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United States Department of Agriculture

Agricultural Research Service

Title: Estimation of Spoilage Bacterial Load in Aerobically Stored Meat by Fluorescein Diacetate Hydrolysis and Resazurin Reduction

item Venkitanarayanan, Kumar - UNIV OF CONNECTICUT
item Faustman, Cameron - UNIV OF CONNECTICUT
item Hoagland, Terry - UNIV OF CONNECTICUT
item Berry, Bradford

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 28, 1996
Publication Date: N/A

Interpretive Summary: The determination of total bacteria counts in meat typically requires 48 hours for results. There is a need for rapid, accurate and inexpensive methods for estimating bacterial numbers, especially with the initiation of Hazard Analysis Critical Control Point Programs (HACCP). Several approaches with either non-meat foods or non-food items involving enzyme activity or transfer of electrons by bacteria have shown promise for determining bacterial numbers. Fluorescein diacetate hydrolysis (FDA-enzyme activity) and resazurin reduction time (RR-electron transfer) were monitored against aerobic bacterial counts on meat placed in retail packaging and stored at various temperatures. Both RR and FDA were found to accurately estimate bacterial loads of 100,000 organisms/square centimeter over a variety of storage temperatures in 3 to 5 hours. Thus, these methods would appear useful in providing rapid and accurate information for a microbiological monitoring program.

Technical Abstract: Resazurin reduction (RR), fluorescein diacetate hydrolysis (FDA), and aerobic plate count (APC) were monitored in aerobically-packaged beef steaks stored at 4 deg C. Throughout the experiment, FDA hydrolysis increased, while resazurin reduction time decreased with increased aerobic plate count of the samples. Linear regression performed between APC and RR, ,and APC and FDA revealed r-values of 0.94 (P < 0.001) and 0.92 (P < 0.001) respectively. RR and FDA hydrolysis were capable of estimating a bacterial load of 100,000 CFU/sq cm in approximately 5 to 5 hr. The results of this study indicated that RR and FDA could be used as rapid methods to estimate spoilage bacterial load in aerobically-stored meat.

Last Modified: 4/22/2015
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