REDUCTION OF BACTERIAL POPULATIONS BY SURFACE 

FLAMING IN BEEF TRIM UTILIZED FOR GROUND 

BEEF PATTIES IN FOOD SERVICE OPERATIONS 

William Benjy Mikel 

Chris Salamone 

Melissa Newman 
ABSTRACT 

Semitendinosus muscles from low quality, cull cows were trimmed, separated into three 

fat levels (10, 20, and 30%), treated with 0, 5, 10, 15, or 20 seconds of surface flame 

application, ground, and formed into patties. Patties were quick frozen (-80 C for 1 hr) and 

stored at -10 C for 0, 4 or 24 days. Hunter “L” and “b” values increased (P<.01) and Hunter “a” 

values decreased (P<.01) as flame time increased. Metmyoglobin and discoloration percentages 

increased (P<.05) as flame time increased. High fat patties (30%) had lower cook losses (P<.01) 

as flame time increased due to initial fat loss whereas low fat patties (10%) had constant cook 

losses. Water-holding-capacity increased (P<.05) at extreme flame time (20 secs) in all patties. 

Juiciness and tenderness scores were significantly decreased and flavor intensity increased in 

lean patties as flame time increased. Juiciness and tenderness scores in high fat patties were not 

affected but patties had lower cohesive scores as flame time increased. Aerobic, anaerobic, 

lactic acid producing, and psychrotrophic bacteria, within each fat level, decreased as flame time 

increased from 0 to 10, 15, or 20 secs. Temperature abused patties had significantly higher 

(P<.01) bacterial populations than original populations of control patties at each fat level. These 

data indicate surface flaming initially reduces bacterial populations and minimizes bacterial 

growth without adverse physical damage to the product. Unfortunately, this method of bacterial 

reduction is not as effective in patties which are temperature abused. 

Key words: beef, bacteria, heat, temperature 
3 

INTRODUCTION 

Bacteria, including those which can cause foodborne illnesses, are found naturally all 

around us and rely on nutrients such as those found in most foods to provide energy for their 

growth and survival. Foodborne illnesses can arise when pathogenic bacteria enter the body 

through the ingestion of food. Although foodborne illnesses have been traced to many types of 

foods, the more common carriers of foodborne pathogens are foods of animal origin. As much 

as 97% of foodborne illnesses are caused by mishandling at home or food service establishments 

(Bryan, 1982). However, if those products were not initially contaminated, bad handling 

practices would not create a hazard (Bjerklie and Stentz, 1996). 

Pathogens known to be transmitted by muscle foods include Escherichia coli, Salmonella, 

and Staphylococcus. Of these, E. Coli O157:H7 has emerged as the most noted due to it’s 

extreme virulence and highly publicized outbreaks. In addition to the public health significance 

of foodborne disease, huge monetary losses are incurred when foods are linked to human illness. 

 In 1992, it was estimated E. coli O157:H7 accounted for 7,668-20,448 of the cases of foodborne 

illnesses with an average cost of $3,360 per case (Anonymous, 1995). Given the importance of 

meat-borne bacteria to the overall quality and safety of meat products, methods which eliminate 

or reduce bacteria, including pathogens such as E. coli O157:H7, are of vital importance to the 

meat industry (Anonymous, 1994). Research in the production of ground beef, which accounts 

for nearly half of the beef consumed in the United States, must be targeted to allow processors to 

identify and utilize resources that currently exist within their facilities. Ideally any method 

should economically reduce microbial loads while not physically degrading the product. The 
4 

experiments in this study were designed to evaluate the capability of producing ground beef with 

lower microbial levels while causing little or no physical damage to the product at very little 

added expense. 

METHODS AND MATERIALS 

Overall Processing Procedure 

Semitendinosus muscles from low quality, cull cows (comparable to USDA Utility) were 

obtained from a local beef processor, vacuum sealed and transported to the Auburn University 

Lambert Meat Science Laboratory. Each muscle was appropriately trimmed and separated into 

three fat levels (10, 20, and 30%). Additional fat was added if necessary to achieve the 

appropriate fat level. Upon separation into fat treatments, the muscles were sliced into 1.27cm2 

strips, with the length of the strips determined by the width of the muscle. Equipment surfaces 

were sanitized using a dilute ethanol solution (70% v/v). Beef strips were weighed and equal 

amounts of each fat level were randomly assigned to one of five flame treatments (0, 5, 10, 15, 

20 sec) and placed on a stainless steel mesh belt, which allowed for simultaneous thermal 

treatment of beef strips at a distance of 6.35 cm between the meat and the flame heat source both 

dorsally and ventrally. 

