Effect of natural antioxidants on oxidative stability of cooked, refrigerated beef and pork

ABSTRACT:  The effect of grape seed extract (GS; 0.01% and 0.02%), oleoresin rosemary (OR; 0.02%) and water-soluble oregano extract (WS; 0.02%) on oxidative and color stability of cooked beef and pork patties stored at 4 °C for 8 d was determined. Fresh beef or pork lean and trim were ground, mixed (30% fat), and divided into 5 portions. Antioxidants mixed with salt (2%) were added. Patties were formed, cooked to an internal temperature of 71 °C, overwrapped in PVC, and stored at 4 °C. Lipid oxidation, assessed using thiobarbituric acid reactive substances (TBARS) and sensory evaluation, instrumental and visual color, and pH were determined after 0, 2, 4, 6, and 8 d. Based on TBARS values and off-odors associated with lipid oxidation such as rancidity, wet cardboard (for beef patties), and grassy (for beef and pork patties), grape seed extract resulted in the best antioxidant activity in both meat species. It did not change instrumental color measures of redness, yellowness, or color intensity, and appeared to reduce visual green discoloration in beef patties. The higher GS concentration (0.02%) exhibited more antioxidant activity than the lower concentration (0.01%). Therefore, grape seed extract at 0.02% has the potential to reduce oxidative rancidity and improve shelf life of refrigerated cooked beef and pork patties.     

Evaluation of the antioxidant potential of grape seed and bearberry extracts in raw and cooked pork

The effect of grape seed extract (GSE) and bearberry (BB), on lipid oxidation (TBARS, mg malondialdehyde (MDA)/kg muscle), colour (CIE ‘a’ redness value), pH, microbial status (log₁₀CFU colony forming units/g pork) and sensorial properties of cooked pork patties was investigated. GSE (0–1000 μg/g muscle) and BB (0–1000 μg/g muscle) were added to raw pork (M. longissimus dorsi) patties which were stored in modified atmosphere packs (MAP) (75% O₂:25% CO₂) for up to 12 days at 4 °C. Cooked pork patties were stored in MAP (70% N₂:30% CO₂) for up to 4 days at 4 °C. Mesophilic plate counts and pork pH were unaffected by GSE and BB. GSE and BB addition decreased (P < 0.05) lipid oxidation (TBARS) in raw pork patties on days 9 and 12 of storage, relative to controls. Antioxidant activity of GSE and BB was observed in cooked pork patties demonstrating the thermal stability of GSE and BB. The ‘a’ redness values of raw and cooked pork patties marginally increased with increasing GSE concentration. The sensory properties of cooked pork patties were unaffected by GSE and BB addition. Results obtained demonstrate the potential for using health promoting nutraceuticals in meat and meat products.     

Inhibition of Lipid Oxidation and Rancidity in Precooked Pork Patties by Radical‐Scavenging Licorice (Glycyrrhiza glabra) Extract

This study investigated the efficacy of licorice extract (LE) to curtail lipid oxidation and protect sensory attributes of ground pork during refrigerated and frozen storage. Pork patties (20% fat) were formulated with 0%, 0.02%, 0.05%, and 0.1% (meat basis) LE or rosemary extract (RE) as comparison or 0.01% (fat basis) BHA with 0 or 1.5% NaCl. Raw and precooked (75 °C) patties were packaged in polyvinylchloride overwrapped trays and stored at 2 °C up to 7 and 14 d, respectively, or at –20 °C up to 6 mo. Lipid oxidation (thiobarbituric acid‐reactive substances [TBARS]) and sensory attributes of stored patty samples were evaluated, radical scavenging activity of the LE was measured, and the active phenolic compounds were identified. Cooking yield (<85%) was similar among antioxidant treatments, and lipid oxidation was minimal in refrigerated or frozen raw samples. However, TBARS values in refrigerated precooked control patties (0.22 mg/kg) rose to 9.3 to 9.4 mg/kg after 14 d, compared to 3.4 to 4.4 and 4.4 to 6.9 mg/kg in patties treated with 0.1% LE and RE, respectively. In frozen precooked samples, TBARS (0.22 mg/kg) increased to 1.3 mg/kg (P < 0.05) in control patties after 6 mo and had no significant change in patties treated with 0.1% LE or 0.01% butylated hydroxyanisol. Sensory panel evaluation confirmed strong inhibition of rancidity production by LE, corroborating its remarkable antiradical activity due to the presence of multiple phenolics. The results indicate that licorice has great potential as a natural antioxidative additive to extend the shelf‐life of precooked pork.     

