Effects of lactate on ground lamb colour stability and mitochondria-mediated metmyoglobin reduction

Previous research suggests that lactate’s colour stabilizing effect in beef is through NADH production and antioxidant activity. However, no research has assessed lactate’s role in lamb colour. Hence, our objectives were to evaluate the effects of lactate on lamb surface discolouration, oxygen consumption, and metmyoglobin reduction. In experiment 1, lactate (final meat concentration = 2.5% w/w) was added to ground lamb (n = 20 carcasses) and patties were stored for 3 days at 1 °C in PVC packaging. Surface colour (CIE L∗ and a∗) and metmyoglobin reducing activity of ground lamb patties were measured. Addition of lactate improved colour stability and metmyoglobin reducing activity (p < 0.05). In experiment 2, mitochondria were isolated from lamb longissimus muscle (n = 3). Addition of lactate–LDH–NAD to mitochondria resulted in significant oxygen consumption and metmyoglobin reduction compared with mitochondrial controls without lactate (p < 0.05). Lactate can improve the colour stability of lamb, possibly by increasing metmyoglobin reducing activity.     

Effect of ripeness and postharvest storage on the evolution of colour and anthocyanins in cherries (Prunus avium L.)

The relationship between colour parameters and anthocyanins of four sweet cherry cultivars, Burlat, Saco, Summit and Van was studied. The colour (L^∗, a^∗, b^∗, chroma and hue angle parameters) and anthocyanins were analysed during two different years at two different ripening stages (partially ripe, and ripe, respectively). The cherries were analysed at harvest and after storage at 1.5 ± 0.5 °C and 15 ± 5 °C for 30 and 6 days, respectively. The colour was measured by tristimulus colourimetry (CIELAB system) directly on the fruits, while anthocyanins were quantified by HPLC-DAD analysis on methanolic extracts of freeze-dried samples of the fresh cherries and on the differently stored cherries. L^∗, chroma, and hue angle values were always lower for the ripe than for the partially ripe cherries. All of the cultivars were found to contain cyanidin-3-rutinoside and cyanidin-3-glucoside as the major anthocyanins. The total anthocyanin content in fruits of the different cultivars varied in the order Burlat > Saco > Van > Summit. The concentration of anthocyanins increased at both temperatures of storage in both ripe and partially ripe cherries, but the extent of increase varied among cultivars. Cherries stored at 15 ± 5 °C showed higher reduction of L^∗, chroma and hue angle than fruits stored at 1.5 ± 0.5 °C. L^∗, a^∗, b^∗, chroma and hue angle correlated negatively (P < 0.001) with the total anthocyanins levels, but not with the total phenols. These results show that chromatic functions of chroma and hue correlate closely with the evolution of colour and anthocyanins levels during storage of sweet cherries and indicate that colour measurements can be used to monitor pigment evolution and anthocyanin contents of cherries (and vice versa).     

Thermal degradation kinetics of anthocyanins and visual colour of Urmu mulberry (Morus nigra L.)

Urmu mulberry (Morus nigra L.) juice was concentrated from 15.02 to 45.20 °Brix by rotary vacuum evaporator at 40 °C. The objectives of this study were to determine the titratable acidity, soluble solid content, antioxidant capacity, total monomeric anthocyanins and total phenolic matter in prepared concentrate, to investigate the thermal degradation kinetics of anthocyanins and Hunter colour parameters (L^∗, a^∗, b^∗) and total colour difference (TCD^∗) and to develop a relationship between visual colour and anthocyanin during thermal processing at 60, 70 and 80 °C. Monomeric anthocyanin degradation showed a first order reaction kinetics. The zero order, first order and a combined kinetics model were applied to the changes in Hunter colour parameters (L^∗, a^∗ and b^∗) and total colour difference (TCD^∗). All colour parameters followed an apparent combined kinetics model. The degradation of anthocyanins showed positive correlation with a^∗, b^∗ and L^∗ and negative correlation with TCD^∗.     

Near-infrared oximetry of three post-rigor skeletal muscles for following myoglobin redox forms

We investigated the response of frequency-domain multidistance (FDMD) near-infrared (NIR) tissue oximetry for detecting absolute amounts of myoglobin (Mb) redox forms and their relationship to meat colour stability. Four packaging formats were used to create different blends of Mb redox forms and meat colours during display. Changes in surface colour and subsurface pigment forms during simulated display time (0, 2, 4, and 10 d at 2 °C) were evaluated using surface reflecto-spectrophotometry (both L∗a∗b∗ and specific wavelengths) and FDMD NIR tissue oximetry. Data for both methods of direct measurement of oxymyoglobin and deoxymyoglobin were strongly related and accounted for 86–94% of the display variation in meat colour. Indirect estimates of metmyoglobin ranged from r² = 59–85%. It appears that NIR tissue oximetry has potential as a noninvasive, rapid method for the assessment of meat colour traits and may help improve our understanding of meat colour chemistry in post-rigor skeletal muscle.     