Immediately after flame treatment, beef strips ground twice through a .32 cm grinding 

plate using a counter top grinder (Kitchen Aid Model #KSM90WH, St. Joseph, MO) and 

formed with a conventional hand pattie press into approximately 100 g patties. Patties were 

transferred onto stainless steel trays, quick frozen within 1 hr at -80 C and stored at -10 C until 
5 

further analysis at appropriate time periods. Storage periods consisted of 0, 4, and 24 days, 

respectively. At day 4 of storage a second set of samples was allowed to thaw at room 

temperature (~ 25 C) for approximately 6 hours to simulate possible temperature abuse and 

analyzed for microbial attributes. 

pH Determination 

Product pH was determined using 10 g of sample from each treatment group at the 

appropriate storage period that was mixed with 99 ml of deionized distilled water. The meat and 

water were mixed for approximately 30 seconds using a homogenizer (Pro 250 Homogenizer, 

Monroe, CT) and a pH meter (Extech Instruments Corporation, Waltham, MA) was used to 

determine the final product pH. 

Percent Metmyoglobin 

Metmyoglobin concentration was determined in triplicate at each storage period using the 

methods of Chen and Trout (1991). A 5 g sample was added to 50 ml of a 0.04M phosphate 

buffer (pH 6.8) and homogenized for 30 sec using a Pro250 Homogenizer (Monroe, CT). The 

homogenized sample was centrifuged for 30 min at 5 C (50,000 x g). The supernatant was 

filtered through Whatman No. 1 filter paper and analyzed with a spectrophotometer (PerkinElmer model #C688-0000 

Lambda 4 UV/VIS). The measurement of metmyoglobin was calculated using the following 

formula (Kryzwicki, 1979): 

Metmyoglobin % = (1.395 - ((572A - (730A*1.45))/(525A - (730A*1.73)))) x 100 
6 

Hunter Color and Visual Evaluation 

Objective product color was determined using three samples at each storage period by a 

Hunter Lab Color Difference meter (Hunter Labs D25 DP9000, Reston, VA). Values were 

obtained and recorded as Hunter color “L”, “a”, and “b” units. The color meter was allowed to 

warm up for 15 minutes and calibrated using both white and black tiles. 

A visual color evaluation was also conducted by a three member experienced panel. The 

panelist evaluated patties under normal retail lighting conditions prior to cooking to determine 

percent surface discoloration. 

Water Holding Capacity 

Water holding capacity was determined in triplicate for each treatment pattie according to 

the procedure of Hamm (1960) using a Carver Lab Press. The amount of free water was 

determined using the following formula: 

mg free water = (area in cm2

/ 0.0948) + 8.0 

Lipid Oxidation 

Triplicate samples were used for the analysis of 2-thiobarbituric acid reactive substances 

(TBARS) according to procedures described by Ke et al. (1984). 

Compositional Analysis 

Percent moisture, fat, and protein was determined in triplicates according to methods 

described by AOAC (1990). Randomly selected samples were taken from the three fat levels of 
7 

beef strips immediately after flame treatment. 

Microbiological Evaluation 

Aerobic-plate counts, psychrotrophic-plate counts, anaerobic-plate counts and 

lactobacilli-plate counts were determined at each storage period. At each sampling time, meat 

patties were removed from storage, thawed, and two 11 g samples were aseptically obtained 

from the centers of each pattie and placed into sterile plastic bags with 99 ml of Butterfield’s 

phosphate buffer. Each sample was homogenized in a stomacher (Model 400 Stomacher, 

Tekmar Company, Cincinnati, OH) for two minutes, serially diluted with Butterfield’s phosphate 

buffer and spiral plated (Model Du2 Spiral Plater, Spiral Systems, Besthesda, MD ). Aerobicplate counts (APC) and anaerobic-plate-counts were enumerated on plate count agar (PCA; 

Difco Laboratories, Detroit, MI) and incubated at 37 C for 24 hrs. Psychrotrophic-plate counts 

were determined on plate count agar incubated at 10 C for 7 days. Lactobacillus-plate counts 

were determined on MRSA (Lactobacilli de Man Rogosa Sharpe Agar, Difco Laboratories, 

Detroit, MI) broth with 2% added BactoAgar (Difco Laboratories, Detroit, MI) with plates 

incubated at 37 C for 24 hrs. After incubation, plates were counted with a laser bacteria colony 

counter (Model 500A, Spiral Systems Instruments, Bethesda, MD). Microbial data were 

expressed in log10 cfu/g of sample. 

