Fresh and cooked color of dark-cutting beef can be altered by post-rigor enhancement with lactic acid

Fresh and cooked color of dark-cutting (DC) beef strip loins (mean pH = 6.56) enhanced with 0.25, 0.50, 0.75 or 1.00% lactic acid (LA) were compared to non-enhanced DC and normal pH (NpH; mean pH = 5.43) strip loins. Even though NpH steaks received the most (P < 0.05) desirable fresh color scores, color scores for steaks from DC sections enhanced with 0.25% LA approached those of NpH steaks after the first day of retail display. Discoloration scores were also similar (P > 0.05) among NpH and 0.25% LA-enhanced DC steaks throughout the 5 d of display. Fresh steaks from NpH strip loins were redder, as evidenced by greater (P < 0.05) a^* values and lower (P < 0.05) hue angles, than DC steaks and DC steaks enhanced with LA, regardless of concentration. However, cooked color scores and proportions of denatured myoglobin were similar (P > 0.05) between untreated NpH steaks and DC steaks enhanced with 0.25% LA. Results from this study indicate that enhancing DC beef with LA may lead to the brightening of the fresh color and prevention of the persistent red cooked color, approaching that of NpH beef.     

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.     

Effect of sodium chloride concentration on pH, water-holding capacity and extractable protein of prerigor and postrigor ground beef

Fifteen beef cattle of similar age and management history were randomly allotted by slaughter days into three groups. Paired sternomandibularis were removed immediately following bleeding and trimmed of visible fat and connective tissue. They were randomly labelled as prerigor and postrigor and assigned to a 0, 0·5, 1·0, 2·0 or 4·0% NcCl treatment. Water-holding capacity (WHC), pH, the ratio of absorbance at 250 nm over the absorbance at 260 nm (R-values), and 1·0m NaCl extractable protein (EP) were monitored over treatment times. The 0 h samples were defined as when the NaCl was incorporated with the muscle. R-values verified that 0 h samples were in the prerigor or postrigor state. Ultimate pH remained higher (P < 0·05) in prerigor homogenates with increasing NaCl concentration. EP and WHC were higher (P < 0·05) in prerigor than in postrigor homogenates with 2 and 4% NaCl at all time periods. Prerigor homogenates containing 0·5 and 1·0% NaCl had higher (P < 0·05) WHC at 12, 24, 24, 48 and 96h than similarly treated postrigor homogenates and as high or higher WHC than any postrigor treatment. Results of this study indicate an advantage to using low NaCl concentrations in prerigor salted beef.     

The effects of high salt and low pH on the water-holding of meat

The study investigated the water-holding (WH) in meat in the pH–NaCl (ionic strength) combinations that prevail in dry sausages during fermentation and drying. WH in raw beef homogenates, with 230% added water, was determined by centrifugation at pH values of 5.47–4.60, and ionic strengths (μ) 0.50–1.50. The minimum WH in relation to pH was at pH 4.8, but at higher pH values, the WH optimum was at 1.0–1.5 μ; at lower pH-values (< 5.0) the optimum was more pronounced at 1.0 μ. The WH reducing effect by pH decrease was stronger than the effect of μ. At lower pH values, the relative effect of μ on WH was higher compared to that of pH than at higher pH values. The pH–salt combinations prevailing in fermented sausage in the beginning of the ripening produced a high WH, which decreased, first with pH decrease and then in the last period of ripening mainly due to the increase of ionic strength.     

Rate and extent of pH decline affect proteolysis of cytoskeletal proteins and water-holding capacity in pork

The objective of this study was to determine the extent to which early postmortem (PM) pH decline influences proteolysis of the intermediate filament protein desmin, the costameric proteins vinculin and talin and autolysis of μ-calpain in the longissimus muscle (LM) of pigs from two genetic lines. Based on the LM 3 h pH (H = 3 h pH of LM > 6.0; L = 3 h pH of LM pH < 5.7) PM, 10 carcasses per line and pH group were selected. The average 3 h pH within pH group was 6.23 (H) and 5.44 (L). The LM samples were collected 24, 48, 72, and 120 h PM and percent drip loss was measured after 1, 2, and 4 d of storage. Samples collected at 24, 48, 72, and 120 h PM were used to monitor desmin, vinculin, and talin degradation and samples collected at 24 h PM were used to determine the extent of μ-calpain autolysis by immunoblotting. Higher (P < 0.01) pH values at 45 min, 6 h, and 24 h PM and lower (P < 0.01) drip losses after 1, 2, and 4 d of storage were recorded in the H-compared to the L-group. Abundance of the 76 kDa μ-calpain autolysis product was greater (P < 0.01), proteolysis of talin at all measured time points and proteolysis of desmin after 24 and 48 h PM was greater (P ? 0.03) in the H-group than in the L-group. The current findings indicate activation rate of μ-calpain may be associated with proteolysis of desmin and talin and could play a role in the development of drip loss. The rate of early PM pH decline can partly explain the variation of desmin and talin degradation by affecting the activation of μ-calpain.     

