Cooking method and endpoint temperature effects on sensory and color characteristics of pumped pork loin chops

The objective of this study was to evaluate the effects of pumping, cooking method and endpoint temperature on quality of fresh pork chops. The longissimus was removed from 30 paired pork sides. One side was pumped to 110% of original weight (0.4% phosphate, 0.4% salt+added water). Chops were cut (2.5 cm thick) then fried or grilled to 70 or 80 °C. As endpoint temperature increased from 70 to 80 °C, pork flavor increased (P<0.05) from 95 to 104 (on a 150 point scale) for pumped samples but remained constant in unpumped samples. Juiciness decreased when unpumped samples cooked to 80 °C (62) rather than 70 °C (78). Warner–Bratzler shear values were lower (P<0.05) in pumped chops than in unpumped controls. Pork flavor was higher and off-flavor was lower in fried chops. Pumping loins appears to enhance sensory attributes of chops even when cooked to abusive endpoint temperatures with limited detrimental effects on physical characteristics.     

Influence of outdoor rearing and indoor temperature on growth performance, carcass, adipose tissue and muscle traits in pigs, and on the technological and eating quality of dry-cured hams

The effects of restricted outdoor rearing during winter (W) or summer (S), and the influence of indoor ambient temperature [17 °C (I17) vs. 24 °C (I24), the latter being considered as control] on pig growth performance, carcass, muscular and adipose tissue traits, and technological and eating quality of dry-cured hams were evaluated. I17 pigs exhibited higher, whereas W had similar and S lower growth rates than the controls (P<0.001). Carcass traits were not different between groups, except in lower back fat weights of S and W pigs (P<0.01). Decrease in environmental temperature affected the fatty acid composition of the back fat leading to higher MUFA and lower SFA and PUFA contents (P<0.001) in I17 and W pigs, whereas S pigs exhibited higher PUFA levels (P<0.001) and fat firmness (P<0.01) than the controls. Rearing system did not significantly influence the intramuscular fat content of Semimembranosus (P=0.08), and had no effect on ultimate pH. In the Longissimus lumborum, percentage and relative area of R fibers increased in W pigs (P<0.05), but citrate synthase activity did not differ between groups. I17 and W hams exhibited higher processing yields of dry-cured hams than controls (P<0.05). Sensory analyses showed that pig rearing conditions influenced the product appearance, the I17 and W hams exhibiting lower homogeneity (P<0.01) and intensity (P<0.05) of colour, and higher marbling scores (P<0.01) than I24 hams, but had no influence on texture or flavour.     

The influence of season on quality characteristics of hot-boned beef m. longissimus thoracis

Samples of m. longissimus thoracis (LT) muscle were randomly collected from 70 Omani beef cattle 1 h after slaughter between August 2001 and July 2002 in the Muscat Municipality central slaughterhouse to investigate the effect of seasonal parameters on meat quality during the hot and cool seasons of Oman. The collection period (12 months) was divided into two seasons according to ambient temperatures and relative humidity and termed: Cool Season (November–March with average temperature of 21.2±1.40 °C and 57.9±1.61% relative humidity) and Hot Season (April–October with average temperature of 34.3±1.67 °C and 48.8±7.57% relative humidity). The season had a significant effect on meat quality characteristics of the LT muscle. Muscles collected during the hot season had significantly (P<0.001) higher ultimate pH values (6.24) with significantly (P<0.001) lower Warner–Bratzler (WB) shear force values (10.12) than those collected during the cool season (5.54 and 15.58). In these hot-boned samples, there was a linear relationship between ultimate pH and WB shear values. Cooking loss was significantly (P<0.001) higher for cool season samples (26.01%) than from hot season samples (19.75%). Beef from the hot season group had significantly (P<0.001) darker meat than that of the cold season group, based on L* (31.45 vs 35.58), a* (18.53 vs 23.19) and b* (4.16 vs 6.40) colour measurements. There was a linear relationship between ultimate pH and cooking loss, L*, a* and b*. These results indicated that heat stress (>30 °C) lead to physiological stress in beef cattle, which in turn increased muscle ultimate pH and influenced related meat quality characteristics.     