Statistical Analysis 

This experiment was conducted as a 3x5 factorial arrangement in a split plot design with 

three replications per treatment. Fresh beef trim (semitendinosus) of 10, 20, and 30% fat was 
8 

randomly assigned to one of five flame treatments (0, 5, 10, 15, and 20 seconds). Storage 

periods utilized were 0, 4, and 24 days. Treatment means were separated by Student-NewmanKuels (SNK) after analysis by the GLM procedure (SAS Institute, 1988). When an interaction 

occurred between treatments, subclass means were separated by the Pdiff test (Steele and Torrie, 

1982). 

RESULTS AND DISCUSSIONS 

Sensory Evaluation 

There was no significant interaction (P<.05) between treatment and storage time for 

sensory attributes (Table 1). There were significant differences (P<.01) in juiciness, tenderness, 

off flavor, and cohesiveness between storage times. Flavor intensity was the only attribute 

which was not significantly different (P<.05) between storage time. Significant interaction 

differences were found for juiciness (P<.01), tenderness, off flavor, and cohesiveness scores 

(P<.05) between fat level and flame time. Juiciness scores were significantly higher in low fat 

patties at 0 flame versus patties at all other flame times which were not different (P<.05). As 

expected, patties with increased fat levels showed no differences between flame times (5.2- 5.6) 

except 20% fat patties treated for 15 secs which were significantly lower (4.9). Day 24 patties 

were significantly less juicy than patties at day 0 and 4. Tenderness was not affected at different 

flame times in 20 and 30% fat patties. However, lean patties (10%) showed decreased tenderness 

scores in higher flame patties with 10, 15, and 20 secs patties not being different. At day 0 

storage, patties were significantly more tender than day 4 and 24. Off flavor was not different at 
9 

extreme flame times compared to control patties. There were no significant differences (P<.05) 

between flame times within 20 and 30% fat patties. In low fat patties, day 24 products had 

significantly higher off flavor scores than day 0 and 4 products. Flavor intensity scores were 

only significant (P<.05) between fat levels. Lean patties (10%) were significantly more intense 

in flavor than 20 and 30% fat patties due to a greater protein content. Cohesiveness scores had a 

significant (P<.05) interaction between fat level and flame time in 20 and 30% fat patties. 

Control patties were extremely more cohesive than all other flame times. Five, 10, 15, and 20 

secs flame time patties were not significantly different in high fat patties for cohesiveness scores. 

 Low fat patties were not different in cohesiveness scores except with extreme flame times (20 

secs). All patties were more cohesive at day 4 and 24 storage than at day 0 storage time. 

Therefore, these data indicates lean patties are significantly affected by increased flame time. 

Juiciness and tenderness were greatly decreased by heat application in lean patties while flavor 

intensity was increased possibly due to product concentration due to moisture loss. 

Cohesiveness was the only factor not affected until extreme flame treatment (20 secs) in low fat 

patties. However, higher fat patties were not significantly different in juiciness and tenderness 

but were less cohesive as flame time increased. Over storage time, all patties were significantly 

less juicy at day 24 and less tender at day 4 and 24. Low fat patties were higher in off flavor at 

day 24. Mikel et al. (1996) also found no sensory differences in ground beef patties made from 

trim treated with low levels of organic acids. 

Visual Characteristics 

Hunter “L” values (lightness) were different over storage times (P<.05), fat levels and 
10 

flame treatments (P<.01) as shown in Table 2. As expected, 0 flame time patties displayed the 

lowest (P<.01) Hunter “L” values with values increasing as flame time increased. Hunter “L” 

values were highest (P<.01) but not different (P<.05) between patties flamed for 10, 15, and 20 

secs. Furthermore, patties of 20 and 30% fat levels were significantly (P<.01) different over 

time as increased fat content increased Hunter “L” values. At 10% fat there were no differences 

between day 0, 4, and 24. Also, 30% fat patties were significantly lower at day 0 than day 4 and 

24. 

Hunter “a” values (redness) decreased (P<.01) as flame time increased within fat levels. 

Patties with 10% fat, at 0 and 5 secs flame were similar (P<.05) with all other patties 

significantly different. Patties with 30% fat were significantly (P<.01) different at 0, 5 and 10 

secs but similar (P<.05) at 15 and 20. Lastly, 20% fat patties showed significantly higher Hunter 

“a” values at 0 and 5 secs of flame. Significant differences for Hunter “a” values were found at 

0 days of storage time for 10 and 20% fat patties with 4 and 24 day patties not significantly 

different. However, higher fat patties (30%) were not different until 24 days of storage. 

