Ground beef microbiome changes with antimicrobial decontamination interventions and product storage

ABSTRACTYeast counts were determined on 111 samples of fresh ground beef along with aerobic plate counts (APC) and counts of gram negative bacteria (GNB). Yeasts ranged from 20–62 × 103/g with a mean of 8.7 × 103 for the 111 samples. APC ranged from 0.02 × 106 to 87 × 106/g with a mean of 9.5 × 106, while GNB ranged from 0.002 × 106 to 66 × 106/g with a mean of 3.5 × 106. When the 111 samples were divided into six groups based upon APC counts from log < 5.50 to 7.50, the mem yeast counts for each one‐half log range increased along with the means for both APC and GNB. The ratios of bacteria to yeasts were determined after dividing the samples into groups of one‐half log cycles employing APC. The ratios of APC to yeasts increased from low‐APC to high‐APC meats as did ratios of GNB to yeasts. Overall, the findings of this study indicate that the numbers of yeasts in ground beef are highly variable relative to APC or GNB. In genual, higher yeast counts were found in samples with high APC and GNB numbers.

The objective of this study was to evaluate the effectiveness of antimicrobial interventions using peroxyacetic acetic acid (PAA) followed by novel organic acids on beef trimmings prior to grinding with conventional spray (CS) or electrostatic spray (ES) on ground beef microbial populations and color. Beef trimmings (80/20; 25kg) were inoculated with E. coli O157:H7, non- O157:H7 shiga toxin producing (STEC) E. coli (EC) and Salmonella spp. (SA) at 105 CFU/g. Inoculated trimmings (1.5 kg /treatment/replicate, 2 replicates) were treated with CS application of 0.02% PAA alone or followed by CS or ES application of 3% octanoic acid (PO), 3% pyruvic acid (PP), 3% malic acid (PM), saturated solution of fumaric acid (PF) or deionized water (W). Findings from this study suggest that PA as a single or multiple chemical hurdle approach with malic, pyruvic, octanoic and fumaric acid on beef trimmings may be effective in reducing E. coli O157:H7 as well as non-STEC serotypes and Salmonella in ground beef up to day 2 of simulated retail display. Results of this study showed that instrumental color properties of ground beef treated with peroxyacetic acid followed by organic acids had little or no difference (P > 0.05) compared to the untreated un-inoculated control ground beef samples. The results also indicate that ES application of some organic acids may have similar or greater efficiency in controlling ground beef microbial populations compared to the CS application of the same acid providing a more economical and waste manageable decontamination approach.

Lactic acid bacteria (LAB) can reduce Escherichia coli O157:H7 and Salmonella spp. in ground beef during storage. Furthermore, the addition of rosemary oleoresin (RO), a natural antioxidant, to ground beef has been shown to increase shelf life and is commonly used in modified-atmosphere packaged (MAP) ground beef. This study evaluated the effects of LAB and RO treatment on the shelf life and stability of MAP ground beef displayed at abusive (10°C) temperatures for 36 h. Subjective and objective sensory analyses were conducted to determine spoilage endpoints. Trained and consumer panel responses and Hunter lightness (L*), redness (a*), and yellowness (b*) values were not affected (P = 0.62, 0.66, 0.45) by LAB addition, although RO inclusion improved (P < 0.05) lean color. Ground beef with LAB and RO had significantly less (P < 0.0001) thiobarbituric acid reactive substance values than control ground beef, indicating decreased lipid oxidation. Additionally, RO inclusion reduced (P < 0.0001) off odors, as determined by trained and consumer odor panelists. Overall, the addition of LAB did not negatively affect beef color, odor, or oxidative rancidity, suggesting that LAB can be added to ground beef in MAP packaging as a processing intervention without detrimentally affecting shelf life or stability.

Single or multiple decontamination interventions involving lauric arginate on beef trimmings to enhance microbial safety of ground beef

OxyraseTM membrane fraction was tested as an additive to nonselective BHI enrichment broth (0.1 unit/ml) to observe effects on growth of three strains of pathogenic Escherichia coli, including O157.H7 serotypes, and one nonpathogenic strain in culture broth and autoclaved ground beef systems. OxyraseTM enhanced the growth of all three pathogenic strains (inoculated at &lt;1 cell/ml) in the broth system by shortening the lag phase period by 2–3 h. Growth of the nonpathogenic E. coli strain tested was suppressed by the presence of OxyraseTM during the initial 4 h of incubation at 37C in both broth and autoclaved ground beef systems. Stimulatory effects of the enzyme added at 0.1 unit/ml were not observed in autoclaved meat systems when E. coli strains were inoculated at 1–100 cells/g of meat during 24 h of incubation at 37C.BHI broth alone and used as a nonselective enrichment for autoclaved and fresh ground beef was evaluated to observe the effect of OxyraseTM on the oxidation‐reduction potential (Eh) of each system after 0, 4 and 18 h of incubation at 37C. OxyraseTM slightly lowered Eh after 4 and 18 h in BHI broth and fresh ground beef (in BHI). However, no Eh‐decreasing effects were seen at this time in systems containing autoclaved ground beef which may explain the lack of a stimulatory effect of OxyraseTM on growth of E. coli in autoclaved ground beef.

