Optimization and characterization of taro starch, nisin, and sodium alginate-based biodegradable films: antimicrobial effect in chicken meat.

Biodegradable films based on polymers from renewable resources have become a feasible technology to preserve the quality (texture, color, flavor) and safety of food. The addition of antimicrobial agents to films can prevent the growth of pathogenic microorganisms that affect meat and poultry products. In this study, a biodegradable film with sodium alginate (SA), taro starch (MS), and nisin (Nis) was optimized to have high tensile strength (TS), breaking force (BF), and a low water vapor permeability (WVP) using a Box-Behnken response surface design, and its antimicrobial effect was evaluated in relation to its use as a packaging material for chicken meat. The OB was characterized via analysis of its mechanical, physical, and chemical properties; in addition, the total migration of Nis was also analyzed, along with its retention ability, the kinetics of the release of Nis into food simulants, and its antimicrobial activity against Listeria monocytogenes in vitro and on inoculated chicken meat. The resulting optimal OB was produced with 1.9% MS, 1% glycerol (G), and 2,369 IU/mL of Nis, and displayed adequate TS and WVP. The OB significantly reduced the microbial load and helped extend the shelf life of the chicken meat under refrigeration by up to 15 d. Total migration and the kinetics of the release of Nis showed that the OB can be used on hydrophilic and acidic foods, making it a natural alternative for use in food packaging.

Short-Term Effects of Atmospheric Pollution on Daily Mortality and Their Modification by Increased Temperatures Associated with a Climatic Change Scenario in Northern Mexico.

Short-term effects of air pollution on the health of residents in the Metropolitan Area of Monterrey, Mexico were assessed from 2012-2015 using a time-series approach. Guadalupe had the highest mean concentrations for SO2, CO and O3; whereas Santa Catarina showed the highest NO2 concentrations. Escobedo and Garcia registered the highest levels for PM10. Only PM10 and O3 exceeded the maximum permissible values established in the Mexican official standards. Most of pollutants and municipalities showed a great number of associations between an increase of 10% in their current concentrations and mortality, especially for people >60 years. Different scenarios resulting from climatic change were built (increases of 5-25% in daily mean temperature), but only the increase of 25% (5 °C) showed a significant association with air pollutant concentrations and mortality. All pollutants and municipalities showed significant increases in relative risk indexes (RRI) resulting from an increase of 5 °C when people >60 years was considered. Results were comparable to those reported by other authors around the world. The RRI were low but significant, and thus are of public concern. This study demonstrated that the elderly is strongly threatened not only by atmospheric pollution but also by climatic change scenarios in warm and semiarid places.