Addition of tea catechins and vitamin C on sensory evaluation, colour and lipid stability during chilled storage in cooked or raw beef and chicken patties

The effects of addition of tea catechins (TC) and vitamin C (VC) on sensory evaluation, colour and lipid stability in cooked or raw beef and chicken meat patties during refrigerated storage were studied. Fresh beef striploin and chicken breast muscles were minced, following removal of external fat and connective tissue. Following mincing, beef and chicken were assigned to one of the following five treatments: control (meat treated with no antioxidant); TC200, meat plus 200 mg TC/kg muscle; TC400, meat plus 400 mg TC/kg muscle; VC200, meat plus 200 mg VC/kg muscle, VC400, meat plus 400 mg VC/kg muscle. Sodium chloride (1%) was added to all samples. Patties (125 g portions), formed from the above-treated minced meat, were oven cooked, cooled, and packaged in 30% CO₂:70% N₂. Fresh raw beef and chicken patties were packaged in 80% O₂:20% CO₂. All samples were stored for up to 7 days under fluorescent lighting at 4 °C. Sensory parameters (colour, flavour, taste, tenderness and overall acceptability) were evaluated on cooked beef and chicken patties after 1, 3 and 6 days of storage. Surface colour (Hunter L, a and b values), and lipid oxidation (2-thiobarbituric acid reactive substances) were measured on days 1, 3 and 6 of storage for cooked meats and on days 2 and 7 for raw beef and chicken. Tea catechins addition (200 or 400 mg/kg) to minced meat caused (P < 0.05) discolouration in cooked beef and chicken meat patties and significantly reduced (P < 0.001) lipid oxidation in cooked or raw beef patties compared to the control. Beef, either raw or cooked, was more susceptible (P < 0.01) to oxidation compared to chicken. Raw meat stored in high oxygen conditions was more susceptible to lipid oxidation than cooked meat stored in anaerobic conditions. Tea catechins treatments (TC200 and TC400) inhibited (P < 0.05) lipid oxidation in raw beef to a greater extent than vitamin C treatments (VC200 and VC400). These results indicate that tea catechins are potent natural antioxidants and exhibit greater antioxidant efficacy compared to vitamin C.     

Antioxidative activity of carnosine in gamma irradiated ground beef and beef patties

The activity of carnosine as a natural antioxidant in gamma irradiated ground beef and beef patties was studied. Samples of ground beef, in the absence and presence of 0.5% or 1.0% carnosine, as well as raw and cooked beef patties prepared with 1.5% salt (NaCl), in the absence and presence of 0.5% or 1.0% carnosine, were gamma irradiated at doses of 0, 2, and 4 kGy. The extent of oxidation in irradiated and non-irradiated samples of ground beef and raw beef patties was then determined during refrigerated (4 ± 1 °C) and frozen (−18 °C) storage, while determined for cooked beef patties during refrigerated storage only. Moreover, the determination of metmyoglobin (MetMb) accumulation and sensory evaluation for the visual color were carried out for samples of ground beef and raw patties. The results indicated that salt or salt and cooking accelerated the oxidative processes and significantly increased the peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) in the prepared non-irradiated samples. However, salt slowed down the accumulation of MetMb in raw patties. Irradiation treatments and storage in the absence of carnosine significantly (P < 0.05) increased the PV and TBARS in samples, at higher rates in salted or salted and cooked beef. Moreover, irradiation and storage significantly (P < 0.05) increased the formation of MetMb in ground beef and raw patties in the absence of carnosine. Addition of carnosine significantly (P < 0.05) reduced the oxidative processes and MetMb formation (proportionally to the used concentration) in samples post-irradiation and during storage. Furthermore, carnosine exerted significant efficacy in maintaining an acceptable visual red color post-irradiation and during storage of ground beef and raw patties. These results demonstrate that carnosine can be successfully used as a natural antioxidant to increase the oxidative stability in gamma irradiated raw and cooked meat products.     

