Use of Cold Plasma To Inactivate Escherichia coli and Physicochemical Evaluation in Pumpkin Puree.

This work aimed to study the pumpkin puree processing by cold plasma corona discharge as an alternative to heat treatment to reduce Escherichia coli contamination and evaluate physicochemical alterations, using argon (Ar) as the process gas. The treatment time to verify E. coli inactivation was between 2 and 20 min, while physicochemical alterations were analyzed at 5, 10, 15, and 20 min. Cold plasma corona discharge technology to inactivate E. coli proved to be promising, reaching 3.62 log cycles of reduction at 20 min of treatment. The inactivation kinectics showed a tendency of higher decrease with time. Physicochemical characteristics indicate that plasma induces a decrease of pH; however, there is an indication that process gases have an important role and react with the environment and procedure reactive species. This technology may reduce the total carotenoid content of pumpkin puree and in color, mainly the a* parameter, which showed great reduction.

Effects of gamma radiation on maize samples contaminated with Fusarium verticillioides.

The efficacy of gamma-irradiation as a method of decontamination of maize containing Fusarium verticillioides under controlled conditions of relative humidity (RH) (97.5%) and water activity has been studied. Maize grains inoculated with a spore suspension of F. verticillioides were irradiated to 2, 5, and 10 kGy. Thereafter, the irradiated and control samples were analyzed for the presence of fumonisins, their viable cells were counted, and their morphology was investigated by electronic microscopy. It was found possible to decrease the risk of exposure to fumonisins by irradiating maize to 5 or 10 kGy. However, at the dose of 2 kGy, the survived fungi (36%) can produce more fumonisins than the fungi in the control unirradiated samples under the same conditions.