet been applied to food freeze-drying. The aim of this work was to evaluate the effects of the freezing rate (0.4, 0.25, and 0.1°C/min), the minimum chamber pressure during vacuum-induced surface freezing (900, 700, and 500 mTorr) and the sample temperature at which the induced vacuum was applied (0, −2, and −4°C) on the total process time, final moisture content, rehydration capacity, total color difference, and total polyphenol content during the lyophilization of mango (Mangifera indica L.) slices. A Box–Behnken design with three factors at three levels was used to design the experiments, to generate the polynomial equations relating the dependent and independent variables, and to determine the optimal operational conditions. The results highlight the reduction of total process time (30%) at high freezing rates and the influence of the tested operating conditions on freeze-drying optimization. It was found that the optimal conditions that satisfy commercial quality goals were pressure between 500 and 650 mTorr, temperature between −2 and 0°C, and freezing rate values close to 0.4°C/min.

Effect of convective drying assisted by ultrasound on drying time and aroma of tamarillo and mango fruits

Healthy food consumption has increased the production of fruit based value-added products as a result of the awareness of their high contents of bio-active compounds like vitamins, minerals, dietary fiber and antioxidants. High moisture content in fruits can generate losses in post-harvest storage. The dehydration process based on water activity reduction, is an option for overcoming such losses. Regular hot air drying could affect negatively the quality properties of the fruit due to the long times at high temperature. Power ultrasound (US) application during the convective drying has been used as a new method to decrease drying time. The aim of this work was to evaluate the effect of the convective drying assisted by ultrasound on drying time and aroma losses of tamarillo (TS) and mango slices (MS). An experimental design was developed, showing the positive effect of ultrasound during convective drying process. Power ultrasound (20 kHz, 45 W) was applied during drying test at 50°C, applying 5 and 10 min...

Compuestos de Poliéster Reforzados con Fibra de Plátano/Banano (Musa paradisiaca) Modificada Químicamente. Comparación con Fibra de Vidrio y Fique (Furcraea andina)

Samples of composites were prepared using the hand lay-up technique with banana seudo-stem fibers (BSF), fique and glass, in a polyester matrix. The BSF was woven and analyzed untreated and chemically treated with acetic anhydride, epichlorohydrin, and their mixtures. The aim of this work was to characterize and compare the composites obtained using tensile tests, impact test, water absorption capacity and micrographs. The average value of tensile strength for the composite with treated BSF increased respect to untreated BSF and fique. Also, according to the water absorption tests, they showed the smallest weight increase. This finding was attributed to the higher hydrophobicity of the treated BSF. This in turn improved the adhesion with the matrix, as it was corroborated by the micrographs that showed lower displacement on the tensile fracture surfaces.