Date of Graduation

5-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Food Science (PhD)

Degree Level

Graduate

Department

Food Science

Advisor

Navam S. Hettiarachchy

Committee Member

Steven C. Ricke

Second Committee Member

Ruben Morawicki

Third Committee Member

Michael F. Slavik

Fourth Committee Member

John A. Marcy

Fifth Committee Member

Edward E. Gbur

Abstract

Ready-to-eat meat (RTE) products such as hotdogs represent a popular segment in convenience food purchases. Increased demand has led the processors to extend the shelf life by minimizing lipid oxidation and post-processing contaminants such as Listeria monocytogenes. There is a growing interest in the food processors and consumers regarding the use of natural alternatives in place of synthetic food additives to control the growth of foodborne pathogens and (or) lipid oxidation. In recent years, green tea (GTE) and grape seed extracts (GSE) are increasing choices as they have demonstrated antioxidant as well as antimicrobial properties in various food applications. Therefore, the main objective of this research study is to reduce conventional chemical preservatives [potassium lactate (PL) and sodium diacetate (SD)] by natural plant extracts (GTE and GSE) along with nisin and EDTA combinations.

Optimal levels of GTE (0.3 %) and GSE (0.22 %) partially replaced PL (1.5 %) and SD (0.11 %) and demonstrated more growth inhibition (2.0 log cfu/g) of L. monocytogenes compared to commercial hotdog formulations (2.0 % PL and 0.11 % SD; 0.9 log cfu/g). Post-process heat treatment intervention inactivated L. monocytogenes in all the samples regardless of the chemicals, plant extracts alone and their combination at day zero. However, in chicken hotdogs, survivors were observed by day 12 and grew over time until spoilage (28 days). In hotdog samples without heat treatment, maximum growth inhibitions (approximately 2.0 log cfu/g) were observed in the treatments having combination of chemical preservatives and plant extracts. Addition of GTE and GSE inhibited the lipid oxidation (no detectable levels of hexanal) until the 6th week of storage (4 ° oC). Consumer panelists observed no significant differences (P > 0.05) in all sensory attributes except texture (P < 0.05; higher scores) in the hotdogs formulated with chemical preservatives and plant extracts that would improve consumer acceptability. Results from the study shows that GTE (0.35 %) and GSE (0.22 %) are potential natural alternatives that can partially replace conventionally used chemical preservatives without affecting physicochemical and sensory attributes of meat products while having positive impact on consumers by providing additional health benefits.

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