BACKGROUND 

Ground beef comprises between 50 and 60% of the beef consumed in the United States and is manufactured from beef trimmings from either commodity, grain‐fed beef or lean trimmings from older, mature cows and bulls. Emerging restaurant concepts that focus on ground beef (Five Guys, Smash Burger, etc.) vary in ground beef formulation, grinding procedures and cooking methods. Flavor is incredibly important to the long‐term success of beef products and serves as the “guard rails” to beef quality. Research has shown that flavor is the most important factor affecting consumers’ buying habits and preferences when tenderness is held constant. Recent research conducted by Texas A&M University has shown that beef flavor is more closely related to overall consumer liking than beef tenderness and juiciness.

The objectives of this study were to determine the impact of final grind (chopped, 3/8 and 1/4 inch final grind), forming (hand and machine), fat/source content (20% and 5% lipid from commodity and mature beef), patty thickness (1/4 inch and 1 inch), cooking (steam and dry heat), and holding (steam table holding for 0, 1 and 3 hours) on ground beef patty descriptive flavor and texture attributes and aromatic volatile chemical compounds.

METHODOLOGY

Ground beef commodity raw material prior to grinding that was projected to be 20% and 5% lipid was obtained from a major, commercial beef processor (grain‐fed), and ground beef raw material was obtained from a major beef processor that harvests mature cows and bulls (mature). Raw material was obtained on three different processing days for each raw material source (grain‐fed and mature; 20 and 5% lipid) to represent three replicates. Grain‐fed beef and mature raw material for the two lipid levels (20 and 5%) within replicate were coarse ground (0.5 inch grind) and then segmented into three treatments: 1) chopped in a bowl chopper to approximately 1/4 inch grind; 2) final grind using a 3/8 inch grind plate; and 3) final grind using a ¼ inch grind plate. After grinding/chopping, patties were formed into 1 inch and 1/4 inch ground beef patties by either hand forming or machine forming into final patties. For sensory evaluation, patties were cooked using a dry heat cooking method (a flat solid surface heated to 350°F) and a steam cooking method (clam‐shell grill with a surface heat of 350°F) to an internal cook temperature endpoint of 70°F. Internal temperature was monitored and raw weight and cooked weight were obtained. Total cooking time was also determined. Patties (n=288; 4 meat sources x 3 grinds x 2 thickness x 2 forming x 2 cooking x 3 replicates) were served to two expert flavor and texture descriptive sensory panels trained to evaluate beef flavor using the Beef Flavor Lexicon and texture attributes (initial juiciness, sustained juiciness, hardness, springiness, cohesiveness of mass, and particle size). A subset of the aforementioned treatments (n=216; 2 thickness x 3 grinds x 2 sources x 2 cook methods x 3 replicates; 21 sensory days) were held for 0, 1 and 3 hours in a steam table set so that the internal environment of the steam table was 140°F. Sensory analysis was done as previously defined at the Sensory Analysis Center at Kansas State University. Volatiles per treatment were captured from the same patties evaluated by the panelists at Texas A&M University and Kansas State University (3 hour hold only) by placing ground beef wedges in heated glass jars with a Teflon septum in the lid. Volatiles were evaluated using the Aroma Trax gas chromatograph/mass spectrophotometer system with dual sniff ports for characterization of aromatics. Chemical lipid, moisture, and fatty acids were determined on the four meat source treatments in the raw state (n=12). 

FINDINGS

Beef identity and brown/roasted flavor aromatics were lowest in ground beef with 5% lipid, regardless of source (commodity or mature). Whereas, ground beef with 20% lipid tended to be highest in overall sweet, burnt, and buttery flavor aromatics. Commodity ground beef patties with 20% lipid were highest in fat‐like flavor and sweet basic tastes.

Commodity ground beef patties containing 5% lipid were highest in bloody/serumy. Mature ground beef patties containing 5% lipid were lowest in fat‐like and smoky/charcoal flavor, umami and sweet basic taste and highest in metallic, liver‐like, leathery, refrigerator/stale, sour milk, cardboard, warmed over, flavor, sour and bitter basic taste. Ground beef containing 20% lipid were juicier, had higher amounts of fat mouth coating, and tended to be springier and harder than ground beef patties that contained 5% lipid. Ground beef patties from mature lean with 5% lipid were the driest, had the lowest amount of fat mouth coating and were the hardest ground beef patties. Thinner ground beef patties (0.25 inch thick) had lower levels of beef identity, brown/roasted, bloody/serumy, fat‐like, metallic, burnt, buttery, and smoky/charcoal flavor aromatics, and umami and bitter basic tastes; and they had slightly higher levels of green hay‐like, refrigerator/stale, cardboard, and warmed over flavor than 1-inch-thick patties. Additionally, thin ground beef patties had slightly smaller particle size, were drier, had more cohesiveness of mass and were springier and harder than thick ground beef patties.

Forming method impacted ground beef patty flavor and texture attributes. Hand‐formed ground beef patties were higher in beef identity, brown/roasted, bloody/serumy, fat‐like, overall sweet, burnt, buttery, and smoky/charcoal flavor aromatics and umami, sweet, and sour basic tastes; and they were lower in green hay‐like, refrigerator/stale, cardboard, and warmed‐over flavor aromatics than machine formed ground beef patties. Hand –formed patties had larger particle size, were juicier, were less cohesiveness of mass, had less fat mouth coating, were less springy, and were softer than machine‐formed patties. Ground beef patties cooked using a flat grill were higher in beef identity, brown/ roasted, overall sweet, burnt, buttery, and smoky/charcoal flavor aromatics, and umami basic tastes; and they were lower in liver‐like, green hay‐like, leathery, refrigerator/stale, sour milk, cardboardy, warmed over and heated oil flavor aromatics, and sour and bitter basic tastes than patties cooked using a George Foreman grill.

Holding time affected flavor of ground beef patties. The major effect of holding was increased cardboard flavor as would be expected as increased levels of cardboardy flavor are due to increased lipid oxidation. Ground beef patties made from mature lean that was 5% lipid were associated with negative flavor attributes of bitter, liver‐like, metallic, barnyard favors and sour basic tastes; and they were harder with a more defined particle size.

IMPLICATIONS

Ground beef constitutes approximately 50 to 60% of the beef consumed in the U.S. Ground beef is sold extensively at retail and in the foodservice industry. One of the most recent trends in the foodservice industry is “premium ground beef concepts” where you can get the best burger in town. The industry has not examined the multiple factors that impact ground beef flavor despite knowing flavor is a key driver of consumer acceptability. This project was intended to extensively evaluate the effect of meat source (mature versus commodity grain fed), fat level (20 versus 5%), grind or chop method (chopping versus 2 grind sizes), patty thickness (1 versus 1/4 inch), formation (hand versus machine), cooking method (dry heat versus steam cooking), and holding time in a steam table (0, 1 or 3 hours) on the flavor and texture of ground beef.