Investigation of mycologic growth, aflatoxin production, and human neural processing associated with quality differences in dry-aged meat products

In the first portion of this program we set out to investigate how mold and toxin profiles of meat are impacted by dry-aging. Fungal growth can occur on meat products during the dry-aging process. Control of environmental conditions can minimize microbial growth, however there is still a lack of knowledge about potential mold growth and toxin production on dry-aged meats. Dry-aged meat samples (n=104) were collected from the carcass, samples were comprised of beef (n=77), pork (n=13), and lamb (n=14). Samples were aged for a period of 14, 21, or 28 d. Microbial samples were plated on Potato Dextrose Agar with tartaric acid (PDAta) before incubation at 25°C for 5-10 d and isolation. Unique mold colonies were sub-cultured on PDAta. Each isolated colony was PCR confirmed as mold, and was evaluated for aflatoxin presence using a quantitative ELISA test kit. Eighty-three mold isolates were observed on 58 dry-aged meat (n=50; 86.21%) and air (n=8; 13.79%) samples, there were also two colonies isolated from one non-aged meat sample. Mean total aflatoxin detected was found to be 0.6425, 0.518, and 4.524 ppb for aged samples of beef, pork, and lamb, respectively. There was no aflatoxin detected in non-aged samples. Furthermore, air samples from the aging environment exhibited mean detectable aflatoxin values of 2.119 ppb. Findings suggest that while mold growth may occur during dry-aging (P ≥ 0.05), aflatoxin production generated through dry-aging had a levels low incidence and were well below the levels allowed by the USDA and were not significantly different from non-aged product (P ≥ 0.05).

In the second portion of this program we wanted to take a closer look at how quality (specifically dry-aging treatment) of beef steaks impact functional connectivity in the human brain. Functional magnetic resonance imaging (fMRI) has been used to unveil how some foods and basic rewards are processed in the human brain. The study evaluated how resting state functional connectivity in regions of the human brain changed after differing qualities of beef steaks were consumed. Functional images of participants (n=8) were collected after eating high or low quality beef steak on separate days, after consumption a sensory ballot was administered to evaluate tenderness, juiciness, flavor, and overall liking. Imaging data showed that high quality steak samples resulted in greater functional connectivity to the striatum, medial orbitofrontal cortex, and insular cortex at various stages after consumption (P ≤ 0.05). Furthermore, high quality steaks elicited higher sensory ballot scores for each palatability trait (P ≤ 0.01). Together, these results suggest that resting state fMRI may be a useful tool for evaluating the neural process that follows positive sensory experiences such as the enjoyment of high quality beef steaks.