Effect of sonication on colour,ascorbic acid and yeast inactivation in tomato juice

Power ultrasound is recognised as a potential non-thermal technique to inactivate micro-organisms pertinent to fruit juices. In this study tomato juice was sonicated at different amplitude levels (24.4–61.0 μm) at a constant frequency of 20 kHz for treatment times (2–10 min) and pulse durations of 5 s on and 5 s off. Hunter colour values (L∗, a∗ and b∗), pH, °Brix, titratable acidity, ascorbic acid and yeast inactivation were measured. No significant differences (p < 0.05) in pH, °Brix or titratable acidity were observed. Regression modelling was used to investigate the main effects of amplitude level and treatment time. Prediction models were found to be significant (p < 0.05) with low standard errors and high coefficients of determination (R²). Model predictions for critical quality parameters of Hunter colour values (L∗, a∗ and b∗), ascorbic acid and yeast inactivation were closely correlated with the experimental results obtained.     

Examination of the effect of ageing and temperature at rigor on colour stability of lamb meat

A study of factors (ageing period, rigor temperature and vitamin E level) impacting on the colour stability of lamb m. longissimus thoracis et lumborum (LL) during 3 days of simulated retail display was undertaken. The LL were taken from 84 lambs from 3 slaughters. Slices of LL were measured fresh (24 h post-mortem) or after ageing for 5 days in vacuum packaging. The oxy/met ratio (630/580 nm), declined with display time, and increased with increasing temperature at pH 6.0. Redness (a*) values also declined with display time and a reduction in redness values was observed as LL pH at 24 h post-mortem and/or pH at 18 °C increased. There was no effect of ageing period or vitamin E level on the oxy/met ratio or a* values when the vitamin E level averaged 3.76 mg/kg LL. These results suggest that maximising vitamin E levels in lambs and achieving a moderate rate of pH decline will optimise colour stability irrespective of ageing period.     

Factors affecting the colour of lamb meat from the longissimus muscle during display: The influence of muscle weight and muscle oxidative capacity

Spectrophotometric measures were used to determine the redness:browness (R630/R580) of 4238 lamb longissimus muscle after 3 days under simulated display. The results were analysed using linear mixed effects models. Environmental factors represented by effects such as kill group and site of production produced the greatest variation of up to 2.76 units in R630/R580. Isocitrate dehydrogenase activity, reflecting muscle oxidative capacity, reduced R630/R580 by 0.5 units. Selection for high muscling sires increased R630/R580 by 0.27 units, likely due to changes in muscle oxidative capacity. Lamb carcass weight also increased R630/R580 by 0.5 units. Analysis of genotypic factors influencing lamb size and growth rate such as sire type and dam breed further supported that increased growth rate improves meat R630/R580. Our findings suggest that breeding for increased growth rate and increased muscle weight could result in Australian lamb meat retaining its red colour for extended periods whilst on display.     

Apoptosis during postmortem conditioning and its relationship to duck meat quality

The aim of this work was to examine the relationship of skeletal muscle apoptosis and postmortem development of meat quality. Colour, cooking loss, myofibril fragmentation index (MFI) and shear force of duck breast and thigh meat postmortem were measured, and changes of positive nuclei were assessed with Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphophate nick end-labelling method (TUNEL). Correlation analysis revealed that apoptosis were positively correlated with colour (L^∗, a^∗ and b^∗), cooking loss and MFI (P < 0.05), while it is negatively correlated with shear force (P < 0.05). Our results indicate the growing level of duck skeletal muscle cell apoptosis was associated with the postmortem development of meat quality traits such as meat colour, water holding capacity and tenderness.     

