Date of Award

5-2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Food Technology

Committee Member

Julie K. Northcutt, Ph.D., Committee Chair

Committee Member

Paul L. Dawson, Ph.D.

Committee Member

Michelle A. Parisi, Ph.D., RD, LD

Committee Member

Thomas Dobbins, Ph.D.

Committee Member

Lance Beecher, Ph.D.

Abstract

The Centers for Disease Control and Prevention has reported that approximately 48 million people become sick from the consumption of food each year in the United States. Additionally, 46% of foodborne illnesses reported between 1998 and 2008 were contributed to the consumption of fresh produce. More specifically between 1996 and 2016, 41 foodborne illnesses have been reported from the consumption of sprouts. Sprouts are most often consumed raw, thus cooking is not used to prevent contamination from pathogens. The FDA Food Safety Modernization Act of 2011 has introduced new regulations for produce and sprout producers under produce safety standards. For sprout producers, these standards include: regulation of soil additives if used, health and hygiene of workers, packaging, temperature monitoring, animal control around produce and irrigation waters, decontamination of seeds before sprouting, testing of spent irrigation water for the presence of Salmonella and Escherichia coli (E. coli), environmental testing for Listeria monocytogenes and prevention of releasing sprouts that test positive for pathogens. Considering these regulations, foodborne illnesses continue to occur. The purpose of this study was to evaluate the microbiological and nutritional quality characteristics of alfalfa and mung bean sprouts grown in different water sources and treated post-harvest. Alfalfa and mung bean sprouts were selected because they are the types of sprouts most frequently consumed. Microbiological characteristics (total aerobic microorganisms, Enterobacteriaceae, total coliforms and yeasts and molds) were studied on alfalfa and mung bean sprouts that were grown in either municipal tap water or aquaponics water, harvested on day 7 and treated post-harvest with tap water, chlorine or organic acid. An additional partitioning study was conducted on alfalfa sprouts inoculated on day 1 or day 4 of growth with E. coli to determine the presence of unrecovered E. coli after sterilization and internalization of E. coli into the sprouts. Finally, due to the lack of previous research on the quality characteristics of sprouts, particularly those grown in nutrient-rich aquaponics water, alfalfa and mung bean sprouts were analyzed to determine if the water sources influenced their nutritional quality characteristics at the time of harvest. Under conditions of this study, the data showed that the microbial load of irrigation water could influence the microbial characteristics of harvested sprouts by increasing numbers of total aerobic microorganisms, Enterobacteriaceae, total coliforms and yeasts and molds on sprouts. Moreover, post-harvest washes did not prove effective in reducing numbers of microorganisms more than 1 log CFU/g (90%), which alludes to the presence of biofilms on sprouts that are not affected by antimicrobial treatments. Further results of the partitioning study revealed that sprouts have the potential to internalize pathogens, particularly if contamination occurs early in growth when the pathogens have access to the seed. The results of this study also led to the conclusion that the proximate composition of sprouts is not affected by irrigation water source, however, micronutrient composition of sprouts can be influenced by the micronutrient characteristics of irrigation water. Data demonstrates that alfalfa and mung bean sprouts grown under controlled conditions harbor large numbers of microorganisms (>9 log CFU/g) and neither irrigation water nor post-harvest antimicrobial treatments improve the microbiological or nutritional composition of treated sprouts.

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