Changes in the mechanical properties of corn tortillas due to the addition of glycerol and salt and selective high pressure treatments

The effects of high pressure processing (HPP) at 500 and 800 MPa for 1 and 10 min, and the addition of glycerol (4% db) and salt (1% db) on the thermal and physical properties of corn tortillas were investigated. Instron analysis illustrated an increase in stiffness following processing at 800 MPa for 10 min as compared to the control. Glycerol and salt decreased the temperature range of the major peak transition characterized by Dynamic Mechanical Analysis and decreased the stress and strain of the tortillas (Instron), thereby suggesting a more homogeneous transition and an increase in softness of the product due to additive addition. Therefore, addition of glycerol and salt along with HPP at short hold times does not adversely effect the mechanical properties of the corn tortillas

Toxicity of Quantum Dots and Cadmium Salt to Caenorhabditis elegans after Multigenerational Exposure

To fully understand the biological and environmental impacts of nanomaterials requires studies that address both sublethal end points and multigenerational effects. Here, we use a nematode to examine these issues as they relate to exposure to two different types of quantum dots, core (CdSe) and coreﾖshell (CdSe/ZnS), and to compare the effect to those observed after cadmium salt exposures. The strong fluorescence of the coreﾖshell QDs allowed for the direct visualization of the materials in the digestive track within a few hours of exposure. Multiple end points, including both developmental and locomotive, were examined at QD exposures of low (10 mg/L Cd), medium (50 mg/L Cd), and high concentrations (100 mg/L Cd). While the coreﾖshell QDs showed no effect on fitness (lifespan, fertility, growth, and three parameters of motility behavior), the core QDs caused acute effects similar to those found for cadmium salts, suggesting that biological effects may be attributed to cadmium leaching from the more soluble QDs. Over multiple generations, we commonly found that for lower life-cycle exposures to core QDs the parents response was generally a poor predictor of the effects on progeny. At the highest concentrations, however, biological effects found for the first generation were commonly similar in magnitude to those found in future generations