Effect of marinating time and low pH on marinade performance and sensory acceptability of poultry meat

The effects of marinating time (30, 60, 120 and 180 min) and acidic marinade pH (3.0, 3.2, 3.4, 3.6, 3.8, 4.0 and 4.2) on the instrumental and sensory properties of cooked Chinese-style marinated chicken were investigated. With increasing marinating time up to 180 min, a significant (P < 0.05) increase in surface redness (a∗ value) and the dark pink sensory attribute was observed, along with a corresponding decrease in lightness (L∗ value) and colour penetration. Increased marinating times of 120–180 min were found to produce more acceptable end products with increased scores for colour, aroma and flavour attributes. Marinade uptake was greater at higher marinade pH levels of 3.8, 4.0 and 4.2, with the highest marinade uptake (3.34%) recorded at pH 4.0. As changes to core meat pH were not observed, the effect of marinating time (up to 180 min) and marinade pH on the instrumental and sensory properties of Chinese-style marinated chicken were located principally at the surface of samples. Consumers considered surface colour as contributing to acceptability of marinated chicken to a greater degree compared to colour penetration.     

Protein and lipid oxidative stability of fresh ostrich M. Iliofibularis packaged under different modified atmospheric packaging conditions

This study investigated the aptness of modified atmospheric packaging (70:30, O₂:CO₂ (O_MAP); 70:30, N₂:CO₂ (N_MAP)) and traditional overwrap (control) for fresh ostrich steaks, stored at 4 ± 1 °C for 10 days. N_MAP showed the least oxidation, O_MAP the highest and the control moderate. Myoglobin (CIE a^∗) was gradually oxidised in all packaging atmospheres, but the O_MAP oxidised at the slowest rate, remaining significantly more bloomed from day 0 (17.86 ± 1.17) to 8 (9.78 ± 1.12). Free carbonyls were constant in all packaging environments. TBARS remained constant for the N_MAP (2.39 ± 0.21 mg MDA/kg meat) and the overwrap (3.06 ± 0.29 mg MDA/kg meat), but the O_MAP increased significantly (9.96 ± 1.02 mg MDA/kg meat) to day 10. The pH increased in the control but remained constant in the MAP treatments. The control also showed the greatest drip loss (>5%). The success of MAP application to ostrich will depend on the ability of the consumer to detect the by-products of lipid oxidation.     

Physicochemical and microbiological changes of “Souvlaki” – A Greek delicacy lamb meat product: Evaluation of shelf-life using microbial,colour and lipid oxidation parameters

Fresh Souvlaki-type lamb meat was packaged under vacuum (VP) and modified atmospheres (MAs) and stored under refrigeration (4 °C) for a period of 13 days. The following gas mixtures were used: M1: 30%/70% (CO₂/N₂) and M2: 70%/30% (CO₂/N₂). Identical samples were aerobically-packaged and used as control samples. Quality evaluation of product stored under the above packaging conditions was conducted using physicochemical and microbiological analyses. Of the chemical parameters determined, pH values of product showed no significant differences for all packaging treatments as a function of storage time. Lipid oxidation of lamb meat was enhanced by aerobic storage and gas mixture M1, whereas VP and gas mixture M2 controlled lipid oxidation to a greater extent. Souvlaki colour stability (as determined by a^∗, b^∗ and L^∗ values) was not negatively affected by either VP or MA conditions during the 13 days of storage. Of the two MAs and VP used, gas mixture M2 and VP were the most effective treatments for the inhibition of total viable counts (TVC), Pseudomonas spp., yeasts and Brochothrix thermosphacta in Souvlaki meat. Lactic acid bacteria (LAB) and Enterobacteriaceae were also found in the microbial flora of Souvlaki and increased during storage under all packaging conditions used. Based on microbiological analysis data and on the proposed a^∗ values, the use of VP and MAP (M2: 70%CO₂/30N₂) extended the shelf-life of “Souvlaki” meat stored at 4 °C by approximately 4–5 days compared to aerobic packaging.     

Stability and colour characteristics of PEF-treated cyanidin-3-glucoside during storage

