Measuring pork color: effects of bloom time, muscle, pH and relationship to instrumental parameters

To evaluate factors affecting pork color, the gluteus medius (GM), longissimus lumborumetthoracis (LT), semimembranosus (SM), biceps femoris (BF), and triceps brachii (TRI) muscles from pork carcasses of varying ultimate pHs were allowed to bloom for 30 min. L*, a*, and b* values, hue angle, chroma and visual color were determined. Color was evaluated using HunterLab (illuminants A, C, D(65) and F) and Minolta (illuminants C and D(65)) Spectrocolorimeters. LT had the highest L* value (51.31; TR=39.93) and hue angle (59.36; TR=46.94), and the lowest a* (7.52; TR=12.88) value. L* value was unaffected by bloom time; hue angle stabilized after 5 min, a* and b* values after 10 min and chroma after 20 min. Using the Minolta/illuminant D65, visual color best correlated with b* and L* values (r=-0.94 and -0.89) of LT. Using the Hunter/illuminant C, visual color correlated with L* value of LT, GM, BF and SM (r >-0.90 for each). Overall, the instrumental measure that best related to visual color was L* value.     

Factors associated with surface iridescence in fresh beef

The objective of this study was to investigate factors associated with surface iridescence in fresh beef. Eight muscles were evaluated for occurrence of surface iridescence: Biceps femoris (BF), Gluteus medius (GM), Longissimus lumborum (LD), Psoas major (PM), Rectus femoris (RF), Semimembranosus (SM), Semitendinosus (ST), and Tensor fasciae latae (TF). Incidence of surface iridescence was 91% for ST, 34% for SM, 27% for LD, 20% for GM, 12% for RF, 9% for BF, 8% for TF, and 6% for PM (P<0.05). Factors associated with surface iridescence in the ST were further examined because iridescence was observed to a much higher degree in the ST as compared with other muscles evaluated. Greater ST surface iridescence was associated with larger ribeye areas, more youthful lean maturity scores, higher L^*, a^* and b^* colorimeter values, lower ultimate pH values, and faster cooking (P<0.05).     

RELATIONSHIP OF CHILLING RATE AND LOCATION WITHIN MUSCLE ON THE QUALITY OF HAM AND LOIN MUSCLES

Halothane negative Durocs (n=36) were slaughtered, and subjected to: accelerated chill (AC: −30C for 2 h, with air circulation, followed by equilibration at 4C for 20–22 h), conventional chill (CC: 4C for 22–24 h with water sprayed every 2 h until 12 h postmortem), and slow chill (SC: 10–12C for 12 h followed by equilibration at 4C for 10–12 h). Color, pH, and drip loss were determined for the Semimembranosus (SM) Biceps femoris (BF) , Longissimus thoracis (LT), and Longissimus lumborum ( LL). In the ham muscles, AC decreased b* values and drip loss. Decreased drip loss was restricted to the outer sites. Ham muscles were darkest in the mid location and lightest in the inner locations. In the Longissimus, AC decreased pH but did not affect color or drip loss. Compared to SC, AC proved beneficial, however, AC had no advantages over CC in pigs with minimal predisposition to quality problems.     

Performance of Cinta Senese pigs and their crosses with Large White 2. Physical, chemical and technological traits of Tuscan dry-cured ham

Technological, chemical and physical traits of cured ham from Cinta Senese and Large White pigs, and their crosses were investigated. Hams were obtained from 29 Cinta Senese (CS), 29 Large White × Cinta Senese (LW × CS) and 12 Large White (LW) pigs, fed a commercial mixture. Sensory and chemical–physical analysis was performed on a sample-slice and on muscles (Biceps femoris – BF; Semimembranosus – SM; Semitendinosus – ST) and subcutaneous fat. CS showed the highest trimming loss and the lowest salting loss. Hams of CS pigs scored higher for fatness than those of LW pigs, LW × CS showing intermediate values. On sample-slice, CS exhibited higher firmness, redness and marbling of lean, and greater fat extension than LW, with crosses having intermediate scores. Muscle moisture was lowest in CS, while both SM and BF from LW had the highest percentage of protein and the lowest of ash. CS showed higher intramuscular fat content than LW × CS and LW. Shear force of BF was higher in CS than in LW × CS and LW. With respect to LW, CS had lower values of L^* in muscles, and higher values of a^* in subcutaneous fat. Subcutaneous fat of CS contained less SFA and more MUFA than LW × CS and LW.     

