Thymol nanoemulsions formed via spontaneous emulsification: Physical and antimicrobial properties.

In this work, we prepared various sub-micron thymol emulsions with high hydrophilic-lipophilic balance (HLB) surfactants via spontaneous emulsification. Emulsion properties, such as size, polydispersity and charge, were assessed for each surfactant type and mass fraction. Emulsion stability was characterized by monitoring droplet size following exposure to physical (centrifugation) and thermal stressors (freeze, thaw cycling). Emulsions were subsequently screened against several challenge pathogens to evaluate antimicrobial efficacy. Based on these time-kill assays, exemplary formulations were further tested as sanitizing washes on lettuce and blueberries inoculated with food-borne bacterial biofilms. Antimicrobial data elucidate both surfactant and formulation specific antagonisms between thymol and the emulsifying agents. However, the best emulsion compositions were capable of reducing planktonic bacteria by >4 logs and biofilm bacteria by 1.5-2.5 logs in 60 s. These results are comparable to the efficacy of chlorine at ∼50-200ppm. The experimental results have implications in emulsion formulations involving thymol and other terpenoids.

Quality and safety attributes of afghan raisins before and after processing.

Raisins are an important export commodity for Afghanistan; however, Afghan packers are unable to export to markets seeking high-quality products due to limited knowledge regarding their quality and safety. To evaluate this, Afghan raisin samples from pre-, semi-, and postprocessed raisins were obtained from a raisin packer in Kabul, Afghanistan. The raisins were analyzed and compared to U.S. standards for processed raisins. The samples tested did not meet U.S. industry standards for embedded sand and pieces of stem, total soluble solids, and titratable acidity. The Afghan raisins did meet or exceed U.S. Grade A standard for the number of cap-stems, percent damaged, crystallization levels, moisture content, and color. Following processing, the number of total aerobic bacteria, yeasts, molds, and total coliforms were within the acceptable limits. Although quality issues are present in the Afghan raisins, the process used to clean the raisins is suitable to maintain food safety standards.