Background 

The food service industry relies heavily on the utilization of anaerobic packing systems (vacuum rollstock packaging) due to its ability maintain freshness and quality during distribution and storage. These products are typically stored in darkness for lengthy periods of time. Similarly, the retail segment of the industry has shown an increase in the use of anaerobic packaging. In contrast to food service, fresh meat products in retail are exposed to lighting sources which may alter flavor development over time. Fresh meat products are exposed to either light-emitting diode (LED) or fluorescent bulbs through the duration of retail display. There is very little data published evaluating the quality of individually packaged beef steaks in vacuum rollstock packaging during storage. Furthermore, little is understood regarding the impact of LED lighting on these products. The objectives of this study were: characterize the eating quality of individually vacuum rollstock packaged beef steaks intended for foodservice establishments, as well as retail displays under two lighting sources (fluorescent and LED). The quality was evaluated through the use of descriptive sensory analysis and cooked volatile flavor compounds.

Methodology 

For this study, USDA Low Choice quality grade (Small⁰⁰-Small¹⁰⁰ marbling score; A maturity) beef strip loins, tenderloins, and top sirloin butts (n = 48/subprimal) were collected separately for Objective 1 and 2 from a commercial processing facility. Subprimals were wet aged in vacuum packaging for 28 d for Objective 1 and 7 d for Objective 2 and fabricated into 2.54 cm steaks. Steaks were randomly assigned to a treatment determined by the project objective. Objective 1 subjected steaks to one of five aging treatments: 28, 35, 42, 49, and 56 d. Objective 2 randomly sorted steaks into one of two lighting treatments, LED or fluorescent, and further separated the assigned steaks into one of four display durations: 0, 2, 6, and 10 d. All fabricated steaks were packaged individually in vacuum rollstock packaging. Steaks in objective 1 were stored in the absence of light for the entirety of the assigned aging period. Following fabrication, steaks in Objective 2 were stored in the absence of light for an additional 7 d, then subjected to retail display in triple-decker retail cases under continuous fluorescent or LED lighting. Following the completion of an aging period or retail display, steaks were frozen at -20℃ until further analysis. 

Following cooking in electric rational ovens at 204 ˚C and 0% humidity to 71℃ internally, steaks from both objectives (n= 640) were evaluated by trained panelists for beef flavor identity, brown/roasted, bloody/serumy, earthy/musty, fat-like, fishy, liver-like, oxidized, umami, salty, bitter, sour, overall tenderness, and overall juiciness using a continuous 100 mm line scale. Each scale was anchored at each endpoint and midpoint (0 = extremely bland/extremely tough/extremely dry; 50 = neither tough nor tender/neither dry nor juicy; 100 = extremely intense/extremely tender/extremely juicy). 

In addition to trained descriptive panel evaluation, cooked steaks from both objectives (n = 640) were homogenized and subjected to volatile compound analysis. Targeted volatile compounds were selected from various flavor development pathways, including lipid degradation and the Maillard reaction.

Findings 

This research suggests long-term refrigerated storage of individually vacuum rollstock packaging has detrimental effects on attributes typically associated with positive beef flavor by inversely increasing negative flavors. Specifically, flavor shifts occurred at d 56 postmortem (Table 1). Likewise, individual steaks deteriorated in flavor at 10 d of display (Table 2). Additionally, this study determined display lighting had little impact on individually packaged vacuum rollstock beef steaks over 10 d of display. Presently it is unclear how lighting might influence beef steaks held under more permeable films. Multiple flavor related volatile compounds were also determined to be discriminating features between days of age and display duration.

Implications 

This study implies that individually packaged beef steaks in vacuum-type packaging may provide positive eating experiences to consumers at food service and retails settings. However, flavor does decline over time. Segments of the industry responsible for handling of individually vacuum packaged beef steaks should establish rigorous shelf-life expectations that consider flavor.