Novel intervention technologies are needed to minimize pathogen contamination of fresh produce. The present study was undertaken to develop an in-package treatment system that combined aerosolized acetic acid (AA) and chlorine dioxide (ClO 2 )releasing film in which the acid triggered the release of ClO 2 from its precursor. A four-strain cocktail of Salmonella enterica (S. Montevideo, S. Typhimurium, S. Newport, and S. Saint-paul) was inoculated onto the surfaces of cut Romaine lettuce and the stem scars of cherry tomatoes. The inoculated samples were placed into clamshell containers containing one ClO 2 -releasing film (2.5 Â 2.5 cm). After the packages were sealed, AA (2 and 4%) was aerosolized for 60 s into the packages through perforated openings. Results demonstrated that the combination of AA with the ClO 2releasing film significantly reduced Salmonella populations with reductions of >4 log and >2 log CFU/piece on lettuce and tomato stem scars, respectively. The ClO 2releasing film or aerosolized AA alone did not result in any significant reductions of Salmonella populations except aerosolized 4% AA, which achieved 2.21 log CFU/piece reductions on lettuce. The combinations and 4% AA treatment caused damage to fresh-cut lettuce during 14 days of storage as evidenced by the deterioration in appearance, softening, and decreased ascorbic acid and antioxidant levels. The treatments did not significantly affect most of the quality attributes of cherry tomatoes during 21 days of storage at 10 C. Overall, our results demonstrate that the novel combination of AA and ClO 2 -releasing film may be used to enhance microbial safety and quality of cherry tomatoes.

Mesquite flour with endogenous high sugar content is often contaminated with Bacillus cereus.  The purpose of the present study was to evaluate the thermal resistance of Bacillus spp. in naturally contaminated mesquite flour. Flours with and without adjusted water activity (aw) were treated at various temperatures (100-140°C) and times (up to 2 h). Total mesophilic bacteria and Bacillus spp. were enumerated using tryptic soy agar and Brilliance Bacillus Cereus Agar media, respectively. Results revealed that naturally contaminated Bacillus spp. and other mesophilic bacteria in mesquite flour (aw=0.34) were highly resistant to heat. To reduce the initial populations (4.75 log CFU/g) of Bacillus spp. to non-detectable levels (<1.18 log CFU/g), thermal treatments of 120°C for 2 h were required. D100°C-values for total mesophilic bacteria were 5.6 fold higher than those of Bacillus spp. With increasing treatment temperature, the D-value between total mesophilic bacteria and B. cereus became smaller. When the aw of flour was adjusted from 0.34 to 0.71, the D-values for Bacillus decreased significantly.  Treatment at 100°C for 1 h reduced Bacillus spp. populations to nondetectable levels.  Our results demonstrate that naturally present Bacillus spp. in flour are highly resistant to heat, while increasing the aw increased their heat sensitivity.  The high thermal resistance of microbes in mesquite flour warrants further investigations.