Therefore, lower fat patties were effected at shorter storage times. Hunter “b” values 

(yellowness) generally increased as flame time increased within each fat level indicating flame 

treatment increased browning both the protein and fat in the product. These results agree with 

Vosen et al. (1995), who found little effect of flame on product appearance at short application 

intervals. 

Metmyoglobin content showed similar patterns in 10 and 20% fat patties over flame time 

(Table 2). In 10% fat patties 0, 5, and 10 secs flame treated patties were not different (P<.05). 

However, patties at increased flame times of 15 and 20 secs were significantly different from 0, 
11 

5, and 10 secs patties containing 10 and 20% fat. As expected, metmyoglobin percentage 

increased within fat levels as flame time increased. High fat patties treated with 20 secs flame 

had higher concentrations (P<.05) than patties flamed for 0, 5, 10, and 15 secs. In low fat patties 

(10%) 10 secs flamed patties were not significantly different than control patties. Storage time 

also effected metmyoglobin percentage. At day 24, 30% fat patties had significantly lower 

metmyoglobin contents than 10 and 20% fat patties. Low fat patties (10%) at day 4 and 24 were 

significantly higher in metmyoglobin than patties at day 0. These data agree with Vosen et al. 

(1995) that as storage time increases, higher fat patties have greater metmyoglobin development 

than low fat patties. Subjective discoloration scores followed similar findings as metmyoglobin 

content and increased proportionally with flame time similar to those findings of Vosen et al. 

(1995). At similar flame times, patties of each fat level showed similar discoloration patterns. 

Furthermore, within fat levels, as flame increased there were significant differences (P<.05). 

High fat patties had higher discoloration scores at 0, 5 flame whereas 10 and 20% fat patties 

were effected more at higher flame times of 15 and 20 secs. Therefore, discoloration within fat 

level is effected more by increased flame time. Storage time also effected discoloration of each 

fat level. Low fat patties (10%) were significantly lower in discoloration scores at day 0 than 4 

but not at day 24. Twenty percent fat patties were significantly higher in discoloration at day 24. 

 High fat patties (30%) were significantly (P<.01) different in discoloration scores between each 

storage period with day 0 having lowest and day 24 highest discoloration. This confirms an 

increase in fat content will increase discoloration of patties over storage time. Reynolds and 

Carpenter (1974) reported that the use of a high molar concentration of organic acids also 

discolored pork carcasses. These data also agree with Mikel et al. (1996) who found increased 
12 

product discoloration in patties made from 4% organic acid treated trim. 

Cook loss is important in controlling final yield of a product. Cook loss is shown in Table 

3. Low fat patties (10%) maintained similar cook losses at each flame time. These results are 

expected since less fat would be lost due to heat application during cooking. In 20% fat patties, 

there were no differences between 0 and 5 secs flaming time with 10, 15, and 20 secs flamed 

patties having less cook loss than 0 and 5 secs flamed patties. This significant decrease in cook 

loss as flame time increases is due to fat loss during flame treatment. High fat patties had less 

cook loss (P<.05) at day 24 but were not different at 0 and 4 days of storage. Therefore, high fat 

patties (30%) tend to lose more weight due to an increase in flame time and subsequent loss of 

fat and moisture. 

Water-holding-capacity was significantly higher at 20 secs flame (P<.05) while all other 

flame times were not different (P<.05). Low fat patties maintained the highest (P<.05) waterholding-capacity. This effect was probably due to an accumulation of free water because of 

decreased fat. Storage periods had no effect (P<.05) in low fat patties while in 20% patties day 4 

and 24 had higher water-holding-capacities than day 0. Also, in high fat patties water-holdingcapacity increased as storage time increased. 

There were differences (P<.05) in pH over storage time (Table 3). Final product pH at 

day 0 was significantly higher than at day 4 and 24 within each fat level. Vosen et al. (1995) 

reported a reduction in product pH of 5.57 at day 0 to 5.53 at day 4 in lean beef patties. One 

reason for this decrease in pH could be an increase in lactic-acid-producing bacteria over storage 

time. 
13 

Lipid oxidation was analyzed as accumulation of 2-thiobarbituric acid reactive 

substances method. Results concluded a significant difference between control patties and all 

flamed patties. TBAR values over storage were higher at day 0 (.7186) and 24 (.7035) than day 

4 (.5370) in low fat patties. This disputes Vosen et al. (1995) findings in which there were 

steady increases in TBARs as storage time increased. There were no significant differences in 

high fat patties (30%). 