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 reduced sodium chloride concentration and tetrasodium pyrophosphate on pH, water-holding capacity and extractable protein of prerigor and postrigor ground beef

The effect of tetrasodium pyrophosphate (TSPP) (0, 0·25, 0·5% w/w) alone or in combination with salt (NaCl) (0, 0·5, 1·0% w/w) on water-holding capacity (WHC), pH, the ratio of absorbance at 250 nm over the absorbance at 260 nm (R-values) and 150m CaCl extractable protein (EP) was studied in prerigor and postrigor sternomandibularis homogenates over time. The 0 h samples were defined as when the NaCl was incorporated with the muscle. R-values verified that 0 h samples were in a prerigor or postrigor state. In prerigor homogenates, increasing phosphate concentration increased the time required to reach ultimate pH. Ultimate pH values of prerigor homogenates containing phosphate were lower (P < 0·05) than homogenates without phosphate and similarly treated postrigor homogenates. After six hours, no differences (P > 0·10) were noted in EP or WHC at different phosphate concentrations when averaged over NaCl concentrations in prerigor homogenates. With increasing phosphate concentration of postrigor homogenates, there was an increase (P < 0·05) in pH and EP at the initial sampling time. However, 0 and 0·25% phosphate WHC values could not be differentiated (P > 0·10). Results of this study indicate no advantages, after six hours post mortem, to using TSPP alone or in combination with NaCl in prerigor meat homogenates at concentrations added in this study.     

转谷氨酰胺酶对碎牛肉保水性和微观结构的影响

为提高碎牛肉的利用率,将碎牛肉制成牛肉肠经转谷氨酰胺酶处理,在单因素实验的基础上,通过响应面分析得到转谷氨酰胺酶降低牛肉肠蒸煮损失率的最适条件为酶量0.3%、反应时间20min、反应温度30℃,提高牛肉肠保水性的最适处理条件为酶量0.4%、反应时间20min、反应温度30℃,且经该条件(酶量0.4%、反应时间20min、反应温度30℃)处理后的牛肉肠各项指标明显优于对照组,微观结构也更加规则有序。由此可知:适当的转谷氨酰胺酶处理可以有效改善碎牛肉的保水性能和微观结构,具有较好的应用前景。      

The effect of various types of poultry pre- and post-rigor meats on emulsification capacity, water-holding capacity and cooking loss

In this study, the relationship between various kinds of poultry meat (quail, partridge, chicken and turkey) on pH, emulsification capacity, water-holding capacity and cooking loss was investigated. The effect of rigor state on pH, emulsification capacity, water-holding capacity and cooking loss was also determined. To investigate these parameters, immediately after slaughter and deboning, meat parts were submitted to both pre- and post-rigor analyses. The results indicated that the emulsification capacity of quail and chicken meat was higher than the values for partridge and turkey meat. Quail meat showed the highest water-holding capacity value in the post-rigor stage. The lowest cooking loss value was found in partridge meat, in both pre- and post-rigor stages. The state of rigor had a significant (P<0.05; P0.01) effect on pH and cooking loss values, respectively.     

