Title page for ETD etd-11072007-161927


Type of Document Master's Thesis
Author Truong, Vy Thuy
Author's Email Address vtruong@vt.edu
URN etd-11072007-161927
Title Effect of cinnamic acid-cyclodextrin inclusion complexes on populations of Escherichia coli O157:H7 and Salmonella enterica in fruit juices
Degree Master of Science
Department Food Science and Technology
Advisory Committee
Advisor Name Title
Williams, Robert C. Committee Chair
Boyer, Renee R. Committee Member
O'Keefe, Sean F. Committee Member
Keywords
  • Escherichia coli O157:H7
  • inclusion complex
  • cinnamic acid
  • cyclodextrin
  • fruit juices
  • Salmonella enterica
  • antimicrobial
Date of Defense 2007-10-30
Availability unrestricted
Abstract
Cinnamic acid (CA) is a naturally occurring organic acid that is found in some fruits and a number of spices. CA has antimicrobial activity against certain spoilage microorganisms and pathogenic bacteria. However, the acid is poorly soluble in water. Cyclodextrin molecules have a hydrophobic cavity that allows them to serve as a host for insoluble molecules in aqueous matrices. This study was conducted to determine if the aqueous solubility of cinnamic acid could be improved via complexation with α- or β-cyclodextrins, and if these complexes could be used to control bacterial pathogens in juices. Based upon phase solubility analysis, α-cyclodextrin was chosen as the host molecule for the remainder of this study. In complex with α-cyclodextrin, the solubility of cinnamic acid increased from approximately 400 mg/L to 3800 mg/L. Prepared cinnamic acid complexed with α-cyclodextrin was aseptically added (400 mg/L and 1000 mg/L) to orange juice inoculated with a Salmonella enterica (7 log CFU/mL) and apple cider inoculated with Escherichia coli O157:H7 (7 log CFU/mL). Cider and orange juice samples were extracted on day 0 and at 24 h intervals for seven days and spread plated onto Tryptic Soy Agar. Cinnamic acid was effective for reducing populations of both bacterial pathogens in juice. Populations of E. coli O157:H7 in the apple cider were significantly reduced after 7 days at 25.6 ± 0.42° C at concentrations of 400 mg/L (5-log CFU/mL reduction) and 1000 mg/L (6-log CFU/mL reduction) cyclodextrin-cinnamic acid. S. enterica counts were also reduced in orange juice at 4° C treated with 400 mg/L (2.7-log CFU/mL reduction) and 1000 mg/L (3.2-log CFU/mL reduction) complexed cinnamic acid. The much improved solubility of this compound provides food processors with greater flexibility in using cinnamic acid in their product formulations.
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