Plant extracts have been found to be effective in reducing microorganisms. This study evaluated antimicrobial activity of 12 plant extracts against Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes by using a disk diffusion assay, and Syzygium aromaticum (clove) showed the highest inhibitory effect. To investigate the efficacy of clove extract that inactivates pathogens on lettuce, inoculated lettuce with S. Typhimurium, E. coli O157:H7, and L. monocytogenes was treated with diluted clove extracts or distilled water for 0, 1, 3, 5, and 10 min. Clove extract treatment significantly reduced populations of the 3 tested pathogens from the surface of lettuce. Practical Application: This result indicated that clove extract is a useful antimicrobial agent to reduce the microbial level of foodborne pathogens on fresh lettuce. It also might be a natural antimicrobial for reducing or replacing chemical sanitizers in food preservation.
An improved method for the analysis of caffeine in foods by HPLC was validated by measuring several analytical parameters. The caffeine contents of 1202 products available from Korean markets were analysed. A consumption study was conducted by using data from the Korea National Health and Nutrition Examination Survey (KNHANES), 2010-12, to estimate the caffeine intakes of the Korean population. The mean intakes of caffeine from all sources in the general population and consumers were 67.8 and 102.6 mg day(-1) for all age groups, respectively. The 95th percentile intakes of the general population and consumers were 250.7 and 313.7 mg day(-1), respectively. In those aged 30-49 years, the caffeine intakes of the general population and consumers were highest at 25.5% (101.8 mg kg(-1) day(-1)) and 36.6% (0.9 mg kg(-1) day(-1)), respectively, compared with the maximum recommended daily intake (400 mg day(-1)) for adults. In the general population, the main contributors to the total caffeine intake were carbonated beverage for the younger age groups and coffee for the adults. These data provide a current perspective on caffeine intake in the Korean population.
A simple GC-MS method has been developed and validated for the direct determination of hexamethylenetetramine (HMT). The separation of HMT was performed using a MXT-1 column. The calibration curve was linear over the concentration range 0.1-25 μg/mL, with a good correlation coefficient ( =0.9996). The recoveries of HMT from foods spiked at 1, 5, and 10 μg/g ranged from 91.7% to 115.2%. Intra-day (=5) and inter-day (=5) precision were less than 7%. The limit of detection and the limit of quantification of the method were 0.05 and 0.15 μg/mL, respectively. The uncertainties associated with food matrix and calibration contributed most to the overall expanded uncertainty. The method validation data indicated that quantitative method could be applied to the direct determination of non-hydrolyzed HMT in foods.
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