Aims:  To study and compare the efficacy of organic acids and chlorine dipping in inactivation of Escherichia coli and Listeria monocytogenes on fresh‐cut iceberg lettuce. Methods and Results:  Fresh‐cut iceberg lettuce leaves were inoculated with E. coli or L. monocytogenes. After inoculation, samples were stored at 4°C for 24 h and dipped in organic acid or chlorine solutions for 2 and 5 min. E. coli and L. monocytogenes were enumerated on selective media. Treatment of fresh‐cut iceberg lettuce with chlorine solution caused 1·0 and 2·0 log10 CFU g−1 reductions in the number of L. monocytogenes and E. coli, respectively. Maximum reduction for E. coli (about 2·0 log10 CFU g−1) was obtained for samples dipped in lactic or citric acids while maximum reduction for L. monocytogenes (about 1·5 log10 CFU g−1) was attained for samples dipped in lactic acid. Conclusions:  Dipping of iceberg lettuce in 0·5% citric acid or 0·5% lactic acid solution for 2 min could be as effective as chlorine for reducing microbial populations on fresh‐cut iceberg lettuce. Significance and Impact of the Study:  Dipping in solutions containing organic acids is shown to be effective to reduce E. coli and L. monocytogenes on fresh‐cut iceberg lettuce.

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Lactic and citric acid and ozonated water dippings could be alternative treatments to chlorine dipping to prolong the shelf life of fresh-cut iceberg lettuce. Copyright © 2007 Society of Chemical Industry.

This study evaluated the efficiency of ozone for the degradation of aflatoxins in pistachio kernels and ground pistachios. Pistachios were contaminated with known concentrations of aflatoxin (AF) B 1 , B 2 , G 1 and G 2 . Pistachio samples were exposed to gaseous ozone in a chamber at 5.0, 7.0 and 9.0 mg L −1 ozone concentrations for 140 and 420 min at 20 • C and 70% RH. Aflatoxin degradation was determined by high performance liquid chromatography (HPLC). The efficiency of ozone for aflatoxin degradation in pistachios increased with increasing exposure time and ozone concentration. The results indicated that AFB 1 and total aflatoxins could be reduced by 23 and 24%, respectively, when pistachio kernels were ozonated at 9.0 mg L −1 ozone concentration for 420 min. Only a 5% reduction in AFB 1 and total aflatoxin levels could be achieved for ground pistachios under the same conditions. No significant changes occurred in pH, color, moisture content and free fatty acid values of pistachio kernels and ground pistachios. Fatty acid compositions of pistachios did not change significantly after the ozonation treatments. No significant changes were found between sweetness, rancidity, flavor, appearance and overall palatability of ozonated and non-ozonated pistachio kernels. Significant changes were observed in the organoleptic properties of ground pistachios, except rancidity, after 5.0 mg L −1 ozone treatment for 140 min. Ozonation was found to be more effective for degrading aflatoxins in pistachio kernels than ground pistachios.

This work investigated the improvement of ethanol production by engineered ethanologenic Escherichia coli to express the hemoglobin from the bacterium Vitreoscilla (VHb). Ethanologenic E. coli strain FBR5 and FBR5 transformed with the VHb gene in two constructs (strains TS3 and TS4) were grown in cheese whey (CW) medium at small and large scales, at both high and low aeration, or with whey powder (WP) or sugar beet molasses hydrolysate (SBMH) media at large scale and low aeration. Culture pH, cell growth, VHb levels, and ethanol production were evaluated after 48 h. VHb expression in TS3 and TS4 enhanced their ethanol production in CW (21-419%), in WP (17-362%), or in SBMH (48-118%) media. This work extends the findings that "VHb technology" may be useful for improving the production of ethanol from waste and byproducts of various sources.