Effects of L- or D-lactate-enhancement on the internal cooked colour development and biochemical characteristics of beef steaks in high-oxygen modified atmosphere

The effects of L- or D-lactate on internal cooked colour development of steaks packaged in high-oxygen (80% O₂/20% CO₂) modified atmosphere packaging (MAP) was investigated. Ten USDA Select beef strip loins were divided individually into 4 equal-width sections, and one of four treatments (control, 0.3% sodium tripolyphosphate, 2.5% L-lactate + 0.3% sodium tripolyphosphate, and 2.5% D-lactate + 0.3% sodium tripolyphosphate) was assigned randomly to the loin sections. Loin sections were injected to approximately 10% of their raw weight. Steaks packaged in high-oxygen MAP were stored in the dark at 1 °C for 10 days. Instrumental internal colour of raw and cooked steaks (70 °C), total reducing activity (TRA), NADH concentration, and percent myoglobin denaturation (PMD) were measured. Cooked steaks enhanced with 2.5% L-lactate/phosphate maintained higher a*/b* ratios, lower hue values, higher TRA and NADH concentration, and lower PMD than the control and D-lactate-injected steaks, whereas enhancement with 2.5% D-lactate did not affect cooked colour, TRA, NADH, or PMD. Thus, inclusion of an L-lactate/alkaline phosphate blend increased the reducing activity of muscle tissues by replenishing NADH and subsequently decreased the thermal denaturation of myoglobin by maintaining the reduced state of myoglobin in the high-oxygen package.     

Effect of processing temperature on tenderness,colour and yield of beef steaks subjected to high-hydrostatic pressure

Our aim was to achieve a single-step pressure-heat process that would produce tender, juicy beef steaks from meat that would otherwise be tough when cooked. Steak portions (25 mm thick) from hind-quarter muscles were subjected to heat treatment at 60, 64, 68, 72 or 76 °C for 20 min, with or without simultaneous application of high pressure (200 MPa). Control steaks were heated at 60 °C for 20 min with or without pressure and cooked at 80 °C for 30 min. Compared with heat alone, pressure treatment resulted in higher lightness scores at all temperatures and overall yield was improved by pressure treatment at each temperature. Even at 76 °C, the overall water losses were < 10% compared with > 30% for heat alone. Meat tenderness (peak shear force) was improved for the pressure–heat samples at temperatures above 64 °C, and was optimal at 76 °C. Therefore, subject to microbial evaluation, this single-step pressure-heat process could be used to produce tender, high moisture content steaks ready for consumption.     

Effects of succinate and pH on cooked beef color

Two experiments were conducted to assess the effects of succinate and pH on cooked beef color. In experiment 1, ten strip loins (M. longissimus lumborum) were divided in half and assigned to either non-enhanced control or 2.5% succinate. Each half-loin was cut into steaks, packaged in vacuum or 80% oxygen, and stored at 1 °C for 0, 6, or 12 days. Steaks were cooked to either 66 °C or 71 °C. Succinate increased (P < 0.05) steak pH, raw a* values, and interior cooked redness when packaged in high oxygen. In experiment 2, to assess the role of succinate in raw and cooked color, succinate or ammonium hydroxide was added to ground beef patties to result in a common meat pH (5.9). At a similar pH, succinate had greater metmyoglobin reducing activity and internal cooked redness compared with ammonium hydroxide (P < 0.05). In addition to ingredient-based changes in muscle pH, succinate may influence color by regenerating reducing equivalents.     