The impact of single antimicrobial intervention treatment with potassium lactate,sodium metasilicate,peroxyacetic acid,and acidified sodium chlorite on non-inoculated ground beef lipid,instrumental color,and sensory characteristics

The effect of using potassium lactate, sodium metasilicate, acidified sodium chlorite, or peroxyacetic acid as a single antimicrobial intervention on ground beef instrumental color, sensory color and odor characteristics, and lipid oxidation was evaluated. Prior to grinding, beef trimmings (90/10) were treated with 3% potassium lactate (KL), 4% sodium metasilicate (NMS), 200-ppm peroxyacetic acid (PAA), 1000-ppm acidified sodium chlorite (ASC), or left untreated (CON). Ground beef under simulated retail display was measured at 0, 1, 2, 3, and 7 of display for instrumental color, sensory characteristics, TBARS values, and pH to evaluate the impact of the treatments. The KL, NMS, PAA, and ASC were redder (a^∗; P < 0.05) than CON. All treatments were scored by sensory panelists to have a brighter (P < 0.05) red color than CON during days 1–3 of display. All treatments had less (P < 0.05) lipid oxidation than CON on days 0, 3, and 7 of display. These results suggest that the use of these antimicrobial compounds on beef trimmings prior to grinding may not adversely affect, and may improve bulk packaged ground beef quality characteristics.     

Effects of potassium lactate, sodium chloride, sodium tripolyphosphate, and sodium acetate on colour, colour stability, and oxidative properties of injection-enhanced beef rib steaks

This study determined the effects of potassium lactate (KL), sodium chloride, sodium tripolyphosphate, and sodium acetate on colour, colour stability, and oxidative properties of injection-enhanced beef rib steaks. Enhancement solutions (8.5% pump) contained combinations of KL (0% or 1.5%), sodium chloride (0.3% or 0.6%), sodium tripolyphosphate (0% or 0.3%), and sodium acetate (0% or 0.1%). Steaks were packaged in a high-oxygen modified atmosphere (80% O(2)/20% CO(2)). Steaks with KL or KL and sodium acetate were darker but more colour stable (P<0.05) than control steaks. Steaks had less glossy surfaces when they contained acetate (P<0.05) and KL (P<0.11). Increasing sodium chloride content resulted in darker, less colour-stable steaks (P<0.05). Removing phosphate had little impact on colour (P>0.05). Both KL and sodium acetate improved visual appearance of injection-enhanced beef rib steaks, whereas the greater salt level were detrimental.     

Impact of muscle type and sodium chloride concentration on the quality, sensory, and instrumental color characteristics of solution enhanced whole-muscle beef

Beef biceps femoris (n = 10; muscle sections, n = 20; BF), infraspinatus (n = 10; muscle sections, n = 20; IS), and longissimus (n = 10; muscle sections, n = 20; LM) muscles were utilized to evaluate the effect of enhancement with phosphate and varying levels of sodium chloride in beef muscles differing in composition and palatability. Muscles were untreated or solution enhanced to 112% of raw product weight with sodium tripolyphosphate at 0.4% of product weight (STPP), or STPP and sodium chloride (NaCl) at 0.5%, 1.0% or 1.5% of product weight. There was a quadratic relationship (P = 0.04) for percent free water to decrease and a linear relationship (P < 0.01) for cook yield to increase as the level of NaCl increased. The IS steaks required less (P < 0.05) shear force than either the BF or LM, with the BF and LM having similar (P > 0.05) shear force values. There was a linear relationship (P < 0.01) for shear force values to decrease with increasing salt concentration. Steaks from all four enhancement treatments had lower (P < 0.05) shear force values than untreated steaks. Sensory overall tenderness ratings revealed that the IS and LM were similar (P > 0.05) and superior (P < 0.05) to the BF in tenderness. Steaks enhanced with STPP and 0.5%, 1.0%, or 1.5% NaCl all were rated more tender (P < 0.05) than untreated or STPP-only treated steaks. The BF exhibited the lowest (P < 0.05) L* (lightness) and a* (redness) values, as well as decreased (P < 0.05) vividness. The LM generally exhibited superior color to the other two muscle types. There was a linear relationship (P < 0.01) for L*, a*, b* (yellowness) values, and vividness to decline with increasing salt concentration, but steaks enhanced with STPP and 0.5% NaCl were similar (P > 0.05) in a* values and vividness to untreated steaks. These results suggest that across three different muscles varying in composition and palatability, enhancement with 0.4% STPP and 0.5% NaCl allowed for improvements in palatability while minimizing the color deterioration associated with phosphate/salt enhancement.     

