Stratification of connective tissue toughness in beef roasts assessed by simultaneous fluorometry and penetrometry

Beef rib roasts were probed to measure connective tissue fluorescence and resistance to penetration at different depths. Data were collected at the aponeurosis on the surface of Longissimus thoracis (site 1), from muscle below the aponeurosis (site 2), and from a major perimysial septum within the muscle (site 3). Penetration force at site 1 was correlated with forces at site 2 (r = 0.51, P < 0.05) and site 3 (r = 0.63, P < 0.025). Fluorescence at site 1 was correlated with fluorescence at site 2 (r = 0.81, P < 0.0005) and at site 3 (r = 0.78, P < 0.005). Thus, the aponeurosis on the muscle surface is related to underlying connective tissues in strength and composition. Aponeurosis was more than three times as strong as muscle alone (P < 0.001). Failure to detect a useful relationship between aponeurosis fluorescence and strength was attributed to loss of linearity (optical saturation) as the aponeurosis wrapped around the probe.     

Meat quality characteristics of springbok (Antidorcas marsupialis). 1: Physical meat attributes as influenced by age, gender and production region

Springbok is the most extensively cropped game species in South Africa. The effects of age (adult, sub-adult, lamb), gender and production region on the physical attributes (pH₂₄, cooking and drip loss, Warner Bratzler shear force and colour) were determined using samples of the M. longissimus dorsi (LD) muscles of 166 springbok. Stressed animals had a higher (P < 0.05) pH₂₄ (6.3 ± 0.07), as observed in the meat originating from the Caledon region. This meat had lower (P < 0.05) cooking loss (27.2 ± 0.62%) and drip loss (1.8 ± 0.08%) values in comparison to meat originating from the other regions. Inverse correlations were noted between pH₂₄ and drip loss (r = −0.26, P < 0.01) and cooking loss (r = −0.42, P < 0.001). Shear force values (kg/1.27 cm diameter) correlated positively (r = 0.25, P < 0.01) with pH₂₄. Age-related effects on tenderness were small in comparison with pH₂₄ effects. CIELab colorimetric values were typical of game meat and venison (L^* < 40, high a^* and low b^* values). It was noted that pH₂₄ correlated negatively (r = −0.51, P < 0.001) and positively (r = 0.33, P < 0.001) with the hue-angle and the chroma value of colour, respectively. Springbok originating from Caledon had a significantly (P < 0.05) higher a^* value, indicating meat to be more red with higher colour saturation.     

Sensory properties of hot-deboned ostrich (Struthio camelus var. domesticus) Muscularis gastrocnemius, pars interna

Cold-deboning is currently practiced in South African ostrich abattoirs. However, the advantages of hot-deboning include the reduction of costs and time, but there is always the risk of cold-shortening. The effects of hot-deboning of ostrich M. gastrocnemius, pars interna on meat sensory attributes were investigated. The data showed that the hot-deboned muscles’ pH₄₈ (6.57 ± 0.18) was significantly negatively correlated (r = −0.7813; P < 0.038) to the mean Warner–Bratzler shear force values (71.28 ± 18.62 N, 12.7 mm⁻¹ diameter) and positively correlated (r = 0.789; P < 0.035) to the mean scores for taste panel tenderness (66.39 ± 15.45). After storage for 48 h post-mortem, the hot-deboned muscles were found to be less juicy (P < 0.004) and, according to both sensory tenderness scores and Warner–Bratzler shear force values, tougher (P < 0.0001) than the cold-deboned muscles.     

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.     

AMP-activated protein kinase is negatively associated with intramuscular fat content in longissimus dorsi muscle of beef cattle

Marbling, or intramuscular fat, is an important factor in meat quality. As a key regulator of lipid metabolism, AMP activated protein kinase (AMPK) may be associated with intramuscular fat accumulation. Our objective was to evaluate the relationship among AMPK and its associated signaling mediators, with marbling and lean growth in beef cattle. Steers with high intramuscular fat content (High IMF, 5.71 ± 0.36%, n = 5) and low intramuscular fat content (Low IMF, 2.09 ± 0.19%, n = 5) were selected. High IMF was associated with increased tenderness (P < 0.05) and backfat thickness (P < 0.01). Muscle weights were higher in Low compared to High IMF (P < 0.05). High IMF steers had a reduced AMPK activity (P < 0.01), reduced acetyl-CoA carboxylase phosphorylation (P < 0.05), and reduced total mTOR (P = 0.02) content. Data provide evidence that AMPK is involved in IMF deposition in beef cattle.     