Processing characteristics of beef roasts made from high and normal pH bull inside rounds

The processing characteristics of roasts manufactured from either high or normal pH bull inside rounds (semimembranosus and adductor muscles), which had been stored chilled or frozen, were investigated. Roasts were injected with a salt/phosphate brine and cooked to an internal temperature of 63 °C in a 70 °C water bath. High-pH meat that had been frozen had less purge than normal pH meat. However, pH did not affect purge from chilled meat. Meat pH and storage conditions did not affect retention of pumped brine. Cook yields were significantly (P<0.05) higher for roasts made from high pH meat (103.8 vs 98.8%). Raw and cooked meat colour was affected by meat pH but not storage condition. Cooking reduced the effect of pH on meat colour but cooked roasts manufactured from high pH meat were redder than roasts manufactured from normal pH meat.     

Assessment of breed type and ageing time effects on beef meat quality using two different texture devices

Forty-two male yearlings were used to assess the influence of breed type and ageing time on beef texture. Samples of the M. longissimus dorsi of four breed types [double muscled (DM), dual purpose (Brown Swiss, BS), fast growth (FG) and unimproved type (UT)] were aged for 1, 3, 7, 10, 14 or 21 days at 4°C and frozen at −18°C until analysed. Cooked samples (to end-point of 70°C) were assessed using a Warner–Bratzler (WB) device. Raw samples were assessed using a compression device in which transverse elongation was prevented. There were no significant differences in WB values of cooked meat due to breed type, but ageing had a significant (P<0.05) on maximum load. Ageing, but not breed type, had a significant effect on the compression values of raw meat at low compression rates (P<0.001). Compression values, of raw samples, at 80% compression differed significantly (P<0.001) between breed types, but were not affected by ageing. Compression values of raw samples, at 80% compression, were affected by breed type, probably because of genotype differences in the contribution of connective tissue.     

The effect of post-exsanguination infusion on the composition, exudation, color and post-mortem metabolic changes in lamb

Twenty-four lamb carcasses were assigned to three treatment groups: (1) control (Ctr), (2) infused with 10% (vol/wt) of a tenderizing blend (NCa), and (3) NCa plus 0·015 CaCl₂ (WCa). Results indicated that the infused carcass solution was retained in the following order: shoulder > lion > leg. Infusion had no effect (P > 0·05) on drip and cooking losses in refrigerated samples. Samples frozen and then thawed from infused carcasses had greater thaw drip (P < 0·05) and cooking losses (P < 0·01) than control samples. The amounts of drip and cooking losses were in the order: WCa > NCa > Ctr. Frozen storage preserved the red color but lowered the lightness and yellowness of ovine muscles; the opposite effect was observed following refrigerated storage. Infused samples were lighter and yellower than control in both fresh and frozen samples (P < 0·01). WCa had less red color (P < 0·01) than NCa and Ctr at all times and storage conditions. Infusion lowered (P < 0·05) the temperature of carcasses over the first 3 h postmortem (pm) compared with Ctr. The rate of glycolysis was higher in infraspinatus (IS) than in longissimus thoracis et lumborum muscle (LTL or longissimus). In both IS and LTL, glycolysis was completed within the first 6 h postmortem in NCa, whereas in Ctr and WCa, it took 12–24 h for glycolysis to be completed. The rate of glycolysis was in the order: NCa > WCa > Ctr.     

Nonenzymic browning during storage of white hard grape pekmez (Zile pekmezi)

Effects of storage period on hydroxymethylfurfural, pH and colour were studied in white hard grape pekmez (Zile pekmezi), a Turkish traditional product. Pekmez samples were stored at 20 °C for 8 months. Analysis of variance revealed significant differences in hydroxymethylfurfural, pH, L, a and b values (P<0.01) based on storage time.     

Effect of season on color of Hanwoo (Korean native cattle) beef

A total of 1278 head of Hanwoo (Korean native cattle) slaughtered over four seasons were used to evaluate the effect of season on color characteristics of beef longissimus dorsi (LD) muscle. CIE L^*, a^*, b^*, C^* values and hue angle were significantly lower (P<0.05) in cattle slaughtered in the winter season. Meat color was darker in the winter than in the spring and autumn seasons. The L^* values among three average daily temperature (T_a) categories were different (P<0.05) in order of: [5 °CT_a<25 °C] > [T_a25 °C] > [T_a<5 °C], indicating that the meat color of cattle slaughtered at T_a<5 °C was darker. The a^*, b^*, C^* values and hue angle were significantly lower (P<0.05) in cattle slaughtered at T_a<5 °C. Season at slaughter is of great importance for meat color. Namely, meat color of Hanwoo beef was influenced by environmental temperature. Overall, cattle slaughtered in the winter season of T_a<5 °C produced beef with more undesirable meat color properties.     