Effects of lactate and modified atmospheric packaging on premature browning in cooked ground beef patties

Our objectives were to determine the effects of lactate and modified atmosphere packaging on raw surface color, lipid oxidation, and internal cooked color of ground beef patties. Eight chubs (85% lean) were divided in half and each half was either assigned to the control (no lactate) or mixed with 2.5% lactate (w/w). Following treatment, patties were prepared and packaged in either vacuum, PVC (atmospheric oxygen level), high-oxygen (80% O₂ + 20% CO₂), or 0.4% CO (30% CO₂ + 69.6% N₂) and stored for 0, 2, or 4 days at 2 °C. After storage, raw surface color and lipid oxidation were measured and patties were cooked to either 66 °C or 71 °C. Lactate improved (p < 0.05) color stability of PVC, high-oxygen, and vacuum packaged raw patties, but had no effect (p > 0.05) on the a∗ values and visual color scores of patties in 0.4% CO. Lactate decreased (p < 0.05) lipid oxidation in all packaging atmospheres. Nevertheless, high-oxygen and PVC-packaged patties had more (p < 0.05) lipid oxidation than patties in CO and vacuum. Lactate had no effect (p > 0.05) on premature browning, whereas patties packaged in high-oxygen demonstrated premature browning. Conversely, cooked patties in 0.4% CO and vacuum were more red (p < 0.05) than both high-oxygen and PVC-packaged patties. Although lactate improved raw color stability, it did not minimize premature browning in cooked ground beef patties.     

Effect of lactate-enhancement, modified atmosphere packaging, and muscle source on the internal cooked colour of beef steaks

Earlier studies on lactate-mediated colour stability in beef did not address the possible influence on cooked colour. Our objective was to examine the effect of lactate-enhancement, muscle source, and modified atmosphere packaging (MAP) on the internal cooked colour of beef steaks. Longissimus lumborum (LL) and Psoas major (PM) muscles from 16 (n = 16) beef carcasses (USDA Select) were randomly assigned to 4 enhancement treatments (non-injected control, distilled water-enhanced control, 1.25% and 2.5% lactate), and fabricated into 2.54-cm steaks. Steaks were individually packaged in either vacuum (VP), high-oxygen MAP (HIOX; 80% O₂ + 20% CO₂), or carbon monoxide MAP (CO; 0.4% CO + 19.6% CO₂ + 80% N₂), and stored for 0, 5, or 9 days at 1 °C. At the end of storage, surface and internal colour (visual and instrumental) was measured on raw steaks. Steaks were cooked to an internal temperature of 71 °C, and internal cooked colour (visual and instrumental) was evaluated. Lactate-enhancement at 2.5% level resulted in darker (P < 0.05) cooked interiors than other treatments. Interior cooked redness decreased (P < 0.05) during storage for steaks in VP and HIOX, whereas it was stable for steaks in CO. Our findings indicated that the beef industry could utilise a combination of lactate-enhancement and CO MAP to minimise premature browning in whole-muscle beef steaks.     

Effect of varying the gas headspace to meat ratio on the quality and shelf-life of beef steaks packaged in high oxygen modified atmosphere packs

Beef steaks (M. longissimus dorsi) were stored in modified atmosphere packs (MAP) (80% O₂:20% CO₂) with gas headspace to meat ratios of 2:1, 1:1 and 0.5:1 for 14 days at 4 °C. The pH, surface colour, texture and microbiology of beef steaks were unaffected (P > 0.05) by varying the gas headspace to meat ratio. APLSR (ANOVA-partial least squares regression) and jack-knife uncertainty testing indicated that lipid oxidation (TBARS) was significantly positively correlated with days 10 (P < 0.05) and 14 (P < 0.001) of storage. Chemical and sensory detection of lipid oxidation in beef steaks were in agreement on day 14 of storage. The sensory quality and acceptability of beef steaks were similar in gas headspace to meat ratios of 2:1 or 1:1 and unacceptable in 0.5:1. Results indicate that pack size and gas volume can be reduced without negatively affecting fresh beef quality and shelf-life.     

Efficacy of bacteriophage LISTEXP100 combined with chemical antimicrobials in reducing Listeria monocytogenes in cooked turkey and roast beef