The effect of feed withdrawal during lairage on meat quality characteristics in ostriches

Commercially reared ostriches (n = 84) were randomly allocated to one of two groups. The first group (stressed: n = 38) was deprived of food for a period of 2.5 days prior to slaughter, to simulate the stress experienced by slaughter ostriches held in holding pens (lairage) at a commercial ostrich abattoir over a weekend. The second group (control: n = 46) was fed normally until 24 h prior to slaughter. Initial live weight as well as hot and cold drumstick weight were independent (P > 0.05) of treatment. Stressed birds lost on average (±SE) approximately three times more weight than control birds over the experimental period (−3.2 ± 0.6 vs. −1.0 ± 0.5 kg, respectively). Full stomach and alimentary tract weights did not differ between treatments although there was a tendency for that derived from stressed birds to have lower stomach contents. The intra-muscular (Muscularis iliofibularis) pH_f of stressed birds was 0.22 units higher (P < 0.01) than that of contemporaries in the control group 1 h post-slaughter (6.03 ± 0.06 vs. 5.81 ± 0.05, respectively). After 26.5 h in a refrigerated room, this difference still remained at 0.25 units (6.46 ± 0.07 vs. 6.21 ± 0.07, respectively; P < 0.05). Post-slaughter changes in intra-muscular pH followed approximately the same trend in stressed and control birds. Intra-muscular temperature was largely independent of treatment, although there was a suggestion of a slightly higher (P = 0.18) temperature in stressed birds immediately post-slaughter. Cooking loss, drip loss and shearing values were not affected (P > 0.05) by the withholding of food for 2.5 days. It can thus be concluded that withholding feed from ostriches on lairage over a period of 2.5 days does not have any negative influence on the meat yield or physical quality traits thereof.     

Meat quality characteristics of springbok (Antidorcas marsupialis). 4: Sensory meat evaluation as influenced by age, gender and production region

The effects of age, gender and production region on the sensory characteristics of springbok M. longissimus dorsi (LD) were investigated in 19 springbok, which originated from two Nature Reserves in the Free State Province of South Africa and were divided into age (adult, sub-adult) and gender categories. The sensory characteristics evaluated were game meat aroma, juiciness, residual tissue, tenderness and game meat flavour. Age, gender and production region had an effect (P < 0.05) on different sensory ratings of the meat. Whereas production region influenced (P < 0.05) the game meat aroma, initial juiciness, sustained juiciness and residual tissue ratings of the meat, gender and age had a significant effect on only the residual tissue rating of the meat. An interaction (P < 0.01) between age, gender and production region was observed for the tenderness attribute where the males from the Gariep Nature Reserve were the only gender that showed a significantly higher tenderness rating in the sub-adult than in the adult category. Sensory ratings were linearly correlated with certain physical and chemical attributes. Warner–Bratzler shear force (kg/1.27 cm diameter) values were inversely correlated with the sensory attributes of tenderness (r = −0.70, P < 0.01), residual tissue (r = −0.68, P < 0.01) and sustained juiciness (r = −0.43; P < 0.05). Age-related effects on perceived tenderness were minor in comparison with pH effects. As the pH₂₄ of the meat increased, tenderness (r = −0.46, P < 0.05) and sustained juiciness (r = −0.54, P < 0.05) decreased significantly. No significant linear correlations were observed between the intramuscular fat (IMF) content and the sustained juiciness ratings of the meat. It can be concluded that production region had some influence on sensory characteristics of springbok meat, whilst the influence of age and gender were negligible.     