Stability of catalase and its potential role in lipid oxidation in meat

The activity of catalase in microbial growth-controlled and uncontrolled ground beef muscle (semimembranosus, SM) did not change (P>0.05) during 6-day storage at 4°C. Likewise, catalase activity in ground, beef SM and longissimus dorsi (LD), pork LD, and chicken breast (B) and thigh (T) muscles was not affected (P>0.05) by 2-month storage at −20°C, with or without mid-month thawing/refreezing. When sodium azide (a catalase inhibitor) was added to ground beef SM, lipid oxidation (as measured by peroxide values) during 4-day refrigeration was higher (P<0.05) in treated samples — 43 and 55% higher at day 2 and day 4, respectively — than in the controls. It was concluded that catalase would be stable during meat storage/distribution and contribute significantly to the antioxidative process in raw meat products.     

Effect of salt and transglutaminase (TG) level and processing conditions on quality characteristics of phosphate-free, cooked, restructured pork shoulder

Six treatments of phosphate-free restructured cooked pork shoulder were produced with two salt levels (2% and 1%) and three transglutaminase levels (0%, 0.075% and 0.15%) under two processing conditions (72 °C/65 min and 78 °C/65 min). Salt level significantly affected (p < 0.05) the chemical composition, the cooking losses, the colour, the sensory attributes and the overall acceptability of the product. Transglutaminase level affected (p < 0.05) only the consistency and the overall acceptability. The processing conditions on the contrary, affected the moisture and the protein content, the cooking losses, the consistency and the juiciness of restructured cooked pork shoulder. Transglutaminase can be used at a level of 0.15% with reduced salt level (1%) and processing at 72 °C/65 min to produce phosphate-free restructured cooked pork shoulder with acceptable sensory attributes.     

Carcass traits, muscle characteristics, and palatability attributes of lambs expressing the callipyge phenotype

Dorset×Suffolk crossbred wethers expressing a normal phenotype (normal, n=10) and callipyge phenotype (CLPG, n=9) were fed individually and slaughtered upon reaching maximum growth potential. Carcass weight did not differ (P>0.05), but fat thickness was lower (0.30 vs. 0.56 cm), ribeye area was greater (24.4 vs. 16.6 cm²), and USDA yield grade was improved (1.6 vs. 2.6) for CLPG carcasses (P < 0.05). Carcasses from CLPG demonstrated higher cutability and a more desirable muscle to bone ratio, with less fat and more lean as a percentage of total side weight (P<0.05). Biceps femoris (BF), semitendinosus (ST), semimembranosus (SM), longissimus thoracis et lumborum (LTL), and triceps brachii (TB) were used to compare muscle characteristics of both phenotypes. Muscle from normal lambs had lower calpastatin activity, higher fat percentages and lower moisture percentages (P<0.05). Total amount and solubility of collagen were not affected by phenotype nor was sarcomere length. Shear force and trained sensory attributes were evaluated for BF and LTL only. Shear force values did not differ between normal and CLPG BF while CLPG LTL had higher (P< 0.05) shear force values than normal LTL. Biceps femoris did not differ between phenotypes in trained sensory panel ratings. However, CLPG LTL received the lowest sensory ratings for connective tissue amount and myofibrillar and overall tenderness (6.11, 4.97, and 4.95, respectively) and the normal LTL received the highest ratings (P < 0.05; 7.10, 7.00, and 6.90, respectively). The CLPG phenotype had a positive influence on carcass characteristics but had a negative influence on tenderness of some muscles, possibly through the myofibrillar component of the muscle.     

