Degree Type

Dissertation

Date of Award

2016

Degree Name

Doctor of Philosophy

Department

Food Science and Human Nutrition

Major

Food Science and Technology

First Advisor

Aubrey Mendonca

Abstract

Natural antimicrobials from plant, animal, or microbial sources have the potential to increase food safety, improve shelf life and promote the idea of “natural foods.” The overall objective of this research was to evaluate the antimicrobial efficacy of cinnamaldehyde and geraniol against E. coli O157:H7 and Salmonella enterica. Growth inhibition of Salmonella enterica and Escherichia coli O157:H7 by cinnamaldehyde or geraniol used singly in brain heart infusion (BHI) broth (35 °C) was evaluated over a 24-hour period using a Bioscreen C Turbidometer (OD 600nm). Subsequently, selected concentrations of the antimicrobials were evaluated for their antimicrobial effectiveness in controlling growth of the pathogenic bacteria in carrot juice and a mixed berry juice at 4 ºC and 12 ºC. Concentrations of antimicrobials in the juices that performed well served as baselines for combining the antimicrobials with high pressure processing. In both juices, at both temperatures, no growth of the pathogens with our without cinnamaldehyde or geraniol was observed. Cinnamaldehyde (2.0 μl/ml) exerted the greatest bactericidal effect (~4-5 log CFU/ml reduction) against both pathogens in both juices throughout storage. When combined with High Pressure Processing (300-400 MPa), lower concentrations of cinnamaldehyde were able to be used to reduce both pathogens by greater than 5 log CFU/ml. Based on results of the present studies it is concluded that: i) Cinnamaldehyde has good potential for controlling the growth of foodborne pathogenic bacteria in refrigerated fruit and vegetable juice and ensuring the microbial safety of this potentially hazardous food product, ii) while Geraniol exhibits great antimicrobial properties, the aroma is too strong, even at low concentrations, and therefore is not suitable for juice applications, and iii) the combination of Cinnamaldehyde and HPP is far more effective for inhibiting growth of pathogens in fruit and vegetable juice than using cinnamaldehyde by itself.

Copyright Owner

David Kareem Manu

Language

en

File Format

application/pdf

File Size

160 pages

Included in

Food Science Commons

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