Temperature shows greater impact on bovine Longissimus dorsi muscle glycogen debranching enzyme activity than does salt concentration

The degradation of glycogen progresses by the co-operation of two enzymes: glycogen phosphorylase (phosphorylase) and glycogen debranching enzyme (GDE). We studied the effect of temperature (4–42 °C) and salt concentration (0–3% NaCl) on bovine M. longissimus dorsi GDE activity. GDE activity (n = 4) decreased significantly with decreasing temperature from about 40–4 °C. GDE exhibited 52% activity at 25 °C and 11% at 4 °C compared to its optimum activity measured at 39 °C. In rapidly chilled meat, the reduction in GDE activity may substantially delay the rate of glycolysis. However, residual GDE activity at 4 °C seems sufficient to enable the attainment of normal ultimate pH if the available time is long enough. An increase in salt concentration from 0% to 2% and to 3% induced a significant (P < 0.001) increase in the ultimate pH of ground bovine meat (n = 6), but showed no effect on GDE activity.     

Nutritional profile of restructured beef steak with added walnuts

Amino acid, fatty acid profile, cholesterol, vitamin E and mineral contents were assessed in restructured beef steak with 20% added walnut (20W). Compared with control restructured beef steak (0% added walnut), the product with added walnut presented a lower (P < 0.05) lysine/arginine ratio, larger (P < 0.05) quantities (mg/100 g product) of monounsaturated (MUFA) and n3 polyunsaturated (PUFA) fatty acids (mainly -linolenic acid), a lower (P < 0.05) n6/n3 PUFA ratio and a higher (P < 0.05) polyunsaturated/saturated fatty acid ratio. The replacement of raw meat material by walnut reduced (P < 0.05) the cholesterol content and increased (more than 400 times) the amount of γ-tocopherol. Iron, calcium, magnesium and manganese contents of 20W sample were greater (P < 0.05) than in the control. Some changes induced by added walnut in the nutritional quality of the restructured product may present health benefits.     

The effect of production system and age on concentrations of fatty acids in intramuscular fat of the longissimus and triceps brachii muscles of Angus-cross heifers

The concentrations of fatty acids were measured in intramuscular fat from the longissimus lumborum (LL) and triceps brachii (TB) muscles of Angus-cross heifers finished either on a high-concentrate ration in Washington, USA, (US cattle, n = 15) or on pasture in New Zealand (NZ cattle, n = 16). Half of the NZ cattle were of a similar age to the US cattle (NZAge) and half were of a similar weight (NZWt). Intramuscular fat levels were higher for the LL muscle and for the US cattle but only within the LL muscle (P < 0.05). Aspects of the fatty-acid patterns that are of relevance to human nutrition tended to favour the pasture-finished NZ cattle with lower n − 6/n − 3 fatty acid ratios (P < 0.001), higher concentrations of an anticarcinogenic conjugated linoleic acid (C18:2 c9,t11) (P < 0.05) and its precursor (trans-vaccenic acid, TVA) (P < 0.01), and lower levels of the 18-carbon trans monounsaturated fatty acids other than TVA (P < 0.01). Concentrations of 20 of the 22 fatty acids analysed differed significantly between the two muscles. When values were adjusted to a common intramuscular fat level by covariance, most of the group differences remained, but a number of the muscle differences became non-significant. For almost half the fatty acids considered, there was a significant interaction between treatment group and muscle, which indicates that the results for one muscle do not necessarily apply to other muscles, although the ranking of the groups was usually the same for both muscles.     