Bacterial Characteristics 

The primary purpose of using surface flaming on beef trim utilized for ground beef 

patties was to decrease bacterial populations and proliferation. Hanna et al. (1983) used flame as 

a method of sterilization. If populations can be decreased, then shelf-life increases as well as 

possible elimination of any pathogenic bacterial present. 

Aerobic, anaerobic, lactic acid producing and psychrotrophic bacterial populations within 

each fat level decreased as flame time increased (Table 4). Colonies were higher in patties prior 

to treatment (P<.01) than in patties flamed for twenty seconds. There were significant treatment 

by fat interactions for aerobic (P<.05), anaerobic and psychrotrophic (P<.01) bacteria. 

Furthermore, there were significant day-by-fat interactions for anaerobic and psychrotrophic 

(P<.05) and treatment-by-day interaction for lactic acid producing and psychrotrophic (P<.05) 

bacteria (Table 1). Initial bacterial populations were highest in 20 percent beef patties. 

Aerobic-plate-counts were different (P<.01) among flamed patties as compared to patties not 

flamed. After 5 seconds of flame treatment, aerobic populations decreased from 4.05 log CFU/g 

at 0 flame time to 3.53 log CFU/g. Further decreases occurred upon flame time increased to 10, 
14 

15, or 20, in 10% fat patties. Storage time appeared to have little effect on the increased aerobic 

plate counts. However, there was a significant difference at day 4pm (Table 4) than other 

storage days when frozen product was analyzed. Aerobic, anaerobic, lactic-acid producing and 

psychrotrophs increased to higher than the original bacterial populations of controls. In fact, 

patties exposed to 20 seconds of flame had aerobic-plate-count increases of 2.46 log CFU/g at 

day 0 to 3.57 at day 4 pm. It may be concluded that exposing patties to an abusive environment 

over time increases bacterial counts as expected. 

Anaerobic bacteria were significantly (P<.01) decreased within all fat levels at 5 secs of 

flame treatment. After 5 secs of flame there was a .6 Log CFU/g reduction in both 10 and 30% 

fat patties while there was more than a 1 Log CFU/g reduction in 20% fat patties. However, in 

20% fat patties there was a 1.9 log CFU/g reduction at 10 secs flame. This may conclude 

anaerobes can be greatly reduced with minimal heat treatment. There were no differences over 

frozen storage times in 20 and 30% fat patties. However, abused patties at day 4 p.m. displayed 

higher anaerobic plate counts than the control patties at day 0. 

Lactobacillus plate counts decreased as flame time increased at day 0. At day 4, 10 secs 

flame significantly decreased counts by over 1.5 log CFU/g. At day 24 there were no differences 

between 10, 15, and 20 secs flame. The abused patties (4pm) again were higher in all treatments 

than patties not flamed. 

Psychrotrophic plate counts showed minimal changes over storage periods except in 

abused patties at day 4 pm. Psychrotrophs followed a similar pattern as Lactobacillus 

populations. A treatment of 10 secs significantly decreased bacterial counts. At day 4 p.m. 

counts were elevated to above the level of control patties at day 0. In conclusion, surface 
15 

flaming initially destroys many bacterial populations. Vosen et al. (1995) flame used in low fat 

patties were not effective in decreasing microbial populations but was in high fat patties. 

However, if patties are temperature abused more than 6 hours, there was an actual increase in 

bacterial populations. Analysis revealed that flaming patties does minimize bacterial growth and 

proliferation if patties are not temperature abused. 

CONCLUSIONS 

In conclusion, flame treatments greatly decreased juiciness and tenderness in lean patties 

while not negatively affecting high fat patties as flame time increased except for decreased 

cohesiveness scores. Evidently, flame treatment of high fat patties was not of duration to affect 

protein integrity. Hunter “a” values decreased and Hunter “L” and “b” values increased as flame 

time increased. Metmyoglobin concentration and percent discoloration also increased 

proportionally as flame time increased indicating increased surface browning of product proteins 

and fat. However, co-mingling of trim pieces during grinding decreased negative effects on 

visual acceptance. In high fat patties, cook loss was reduced as flame time increased due to the 

initial loss of fat and moisture during flaming. 

