Physical–chemical characterization and antioxidant properties of extruded products made from mixtures composed of corn grits and red potato flour (Oxalis tuberosa)

Some physicochemical characteristics and antioxidant activity of extrudates made from corn grits and red potato flour were evaluated. The inclusion of red potato flour altered values of water absorption index, water solubility index, expansion index and fracturability of extrudates. Color analysis of extrudates showed a reduction of luminosity from 44.37 ± 0.87 to 25.06 ± 1.74. Likewise, extrudates made with red potato flour at 100% presented higher content of total phenols compared to the control extrudates (0.44 ± 0.02 and 2.88 ± 0.03 mg GA/g dry sample, respectively); consequently, an increase in antioxidant capacity was observed using DPPH, ABTS and FRAP assays. The images obtained by fluorescence microscopy provided information on the protein content. The proximal chemical analysis indicated that extrudates substituted with red potato flour at 10% showed higher protein content (7.78 g/100 g), compared to T5. This study concludes that when adding red potato flour, is possible to develop extrudates with good physicochemical characteristics and antioxidant properties

Application of Ultrasound in a Closed System: Optimum Condition for Antioxidants Extraction of Blackberry (Rubus fructicosus) Residues

Blackberry processing generates up to 20% of residues composed mainly of peel, seeds and pulp that are abundant in flavonoids. The objective of this study was to optimize the ultrasound conditions, in a closed system, for antioxidants extraction, using the response surface methodology. Blackberry (Rubus fructicosus) residues were analyzed for total phenolics, total anthocyanins, and antioxidant activity by ABTS and DPPH. The selected independent variables were ultrasound amplitude (X1: 80%–90%) and extraction time (X2: 10–15 min), and results were compared with conventional extraction methods. The optimal conditions for antioxidants extraction were 91% amplitude for 15 min. The results for total phenolic content and anthocyanins and antioxidant activity by ABTS and DPPH were of 1201.23 mg gallic acid equivalent (GAE)/100 g dry weight basis (dw); 379.12 mg/100 g·dw; 6318.98 µmol Trolox equivalent (TE)/100 g·dw and 9617.22 µmol TE/100 g·dw, respectively. Compared to solvent extraction methods (water and ethanol), ultrasound achieved higher extraction of all compounds except for anthocyanins. The results obtained demonstrated that ultrasound is an alternative to improve extraction yield of antioxidants from fruit residues such as blackberry

Physicochemical characterization of nopal pads (Opuntia ficus indica) and dry vacuum nopal powders as a function of the maturation

This paper presents the physicochemical and nutrimental characterization of fresh nopal (Opuntia ficus indica, Redonda variety) and nopal powder produced at different stages of development. Nopal powder was obtained by dry vacuum technique using 10(2) Torr and low temperature (40 degrees C). The results showed that the nutrimental and mineral composition of nopal changes as a function of the maturation as follow: The ash content increases from 18.41 for nopalitos (60 g of weight) to 23.24% (nopal pads 200 g

Coal fly ash-based geopolymer spheres coated with amoxicillin and nanosilver for potential antibacterial applications

Geopolymers are emerging “green” materials for its low embodied energy and carbon footprint, and its potential to valorize wastes, such as coal fly ash. It is an inorganic cementitious material formed from the polymerization of aluminosilicates in an activating solution such as that of alkali hydroxides or silicates. Their superior mechanical properties, including heat and fire resistance make them an excellent material for diverse applications. Recent studies have also exploited the tunable open porosity and adsorbing properties of geopolymers. Our work thus explores the potential of porous geopolymer spheres for antibacterial applications. These spheres were synthesized using coal fly ash as the geopolymer precursor and the porous surface is coated with either amoxicillin or silver nanoparticles (AgNPs) adsorbed in the matrix. For the AgNP geopolymer spheres, SEM images show spherical nanostructures when using ascorbic acid as a reducing agent, while spherical, cubical, and wire structures were observed when reduced using NaBH4. Indication from UV-Vis results also suggests the gradual release of both amoxicillin and AgNPs in the solution from the functionalized geopolymer spheres. Using E. Coli as the test organism for a modified disk diffusion assay, both showed zones of inhibition against the bacteria. Further tests on antibacterial application of AgNP geopolymer spheres show their effectiveness to kill at least 95% of the E. coli in a water sample initially containing 105 cfu/mL in just 30 minutes. © 2019, Gadjah Mada University. All rights reserved