This study evaluated the effects of dry-aged beef trimmings inclusion on quality and flavor precursors of ground beef patties. Lean and fat trim were collected from beef loins aged for 28 d using 4 different methods: wet aging (WA), dry aging (DA), dry aging in water-permeable bag (DWA), and UV-light dry aging (UDA). Trimmings were ground and incorporated with ground fresh beef top rounds and subcutaneous fat (3 d postmortem) to make patties (80% lean and 20% fat) with different formulations: fresh beef and fat (CON), fresh beef and DA fat only (DA-FAT), and mixtures of 50% fresh lean along with 30% aged lean and 20% aged fat from different aging treatments (WA, DA, DWA, and UDA). Patties were manufactured in 3 independent batches (n = 3) to conduct pH, cooking loss, texture analysis, lipid oxidation, 5 d aerobic display color, trained sensory evaluation, volatile compounds, and metabolomics analyses. The inclusion of aged beef trimmings did not impact the pH and cook loss of the patties (P &amp;gt; 0.05). DWA trimmings lowered chewiness compared to CON (P &amp;lt; 0.05) and induced greater product discoloration compared to all other treatments at the end display (P &amp;lt; 0.05). The addition of DA and UDA trimmings in ground beef reduced bloody flavor and promoted more volatile production compared to other treatments (P &amp;lt; 0.05). Metabolomics profiling revealed different flavor precursor profiles from the inclusion of trimmings aged differently, demonstrating that the addition of the lean trim portion influenced the flavor profile more significantly than the fat trim portion after cooking. Cooking significantly altered the metabolite profile, reducing variations between the different treatments and explaining the observed flavor changes. The results suggested that aged trimmings modify the flavor precursor profile in ground beef products. Further research to identify the impact of different cooking methods on the flavor generation potential of dry-aged trimming inclusion products would be beneficial.

Tracking the sources of salmonella in ground beef produced from nonfed cattle.

Effect of ultraviolet light, organic acids, and bacteriophage on Salmonella populations in ground beef

Validation comparing the effectiveness of a lactic acid dip with a lactic acid spray for reducing Escherichia coli O157:H7, Salmonella, and non-O157 Shiga toxigenic Escherichia coli on beef trim and ground beef.

Efficacy of Antimicrobial Interventions Used in Meat Processing Plants against Antimicrobial Tolerant Non–Antibiotic-Resistant and Antibiotic-Resistant Salmonella on Fresh Beef

Escherichia coli O157 and six additional serogroups of Shiga toxin-producing E. coli (STEC) (O26, O45, O103, O111, O121, and O145) account for the majority of STEC infections in the United States. In this study, O serogroup-specific genes (wzx or wzy) were used to design loop-mediated isothermal amplification (LAMP) assays for the rapid and specific detection of these leading STEC serogroups. The assays were evaluated in pure culture and spiked food samples (ground beef, beef trim, lettuce, and spinach) and compared with real-time quantitative PCR (qPCR). No false-positive or false-negative results were observed among 120 bacterial strains used to evaluate assay specificity. The limits of detection of various STEC strains belonging to these target serogroups were approximately 1 to 20 CFU/reaction mixture in pure culture and 10(3) to 10(4) CFU/g in spiked food samples, which were comparable to those of qPCR. Standard curves generated suggested good linear relationships between STEC cell numbers and LAMP turbidity signals. In various beef and produce samples spiked with two low levels (1 to 2 and 10 to 20 CFU/25 g) of respective STEC strains, the LAMP assays consistently achieved accurate detection after 6 to 8 h of enrichment. In conclusion, these newly developed LAMP assays may facilitate rapid and reliable detection of the seven major STEC serogroups in ground beef, beef trim, and produce during routine sample testing.

Lipid, instrumental color and sensory characteristics of ground beef produced using trisodium phosphate, cetylpypiridinium chloride, chlorine dioxide or lactic acid as multiple antimicrobial interventions