Irradiation effect on fatty acid composition and conjugated linoleic acid isomers in frozen lamb meat

The effect of gamma radiation processing on the lipid content, fatty acid composition and conjugated linoleic acid (CLA) profile in frozen lamb meat was investigated. Samples of longissimus thoracis muscle from lambs fed lucerne basal diets either unsupplemented or supplemented with polyunsaturated vegetable oils were irradiated (7 kGy) and analysed. CLA contents in lamb meat did not affect (P > 0.05) the levels of lipid oxidation induced by the irradiation. No significant differences (P > 0.05) were observed for fatty acid composition, related nutritional indexes (n − 6/n − 3 and PUFA/SFA), as well as for total lipid and CLA contents, between non-irradiated (control) and irradiated meat samples. In contrast, meat irradiation affected the relative proportions of total trans, trans and cis/trans CLA isomers (P < 0.001), in addition to the percentage of some minor individual CLA isomers (t11, t13 and t9, t11, with P < 0.05 and P < 0.001, respectively). The percentage of total cis/trans CLA isomers slightly decreased in irradiated samples, while the relative proportion of total trans, trans isomers slightly increased. This observation may be explained by the higher susceptibility to autoxidation of the cis double bond relative to the trans configuration.     

Chemical, physical and sensory properties of meat from pure and crossbred Podolian bulls at different ageing times

The present study aimed to investigate the effect of crossbreeding with Limousine sires on fatty acid profile, physical and sensory properties of meat produced by Podolian young bulls. Polyunsaturated fatty acid content was influenced by crossbreeding (P < 0.01) with Podolian bulls (P) producing beef characterised by a higher level of unsaturation in comparison with crossbred animals (LP). As a consequence, P/S ratio was significantly higher in meat produced by P animals than LP (P < 0.01). P animals had higher linoleic (P < 0.05), linolenic (P < 0.05), EPA (P < 0.05) and DHA acids (P < 0.001) levels than LP subjects. No breed effect was observed for the ratio n − 6/n − 3 (P > 0.05). WBS force of LD was significantly lower in meat from crossbred subjects (P < 0.05). Both crossbreeding with Limousine and extension of ageing from 2 to 7 days improved LD tenderness as assessed by panel taste (P < 0.001).     

Meat quality characteristics of springbok (Antidorcas marsupialis). 2: Chemical composition of springbok meat as influenced by age, gender and production region

The effects of age, gender and production region on the chemical, mineral and amino acid composition of the M. longissimus dorsi (LD) muscle of springbok were investigated. There was a significant gender^*region interaction for protein content – for the four production regions it varied between 18.80 and 21.16 g/100 g. The intramuscular fat (IMF) content of the LD muscle varied between 1.32 and 3.46 g/100 g. Females (3.13 ± 0.28 g/100 g) had a higher (P < 0.05) fat content than males (1.35 ± 0.08 g/100 g). The IMF content of the adult (2.45 ± 0.26 g/100 g) and sub-adult (2.50 ± 0.28 g/100 g) categories was higher (P < 0.05) in comparison to that of the lambs (1.32 ± 0.11 g/100 g). An inverse correlation was noted between the IMF and moisture content (r = −0.49, P < 0.001) of the meat. The two main amino acids were glutamic and aspartic acid, which contributed 2.47–2.74 and 2.31–2.54 g/100 g of dry matter, respectively. Phosphorous was the predominant mineral in the LD muscle (122.92–159.78 mg/100 g of dry matter), followed by potassium (119.44–131.25 mg/100 g of dry matter) and calcium (6.57–145.18 mg/100 g of dry matter). Production region had a significant effect on the mineral and amino acid composition of the meat, while the effects of age and gender were found to be insignificant.     

Influence of dietary inclusion level of manganese on pork quality during retail display

