P1-198 Molecular Evaluation of Mold Growth and Aflatoxin Presence on Dry Aged Beef

Sunday, July 26, 2015
Exhibit Hall (Oregon Convention Center)
William Tapp III, Texas Tech University, Lubbock, TX
Keelyn Hanlon, Texas Tech University, Lubbock, TX
Kendra Nightingale, Texas Tech University, Lubbock, TX
Michael San Francisco, Texas Tech University, Lubbock, TX
Markus Miller, Texas Tech University, Lubbock, TX
Mindy Brashears, Texas Tech University, Lubbock, TX
Introduction: Dry aging beef is commonly used to enhance quality.  During dry aging there may be fungal growth.  There is a lack of knowledge about the mold profile and possible toxins produced during dry aging.  Strict control of environmental factors, including temperature and relative humidity, can minimize microbial growth.

Purpose: To evaluate the fungal characteristics of dry aged beef.  Our objectives were to 1) identify molds present on beef trim samples, and 2) determine the change in concentration of aflatoxin during aging.

Methods: Beef trim samples (n = 8) were taken from subprimals prior to and after aging.  The subprimals were dry aged for 21 days, with a relative humidity < 80%, at 1.7°C, approximately.  Trim samples were swabbed using pre-hydrated spongesicles, plated on Potato Dextrose Agar, and incubated at 25°C for 72 - 144 h. Aflatoxin presence for each isolated colony was analyzed using a quantitative ELISA, and sequenced for identification by 18S rDNA sequencing.  Sequences were assembled and proofread, and a BLAST search was performed in GenBank for identification.

Results: There was no mold or aflatoxin production for samples prior to aging (P < 0.05).   Sequence data identified mold isolates on dry aged samples as Cochliobolus sp. (n = 2), Cochliocolus sativus (n = 1), and Mucor racemosus (n = 2). Mean aflatoxin concentration of aged samples was 0.1875 ppb (P > 0.05), which was not significantly different from non-aged samples.

Significance: Production of molds that may cause spoilage or be pathogenic can occur during dry aging.  Aflatoxin production generated after dry aging was not significantly different from non-aged samples.  The current aflatoxin action level of the United States federal government is 20 ppb, which is vastly higher than the mean values in these products.  While molds were not isolated from each sample, the presence of mold and aflatoxin could still be a concern to public health.