Methanol detection in commercial sanitizing gels, during the COVID-19 Pandemic

The ethanol (active) and methanol (toxic) substances content were quantified for commercial sanitizing gels. The health emergency caused by the COVID-19 epidemic has motivated to production of sanitizing gels to cover higher demand. The analytical composition of 24 commercial gels is reported (15 produced by national and transnational companies, and 9 collected gels which were in use at public areas). From the results it was found, that only one brand of 15 gels meets the quality requirements regarding 70% (wt./wt.) of ethanol content. Concerning to the collected gels, none of them contains the minimum active compound required. The non-compliance of this requirement means that these gels present its sanitizing action diminished. A striking result is that 25% of commercially packaged gels contain methanol - a toxic substance - in alarming amounts, hundreds of times more than the FDA upper limits requirement. DOI: https://doi.org/10.54167/tecnociencia.v15i1.76

Low-cost and novel Arduino®-Load cell-based prototype to determine transition temperatures

Abstract The polymer transition temperature is a crucial parameter in the industry for knowing raw materials before starting the manufacturing process. The current work reports a novel low-cost prototype instrument to measure the transition temperature with reliable accuracy. The equipment was built using commercial load cells composed of strain gauges in combination with an Arduino® microcontroller. The prototype measurement quality was validated by measuring the transition temperatures of most commercial polymers. The obtained values were compared with values obtained by conventional thermal analysis known as differential scanning calorimetric and thermo-mechanical analysis (DSC and TMA), which results in identical values

Physicochemical Changes and Resistant-Starch Content of Extruded Cornstarch with and without Storage at Refrigerator Temperatures

Effects of extrusion cooking and low-temperature storage on the physicochemical changes and resistant starch (RS) content in cornstarch were evaluated. The cornstarch was conditioned at 20%–40% moisture contents and extruded in the range 90–130 °C and at screw speeds in the range 200–360 rpm. The extrudates were stored at 4 °C for 120 h and then at room temperature. The water absorption, solubility index, RS content, viscoelastic, thermal, and microstructural properties of the extrudates were evaluated before and after storage. The extrusion temperature and moisture content significantly affected the physicochemical properties of the extrudates before and after storage. The RS content increased with increasing moisture content and extrusion temperature, and the viscoelastic and thermal properties showed related behaviors. Microscopic analysis showed that extrusion cooking damaged the native starch structure, producing gelatinization and retrogradation and forming RS. The starch containing 35% moisture and extruded at 120 °C and 320 rpm produced the most RS (1.13 g/100 g) after to storage at low temperature. Although the RS formation was low, the results suggest that extrusion cooking could be advantageous for RS production and application in the food industry since it is a pollution less, continuous process requiring only a short residence time

Elaboration and Characterization of Active Apple Starch Films Incorporated with Ellagic Acid

Apple starch films were obtained from apples harvested at 60, 70, 80 and 90 days after full bloom (DAFB). Mechanical properties and water vapor permeability (WVP) were evaluated. The apple starch films at 70 DAFB presented higher values in the variables of tensile strength (8.12 MPa), elastic modulus (3.10 MPa) and lower values of water vapor permeability (6.77 × 10−11 g m−1 s−1 Pa−1) than apple starch films from apples harvested at 60, 80 and 90 DAFB. Therefore, these films were chosen to continue the study incorporating ellagic acid (EA). The EA was added at three concentrations [0.02% (FILM-EA0.02%), 0.05% (FILM-EA0.05%) and 0.1% (FILM-EA0.1%) w/w] and compared with the apple starch films without EA (FILM-Control). The films were characterized by their physicochemical, optical, morphological and mechanical properties. Their thermal stability and antioxidant capacity were also evaluated. The FILM-Control and FILM-EA0.02% showed a uniform surface, while FILM-EA0.05% and FILM-EA0.1% showed a rough surface and insoluble EA particles. Compared to FILM-Control, EA modified the values of tensile strength, elasticity modulus and elongation at break. The antioxidant capacity increased as EA concentration did. EA incorporation allowed obtaining films with higher antioxidant capacity, capable of blocking UV light with better mechanical properties than film without EA