Influence of sodium chloride, pH, and lactic acid bacteria on anaerobic lactic acid utilization during fermented cucumber spoilage

Cucumbers are preserved commercially by natural fermentations in 5% to 8% sodium chloride (NaCl) brines. Occasionally, fermented cucumbers spoil after the primary fermentation is complete. This spoilage has been characterized by decreases in lactic acid and a rise in brine pH caused by microbial instability. Objectives of this study were to determine the combined effects of NaCl and pH on fermented cucumber spoilage and to determine the ability of lactic acid bacteria (LAB) spoilage isolates to initiate lactic acid degradation in fermented cucumbers. Cucumbers fermented with 0%, 2%, 4%, and 6% NaCl were blended into slurries (FCS) and adjusted to pH 3.2, 3.8, 4.3, and 5.0 prior to centrifugation, sterile-filtration, and inoculation with spoilage organisms. Organic acids and pH were measured initially and after 3 wk, 2, 6, 12, and 18 mo anaerobic incubation at 25 °C. Anaerobic lactic acid degradation occurred in FCS at pH 3.8, 4.3, and 5.0 regardless of NaCl concentration. At pH 3.2, reduced NaCl concentrations resulted in increased susceptibility to spoilage, indicating that the pH limit for lactic acid utilization in reduced NaCl fermented cucumbers is 3.2 or lower. Over 18 mo incubation, only cucumbers fermented with 6% NaCl to pH 3.2 prevented anaerobic lactic acid degradation by spoilage bacteria. Among several LAB species isolated from fermented cucumber spoilage, Lactobacillus buchneri was unique in its ability to metabolize lactic acid in FCS with concurrent increases in acetic acid and 1,2-propanediol. Therefore, L. buchneri may be one of multiple organisms that contribute to development of fermented cucumber spoilage. PRACTICAL APPLICATION: Microbial spoilage of fermented cucumbers during bulk storage causes economic losses for producers. Current knowledge is insufficient to predict or control these losses. This study demonstrated that in the absence of oxygen, cucumbers fermented with 6% sodium chloride to pH 3.2 were not subject to spoilage. However, lactic acid was degraded by spoilage microorganisms in reduced salt, even with pH as low as 3.2. Efforts to reduce salt in commercial brining operations will need to include control measures for this increased susceptibility to spoilage. Lactobacillus buchneri was identified as a potential causative agent and could be used as a target in development of such control measures.     

Impact of citric acid on the tenderness,microstructure and oxidative stability of beef muscle

Acidification of meat can improve texture however it also increases susceptibility to lipid oxidation. The effect of injection and marination of citric acid to acidify and sodium carbonate or sodium tri-polyphosphate to increase pH of beef on tenderness, microstructure and oxidative stability was determined. Water-holding capacity and tenderness of beef semitendinosus muscle increased significantly at pH 3.52 upon addition of citric acid and returned to the level of untreated sample after pH was increased (pH ∼5.26) by sodium tri-polyphosphate. The microstructure of the muscle was lost upon acidification but reformed upon increasing muscle pH. Lipid oxidation was inhibited in cooked beef blocks and ground muscle acidified with citric acid. Lipid oxidation was also inhibited in citric acid acidified beef that was readjustment to pH values equal to or greater than the raw beef muscle with sodium tri-polyphosphate or sodium carbonate. In addition, citric acid that was adjusted to the pH of the raw beef so that it did not alter the pH of the beef also inhibited lipid oxidation. These results indicate that citric acid and not sodium tri-polyphosphate or pH adjustment was responsible for inhibiting lipid oxidation in beef. These results suggest that the best acid marination technique for beef would be citric acid since it is effective at both improving texture and inhibiting lipid oxidation.     

Mathematical modelling of microbial growth in ground beef from Argentina. Effect of lactic acid addition, temperature and packaging film