The aim of this study was to verify the effectiveness of the commercially available anti-Listeria phage preparation LISTEX^™P100 in reducing Listeria monocytogenes on ready-to-eat (RTE) roast beef and cooked turkey in the presence or absence of the chemical antimicrobials potassium lactate (PL) and sodium diacetate (SD). Sliced RTE meat cores at 4 and 10 °C were inoculated with cold-adapted L. monocytogenes to result in a surface contamination level of 10³ CFU/cm². LISTEX^TMP100 was applied at 10⁷ PFU/cm² and samples taken at regular time intervals during the RTE product's shelf life to enumerate viable L. monocytogenes. LISTEX^™P100 was effective during incubation at 4 °C with initial reductions of L. monocytogenes of 2.1 log₁₀ CFU/cm² and 1.7 log₁₀ CFU/cm², respectively, for cooked turkey and roast beef without chemical antimicrobials (there was no significant difference to the initial L. monocytogenes reductions in the presence of LISTEX^TMP100 for cooked turkey containing PL and roast beef containing SD-PL). In the samples containing no chemical antimicrobials, the presence of phage resulted in lower L. monocytogenes numbers, relative to the untreated control, of about 2 log CFU/cm² over a 28-day storage period at 4 °C. An initial L. monocytogenes cell reduction of 1.5 log₁₀ CFU/cm² and 1.7 log₁₀ CFU/cm², respectively, for cooked turkey and roast beef containing no chemical antimicrobials was achieved by the phage at 10 °C (abusive temperature). At this temperature, the L. monocytogenes cell numbers of samples treated with LISTEX™ P100 remained below those of the untreated control only during the first 14 days of the experiment for roast beef samples with and without antimicrobials. On day 28, the L. monocytogenes numbers on samples containing chemical antimicrobials and treated with LISTEX^TMP100 stored at 4 and 10 °C were 4.5 log₁₀ CFU/cm² and 7.5 log₁₀ CFU/cm², respectively, for cooked turkey, and 1.2 log₁₀ CFU/cm² and 7.2 log₁₀ CFU/cm², respectively, for roast beef. In both cooked turkey samples with and without chemical antimicrobials stored at 10 °C, the phage-treated samples had significantly lower numbers of L. monocytogenes when compared to the untreated controls throughout the 28-day storage period (P < 0.0001). For roast beef and cooked turkey containing chemical antimicrobials treated with LISTEX^TMP100 and stored at 4 °C, no more than a 2 log CFU/cm² increase of L. monocytogenes was observed throughout the stated shelf life of the product. This study shows that LISTEX^™P100 causes an initial reduction of L. monocytogenes numbers and can serve as an additional hurdle to enhance the safety of RTE meats when used in combination with chemical antimicrobials.     

Evaluation of antioxidant capacity and colour stability of calcium lactate enhancement on fresh beef under highly oxidising conditions

Fifteen USDA Select beef strip loins were divided individually into four equal width sections, and one of six treatments containing phosphate and/or calcium lactate (CAL) enhancement solutions were assigned randomly to each loin section (n = 10). Steaks from each loin section were packaged with high-oxygen (80% O₂) modified-atmosphere packaging, and/or irradiated at 2.4 kGy, stored 10 days and then displayed for 5 days at 1 °C. Instrumental colour, total reducing activity (TRA), 2-thiobarbituric acid value (TBARS), and NADH concentration were measured. Loins with CAL and phosphate maintained the most stable red colour, increased NADH (p < 0.05), and were the least oxidised. Among irradiated steaks, CAL with phosphate treatment significantly minimised lipid oxidation, increased NADH and TRA, and consequently had a higher a^∗ value. These results suggest that lactate inclusion improves colour stability of fresh beef by providing superior antioxidant capacity and increased reducing activity of myoglobin by elevating NADH concentration.     

The effects of high oxygen modified atmosphere packaging on protein oxidation of bovine M. longissimus dorsi muscle during chilled storage

Modified atmosphere packaging (MAP) extends the shelf life of beef, especially in the context of visual colour. High O₂ MAP (70-80%) may cause quality deterioration through lipid and protein oxidation, the latter linked to a reduction in meat tenderness. The objective of this study was to investigate the effects of MAP in comparison to vacuum packaging (VP) on protein oxidation and subsequent tenderness of LD (M. longissimus dorsi) beef steaks during chilled storage (4 °C) of periods up to 14 days. Steaks were analysed for carbonyl content, free thiol groups, drip loss, Warner-Bratzler shear force (WBSF) and SDS-PAGE of extracted myofibrillar proteins. Free thiol groups were lower in high O₂ MAP (80% O₂/20% CO₂) steaks, after 14 days of storage, indicating protein oxidation compared to VP steaks. SDS-PAGE (non reducing conditions) showed the presence of high molecular weight cross linked myosin heavy chain aggregates in the high O₂ atmosphere packaged steaks, which were absent in VP steaks.     