The stability and colour characteristics of PEF (pulsed electric field)-treated cyanidin-3-glucoside (Cy-3-glu) was investigated during storage at 4, 24 and 37 °C. The degradation of Cy-3-glu was analyzed using a first reaction kinetics while its colour characteristics was evaluated using colour indices such as colour density (CD) and CIE L^∗a^∗b^∗ parameters. PEF had no post-effect on the stability and colour characteristics of Cy-3-glu during storage while the storage temperature had a significant effect (p < 0.05). The degradation of PEF-treated Cy-3-glu during storage conformed to the first-order reaction kinetics with regression coefficients R² greater than 0.9300. Corresponding to 4, 24 and 37 °C, the degradation rate constant k in Cy-3-glu significantly increased in the exponential order level of 10⁻⁴, 10⁻³ and 10⁻², while the t_1/2 (the time that 50% Cy-3-glu degradation would take) and D-value (the time that 90% Cy-3-glu degradation would take) of Cy-3-glu during storage decreased in the exponential order level of 10³, 10² and 10. The reduction of CD was closely related to the Cy-3-glu content in this study, the Cy-3-glu content was perfectly predicted using CD with a higher coefficient R² > 0.9999. A significant decrease in b^∗ and H⁰ value was obtained at all storage temperature (p < 0.05). A positive correlation was found between the Cy-3-glu content and b^∗ value or H⁰ value with a coefficients R² > 0.8400 during storage. ΔE increased significantly, ΔE was less than 2 at 4 °C while it was greater than 2 at 24 and 37 °C.     

Effect of low voltage electrical stimulation on biochemical and quality characteristics of Longissimus thoracis muscle from one-humped Camel (Camelus dromedaries)

The effects of electrical stimulation (90 V) 20 min post mortem on meat quality and muscle fibre types of four age group camels (1–3, 4–6, 7–9, 10–12 years) camels were assessed. Quality of the Longissimus thoracis at 1 and 7 days post mortem ageing was evaluated using shear force, pH, sarcomere length, myofibrillar fragmentation index, expressed juice, cooking loss and L^∗, a^∗, b^∗ colour values. Age of camel and electrical stimulation had a significant effect on meat quality of L. thoracis. Electrical stimulation resulted in a significantly (P < 0.05) more rapid pH fall in muscle during the first 24 h after slaughter. Muscles from electrically-stimulated carcasses had significantly (P < 0.05) lower pH values, longer sarcomeres, lower shear force value, higher expressed juice and myofibrillar fragmentation index than those from non-stimulated ones. Electrically-stimulated meat was significantly (P < 0.05) lighter in colour than non-stimulated based on L^∗ value. Muscles of 1–3 year camels had a significantly (P < 0.05) lower shear force value, and pH, but longer sarcomere, and higher myofibrillar fragmentation index, expressed juice, and lightness colour (L^∗) than those of the 10–12 years camels. The proportions of Type I, Type IIA and Type IIB were 25.0, 41.1 and 33.6%, respectively were found in camel meat. Muscle samples from 1–3 year camels had significantly (P < 0.05) higher Type I and lower Type IIB fibres compared to those from 10–12 year camel samples. These results indicated that age and ES had a significant effect on camel meat quality.     

On-line application of visible and near infrared reflectance spectroscopy to predict chemical–physical and sensory characteristics of beef quality

The aim of this study was to assess the on-line implementation of visible and near infrared reflectance (Vis-NIR) spectroscopy as an early predictor of beef quality traits, by direct application of a fibre-optic probe to the muscle immediately after exposing the meat surface in the abattoir. Samples from M.longissimus thoracis from 194 heifers and steers were scanned at quartering 48 h postmortem over the Vis-NIR spectral range from 350 to 1800 nm. Thereafter, samples from M.longissimus thoraciset lumborum were analysed for colour (L^∗, a^∗, b^∗; 48 h postmortem), cooking loss (14 days postmortem), instrumental texture (Volodkevitch, 10 days aged meat; slice shear force, 3 and 14 days aged meat) and sensory characteristics. Vis-NIR calibrations, tested by cross-validation, showed high predictability for L^∗, a^∗ and b^∗ (R² = 0.86, 0.86 and 0.91; SE_CV = 0.96, 0.95 and 0.69, respectively). The accuracy of Vis-NIR to estimate cooking loss and instrumental texture ranged from R² = 0.31 to 0.54, suggesting relatively low prediction ability. Sensory characteristics assessed on 14 days aged meat samples showed R² in the range from 0.21 (juiciness) to 0.59 (flavour). Considering the subjective assessment of sensory characteristics the correlations of Vis-NIR measurements and several meat quality traits in the range from 0.46 to 0.95 support the use of on-line Vis-NIR in the abattoir. Improvement of predictability was achieved if only extreme classes of meat characteristics have to be predicted by Vis-NIR spectroscopy.     