The effects of: (i) storage temperature (0, 4 and 10°C), (ii) gaseous permeability of the packaging film (polyethylene and EVA SARAN EVA for vacuum packaging), and (iii) natural beef pH (5.6, 5.8 and 6.1) on the growth of different bacteria isolated from beef muscle were examined. The bacteria were Klebsiella, Pseudomonas sp. and Escherichia coli. Microbial growth was modelled using Gompertz and linear equations. The effects of temperature on microbial growth rate (μ) and on lag phase duration were modelled using an Arrhenius type equation. In polyethylene, E. coli was the microorganism, that showed the highest μ values and also the greatest effect of pH on μ, especially in samples stored at 4 and 10°C. In the case of Klebsiella sp., neither pH nor temperature had marked effects on μ and on LPD. In ESE film, μ of all the microorganisms were less affected by pH and temperature than in polyethylene. In ESE film E. coli showed the highest effect of pH on μ, at 4 and 10°C. LPD increased significantly with respect to the values in polyethylene, with Klebsiella sp., showing the highest values of LPD, followed by E. coli. Experiments in ground beef with added lactic acid producing a decrease of the original muscle pH from 6.1 to 5.6 showed that the kinetic parameters of the microbial flora did not differ significantly from those of beef samples in which the original pH was 5.6.     

Effects of hot water and lactic acid treatment of beef trimmings prior to grinding on microbial, instrumental color and sensory properties of ground beef during display

The impact of 82°C hot water (HW) or 5% lactic acid (LA) applied aerobically or by vacuum to beef trimmings prior to grinding on Salmonella Typhimurium (ATCC 1769NR; ST), Escherichia coli (ATCC 11775; EC), coliform (CO), aerobic plate count (APC), instrumental color and sensory characteristics of ground beef through simulated retail display was investigated. For this, beef trimmings were inoculated with a mixture (7 log CFU/ml each) of ST and EC, and treated either aerobically or under vacuum in a tumbler with HW or LA antimicrobials. Trimmings were ground, packaged and sampled on days 0, 1, 2, 3 and 7 of display for ST, EC, CO, APC, sensory and instrumental color characteristics. Vacuum HW or LA application had no additive effect (P>0.05) when compared with aerobic application for reducing EC, ST, CO or APC. However, lactic acid was effective for reducing (P<0.05) EC, CO and APC, but reduced ground beef redness.     

Lactic acid and pH as indicators of spoilage for vacuum-packed cooked ring sausages

Lactic acid production and pH changes of 206 vacuum-packed cooked ring sausages stored at 2, 4 and 12°C from 21 different production runs were monitored as a function of time and of microbial growth. The total lactic acid concentrations and pH values were first at a constant level, starting to increase sharply after the lactobacilli count reached about 5 × 10⁷ or 6 × 10⁷ cfu/g, respectively. The lactic acid and pH changes as a function of the lactobacilli count were similar at 4 and 12 ° C. The sharp increase at high lactobacilli counts was observed in both -lactic acid and -lactic acid. The variation was lesser and the increase greater in -lactic acid formation than in -lactic acid. Above a level of 3–4 mg lactic acid/g most of the samples were deemed unfit. The pH started to decrease from a level of approx. 6.3; below 5.8–5.9 the samples were deemed unfit. The lowest pH value observed was 4.58. Both a high lactic acid content and a low pH indicated that the sausage was spoiled. These changes, however, took place at later stages of storage, and do not give information about the early phase of spoilage.     

Post-mortem changes in the concentration of lactic acid, phosphates and pH in the muscles of wild rabbits (Oryctolagus cuniculus) according to the perimortal situation

In this study changes in the concentrations of lactate, phosphates, and pH values of water extracts of muscles of transported and hunted rabbits during ripening were determined. Concentrations of lactate were higher in the muscles of hunted rabbits. The highest differences were obtained 24h after kill/hunt. Concentrations of lactate in the muscles of hunted rabbits were decreasing, while in the muscles of transported rabbits we observed it to increase in the 7th day and then decrease in the 14th day. Higher concentrations of phosphates were found in the muscles of transported wild rabbits. During the ripening process concentrations of phosphates were decreasing in muscles of both groups. Muscles of hunted rabbits had lower pH values during the whole ripening process. Our research showed that concentrations of lactate, phosphates and pH value post-mortem depended on the perimortal situations.     

Selective production of lactic acid in continuous anaerobic acidogenesis by extremely low pH operation

The selective production of lactic acid by anaerobic acidogenesis with low pH control was examined using a chemostat culture. By decreasing culture pH to 3.5 in a chemostat culture containing mixed microbial populations for anaerobic acidogenesis, heterolactic fermentation became dominant, resulting in the selective production of lactic acid and ethanol. This phenomenon was reversible between the acidic and neutral conditions, and was not affected by the dilution rate. The extremely low pH operation was effective for selective lactic acid production in anaerobic acidogenesis.