CHARACTERIZATION OF THE DIFFERENT STATES OF MYOGLOBIN IN PORK USING COLOR PARAMETERS AND REFLECTANCE RATIOS

Because color is becoming more important to the food industry, color studies are being conducted to improve the control of both raw materials and processes. Several studies have pointed to the importance of the different states of myoglobin in determining the color changes which take place during processing. The aim of this study was to characterize the color parameters (CIE LAB coordinates, reflectance spectrum and reflectance ratios) of the three myoglobin forms (deoxymyoglobin, oxymyoglobin and metmyoglobin) in pork Subscapularis muscle. The deoxymyoglobin present in fresh pork lean meat was converted into the pure states, and color parameters (lightness, redness, yellowness, hue, chroma and a*/b* ratio), reflectance spectrum (400–700 nm) and reflectance ratios (R560/R500, R650/R570, R630/R580 and R630-R580) were obtained. All the color parameters and reflectance ratios (except redness values) varied according to the state of the myoglobin.     

EFFECT OF ULTIMATE pH UPON THE WATER-HOLDING CAPACITY AND TENDERNESS OF MUTTON

SUMMARY— Ultimate pH values in the musculature of sheep ranging from 5.6–7.0 have been obtained by using pre-slaughter injections of epinephrine. A high speed centrifugal method was used to measure the water-holding capacity of raw M. semitendinosus (ST), semimembranosus (SM) and biceps femoris (BF). Results showed a high correlation with ultimate pH. Cooking losses end the amounts of centrifugally expressed juice were determined for the SM and BF cooked for 1 hr at either 65°C or 90°C. Cooking losses at 65°C decreased linearly with increasing pH while the losses at 90°C showed little change up to o raw meat pH of ca. 5.9, then decreased linearly with increasing pH. The amount of juice centrifugally expressed from the cooked meat, which has a high positive correlations with organoleptic juiciness, increased linearly with pH. Tenderness of the cooked SM and BF muscles was measured using o Warner-Bratzler shearing device and an Instron Universal Testing Machine: both gave high objective-subjective correlations. Instron measurements have high negative linear correlations with ultimate pH for both the 65°C and 90°C cooked samples. Hardness of these muscles, cooked at 65°C or 90°C. decreased approximately three-fold as ultimate pH increased from 5.6–6.9. Results obtained using the Warner-Bratzler device showed linear regressions with a significant quadratic component for one muscle at both 65°C and 90°C.     

Initial chilling rate of pre-rigor beef muscles as an indicator of colour of thawed meat

The effect of three rigor temperatures and two muscles of different fibre composition on the colour of thawed meat were determined. Within 45 min post-mortem, m. semitendinosus (ST) and m. biceps femoris (BF) from unstimulated heifer sides were held at 0, 10 and 35°C until they entered rigor. The rate of pH fall was higher at 35°C than at 0 and 10°C; and the pH values were lower (first 12 h post mortem) in the ST than the BF. Hunter L*, a* and b* and the hue angle increased with increasing rigor temperature (P<0.001). The ST was lighter and yellower and had greater hue angle than the BF. Colour parameters were plotted against the rate of muscle cooling in the first hour post mortem and linear regression lines were fitted to the data and equations were derived that gave a good indication of the colour and colour stability of the muscles as meat.     

Chemical composition,quality and histochemical characteristics of individual dromedary camel (Camelus dromedarius) muscles

This study characterized the chemical composition, quality and histological traits of six muscles from 10 dromedary carcasses. There were significant differences in moisture, fat, protein, mineral, saturated and unsaturated fatty acid contents between muscles. The longissimus thoracis (LT) had the highest cooking loss (33.5%) and triceps brachii (TB) the lowest (29.2%). The shear force value of semitendinosus (ST), semimembranosus (SM) and biceps femoris (BF) were significantly higher than infraspinatus (IS), TB and LT. The LT had significantly higher values for L*, a*, b* than ST. The SM had the lowest MFI (65.3), while IS had the highest value (75.8). The ST significantly had the highest and lowest proportions of Type I and Type IIA muscle fibers, respectively than other muscles. This study indicated that composition, quality, and histochemical parameters varied among camel muscles and the knowledge of this variation allows for better marketing and processing of camel meat.     