Aerobic, anaerobic, lactic acid producing, and psychrotrophic bacteria populations within 

each fat level decreased as flame time increased. However, as products were temperature abused 

at day 4, all bacterial populations increased indicating this method is successful in controlling 

bacterial populations only if product temperature as well good manufacturing practices are well 

maintained. 
16 

REFERENCES 

AOAC. 1990. Official Methods of Analysis, 15th ed., Association of Official 

Analytical Chemists. Washington, DC. 

Anonymous, 1995. Meat Business editors honored for excellence. Meat Business, December, 

1995. 

Anonymous, 1994. Food Safety Backgrounder. National Livestock and Meat 

Board. Chicago, IL. 

Bjerklie, S. and Stentz, Z. 1996. Industry Forum: “Not Whether, But How.” Meat and Poultry 

42(1):52-57. 

Bryan, F.L. Microbiological Hazards in Feeding Systems, Microbiological Safety of Foods in 

Feeding Systems, National Academy Press, Washington, D.C., 1982. 

Chen, C.M. and Trout, GO. 1991. Color and its stability in restructured beef steaks during 

frozen storage: Effects of various binders. J. Food Sci. 56:1461-1465, 1475. 

Hamm, R. 1960. Biochemistry of meat hydration. Advances in Food Research. 

Vol. 10 p.363-367. 

Hanna, M.O., Seville, J.W., Smith, G.C., Purser, D.E., Gardner, F.A. and 

Vanderzant, C. 1983. Effects of growth of individual meat bacteria on pH, color, and 

odor of asceptically prepared vacuum-packaged round steaks. J. Food Prot. 46(3):216-

221. 

Ke, P.J., Cervantes, E., and Robles-Martinez, C. 1984. Determination of 

thiobarbituric acid reactive substances (TBARS) in fish tissue by an improved 

distillation-spectrophotometric method. J. Sci. Food Agric. 35:1248. 

Kryzwicki, K. 1979. Assessment of relative content of myoglobin, oxymyoglobin, and 

metmyoglobin at the surface of beef. Meat Sci. 3:1. 

Mikel W.B., Conner, D.E., Dale, S., Mikel, L.S. and Jones, W.R. 1996. Quality 

attributes of beef patties treated with lactic and acetic acids to reduce microbial 

populations. (Abstract) J. Food Science 96:26E-6. 

Reynolds, A.E. and Carpenter, J.A. 1974. Bactericidal properties of acetic and 

proprionic acids on pork carcasses. J. Anim. Sci. 38(3):515-519. 
17 

SAS. 1988. SAS User’s Guide: Statistics, 5th ed. Statistical Analysis System 

Institute, Inc., Cary, NC. 

Steele, R. G. And Torrie, J, H, 1982. Principles and Procedures of Statistics, 

2nd ed. McGraw-Hill Book Co., New York, NY. 

Vosen ,T.R., Mikel, W.B., Dale, S., Conner, D.E., Kotrola, J.S., Jones, W.R. 

andGregory, W.H. 1995. Reduction of microbial populations in high and low fat beef 

trim in response to surface flaming. Ph.D. dissertation in Proceedings of 41st Annual 

International Congress of Meat Science and Technology. C26 p.286. 
18 

TABLE 1. Sensory evaluation of three fat levels of ground beef patties over 

storage time as affected by surface flaming. 