Quality characteristics of pork patties irradiated and stored in different packaging and storage conditions

Patties were made from pork loin, individually vacuum- or aerobic-packaged and stored either at 4 or -40°C. Refrigerated patties were irradiated at 0, 1.5, 3.0 or 4.5 kGy absorbed dose, and frozen ones were irradiated at 0, 2.5, 5.0, or 7.5 kGy. Samples were analyzed for lipid oxidation, volatile production and odor characteristics. Refrigerated samples were analyzed at 0, 1 and 2 weeks, and frozen ones after 0, 1.5 and 3 months of storage. With vacuum packaging, the lipid oxidation (TBARS) of both refrigerated and frozen patties was not influenced by irradiation and storage time except for the patties irradiated and refrigerated at 7.5 kGy. With refrigerated storage, panelists could detect irradiation odor at day 0, but not after 1 week at 4°C. With frozen storage, however, irradiation odor was detected even after 3 months of storage. With aerobic packaging, the TBARS of refrigerated pork patties increased with storage time. The TBARS of pork patties increased as irradiation dose increased at day 0, but the effect disappeared after 1 week at 4°C. Nonirradiated patties were preferred to the irradiated ones at day 0 because of the significant irradiation odor in the irradiated ones, but the off-odor disappeared after 1 week at 4°C. With frozen storage, patties irradiated at 7.5 kGy had higher TBARS than those irradiated at lower doses. Nonirradiated patties had higher preference scores than the irradiated ones for 1.5 months in frozen storage. Sulfur-containing compounds were responsible for most of the irradiation off-odor, but these volatilized quickly during storage under aerobic conditions. Overall, vacuum packaging was better than aerobic packaging for irradiation and subsequent storage of meat because it minimized oxidative changes in patties and produced minimal amounts of volatile compounds that might be responsible for irradiation off-odor during storage.     

Antioxidant and Antimicrobial Activity of Commercial Propolis Extract in Beef Patties

The objective of this study was to evaluate the efficacy of propolis extract (PE) to reduce lipid oxidation and microbial growth on beef patties during refrigerated storage. Beef patties were manufactured by incorporating PE in 4 different treatments: (1) Control (no PE addition); (2) commercial propolis 1 (2% w/w; CP1); (3) commercial propolis 2 (2% w/w; CP2); and (4) noncommercial propolis (2% w/w; NCP). Raw patties were wrapped with polyvinyl chloride and stored at 2 °C for 8 d. Total phenolic content (TPC), free‐radical scavenging activity (FRS), and polyphenolic content of the PE were evaluated using high‐performance liquid chromatography (HPLC). Lipid oxidation (thiobarbituric acid‐reactive substances (TBARS), conjugated dienes (CnDs), metmyoglobin (MetMb%), pH variation, and color (L*, a*, b*, C*, and h*), and microbial growth (mesophilic and psychrotrophic bacteria) of patty samples were measured. NCP treatment demonstrated the highest FRS (64.8% at 100 μg/mL), which correlated with TPC and the presence of polyphenolic compounds. Lipid oxidation (78.54%, TBARS; 45.53%, CnD; 58.57%, MetMb) and microbial mesophilic and psychrotrophic growth (19.75 and 27.03%, respectively) values were reduced by NCP treatment in refrigerated samples after 8 d. These results indicate that PE has great potential as a natural antioxidant and antimicrobial additive to extend the shelf life of beef patties.     

Cholesterol oxidation products in irradiated raw meat with different packaging and storage time

The effect of irradiation and packaging conditions on the formation of cholesterol oxidation products (COPs) as well as lipid oxidation products was determined in raw turkey leg, beef, and pork loin meat during 7 days of storage. Ground turkey leg, beef, and pork loin muscles were prepared as patties. The patties were individually packaged either in oxygen-permeable or impermeable bags, irradiated at 0 or 4.5 kGy using a Linear Accelerator, and stored at 4°C. The COPs such as 7-hydroxycholesterol, 7β-hydroxycholesterol, and 7-ketocholesterol were detected in fresh raw meats at 0 day at the level of 10.9 to 49.2 μg/g lipid. After 7 days of storage, other COPs such as epoxides, 20-hyroxycholesterol, and choletanetriol were formed in mainly aerobically packaged and irradiated raw meats. Packaging effect was more crucial on the cholesterol and lipid oxidation than irradiation. In aerobically packaged and irradiated meats, turkey leg muscles had higher COPs value than beef or pork did. COPs and thiobarbituric acid reactive substances (TBARS) values had a strongly positive correlation in turkey leg and pork. But, cholesterol oxidation in beef proceeded in irradiated and aerobically stored samples despite of its low level of TBARS value.     