Boneless pork loins (n = 112) were used to test the influence of dietary manganese (Mn) inclusion level on pork quality traits during retail display. Crossbred barrows and gilts were fed diets formulated with 0, 20, 40, 80, 160, or 320 ppm Mn from Availa^®Mn (AvMn; a Mn–amino acid complex) from 23.8 to 106.8 kg live weight. At approximately 48 h postmortem, boneless pork loins were fabricated into longissimus thoracis et lumborum (LM) chops, which were subsequently placed in open-topped, coffin-chest display cases (2.6 °C) under continuous warm-white, fluorescent lighting (1600 lx) for 7 days. Dietary Mn level had no effect on LM pH (P = 0.47), purge volume (P = 0.60) and loss (P = 0.53), or moisture loss (P = 0.95) during retail display. Chops from pigs fed 80 ppm Mn received higher (P < 0.05) American and Japanese color scores than pigs fed 0 and 40 ppm Mn. Even though the LM from pigs fed 80, 160, and 320 ppm Mn tended to be darker (lower L^* values; P = 0.07) than chops from pigs fed 40 ppm Mn, a^* (redness) and b^* (yellowness) values, as well as hue angle and chroma, were not (P  0.19) affected by dietary Mn. On days 0 and 1, the reflectance ratio of 630 nm/580 nm was similar (P > 0.05) among dietary Mn supplementation levels; yet, by day 4 of retail display, chops from pigs fed 80 ppm Mn had higher (P < 0.05) reflectance ratios than chops from pigs fed 0, 20, 40, and 160 ppm, whereas LM chops from pigs fed 40 ppm Mn had lower (P < 0.05) reflectance ratios than all other dietary treatments on day 7 (Mn supplementation level × display day; P = 0.04). Although TBARS were greater (P < 0.001) on day 7 than 0 of retail display, TBARS values did not (P = 0.43) differ among dietary Mn levels. Results indicate that supplementing swine diets with 80 ppm Mn may improve pork color during retail display without increasing the likelihood of lipid oxidation.     

Prediction of intramuscular fat by impedance spectroscopy

Multiple multi-frequency impedance measurements during the computer controlled passage of a probe through the M. longissimus dorsi in pork and beef were applied. It was expected that the variability in impedance would correlate with the intramuscular fat (IMF) due to the inhomogeneous distribution of electrolytes and fat. We conducted our experiments in pig carcasses at different, well defined times post-mortem in varying directions of puncture (Experiment 1) and predicted the intramuscular fat in pork and beef by regression (Experiment 2). The highest correlations were obtained in experiment 1 for parameters characterising the variability of the impedance 24 h post-mortem and insertion of the probe through the back fat and muscle towards the body cavity (r = 0.54–0.79, P < 0.001). Both of these were chosen for the measurements in experiment 2. Regression for the prediction of IMF in pork and beef in experiment 2 resulted in R² values of 0.12 and 0.48, respectively; and in RMSE values of 0.67 and 0.64, respectively. The correlation between the predicted and the IMF analysed by n-hexane extraction or Near Infrared Transmission varied from 0.28 to 0.69 (P < 0.001) depending on species and breed. A selection of the carcasses for high IMF (above a certain threshold) using the impedance measurements agreed poorly with the analysed IMF. Depending on the level of IMF within a breed, low IMF contents were often over-predicted (3.4–92.7%) or high IMF contents were estimated as too low (0–80.9%). Breed specific regression equations could improve the accuracy. These data indicate that the selectivity of the impedance method in the configuration presented here is not yet sufficient for practical use.     

Effect of dietary ractopamine on tenderness and postmortem protein degradation of pork muscle

Twenty-four finishing pigs with a mean starting weight of 82 kg were assigned to two dietary regimens: (1) a corn–soybean meal basal diet (control; n = 12), and (2) the basal diet supplemented with 20 ppm ractopamine HCl (RAC; n = 12). After 28–30 days on the feeding trial, pigs were slaughtered, and the growth and carcass characteristics were measured. Furthermore, the 3rd–13th rib section of longissimus muscle was excised at 48 h postmortem, sliced into 19-mm thick chops, vacuum packaged, stored at 2 °C, and subjected to Warner–Bratzler shear force (WBSF) and electrophoretic tests after 2, 4, 7, 10, 14, and 21 days (postmortem). RAC feeding increased (P < 0.01) pig carcass weight and percent lean, but it also increased the day-2 muscle WBSF by 20% (P < 0.01). The shear force difference between control and RAC pig muscles gradually decreased and vanished by day 10 (P > 0.05) when both muscle groups became more tender. The muscle from RAC-fed pigs exhibited a slower protein degradation rate than muscle from the control animals, notably for proteins in the 15–45 kDa range. The results suggested that the tenderness difference between ractopamine-treated and control pig muscles was related to the proteolysis rate, and could be diminished with adequate postmortem ageing.     

