Effect of cinnamic acid-cyclodextrin inclusion complexes on populations of Escherichia coli O157:H7 and Salmonella enterica in fruit juices

by Truong, Vy Thuy

Abstract (Summary)
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.
Bibliographical Information:

Advisor:Renee R. Boyer; Sean O''Keefe; Robert C. Williams

School:Virginia Polytechnic Institute and State University

School Location:USA - Virginia

Source Type:Master's Thesis

Keywords:food science and technology


Date of Publication:11/14/2007

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