CHEMICAL AND COLOR CHARACTERISTICS OF "LOMO EMBUCHADO" DURING SALTING SEASONING

"Lomo embuchado" is a traditional Spanish dry-cured meat product with two principal stages (salting-seasoning and dry-maturation) in its process. The evolution of chemical (moisture, nitrite, pH and lactic acid) and physical parameters: (CIELAB color space, chroma and hue, a*/b*, ΔE* and reflectance ratios R560/R500, R650/R570 and R630/RS80), during the salting-seasoning stage were measured. Three zones in the salted-seasoned loins were identified, and all parameters in each zone were analyzed. ANOVA and regression analyses were conducted. Moisture, pH and residual nitrite decreased with time (P<0.01), and lactic acid increased (P<0.05). Only moisture showed differences between zones (P<0.05). Color parameters changed during the salting-seasoning stage. Lightness (P<0.01), redness (only during the first 24 h (P<0.05)), and a*/b* ratio (P<0.01) increased. Yellowness (P<0.01), hue (P<0.01) and chroma (P<0.05) decreased during the process. The only parameter that was not affected by time and zone was reflectance ratio R630/R580 (P>0.05). Moisture and reflectance ratio R560/R500 were affected by zones (PCO.05). An excellent cured color was obtained during salting and seasoning.     

DIFFERENCES IN THE RATE OF COLORATION IN TOMATO FRUIT

The evolution of fruit color of twelve tomato (Lycopersicon esculentum Mill.) cultivars during ripening was evaluated. Final color of each of the cultivars was determined by calculating its fresh tomato color index (TCI_f). Luminosity (L*), red-green component (a*), a*/b* ratio, hue angle (h*), dominant wavelength (DW) and fresh tomato color index (TCI_f) were the parameters that best differentiated the ripening stages of tomato fruit. Dominant wavelength and purity of excitation were correlated with a* and b*. Fresh tomato color index (TCI_f) was related to the luminosity (L*) and yellow-blue component (b*).     

Moisture diffusivity in the lean tissue of dry-cured ham at different process times

The aim of this study was to determine the effective moisture diffusivity coefficient (D(e)) during dry-cured ham processing in two muscles, an internal one (Biceps femoris, BF) and an external one (Semimembranosus, SM), at different temperatures. Two adjacent samples, which included both SM and BF muscles, were selected after salting (PS), after resting (PR), after 4 months of drying (D1) and at the end of the process (D2). One was used to determine the initial profiles of moisture and NaCl/moisture and the other to determine D(e) at different temperatures (1 and 5°C in PS; 5 and 12°C in PR; 12, 19 and 26°C in D1; 19 and 33°C in D2). D(e) was higher in the muscle with the higher moisture content (BF) except in PS and PR, where a gradient of NaCl/moisture ratio was observed in SM muscle. There was a positive effect of temperature on D(e), but it decreased during processing of the dry-cured ham. A simple diffusive model, with a unique and constant moisture diffusivity coefficient or with a coefficient depending only on temperature, does not explain the whole drying process correctly. The effects of moisture content and the gradient of NaCl/moisture ratio on D(e) have to be considered.     

Optimization of instrumental colour analysis in dry-cured ham

Colour of dry cured ham was measured by instrumental techniques in order to determine the optimum measurement index. Five different colour systems were used: CIE L(?)a(?)b(?), Hunter Lab, CIE L(?)u(?)v(?), xyY and XYZ, each with illuminants D65, C and A, and with both 10 and 2° observer angles. Measurements were taken in both Semimembranosus (SM) and Biceps femoris (BF) muscles. Hunter Lab system with illuminant A gave the most reproducible results within muscles for the three colour parameters evaluated. A further comparison of results obtained with 10 and 2° observer angles of Hunter Lab with illuminant A showed there were no significant differences between the angles. Significant differences between results from SM and BF muscles were found in all the hams, the BF always showing higher values than SM for every colour parameter.     

