Browsing by Subject "lactic acid"
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Item Effects of Lactic Acid and Commercial Chilling Processes on Survival of Salmonella spp., Yersinia enterocolitica, and Campylobacter coli in Pork Variety Meats(2011-10-21) King, Amanda MardelleCurrent industry chilling practices with and without the application of 2 percent L-lactic acid were compared for their effectiveness at reducing levels of Salmonella, Yersinia enterocolitica, Campylobacter coli, and common indicator organisms used in industry (aerobic plate count APC, Escherichia coli, and coliforms) on pork variety meats. Pork livers, hearts, intestines, and stomachs were either inoculated individually with 1 of the 3 pathogens or not inoculated and subjected to 1 of 5 treatments: 1 (water wash + lactic acid spray + freeze), 2 (freeze), 3 (water wash + lactic acid spray + chill + freeze), 4 (chill + freeze), and 5 (water wash + freeze). Samples were analyzed between treatment steps and after 2 months, 4 months, and 6 months of frozen storage. Results of effects of the steps within treatments showed that reductions in levels of pathogens after the water wash and lactic acid spray were significantly different (P<0.05) across variety meats. Treatment of variety meats with water wash and lactic acid before chilling resulted in >/= 0.5 log CFU/sample (P<0.05) reductions when compared to chilling alone. Regardless of treatments, reductions in levels of Salmonella and Y. enterocolitica of 0.6-1.3 log CFU/sample were observed after freezing (0 degrees C) overnight. Freezing reduced C. coli by >/= 2.2 log CFU/sample regardless of previous treatment. Throughout 6 months of frozen storage, reductions were observed in levels of all microorganisms equal to or greater than 1.3 log CFU/sample. The greatest reductions were observed on samples treated with lactic acid (Treatments 1 and 3) (1.3-5.0 log CFU/sample) while the smallest reductions were reported for samples without any spray treatment (Treatments 2 and 4) (0.7-4.5 log CFU/sample). Large reductions were observed in levels of C. coli (2.9-5.0 log CFU/sample) for all treatments. The results of this study suggest that, while the application of a water wash followed by freezing reduced levels of pathogens by approximately 1 log CFU/sample, the application of lactic acid before chilling and freezing variety meats results in significantly larger (P<0.05) reductions in microorganisms. Results also show that aerobic plate counts, E. coli, and coliforms follow similar trends to the pathogens.Item The Influence of Equilibrium Reactions on the Kinetics of Calcite Dissolution in Lactic Acid Solutions(2014-08-07) Shedd, Daniel CMatrix acidizing has historically been a common means of removing formation damage and increasing the productivity of petroleum wells. Organic acids have been used in an effort to minimize the corrosion problem and the rapid reaction rate encountered when using strong acids, such as hydrochloric acid (HCl). The reaction of an organic acid with carbonates is reversible and thermodynamically limited by the presence of reaction products. This thermodynamic limitation must be considered when studying the reaction kinetics of organic acids with carbonates. A kinetic model was developed to account for both the equilibrium reactions on the rock surface and the mass transfer of the reactants and products. This study provides both mass transport and reaction kinetics parameters, which can be combined with the reservoir temperature to determine treatment duration or soaking time. While lactic acid has been used successfully in the field, having a more detailed knowledge of the reaction between lactic acid and calcite will allow for optimized treatment design. The kinetic model was also used to isolate the contributions of the transport of reactants, the surface reaction, and the transport of products to the overall resistance of the reaction. At all temperatures investigated, the transport of products away from the surface represented the largest contribution to overall resistance. A coreflood experiment was also performed to observe and confirm the wormholing tendencies of lactic acid in calcite. Lactic acid formed a single dominant, minimally-branched wormhole through the core.