FACTOR Juicek

 Tenderk Off Flavork Flav Intk Cohesk 

Day 

Trtl 

**m 

*m 

** 

NS 

** 

NS 

NSm 

NS 

** 

** 

Fatl ** ** NS * ** 

Day x Trtl 

Fat x Trtl 

NS 

** 

NS 

* 

NS 

* 

NS 

NS 

NS 

* 

10 0 4.8c 5.6b 5.9bc 5.8a 5.8a 

20 0 5.5a 6.5a 6.5a 5.5a 4.8b 

30 0 5.2ab 6.5a 6.1ab 5.6a 5.0b 

10 5 4.0d 5.5bc 6.3ab 5.8a 5.5ab 

20 5 5.3ab 6.6a 6.4ab 5.3a 4.4c 

30 5 5.6a 6.6a 6.3ab 5.3a 3.8de 

10 10 3.8d 5.1cd 6.5a 5.7a 5.7a 

20 10 5.4a 6.6a 6.1ab 5.5a 4.1cd 

30 10 5.5a 6.7a 6.4ab 5.4a 3.6de 

10 15 3.9d 5.2cd 6.1ab 5.6a 5.4ab 

20 15 4.9bc 6.4a 6.3ab 5.3a 4.0cd 

30 15 5.6a 6.7a 6.1ab 5.6a 3.5e 

10 20 3.6d 5.1d 5.5c 5.6a 5.2b 

20 20 5.4a 6.7a 6.2ab 5.6a 4.1cd 

30 20 5.4a 6.4a 6.3ab 5.5a 3.5e 

SEMn .1631 .1307 .1847 .1338 .1586 

Fat x Day 

10 0 

NS 

4.4a 

NS 

5.4a 

** 

6.6a 

NS 

5.6 

** 

5.2b 

10 4 4.2a 5.3b 6.3ab 5.8 5.8a 

10 24 3.4b 5.2b 5.4c 5.7 5.6a 

20 0 5.6a 6.9a 6.2ab 5.4 3.7de 

20 4 5.3a 6.5b 6.7a 5.6 4.8b 

20 24 4.9b 6.3b 6.0b 5.4 4.3c 

30 0 5.7a 6.8a 6.7a 5.6 3.4e 

30 4 5.7a 6.5b 5.9b 5.4 3.9d 

30 24 5.1b 6.5b 6.1b 5.5 4.3c 

SEMn .1264 .1013 .1431 .1036 .1586 

abcdefghij Means within columns with uncommon superscripts are significantly 

different. 

k Juiciness, Tenderness, Off Flavor, Flavor Intensity, and Cohesiveness scores 

(8=extremely juicy, tender, intense and cohesive and no off flavor;1=extremely dry, tough, 

bland, non-cohesive and strong off flavor). 

 TRT = time in seconds of surface flame application. Fat = expressed as %. 

m NS = not significant; * = P<0.05; ** = P<0.01. n

 SEM = standard error of the means. 

l 
19 

TABLE 2. Visual characteristics of three fat levels of ground beef patties over storage time 

as affected by surface flaming. 

FACTOR Hunter L Hunter a Hunter b Metmyoh Discolorh 

Day *j **j   **  

Fati **   **  ** 

Trti   **  ** ** 

Day x Trti NS NS NS NS NS 

Fat x Trti NSj ** ** * * 

10 0 35.9 12.8c 8.4g 27.8bcd 8.1j 

20 0 45.7 18.0a 12.6ab 25.5de 7.9j 

30 0 45.6 15.7b 13.1b 21.7e 14.1ij 

10 5 37.2 13.0c 9.8ef 28.1bcd 20.0hi 

20 5 46.3 15.0b 12.6ab 32.3b 21.6hi 

30 5 48.1 12.6cd 12.1bc 22.9c 26.9h 

10 10 40.2 11.8d 9.9ef 32.9b 35.0g 

20 10 47.2 12.2cd 10.9de 31.3bc 35.9fg 

30 10 50.0 10.7e 11.9bc 25.2de 43.1f 

10 15 40.7 10.1e 9.4f 37.5a 55.6e 

20 15 46.3 10.8e 10.8de 38.9a 68.1cd 

30 15 50.6 9.1f 10.5de 27.5bcd 64.6d 

10 20 40.4 9.1f 9.6f 39.8a 72.3bc 

20 20 46.0 9.1f 10.2ef 40.4a 85.0a 

30 20 48.3 8.8f 11.3cd 39.9a 77.6ab 

SEMk .8394 .3508 .3170 1.6085 2.673 

Fat 

10 

x Day 

0 

* 

38.4e 

** 

13.3ab 

** 

10.4d 

** ** 

29.1de 34.0f 

10 4 39.4e 10.5d 9.0e 34.6bc 42.1cd 

10 24 38.8e 10.3d 8.8e 36.0ab 38.8def 

20 0 45.3d 13.9a 11.3bc 30.6d 40.8cde 

20 4 47.8bc 12.4c 10.9cd 38.7a 41.0cde 

20 24 45.8d 12.8bc 11.9ab 31.8cd 49.3b 

30 0 46.4cd 12.5c 12.4a 25.9e 35.2ef 

30 4 48.6ab 12.6bc 12.3a 30.4d 45.2bc 

30 24 50.2a 9.0e 10.6d 26.1e 55.4a 

SEMk .6502 .2717 .2458 1.2460 2.079 

abcdefg Means within columns with different superscripts are significantly different. 

h

 Metmyoglobin and Discoloration expressed as %. 

 TRT = time in seconds of surface flame application. Fat = expressed as %. 

NS = not significant; * = P<0.05; ** = P<0.01.

k

 SEM = standard error of the means. 

 i 
20 

TABLE 3. Physical characteristics of three fat levels of ground beef patties over storage time 

as affected by surface flaming. 