Quality properties of pork sausage prepared with water-soluble chitosan oligomer

Emulsion type sausage was prepared with the addition of a chitosan oligomer (molecular weight 5000, 0.2%) and compared to a control. Sausages were aerobic- or vacuum-packaged and stored in a 4°C refrigerator for 3 weeks. Difference of microbial growth between the sample with added chitosan oligomer or control was not observed (P>0.05). Lipid oxidation was lower in the sausage with chitosan oligomer at 3 weeks in aerobic packaging (P<0.05) than in the control sausage. The surface color of the sausage with chitosan oligomer had higher Hunter color L*- and b*-value. Hunter color a*-values were lower in the chitosan oligomer-added sausage and the a*-value increased during storage regardless of packaging (P<0.05). Sensory panels did not detect any difference in color, flavor, texture, and overall acceptance, and mechanical texture analysis also showed no difference. Therefore, the quality of the sausage with added chitosan oligomer (0.2%) was acceptable.     

Positional distribution of fatty acids in triacylglycerols from subcutaneous adipose tissue of pigs fed diets enriched with conjugated linoleic acid, corn oil, or beef tallow

This study was conducted to determine the effects of dietary beef tallow, corn oil, and conjugated linoleic acid (CLA) on the distribution of fatty acids among positions within triacylglycerols. Crossbred barrows (n=6 per treatment group) received diets containing 1.5% beef tallow, 1.5% corn oil, or 1.5% CLA for 5 weeks. Subcutaneous adipose tissue samples were obtained immediately postmortem. The fatty acid composition was determined for the sn-2 positions of the triacylglycerols by digestion with Rhizopus arrhizus lipase. Fatty acids in the sn-1/3 position were calculated from these data. Feeding CLA increased (P<0.05) the concentration of total saturated fatty acids (SFA, especially 16:0) and isomers of CLA in adipose tissue lipids, but reduced (P<0.05) the concentration of total monounsaturated fatty acids (MUFA, especially 18:1n−9). Dietary CLA caused an accumulation of total SFA in the sn-1/3 position, with a proportional decrease in total MUFA and 18:2n−6 in the outer positions. Correspondingly, lipids extracted from CLA-fed pigs had slip points that were 10 °C higher (P<0.05) than those from corn oil- or tallow-fed pigs. These data suggest that dietary CLA increases the melting point of lipids in porcine adipose tissue by increasing the proportion of SFA at the sn-1/3 position of lipids.     

Studies of plasmin activity in whey

The presence of the indigenous milk alkaline proteinase, plasmin, in whey products may adversely affect the quality of food products that utilise such ingredients; factors promoting the release of plasmin into whey were therefore investigated. Acidification of pasteurised skim milk (PSM) with glucono-δ-lactone (GDL) or HCl resulted in acid whey with significantly higher (P<0.05) plasmin activity than PSM. Plasmin activity in such whey was inversely correlated with rate of acidification; thus, activity in the whey made with GDL was significantly higher (P<0.05) than in whey made with HCl. Negligible levels of plasminogen in acid whey suggested that activation of the zymogen, plasminogen, contributed to the elevated plasmin activity observed. Sweet whey, manufactured by addition of rennet to PSM, had plasmin and plasminogen-derived activities significantly lower (P<0.001) than those in PSM; the release of plasmin from renneted casein micelles into whey increased in a linear manner with cooking temperature in the range 45–65°C. However, dissociation of plasmin from casein micelles into acid whey reached a maximum at a cooking temperature of 50°C. Analysis of plasmin and plasminogen levels in ultracentrifugal supernatants of pH-adjusted milk indicated that plasmin was released from the micelles at pH>5.0, while plasminogen was released more gradually over the pH range 6.6–4.6. Overall, the technology of manufacture has significant implications for plasmin activity in whey and hence, inversely, for casein products and cheese.     

Effect of selection for growth rate on biochemical, quality and texture characteristics of meat from rabbits

Biochemical characteristics, including myosin heavy chain I (MHC-I) percentage, isocitrate dehydrogenase and aldolase activities, meat quality traits and instrumental texture properties of rabbits selected for different growth rates were studied. The animals of the control (C) group (7th generation; n=60) were raised in parallel with those of selection (S) group (21st generation; n=60). Carcass weights (1230.1 ± 19.8 and 1348.3 ± 20.1 g, for C and S, respectively) and perirenal and scapular fat content differed significantly (P<0.01) between the two groups. Water holding capacity was expressed as the percentage of pressure released water and was significantly different (P<0.05) between groups C and S (33.29% and 35.57%). MHC-I percentage and aldolase activity also differed significantly (P<0.05) between groups, group C showing higher oxidative traits than group S (MHC-I: 12.5% and 9.8%; aldolase: 597.11 and 636.83 UI/g muscle). Texture properties from the Warner-Bratzler test showed higher (P<0.001) shear firmness for loin in the S group (1.69 kg/s cm²) than in the C group (1.34 kg/s cm²). In addition, the texture profile analysis indicated that chewiness, gumminess and hardness were also higher in the S group (P<0.01). In conclusion, the results confirmed a positive effect of the selection on productive traits and a negative effect on instrumental texture properties and on the water holding capacity of the meat.     