Influences of dietary conjugated linoleic acid (CLA) and total lysine content on growth, carcass characteristics and meat quality of heavy pigs

To assess the effects of dietary CLA, lysine and sex on performance, blood metabolites, carcass characteristics, meat quality and skeletal development, seventy-two pigs (initially 105.3 ± 6.6 kg live weight) barrows and gilts, were assigned to one of four diets in a 2 × 2 × 2 factorial arrangement. The diets contained 0% or 0.75% CLA, and 0% or 0.16% of l-lysine–HCl. All pigs were slaughtered at an average weight of 153.4 ± 11.0 kg. Neither CLA nor lysine supplementation influenced growth, blood metabolites or carcass characteristics. CLA reduced (P < 0.05) pH₂₄ and increased (P < 0.01) yellowness (b^*) of the Longissimus muscle. Lysine increased (P < 0.01) pH₂₄ and reduced (P < 0.01) muscle ash content. CLA reduced (P < 0.05) collagen synthesis, and lysine increased (P < 0.05) collagen synthesis in Longissimus muscle, but no influence on intramuscular collagen maturity or muscle hydroxylysylpyridinoline crosslink concentration were observed. In addition, metacarpal bone diameter was reduced (P < 0.05) by CLA. Barrows had higher ADG, final weight (P < 0.01), carcass weight, lean percentage (P < 0.05), serum cholesterol (P < 0.05) and triacylglycerol (P < 0.001) than gilts. Metatarsal diameter was larger in gilts than barrows (P < 0.05).     

The effects of antioxidant combinations on color and lipid oxidation in n-3 oil fortified ground beef patties

This study was carried out to determine an effective combination of chelators, reductants and free radical scavengers for enhancing color stability and minimizing lipid oxidation in muscle foods fortified with n − 3 fatty acids. Chelators (sodium tripolyphosphate, STPP; sodium citrate, CIT), reductants (sodium erythorbate, ERY) and radical scavengers (butylhydroxyanisole, BHA; mixed tocopherols from two different sources, 30 or 95TOC; rosemary extract, ROSE) were incorporated in various combinations into ground beef (15% fat) with or without n − 3 oil fortification (n = 8). Individually, STPP and CIT had no significant effect on a* values except day 4, but showed higher a* values when combined with ERY (STPP + ERY and CIT + ERY) (P < 0.05). CIT had lower hue angle values than STPP on days 4 and 6, but CIT + ERY showed more discoloration than STPP + ERY (P < 0.05). CIT + ERY showed less lipid oxidation than CIT alone (P < 0.05), whereas there was no difference between STPP and STPP + ERY. CIT + ERY + ROSE demonstrated higher a* values than CIT + ERY + 95TOC on days 4 and 6 (P < 0.05); there was no difference between ROSE and 95TOC groups when n − 3 oil was incorporated into ground beef patties (P > 0.05). The combination of ROSE and ERY appeared to be effective in slowing the decline of a* values. All antioxidant combinations were effective at delaying lipid oxidation when compared to CON or n − 3. A combination of CIT, ERY and ROSE was most effective for stabilizing color and delaying lipid oxidation.     

Sodium chloride levels in comminuted chicken muscle in relation to processing characteristics and Fresnel reflectance detected with a polarimetric probe

Increasing NaCl from 0 to 2% in comminuted samples of chicken breast meat increased the resistance to compression of cooked samples (r=0.98, p < 0.001), increased water-holding capacity (r=0.95, p < 0.001), decreased cooking losses (r=−0.97, p < 0.001) and decreased paleness (L^*) before and after cooking (r = −0.96 and r=−0.99, respectively, p < 0.001). The decrease in paleness caused by NaCl was associated with an increase in the relative amount of reflected light maintaining its original plane of polarisation, so that NaCl% was correlated with an extinction coefficient for polarised light, r=0.91, p < 0.001. A possible explanation is that myofibrillar proteins may have been dissolved at high levels of NaCl, thus reducing light scattering by myofibrils and allowing more Fresnel reflectance to be detected.