Evaluation of the antioxidant activities and nutritional properties of ten edible plant extracts and their application to fresh ground beef

In this study, we assessed the antioxidant efficacy and nutritional value of 10 leafy edible plants and evaluated their potential as natural antioxidants for meat preservation. We measured total phenolic content, 2,2-diphenyl-1-picryl-hydrazil (DPPH) radical scavenging activity, and vitamin C, chlorophyll, and carotenoid contents of 70% ethanol and water extracts of the edible plants. Based on these results, we investigated the effects of butterbur and broccoli extracts on lipid oxidation in ground beef patties. Plant extracts and butylated hydroxytoluene (BHT) were individually added to patties at both 0.1% and 0.5% (w/w) concentrations. Thiobarbituric acid reactive substance (TBARS) values and color parameters were tested periodically during 12 days of refrigerated storage. TBARS levels were significantly lower (p ≤ 0.05) in the samples containing plant extracts or BHT than the non-treated control. In addition, the beef patties formulated with the selected plant extracts showed significantly (p ≤ 0.05) better color stability than those without antioxidants. These results indicate that edible plant extracts are promising sources of natural antioxidants and can potentially be used as functional preservatives in meat products.     

The triacylglycerol preparation of conjugated linoleic acid reduces lipid oxidation in irradiated, cooked ground beef patties

It is proposed that conjugated linoleic acid (CLA) would depress the lipid oxidation caused by irradiation of cooked, aerobically stored ground beef patties. The free fatty acid (FFA–CLA) and triacylglycerol (TAG–CLA) preparations of CLA were added at 0%, 1%, 2%, or 4% during the grinding process. Patties were irradiated at 1.5–2.0 kGy and frozen at −20 °C. Subsequently, the patties were tempered to 4 °C, cooked to 70 °C and held at 4 °C for 7 d. Enrichment of ground beef with CLA increased the cis-9,trans-11 and CLA trans-10,cis-12 CLA isomers in ground beef patties, even after cooking. Weight loss (P = 0.03) and percentage fat (P = 0.05) were higher in irradiated beef patties than in control patties. Irradiation decreased the concentration of α-linolenic acid (18:3n − 3) in the ground beef by over 60% (P = 0.07), whereas thiobarbituric acid reactive substances (TBARS) values were higher (P = 0.004) in irradiated beef patties than in control patties. The 1% concentration of added TAG–CLA reduced TBARS in irradiated ground beef patties, whereas 2% and 4% FFA–CLA depressed TBARS (CLA type × percentage interaction P = 0.04). Irradiation increased the cardboard and painty aromatic attributes (P  0.05), and FFA–CLA preparation increased the painty aromatic attribute and afterburn aftertaste, but these effects were not observed with the TAG–CLA preparation (CLA type × treatment interaction P < 0.04). Adding 1% TAG–CLA to ground beef during grinding can reduce lipid oxidation in irradiated, cooked ground beef patties without the negative aftertastes associated with the FFA–CLA preparation.     

Packaging Cooked Turkey Meat Patties while Hot Reduces Lipid Oxidation

Elimination of oxygen by “hot packaging” reduced the 2-thiobarbituric acid reactive substances (TBARS) value of meat patties by about 50% in control and myoglobin added, and between 30-40% in ferrous iron added turkey patties, as compared with “cold packaging.” The TBARS values of hot and cold vacuum packaged patties were significantly lower than those of loosely packaged patties after 1 wk refrigerated storage. Most lipid oxidation in meat patties occurred at day 0, and only small changes in TBARS values were observed after 1 wk storage. Although the prooxidants in meat were major factors in promotion of lipid oxidation of cooked meat, hot packaging minimized their effects.     

WILD RICE AS AN ANTIOXIDANT FOR FRESH-FROZEN AND PRECOOKED BEEF PATTIES

Antioxidant effects, as measured by thiobarbituric acid reactive substances (TBARS), of ground cooked Minnesota wild rice (WR) added at 0, 15 and 25% (weight-weight) to fresh-frozen and precooked extra lean ground beef patties were investigated. WR generally resulted in more desirable sensory panel ratings and lower TBARS values for the fresh-frozen product at 8 weeks frozen storage but not at 0 week or 16 weeks. WR, especially at the 25% level, generally resulted in more desirable sensory panel ratings and lower TBARS in the precooked product at 4 and 8 weeks frozen storage. Ground WR can be an effective antioxidant in fresh-frozen and precooked ground beef patties stored at ?23C.     