FACTOR 

Day 

Fatj 

Cook Lossi 

NSk 

** 

WHC 

**k

 ** 

pH 

** 

*k 

TBAR 

** 

** 

Trtj   **  ** 

Day x 

Fat x 

Trtj 

Trtj 

NS 

** 

NS 

NS 

NS 

* 

NS 

NS 

10 0 26.1defg 240.6 5.68bcd .5637 

20 0 27.5de 114.4 5.73abc .6157 

30 0 36.8a 128.8 5.79a .3268 

10 5 25.7defg 247.3 5.66cde .7011 

20 5 29.2cd 108.1 5.76ab .8072 

30 5 32.8bc 110.9 5.78a .4405 

10 10 27.8de 245.3 5.61def .6644 

20 10 23.4fgh 120.3 5.59ef .5719 

30 10 33.5ab 105.6 5.62de .4324 

10 15 25.2efgh 242.8 5.58ef .6299 

20 15 22.8gh 134.3 5.63de .6111 

30 15 27.3def 116.7 5.53f .4860 10 20 

20 20 21.6h 138.3 5.61def .6250 

30 20 26.2defg 138.9 5.65cde .4220 

SEMl 1.4410 7.090 .0286 .0449 

Fat 

10 

x Day 

0 

* 

27.5c 

** * 

245.8a 5.76ab 

** 

.7186b 10 4 

4 26.3cd 124.5c 5.65cd .8432a 

20 24 24.9d 136.6c 5.61de .6404b 

30 0 32.6a 88.4e 5.80a .3765d 30 4 

abcdefgh Means within columns with different superscripts are significantly different. 

i Cook Loss expressed as %.

j

 TRT = time in seconds of surface flame application. FAT = expressed as %.

k NS = not significant; * = P<0.05; ** = P<0.01.

l

 SEM = standard error of the means. 
21 

TABLE 4. Bacterial populations of three fat levels of ground beef patties over storage time as 

affected by surface flaming. 

FACTOR 

Day 

Fati 

APC 

**j 

** 

Anaerobes 

** 

** 

Lactobacillus 

** 

** 

Psychrotrophs 

** 

** 

Trti   **  ** 

Day x Trti 

Fat x Trti 

NS 

* 

NS 

** 

** 

** 

*j 

NSj 

10 0 3.7bc 3.7bc 3.6b 3.4 

20 0 4.8a 4.8a 4.8a 4.7 

30 0 3.6bc 3.8b 3.5bc 3.2 

10 5 3.3cd 3.1de 3.2bcd 3.3 

20 5 4.0b 3.7b 3.4bc 4.1 

30 5 3.2cd 3.2de 3.1cde 2.4 

10 10 3.2cd 3.2de 2.8def 2.6 

20 10 3.3cd 2.9de 2.7ef 3.7 

30 10 2.9de 2.9de 2.6fg 2.3 

10 15 2.7ef 3.0de 2.8def 2.7 

20 15 3.5c 2.9de 3.0def 3.3 

30 15 2.4f 2.7e 2.7ef 1.6 

10 20 2.7ef 2.8de 2.2g 2.0 

20 20 3.3cd 3.1de 3.0def 3.8 

30 20 3.0de 2.7e 2.8def 1.6 

SEMk .1574 .1701 .1521 .1859 

Fat x Day NS * NS * 

10 0 3.0 2.8d 2.6 2.5de 

10 4amh 2.8 3.0cd 2.8 2.5de 

10 4pmh 3.5 3.5b 3.3 3.5c 

10 24 3.3 3.2c 3.0 2.9cd 

20 0 3.4 3.3bc 3.0 3.8b 

20 4am 3.4 3.3bc 3.0 3.8b 

20 4pm 4.4 4.3a 4.1 4.4a 

20 24 4.0 3.0cd 3.3 3.3c 

30 0 3.0 3.0cd 3.0 1.9f 

30 4am 2.9 3.0cd 2.8 2.4e 

30 4pm 3.3 3.3bc 3.2 2.6d 

30 24 2.9 2.8d 2.8 1.9f 

SEMk .1408 .1521 .1361 .1663 

abcdefg Means within columns with different superscripts were significantly different. 

h

 4 am = frozen product; 4 pm = product thawed at room temperature for 6 hr. 

 TRT = time in seconds of surface flame application. FAT = expressed as %.

j NS = not significant; * = P<0.05; ** = P<0.01.

k

 SEM = standard error of the means. 

i