Structural and biochemical characteristics of bovine intramuscular connective tissue and beef quality

The aim of the study was to evaluate the impact of structural and biochemical characteristics of muscle intramuscular connective tissue on beef quality. The experimental design was based on three muscles of three breeds sampled as fresh material and cooked at 55 °C (Longissimus thoracis and Semimembranosus) or at 70 °C (Semimembranosus and Biceps femoris) for quality assessment. The results showed that muscle characteristics influence beef quality differently from one muscle to another. In grilled LT, proteoglycan content contributed negatively to juiciness, and intramuscular lipids were linked positively to tenderness, flavour, residues and overall liking scores. In grilled SM, cross-link and lipid contents were involved in beef quality. In BF cooked to 70 °C, perimysial branch points were negatively linked to tenderness. In SM cooked to 70 °C, perimysial area was involved in beef quality. These results should allow a better understanding of the factors involved in background toughness, in juiciness and flavour of meat.     

The effect of phytic acid on oxidative stability of raw and cooked meat

The effects of phytic acid addition (0.1, 1 and 5 mM) to pork and beef homogenates on TBARS and metmyoglobin levels in raw meat, and TBARS and heme iron contents in cooked meat during 3 days of storage at 4 °C were investigated. Also, the role of inositol as a potential synergist of IP₆ (phytic acid) was examined. IP₆ effectively decreased the TBARS accumulation in raw and cooked meat homogenates. The metmyoglobin formation was inhibited in raw beef by phytic acid in a dose-dependent manner. The effect of IP₆ was more pronounced in cooked meat than in raw and in cooked beef homogenates more than pork. Inositol did not enhance antioxidant action of phytic acid in minced meat.     

Efficacy of performing Warner–Bratzler and slice shear force on the same beef steak following rapid cooking

The ability to perform Warner–Bratzler and slice shear force on the same beef top loin steak was investigated. Three, 2.54-cm steaks from top loins (n = 99) were allotted to either Warner–Bratzler only (WBS), slice shear force only (SSF), or Warner–Bratzler and slice shear force (WBS/SSF). Steaks were thawed at 2 °C for 48 h prior to cooking. Steaks were cooked to 71 °C using a conveyor convection oven and allowed to cool at room temperature for a minimum of 4 h. Steaks allotted to WBS used six 1.27-cm cores and steaks allotted for WBS/SSF used four cores. Steaks allotted to SSF and WBS/SSF used one, 1 cm × 5 cm slice. Correlations among WBS and SSF for all steaks ranged from 0.49 to 0.69 (P < 0.0001). When correlations were generated for steak location within the top loin, the relationships among WBS and SSF performed in the same steak ranged from 0.53 to 0.70 (P < 0.05). These results indicate that it may be feasible to conduct WBS and SSF on the same top loin steak, and that the steak taken 2.54 cm from the 13th rib is the optimal location for this combination of procedures.     

Effects of dry,vacuum, and special bag aging; USDA quality grade; and end-point temperature on yields and eating quality of beef Longissimus lumborum steaks

This study evaluated the effects of three aging methods: (dry (D), wet (W), and special bag (SB)); two quality grades [USDA Choice((≥ Small⁵⁰ marbling) and Select); and two cooked end-point temperatures (62.8 °C and 71.1 °C) on physico-chemical traits of instrumental tenderness, color, and sensory properties of Longissimus lumborum beef muscle. Dry-aged loins had higher (P < 0.0001) weight loss than W or SB aged loins. However, D and SB aged loins had similar (P > 0.05) combined losses. W aged loins had higher (P < 0.01) L* values than D or SB aged loins. Warner–Bratzler shear force of steaks was not affected (P > 0.05) by aging method or quality grade but increased (P < 0.0001) as end-point temperature increased. Sensory panel evaluation also showed no effect (P > 0.05) of aging method or quality grade on myofibrillar tenderness, juiciness, connective tissue amount, overall tenderness or off flavor intensity. Steaks cooked to 62.8 °C were juicier (P < 0.05) than those cooked to 71.1 °C. Neither D nor SB aging had advantages over W aging.     