Grape seed extract inhibits lipid oxidation in muscle from different species during refrigerated and frozen storage and oxidation catalyzed by peroxynitrite and iron/ascorbate in a pyrogallol red model system

The antioxidant effect of grape seed extract (GSE) was determined by assessing the bleaching of pyrogallol red (PGR) by peroxynitrite or iron/ascorbate, and the formation of lipid hydroperoxides (LOOH) and thiobarbituric acid substances (TBARS) in raw or cooked ground muscle during refrigerated or frozen storage. In PGR models, GSE was more effective than gallic acid in inhibiting oxidation. The formation of LOOH and TBARS was inhibited by GSE (0.1% and 1.0%) compared to untreated controls and samples treated with sodium tripolyphosphate. Diethylenetriaminepentaacetic acid (DTPA), alone or in combination with GSE, had no effect on LOOH or TBARS, which provides clues about the possible mechanism of action of GSE. These results show that GSE at concentrations as low as 0.1% is a very effective inhibitor of primary and secondary oxidation products in various muscle systems and has potential as a natural antioxidant in raw and cooked meat systems.     

Lipid and colour stability of beef from grazing heifers supplemented with sunflower oil alone or with fish oil

The effect of sunflower and fish oil supplementation of grazing heifers on lipid oxidation and colour stability in beef was investigated. For 150 days, heifers were assigned unsupplemented grazing (G) or restricted grazing with 2.5 kg concentrates containing 1250 I.U. -tocopheryl acetate and 290 g sunflower oil (S1), 415 g sunflower oil (S2), 290 g sunflower + 85 g fish oil (FS1) or 415 g sunflower + 85 g fish oil (FS2). Longissimus dorsi muscle was excised 24 h post-mortem and stored at −30 °C prior to analysis. Muscle -tocopherol in the oil-supplemented groups was higher (P < 0.05) than the G group. Lipid oxidation in refrigerated, minced raw or cooked beef was not significantly affected by diet but metmyoglobin was higher (P < 0.05) in raw beef from oil-supplemented groups compared to the G group. Lipid oxidation and metmyoglobin formation increased (P < 0.001) during refrigerated storage. Vitamin E supplementation together with pasture grazing appeared to offset any potential deleterious effect of oil supplementation on lipid and colour stability.     

Effects of Various Fiber Additions on Lipid Digestion during In Vitro Digestion of Beef Patties

ABSTRACT:  The purpose of this study was to examine the effect of various fiber additions on lipid digestion during the  in vitro  digestion of beef patties. The control patties were prepared with 90.5% lean meat and 9.5% tallow. Treatments consisted of 90% lean meat with 9.5% tallow and either 0.5% cellulose, 0.5% chitosan, or 0.5% pectin. The beef patties were then passed through an  in vitro  digestion model that simulated the composition of the mouth, stomach, and small intestine juices. The change in structure and properties of the lipid droplets was monitored by laser scanning confocal fluorescence microscopy. In general, there was a decrease in lipid droplet diameter as the droplets moved from mouth to stomach to small intestine. The amount of free fatty acid dramatically increased after  in vitro  digestion in all beef patties. The amount of free fatty acid was, however, lower in beef patties containing chitosan and pectin than other beef patties after  in vitro  digestion. Beef patties containing various fibers had lower thiobarbituric acid-reactive substances (TBARS) values than samples with no fibers. Among the samples to which fibers were added, chitosan and pectin had lower TBARS than beef patties with cellulose. The cholesterol content decreased after  in vitro  digestion in all beef patties but was not different among the beef patties before and after  in vitro  digestion. These results enhance our understanding of the physicochemical and structural changes that occur to ground beef within the gastrointestinal tract.     