The Uruguay Round trade negotiations completed in April 1994 reduced beef trade barriers. Trade barriers for beef products have historically been significant. The Uruguay Round essentially converts many nontariff barriers (quotas) to tariffs (tariffication), includes safeguards for import surges, establishes minimum access commitments, reduces domestic subsidy supports, and provides special tariff allowances for developing countries. These provisions, commensurate with a growing world demand for animal source proteins, will likely increase U.S. fed beef exports and ground beef imports. The United States is a major world producer as well as exporter of beef. In 1996, the United States represented 35 percent of world beef production (ranked first) and 28 percent of world beef exports (ranked second to Australia). U.S. quantity share of the annual world beef export market averaged 5.9 percent between 1980 and 1994 but has increased in recent years. In terms of beef and veal, the United States exports primarily higher-value beef cuts. The United States is the largest single-country beef importer. The U.S. annual quantity share of the world fresh beef import market averaged 16.5 percent between 1980 and 1994. U.S. beef imports primarily consist of lower-quality, manufacturing-grade (ground) beef which is primarily used by the fast-food service industry. The Uruguay Round Agreement will reduce trade restrictions gradually over an implementation period (1995–2000). Specifically, Japan is to reduce its beef tariffs and South Korea will increase its beef import quota by the year 2000. In 2001, South Korean import quotas will be replaced by a tariff. The European Union has agreed to reduce quantities of subsidized exports. In 1995, the United States replaced import quotas with a tariff and a tariff-rate quota. The reduction in trade barriers will increase U.S. beef imports and exports. Because U.S. beef imports are primarily ground beef and exports are primarily table cut beef, beef trade liberalization will have different impacts on producers and consumers of these products. In general, increased imports decrease the price of ground beef and increase per capita ground beef consumption. However, increased beef imports reduce nonfed cattle prices and slaughter. Increased exports cause the prices of table cut beef, fed cattle, and feeder cattle to increase. Per capita consumption of table cut beef declines slightly, and fed cattle slaughter and feeder cattle production both increase. Researchers have estimated that the Uruguay Round Agreement could increase U.S. beef imports by 6–19 percent and U.S. beef exports by 10–75 percent over 1990–1994 average levels. For example, the ground beef price could decline by $0.01–$0.04/lb from average 1990–1994 levels because of increased imports. Thus, the price of nonfed cattle (which generally produce ground beef) could decline by $0.71–$2.55/cwt. Conversely, because the United States exports primarily table cut beef, the table cut beef price in the United States could increase by $0.01–$0.09/lb. Increased foreign demand for table cut beef would cause the price of boxed beef to increase by $0.05–$0.10/lb and the price of fed cattle to increase by $0.62–$5.46/cwt relative to average prices received during the 1990–1994 period. B extension, increased demand for fed cattle would increase feeder cattle price by $0.61–$5.40/cwt over average prices received during the 1990–1994 period.

ObjectivesGround beef comprises between 50 and 60% of the beef sold and consumed in the U.S. It is one of the most popular protein sources due to its affordability and versatility. Emerging trends in the industry are changing the way ground beef is formulated to include different formulations and grind treatments to change the flavor and texture attributes. In this study, 16 treatments were utilized, including 4 meat sources (chuck, regular, sirloin, round), 2 fat percentages (10 and 20%), and 2 grind treatments (6.4 mm grind and bowl chopped) to better understand consumer attitudes and preferences of ground beef in a home use test.Materials and MethodsKnuckle, outside round flat, and chuck shoulder clod subprimals and 50/50 beef trim were used to formulate the sirloin, round, and chuck treatments, respectively for both fat percentages. Regular 80/20 coarse ground beef was used for the 20% fat and it was supplemented with trimmed knuckle to formulate the 10% fat treatment. For each source, the ground beef was divided into 2 final grind batches either 6.4 mm or bowl chopped to approximately 6.4 mm grind. Patties were then formed with a patty maker using a 2.5 cm mold or 454 g chubs. Patties and chubs were vacuum packaged and frozen until use. Each consumer received 8 samples including 4 patties and 4 chubs from the same treatment. Treatments were randomly selected for each consumer. Eighty consumers were recruited from Griffin, GA; Portland, OR; Manhattan, KS, and State College, PA. Of the 314 consumers that were given product, 218 actively participated and returned the ballots.ResultsConsumers varied in their preparation methods. More consumers used an outdoor grill to cook the patties and more consumers pan fry/sautéed the meat when given chubs. More consumers ate the patties as a main course when compared to the chubs.Meat source affected raw appearance, overall, flavor and texture liking. Raw appearance liking was highest (P < 0.05) for the regular meat source treatments and lowest (P < 0.05) for the round and sirloin. For overall, flavor, and texture liking, the consumers rated chuck the highest (P < 0.05) and regular and round the lowest (P < 0.05). Patties with 6.4 mm grind size were rated higher (P < 0.05) than the bowl chop method for overall, flavor and texture liking. Fat level affected the raw appearance, cooked appearance and texture liking. Consumers preferred the 10% lipid level over the 20% lipid level. Form did not affect overall liking.A grind by fat interaction was present for overall liking (P < 0.05). Consumers preferred the 6.4 mm grind size with 10% lipid over the 6.4 mm with 20% lipid and both bowl chop treatments. The meat source by fat interaction was significant for texture liking (P < 0.05). Regular 20% lipid, round 10% lipid, and sirloin 20% lipid beef patties rated lowest in texture liking compared to chuck and sirloin ground beef patties. Texture liking also had a grind by form interaction (P < 0.05). Both the 6.4 mm treatments for patties and chubs were liked more than (P < 0.05) the bowl chop patties and chubs.ConclusionWith ground beef accounting for such a large percentage of beef consumption, it is crucial to understand how flavor and texture affect overall liking. Overall, consumers preferred 10% lipid ground chuck beef in patties or chubs ground to a 6.4 mm grind size.

Multiplex PCR detection of Shiga toxin-producing Escherichia coli strains belonging to serogroups O157, O103, O91, O113, O145, O111, and O26 experimentally inoculated in beef carcass swabs, beef trim, and ground beef.