Thermal transition of collagen in ovine connective tissues

The thermal transition temperature (T(m)) of collagen in a range of muscle and non-muscle connective tissues from lambs, hoggets and mature sheep was measured by differential scanning calorimetry. The muscles selected were: semimembranosus (SM), semitendinosus (ST), biceps femoris (BF), Longissimus dorsi (LD) and psoas major (PM). Although the T(m) of intramuscular SM collagen from an aged ewe underwent no significant change with time post mortem, that of a 5-months-old lamb had dropped by 0·9°C after 2 days at 19°C. The epimysium of each muscle exhibited a higher T(m) than the corresponding intramuscular connective tissue. The LD and BF tendons each had a lower T(m) than corresponding intramuscular connective tissue but this was not true for the PM. Furthermore, the PM tendon generated an isometric tension more than five times that of the LD, BF or psoas minor tendons. This indicates that the PM tendon is richer in heatstable crosslinks than any of the other tendons investigated. In all tissues, except the liver capsule, there was an increase in T(m) with animal age. However, the rate of change T(m) varied from one tissue to another. For example, the SM intramuscular collagen matured at an earlier age than that of other muscles, the PM being slowest to mature. In keeping with the changes in T(m) values, the Warner-Bratzler peak force of ST muscles increased markedly in older sheep, but there was no significant difference in peak force of SM muscles between lambs, hoggets and mature sheep.     

Effect of moisture content on CIE color values in dried apricots

The color change in dried apricots at various moisture contents was studied. Dried apricots originally at 19.32% moisture were first dried to 15.49% and then rehydrated to 20.10%, 25.21% and finally 30.20% moisture levels. The CIE L*, a*, and b* color variables were measured to determine the color of dried apricots, and C* (chroma) and h* (hue) values were calculated from a* and b* values. A linear relationship was found between the color variables and moisture contents at 15.49-30.20%. As the moisture content increased, the L* (lightness), b* (yellowness), C* and h* color values increased while the a* (redness) value decreased for the dried apricots at all moisture levels. Results showed that the moisture content of dried fruits should be specified once the reflectance color variables are reported.     

Quality attributes and color characteristics in three-piece boneless hams

One hundred and fifty hams were selected on visual assessment of quality into normal (C) and two-tone (TT) groups. CIE LAB color and pH measurements were collected at the plant 48 h postmortem on the gluteus medius (GM), gluteus profundus (GP), and rectus femoris (RF), and again at 72 h on the semimembranosus (SM), biceps femoris (BF), semitendinosus (ST), and RF. Data were analyzed using GLM procedures of SAS, and correlations between color scores, pH, and drip loss were calculated. Plant and fabrication pH were lower (P < 0.01) in GM from TT hams compared with C. Muscles from TT hams had lower (P < 0.01) L* and a* values compared with C. The GM L* and GM pH values were correlated (P < 0.05) with L* values for all other muscles and drip loss in SM. These data show that GM color and pH are accurate predictors of pork quality attributes in the muscles of a three-piece boneless ham.     

USE OF MECHANICAL TENDERIZATION TO INCREASE THE TENDERNESS OF BULLOCK BEEF1

The biceps femoris (BF), semimembranosus (SM) and longissimus dorsi (LD) muscles from bullocks and steers were passed through a mechnical tenderizer zero (OX), once (1X), twice (2X) or three times (3X). All three muscles were evaluated for cooking loss, cooking time and textural properties on an Instron Universal Testing machine. In addition, LD muscle steaks were presented to a sensory panel for evaluation. The passing of the SM and LD muscles through a mechanical tenderizer one or two times decreased peak load and fail energy and increased peak elongation and fail load values. LD steaks from bullocks not passed through the mechanical tenderizer (OX) were least esy to fragment, had the most detectable connective tissue and had lowest overall tenderness ratings. Passing bullock beef once (1X) through a mechanical tenderizer improved palatability ratings to a level comparable to untenderized steer beef.     

Influence of repeated restraint and isolation stress and electrolyte administration on carcass quality and muscle electrolyte content of sheep

Crossbred lambs were assigned, within weight blocks, to one of four treatments applied in a 2 × 2 factorial design (n = 6 per treatment). Treatment main effects included no stress (NS) or three consecutive days of restraint and isolation stress (RIS) and treatment with either water (W) or electrolytes (E). The experimental design resulted in four treatments, namely NS-lambs given W, NS-lambs given E, RIS-lambs given W, and RIS-lambs given E. Stress treatment consisted of moving each lamb from its home stanchion to a separate location and isolation from visual and tactile contact with other lambs for 6 hours daily for 3 days before slaughter. All lambs received a 320 ml oral drench of either W or E on each day after the stress treatment. Stress treatment reduced (P < 0·05) semitendinosus (ST) muscle glycogen by 4·8-fold. At 24 h post mortem, muscle pH for semimembranosus (SM), biceps femoris (BF) and infraspinatus (IF) was higher (P < 0·05) in RIS-lambs that in NS-lambs. Hunter L(?)a(?)b(?) values, measured on muscle cross-section, revealed a lighter (P < 0·05) BF; more (P < 0·05) red BF, ST, and longissimus dorsi (LD); and more (P < 0·05) yellow ST, SM, BF, and LD for NS-than for RIS-lambs. Muscle from RIS-lambs contained less (P < 0·05) potassium than that from NS-lambs. Restraint and isolation stress of lambs resulted in a reduction in muscle glycogen, but only slight increases in ultimate pH and minimal influences on muscle color. Administration of electrolytes had no effect on lamb carcass quality.     