Relationship between lipid peroxidation and fat content in Japanese Black beef Longissimus muscle during storage

We examined the relationship of crude fat content to lipid peroxidation of beef during storage. Longissimus muscle samples (fat content; 6.5–39.4%) from 27 Japanese Black beef steers were stored for 1, 4, 7 and 10 days, and thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides (LOOH) were determined. TBARS values increased significantly (P<0.05), but LOOH did not change during the 10- day storage period. TBARS values were negatively correlated (P<0.05) with fat content in samples stored for 1, 4, 7 and 10 days. LOOH values, however, were not significantly correlated with fat content except on day 1. Phospholipid contents were correlated (P< 0.01) with LOOH values on each measurement day, but not significantly correlated with TBARS values except on day 1. These findings indicated that: (1) high-fat beef had high preservative properties, and that; (2) TBARS formation was correlated with LOOH derived from phospholipid oxidation in the initial period of storage, and was correlated directly with fat content in a later period.     

Culinary herbs inhibit lipid oxidation in raw and cooked minced meat patties during storage

The effect of dried spices and the ethanol extract of those spices was studied on the stability of fresh chicken minced meat, and fresh and cooked pork patties pretreated with NaCl during refrigerated and frozen storage. The antioxidant activities of the spices were measured by thiobarbituric acid reactive substances (TBARS) and peroxide value (POV) in meat samples. The lipid oxidation was effectively inhibited in the chicken meat treated with several dry spices diminishing the TBARS to a range of 32% and 83% of those found in the control samples in frozen stored meat for 6 months. Marjoram, wild marjoram and caraway were the most effective dry spices. Ethanolic extracts of the same spices were more potent as antioxidants by lowering the concentration of the TBARS to a range of 20–27% of those found in the control samples. Addition of sodium salt to the minced pork resulted very high concentrations of the oxidation products originated from the polyunsaturated fatty acids. The treatment with ethanolic extract of spices (sage, basil, thyme and ginger) significantly inhibited the lipid peroxidation in refrigerated and chilled pork patties pretreated with NaCl by reducing both POV and TBARS. Heat treatment with microwaves produced significantly elevated levels of both lipid peroxides and TBARS, but the amount of these oxidation products was less than 10% in spice‐treated salted meat samples compared to that in untreated ones. Lipid peroxidation also grew continuously during the storage period at −18°C in raw and cooked samples. Ethanolic extracts of spices had a very strong antioxidative effect inhibiting lipid peroxidation in heat‐treated meat products during frozen storage. The highest antioxidant activity was observed in the case of ginger. High correlation coefficients were found between TBARS and POV both in raw and cooked pork patties (0.86, 0.91, respectively) during frozen storage. It is supposed that these compounds originated from the polyunsaturated fatty acids during oxidation processes but at different stages. Utilization of spices, spice mixtures or spice extracts in semi‐prepared meat products intended to be frozen for up to 6 months or more before consumption is proved to be advantageous in regard of shelf life of the food, as well as of human health, because of the beneficial effect of spices in inhibition of lipid peroxidation during heat treatment and chilling storage. © 1999 Society of Chemical Industry     

Properties of Low-Fat Ground Beef Containing Potassium Lactate During Aerobic Refrigerated Storage

Low-fat patties containing water, carrageenan, encapsulated salt and hydrolyzed vegetable protein (carrageenan-based patties) with 0, 1, 2 or 3% potassium lactate were compared to low-fat all-beef patties with no additives. Carrageenan-based patties had enhanced (P<0.05) sensory properties (juiciness, tenderness, mealiness and beef flavor intensity) compared to all-beef patties. The bacterial populations of low-fat, carrageenan-based patties did not differ (P<0.05) from low-fat all-beef patties. Bacterial growth in low-fat, carrageenan-based patties was reduced through the use of 2 or 3% potassium lactate with no deleterious effects on the sensory properties of the low-fat, ground beef. However, low-fat, carrageenan-based patties underwent greater (P<0.5) discoloration and lipid oxidation during aerobic refrigerated storage than all-beef patties.     

Flavor and Oxidative Stability of Ground Beef Patties as Affected by Source and Storage

Chuck muscles and fat from silage plus grain- and forage-fed steers were stored 7 days at 4°C before patty manufacture or processed into patties and stored at 4°C or ?32°C. The thiobarbituric acid values were constant from 0 to 4 days for frozen patties but decreased (P<0.05) for refrigerated patties. Evaluated by an 11-member trained sensory panel, frozen patties had lower (P<0.05) rancid flavor intensity than refrigerated patties; rancid flavor increased from 0 to 2 or 4 days storage in refrigerated patties. Frozen patties from silage plus grain-fed steers had higher (P<0.05) beefy flavor intensity scores than those from forage beef. However, diet source had no effect (P>0.05) on refrigerated patties.