Improving The Safety And Stability Of Acid, Acidified And Water Activity Controlled Foods Produced By Small-Scale Processors

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Products with pH below 4.6 or aw below 0.91 are typically processed by less severe thermal treatments due to the lower public health concerns associated with these products. However, thermal processes and acidification steps should be evaluated and optimized, in order to guarantee commercial sterility and shelf stability, as well as reduce energy consumption and processing time. The effects of brine acetic acid concentration and packing conditions on the acidification rate of hard-boiled eggs were evaluated. Mixed models were used to predict accumulated lethality values given process conditions and heating times of pickled carrots, processed using a water bath. Mixed models were also used to assess and model the effect of process conditions on accumulated lethality values measured on the underside of the lid and vacuum formation, during a hot-fill-hold operation. Finally, the thermal tolerance (D- and zvalues) and survival of S. enterica serovars Tennessee and Senftenberg were evaluated in milk caramel. Results demonstrated the importance of conducting acidification studies with proper pH measurements to determine safe conditions to manufacture commercially stable pickled eggs, produced satisfactory models (residual unexplained replicate-to-replicate variability of all constructed models was always < 3%) of the effects of process conditions on accumulated lethality values, and showed interactions between serovar, temperature and aw from the thermal inactivation studies of S. enterica. These results contribute to the establishment of science-based processing guidelines that ensure production of safe and stable products, with optimized processing temperatures and times, to enhance quality parameters of low pH and aw products.
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Acidification; Thermal processing; Water activity
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Union Local
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Padilla-Zakour, Olga I.
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Gomez, Miguel I.
Worobo, Randy W.
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Food Science and Technology
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Ph. D., Food Science and Technology
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Doctor of Philosophy
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Government Document
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dissertation or thesis
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