Browsing by Author "Zambrano, Yadira "

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    CuAu bimetallic plasmonic-enhanced catalysts supported on alginate biohydrogels
    (2022) Ramirez, Oscar; Bonardd, Sebastian; Saldias, Cesar; Zambrano, Yadira; Diaz Diaz, David; Leiva, Angel
    We describe the synthesis, characterization and catalytic properties of a series of hybrid materials composed of inorganic plasmonic mono-and bimetallic nanoparticles supported on organic bio-based hydrogel beads. The bimetallic materials showed a localized surface plasmon resonance in the visible region, with a maximum light absorption correlated to the metal composition of the alloyed systems. Thermogravimetric analysis revealed a total water content near to 90 % w/w, which was in good agreement with the free-volume calculated from mu CT scan reconstruction of lyophilized samples. Catalytic essays for the reduction of 4-nitrophenol demonstrated that alginate beads loaded with bimetallic nanoparticles exhibit a 5.4-fold higher apparent kinetic constant (k(app)) than its monometallic counterparts. Additionally, taking advantage of the plasmonic properties given by the nanoparticles is that the materials were tested as photocatalysts. The activity of the catalysts was enhanced by near 2.2 times higher in comparison with its performance in dark conditions.
  • Thumbnail Image
    Item
    Effect of Extrusion Temperature and Feed Moisture Content on the Microstructural Properties of Rice-Flour Pellets and Their Impact on the Expanded Product
    (2022) Zambrano, Yadira ; Contardo, Ingrid ; Moreno, María Carolina ; Bouchon, Pedro
    Extrusion can lead to an expanded product or to a slightly expanded pellet, known as a third-generation (3G) snack. In this case, expansion occurs subsequently, in an independent thermal device (e.g., oven), out of the extruded pellet. During both processes, several structural changes occur which are linked to processing conditions, including cooking temperature, screw speed, formulation, and initial moisture content. However, a clear relationship between processing variables and the structure of pellets and expanded products has not yet been identified. Accordingly, this work aimed to study the effect of extrusion temperature (110, 135, and 150 degrees C) and moisture content (27, 29, and 31%) in rice-flour pellets and their microwave expansion, through a microstructural approach using micro-CT. The results showed that the lowest moisture content (27%) and the highest extrusion temperature (150 degrees C) led to the highest pellet volume and the highest wall thickness, which in turn led to the highest expansion after microwave heating (50 s, 800 W). Interestingly, no significant differences were observed when analyzing the ratio between the volume of the expanded products and the volume of the pellet (~2.4) when using the different processing conditions.
  • No Thumbnail Available
    Item
    Understanding the physical breakdown and catechin bioaccessibility of third generation extruded snacks enriched with catechin using the human gastric simulator
    (2024) Zambrano, Yadira; Bornhorst, Gail M.; Bouchon, Pedro
    The nutritional quality of third-generation snacks prepared from rice flour by extrusion can be improved by the addition of polyphenols such as catechins, which are known to be more stable at high temperatures. However, the extrusion parameters can impact the breakdown and release of bioactive compounds and decrease the catechin bioaccessibility. Accordingly, this study investigated the impact of different extrusion parameters, including different extrusion temperatures (110, 135, and 150 degrees C) and moisture content prior to extrusion (27 and 31%), on the breakdown and bioaccessibility of catechin-enriched snacks during in vitro dynamic digestion using the Human Gastric Simulator (HGS). The extrusion parameters did not significantly impact most measured variables by themselves, indicating that within the tested ranges, any of the processing conditions could be used to produce a product with similar digestive behavior. However, the interaction of extrusion parameters (temperature and moisture content) played a significant role in the snack behavior during digestion. For example, the combination of 27% moisture content and 150 degrees C extrusion temperature had higher catechin bioaccessibility and higher starch hydrolysis than the other treatments. Overall, these findings suggest that the processing conditions of third generation snacks enriched with catechin can be optimized within certain ranges with limited modifications in the digestive properties.