High-oxygen modified atmosphere packaging system induces lipid and myoglobin oxidation and protein polymerization

Beef steaks from longissimus lumborum, semimembranosus, and adductor muscles (n = 10; respectively) were cut at 24 h postmortem, randomly assigned to either high-oxygen modified atmosphere packaging (HiOx-MAP; 80% O₂, 20% CO₂) or vacuum (VAC), and displayed for 9 days at 1 °C. HiOx-MAP packaged beef steaks had a rapid increase in lipid oxidation and a decrease in color stability during display. The steaks in HiOx-MAP had significantly lower tenderness and juiciness scores, and higher off-flavor scores compared to steaks in VAC. HiOx-MAP condition did not affect the postmortem degradation of troponin-T or desmin. Furthermore, autolysis of μ-calpain was not influenced by packaging. SDS–PAGE, immunoblotting, and diagonal-PAGE revealed oxidative cross-linking of myosin heavy chain in meat packaged in HiOx-MAP. These results suggest that the HiOx-MAP system may negatively affect meat quality characteristics by inducing lipid and myoglobin oxidation and cross-linking/aggregation of myosin by protein oxidation.     

Effects of cooking methods and chemical tenderizers on survival of Escherichia coli O157:H7 in ground beef patties

This study evaluated chemical tenderizers and cooking methods to inactivate Escherichia coli O157:H7 in ground beef patties (model system for non-intact beef). Ground beef was inoculated with E. coli O157:H7 and mixed with (i) nothing (control), (ii) calcium chloride (CC) and flavoring agents (FA), (iii) CC, FA, and acetic acid (AA), (iv) sodium chloride (SC), sodium tripolyphosphate (ST), and potassium lactate (PL), and (v) the combination of SC, ST, PL, and AA. Patties were stored in aerobic or vacuum bags at − 20, 4, and 12 °C. Samples were grilled, broiled, or pan-fried to 60 or 65 °C. Total bacterial and E. coli O157:H7 populations remained unchanged during storage. Broiling was more effective in reducing E. coli O157:H7 than grilling and pan-frying, and acidified tenderizers reduced E. coli O157:H7 more than non-acidified tenderizers in broiling. Higher reductions were observed at 65 °C than 60 °C in broiled and grilled samples. These results indicate that acidified tenderizers and broiling may be useful in non-intact beef safety.     

Potential prediction of the microbial spoilage of beef using spatially resolved hyperspectral scattering profiles

Spoilage in beef is the result of decomposition and the formation of metabolites caused by the growth and enzymatic activity of microorganisms. There is still no technology for the rapid, accurate and non-destructive detection of bacterially spoiled or contaminated beef. In this study, hyperspectral imaging technique was exploited to measure biochemical changes within the fresh beef. Fresh beef rump steaks were purchased from a commercial plant, and left to spoil in refrigerator at 8 °C. Every 12 h, hyperspectral scattering profiles over the spectral region between 400 and 1100 nm were collected directly from the sample surface in reflection pattern in order to develop an optimal model for prediction of the beef spoilage, in parallel the total viable count (TVC) per gram of beef were obtained by classical microbiological plating methods. The spectral scattering profiles at individual wavelengths were fitted accurately by a two-parameter Lorentzian distribution function. TVC prediction models were developed, using multi-linear regression, on relating individual Lorentzian parameters and their combinations at different wavelengths to log₁₀(TVC) value. The best predictions were obtained with r² = 0.95 and SEP = 0.30 for log₁₀(TVC). The research demonstrated that hyperspectral imaging technique showed potential for real-time and non-destructive detection of bacterial spoilage in beef.     