Quality attributes of major porcine muscles: A comparison with the Longissimus Lumborum

Quality attributes of the longissimus lumborum (LL) were compared to the attributes of the muscles semimembranosus (SM), rectus femoris (RF), biceps femoris (BF), gluteus medius (GM) and the lateral portion of the semitendinosus (ST) in the ham, the psoas major (PM) in the loin and the supraspinatus (SS), infraspinatus (IS) and triceps brachii (TB) in the shoulder. Carcasses were allocated to quality groups based on measurements of muscle exudate and lightness (CIE-L^*) in the LL. The SM, BF, GM and ST in the ham were similar to the LL (P > 0·05) in meat ultimate pH (pHu) and exudate and the GM, ST and LL were similar (P > 0·05) to the LL in lightness. The TB, RF, SS, PM and IS were similar (P > 0·05) in exudate, lightness and pHu and compared to the LL, were less exudative (P < 0·05) and darker (P < 0·05). When the LL was classed pale, and exudative, the GM, BF, SM and ST were also pale and exudative but the other muscles were darker and non-exudative. When the LL was classed dark and non-exudative, all other muscles were dark, non-exudative and the pHu was high. Therefore, the LL could serve as a reliable indicator of colour and exudate for all porcine musculature when the condition was dark and non-exudative (i.e. DFD). However, when the condition was pale and exudative (i.e. PSE), then the LL would serve as a reliable indicator only for the four major ham muscles, excluding the RF.     

SHEAR PROPERTIES AND WARNER-BRATZLER TENDERNESS MEASUREMENT OF BEEF 1

The shear properties of raw and cooked beef and their relationship with Warner-Bratzler (WB) tenderness measurement were evaluated. Shear tests were performed on four muscles, biceps femoris (BF), longissimus dorsi (LD), semimembranosus (SM), and semitendinosus (ST), with three different aging treatments (0, 1, and 2 weeks), using a specially designed device and the WB shear device. Raw beef exhibited a nonlinear behavior characterized by linearity at small deformations, stress yield at intermediate deformations, and work hardening at large deformations. Cooked beef had a different nonlinear behavior with the slope of the force-displacement curve increasing with displacement before the peak force. Cooking resulted in a large increase (p=0.01) in maximum shear force and strain energy. The effect of muscle type and aging on shear properties was mostly significant (p=0.05). The maximum shear force of cooked beef was correlated with WB measurement with the R² value ranging from 0.65 to 0.34 for LD, SM, and BF except for ST with a R² value of 0.10. Correlations of the shear properties of raw meat with WB measurement were low (R²<0.36), indicating the difficulty of predicting WB tenderness from the shear properties of raw meat.     

Effect of marination and microwave heating on the quality of Semimembranosus and Semitendinosus muscles from Friesian mature cows

Semimembranosus (SM) and Semitendinosus (ST) muscles from 8 mature cows were used to evaluate the effect of marination, power of microwave heating, and internal temperature of cooking on the quality of calibrated beef roasts. Four treatments, using combinations of power (182W and 654W) and temperature (60 and 80°C) were applied to marinated (10% added brine: salt, sodium lactate, lactose, and ascorbate) and control roasts from SM (15×5×3cm) and ST (10×4×3cm) muscles in a 2×2×2 factorial arrangement. Microwave cooking was heterogeneous resulting in a gradient of temperatures within the roasts. Either high or low microwave power were appropriate for cooking ST roasts, but SM roasts cooked at 654W showed higher cooking losses, and lighter and less red cooked color than 182W. Cooking to 80°C increased cooking and color losses in both muscles and decreased tenderness of SM roasts compared with 60°C. Marination can be used successfully to enhance beef tenderness of ST and SM muscles cooked in microwave.