Effects of stunning with different carbon dioxide concentrations and exposure times on suckling lamb meat quality

Forty-nine Manchega breed male suckling lambs were used to determine the effect of different stunning methods (using two different CO₂ concentrations and exposure times) on lamb meat quality. The lambs were allocated to five stunning treatments including four CO₂ treatments [80% CO₂ for 90 s (G1); 90% CO₂ for 90 s (G2); 90% CO₂ for 60 s (G3); 80% CO₂ for 60 s (G4)] and an electrically stunned control group (G5). The gas-stunning treatments did not cause neither haematomas nor blood splash in the carcasses. Meat quality was evaluated by testing pH, colour (L^∗, a^∗, b^∗, chroma, hue values), water holding capacity (WHC), cooking loss (CL), shear force (SF), drip loss (DL) and total aerobic bacteria. Statistical differences in pH at 24 h post-mortem, colour, WHC and CL were not found among groups. After 7 days post-mortem, there were statistical differences among groups in pH (highest in G4 and G5) and in DL (highest in G1). There were differences in SF due to stunning method evident after 72 h and 7 days ageing. The statistical differences (P < 0.01) among groups on total aerobic bacteria at 24 h (lower and higher values in G2 and G5, respectively) disappeared at 7 days post-mortem. As G2 as G3, could be recommended to stunning suckling lambs since a highest stability with ageing time on meat quality was found using 90% CO₂.     

CT scanning carcases has no detrimental effect on the colour stability of M. longissimus dorsi from beef and sheep

This study investigated the effect of computerised tomography imaging (CT scan), for carcase composition determination, on the oxy/metmyoglobin ratio, hue and L^∗, a^∗ and b^∗ scores of M. longissimus dorsi from both beef and lamb. Beef and lamb M. longissimus dorsi were divided into four proportions and randomly allocated to one of the following treatments; CT 30 day aged; CT fresh; control 30 day aged; control fresh. Colour measurements were made over a 96 h retail display period. CT scan had little effect on the colour of both lamb and beef across all colour parameters. There was a small negative affect observed in CT aged samples (P < 0.05) for ratio, hue, a^∗ and b^∗ values, however these differences were so small that they are unlikely to impact upon the commercial shelf-life of the product. Other factors such as aging, species and vitamin E concentration play a much greater role in colour stability than CT. Aged M. longissimus dorsi clearly had a worse colour stability than the fresh packaged samples, while beef was a lot more colour stable than lamb. It appears that CT scan for the purpose of body composition determination will not have any commercially relevant impact on colour stability of both beef and lamb.     

Effect of freeze-thaw cycles on physicochemical properties and color stability of beef semimembranosus muscle

The effects of freeze-thaw cycle on the physicochemical properties and color stability of beef semimembranosus muscle during cold storage were investigated. Meat was tested for effects on color (CIE L^?, a^?, b^?), myoglobin content (%), metmyoglobin reducing ability (MRA), thiobarbituric acid reactive substances (TBARS), heme pigment content (ppm), SDS-PAGE profile, and tissue microstructure. Fresh meat showed significantly (p < 0.05) higher values of CIE a^?, CIE b^?, and oxymyoglobin content (%) compared to freeze-thawed meat during cold storage. However, metmyoglobin content (%) was higher in freeze-thawed meat than in fresh meat during 7 days of cold storage. There were no significant differences (p > 0.05) in MRA among the treatments during cold storage. The TBARS value (0.387 mg/kg) of fresh meat was significantly (p < 0.05) higher than those of freeze-thawed meats after 5 days of cold storage. These results suggest that the freeze-thaw process could accelerate the deterioration of meat color.     

Antioxidant capacity,total phenolics,glucosinolates and colour parameters of rapeseed cultivars

The antioxidant capacity of twenty nine rapeseed varieties was determined by using ferric reducing antioxidant power (FRAP) and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) methods. Mean FRAP (3190–6326 μmol Trolox/100 g) and DPPH (3194–6346 μmol Trolox/100 g) values for methanolic extracts of rapeseed cultivars did not differ significantly. Moreover, the total content of phenolics (756–1324 mg sinapic acid/100 g), glucosinolates (4.2–87.5 μmol/g, respectively), erucic acid (0.0–56.1%) and colour parameters of the studied rapeseed cultivars were analysed. Antioxidant capacity determined by FRAP and DPPH methods correlated significantly with total phenolic content (TPC) in rapeseed cultivars (r = 0.9332, 0.9339, p < 0.001). Also, significant, inverse correlations were found between antioxidant capacity, total phenolics and luminosity (L^∗) or red colour intensity (a^∗) of rapeseed cultivars. Principal component analysis (PCA) allowed the rapeseed varieties to be differentiated based on their antioxidant capacities, total amounts of phenolics, glucosinolates, erucic acid and colour parameters.     

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.