Algin/Calcium Gel as a Raw and Cooked Binder in Structured Beef Steaks

Structured meat products which could bind raw as well as cooked would be superior to existing structured products. Therefore, the algin/calcium gel system was, studied. Structured beef steaks were made using three levels of sodium alginate and three levels of CaCO₃. Three additional treatments were included as controls. Treatments were subjectively evaluated for six raw parameters: discoloration, color intensity, alginate pocket area, alginate pocket size, percentage fat and raw bind. Treatments were also subjectively evaluated for four cooked parameters: aroma, flavor, mouthfeel and cooked bind. The algin/calcium gel mechanism can be used to produce structured beef steaks which bind in both the raw and cooked state. Optimum ingredient levels were 0.8–1.2% sodium alginate, 0.144–0.216% CaCO₃ with 500 ppm sodium erythorbate.     

Plant extracts combined with vitamin E in PUFA-rich diets of cull cows protect processed beef against lipid oxidation

The effect of supplementing PUFA-rich cull cow diets with vitamin E (2.8 g/animal/day) or vitamin E plus plant extracts rich in polyphenols (PERP) (126 g/animal/day), for 101 ± 3 days preceding slaughter, on the oxidative stability of longissimus thoracis (LT) and semitendinosus (ST) steaks was evaluated after ageing (for 12 d at 4 °C either in carcass or under-vacuum) and packaging (14 d under-vacuum (V), 4 d aerobic (A) and 7 d under modified atmosphere (70:30, O₂/CO₂) (MA)). The ageing method had no effect on a beef lipid oxidation intensity marker (malondialdehyde (MDA)), whereas packaging systems containing O₂ (A and MA) significantly increased lipid oxidation intensity (5 and 13 times higher than under V, respectively). Adding antioxidants to diets of animals given a PUFA-rich diet significantly improved lipid stability in steaks; the combination of vitamin E and PERP was more efficient than vitamin E alone for the most deleterious beef packaging.     

Beef hamburgers enriched in lycopene using dry tomato peel as an ingredient

The direct addition of dry tomato peel (DTP) to hamburgers may be useful both to obtain a new product enriched in lycopene and for providing a use for this by-product from the tomato industry. In this study, different amounts of DTP (0–6.0% w/w) were added to raw and cooked hamburgers, and the effects on the meat’s physico–chemical and sensorial characteristics were studied. The maximum DTP concentration compatible with good sensory acceptability and high lycopene content was determined. Addition of DTP increased the colour parameters a^∗ and b^∗ of raw and cooked hamburgers, and modified all textural properties probably because of the presence of fibre. The hardness values of cooked samples was significantly higher in the batch containing 6% DTP (67.6 N) than in a control batch (50.9 N, p < 0.05). The addition of DTP to 4.5% results in hamburgers with good overall acceptability and a lycopene content of 4.9 mg/100 g of cooked hamburger.     

Color-stabilizing effect of lactate on ground beef is packaging-dependent

Previous research on lactate-induced color stability in ground beef did not address the potential influence of packaging. The objective of the present study was to examine the effects of lactate on the color stability of ground beef patties stored in different modified atmosphere packaging (MAP) systems. Ground beef patties with either 2.5% potassium lactate or no lactate were packaged in vacuum (VP), high-oxygen MAP (HIOX; 80% O₂ + 20% CO₂), carbon monoxide MAP (CO; 0.4% CO + 19.6% CO₂ + 80% N₂), or aerobic packaging (PVC) and stored for 0, 2, or 4 days at 2 °C. Lactate-treated patties were darker (P < 0.05; lower L∗ values) than control patties. Surface redness (a∗ values) was greater (P < 0.05) for lactate patties than the controls when stored in PVC, HIOX, and VP. However, lactate’s effects on a∗ values were not evident when packaged in CO (P > 0.05). The color-stabilizing effect of CO could have masked lactate’s effect on surface redness. While lactate patties in PVC and VP demonstrated lower (P < 0.05) discoloration than controls, no differences (P > 0.05) existed between controls and lactate samples in CO and HIOX. Our results indicated that the effects of lactate on ground beef color are dependent on packaging.