Physicochemical and sensory characteristics of restructured beef steak with added walnuts

The effects of different proportions (0, 5, 10, 15%) of added walnuts on the physicochemical and sensory characteristics of restructured beef steak were evaluated. The addition of 10 and 15% walnut reduced (P<0.05) cooking loss. Increasing proportions of walnut in the beef steak increased (P<0.05) water binding and reduced (P<0.05) fat binding properties. The addition of walnut did not affect (P>0.05) textural properties in uncooked restructured beef steak, but in cooked products Kramer shear force and bind strength were reduced (P<0.05) when 10% or more of walnut was added. Product morphology characteristics suggest that walnut interferes with the formation of protein network structures. Restructured steaks made with added walnut presented acceptable sensory properties. Incorporation of nuts in meat products can be use to confer potential heart-healthy benefits (Spanish Patent Application 200300367).     

Chemical composition and quality attributes of goat meat and lamb

Chemically, goat meat had significantly (P < 0·05) less intramuscular fat and significantly (P < 0·001) more moisture than lamb. The sarcoplasmic protein concentration of the goat meat was significantly (P < 0·001) greater than that of lamb while the myofibrillar protein concentration was similar in the two species.

Goat meat was darker red in colour than lamb. It had significantly (P < 0·001) superior water-holding capacity and less cooking losses than lamb. Meat flavour was significantly (P < 0·05) less strong in goat meat than in lamb.     

Storage and packaging effects on sensory and color characteristics of ground beef

Effects of irradiation (2 kGy) of ground beef patties from trimmings stored aerobically for 0 or 6 days on lean color, odor, and sensory attributes were investigated. Beef trimings were coarse ground and split into 2 groups. Group one was fine ground, pattied, and packaged immediately; group-two was stored 6 days then fine ground, pattied, and packaged. Irradiated beef patties had greater (P<0.05) off-odors, and off-flavors, lower (P<0.05) CIE L^*, a^* and b^* and saturation indexes values (P<0.05) after four days of storage at 0±1 °C. Irradiation of patties produced from trimmings aged an extra 6 days resulted in increased (P<0.05) saturation indexes and b^* values, but not off-odors when compared to non-aged and irradiated patties. Thus, the production of irradiated beef patties should utilize beef trimmings with the shortest postmortem aging time and a dose of less than 2 kGy to minimize discoloration and off-odors.     

Thermophysical properties of silver hake and mackerel surimi at cooking temperatures

Thermal diffusivity values obtained using a transient method both from heating and cooling information and apparent specific heat of surimi made from silver hake and mackerel as a function of temperature (60–110 °C) and added potato starch content (3% and 7%, w/w) were determined. The water content of all samples was kept constant at about 77% (w/w) in order to determine the effect of starch. Thermal diffusivity and apparent specific heat of all samples increased with temperature. The effect of temperature on diffusivity was found significant (p=0.001) in all samples at temperatures above 85 °C. This effect may be caused by structural changes as temperature is raised. Thermal diffusivity increased with temperature more rapidly in samples with high levels of starch than in those with no starch. However, thermal diffusivity of silver hake surimi preset at 40 °C for 30 min did not show a significant increase (p<0.05) over the temperature range studied. Thermal diffusivities calculated from cooling and heating data were significantly different (p<0.05).

The differential scanning calorimetry (DSC) thermograms of silver hake and mackerel surimi showed three endothermic peaks. When starch was added to surimi samples an endothermic peak having a large area was observed, which overlapped the third highest temperature peak of surimi samples. No significant shifts in the endothermic peaks of myofibrillar proteins were detected with increasing starch content. Transition temperatures for starch–surimi system were higher than those for starch–water system. There were deviations in the apparent heat capacity function calculated from DSC measurements in surimi samples containing starch. These are attributed to gelatinization of starch and modification of water structure.