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Master of Science (M.S.)
Year Degree Awarded
Month Degree Awarded
Activated carbon, β-cyclodextrin, ground beef, PCR, Salmonella
Foods contaminated with pathogens are common sources of illness. Currently the most common and sensitive rapid detection methods involve the PCR. However, food matrices are complex and limit the sensitivity and thus detection limits. The use of coated activated carbon can effectively facilitate the removal of PCR inhibitors while not binding targeted bacterial cells from food samples. With activated carbon coated with the optimal amount of milk proteins a cell recovery at pH 7.0 of 95.7 ± 2.0% was obtained, compared to control uncoated activated carbon, which yielded a cell recovery of only 1.1 ± 0.8%. In addition, the milk protein coated activated carbon (MP-CAC) was able to absorb similar amounts of soluble compounds as uncoated activated carbon with the exception of bovine hemoglobin. This is evidence that the use of milk proteins to coat activated carbon should therefore serve as a suitable replacement for bentonite in the coating of activated carbon, which has previously been used for the removal of PCR inhibitors from food.
The high amount of PCR inhibitors present in ground beef is a major factor that affects molecular based techniques such as the PCR for the detection of Salmonella enterica. In this study, a novel detection system was developed for eliminating PCR inhibitors and increasing the recovery of S. enterica in ground beef samples with the use of β-cyclodextrin and MP-CAC without enrichment of samples. invA, present in all Salmonella, was used as target the gene in the conventional PCR protocol. With ground beef containing 7.0, 15, and 27 % fat, treatment of stomached samples with 5.0, 10, and 15 % β-cyclodextrin respectively followed by treatment with MP-CAC, resulted in detection of 3 CFU/g which is equivalent to 75 CFU in 25 g samples. The total assay time was 4.5 hr. The methodology described in this study for the detection of S. enterica in ground beef without enrichment is rapid, sensitive, and has the potential to be applied to a number of food matrices to detect low numbers of food-borne bacterial pathogens before product is shipped to prevent costly recalls.
Robert E Levin