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The chemical and rheological properties of spent hen proteins recovered by acid and alkaline extraction have been studied with/without cryoprotectants (CP) after 3 weeks of frozen storage. Four pH values (2.0, 2.5, 11.5, and 12.0) were used for extraction. CP addition prevented freeze-induced denaturation and oxidation in all extracted proteins, as revealed by significant increases in reactive sulphydryl groups (p<0.0001), and a decrease in the formation of carbonyl groups (p<0.0001). The alkaline extracted proteins with CP formed more viscoelastic gels compared to the others, while samples without CP failed to form a gel network. FTIR of the protein isolates with CP showed a protective effect on the secondary structure of the isolated proteins. Scanning electron micrographs showed a protective shield of CP around the isolated proteins., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The possibilities of replacing soy protein isolate (SPI) and reducing the amount of phosphate in marinated chicken breasts using poultry protein isolate (PPI) were investigated. PPI, prepared from mechanically separated turkey meat through the pH-shift technology, was used as a marinade ingredient for chicken breasts at 2 different concentrations (1.0% and 1.5%, w/w on a dry weight basis). Product characteristics were compared to samples marinated with salt, phosphate, or SPI. All the 5 treatments were subjected to instrumental and sensory analyses. Tumbling yield, drip, and cooking losses as well as expressible moisture showed that PPI can be used as a substitute for SPI in brine. The sensory analysis revealed that there were no differences among treatments in terms of appearance, color, flavor, saltiness, juiciness, tenderness, and overall acceptability of the marinated chicken breasts. However, chicken breasts marinated with phosphate had significantly higher aroma acceptability scores than those treated with 1% PPI., (© 2013 Institute of Food Technologists®)

The yield of deboned meat is an important economic factor affecting the profit of the meat industry. This study was undertaken to determine whether the yield of boneless meat from broiler chicken leg (thigh and drumstick) and wing (drumette and winglet) is improved by introducing a new deboning method consisting of articular cartilage dislocation followed by stripping periosteum. A total of 44 broiler chicken carcasses were used in the deboning experiment. Right and left legs or wings from the first 22 carcasses were assigned to the new and ordinary hand deboning methods, respectively. For the remaining 22 carcasses, right and left legs or wings were assigned to the ordinary and new methods, respectively. The weight of residue, composed of bone and small amounts of cartilage and noncartilaginous tissues obtained after deboning, was then compared between the right and left legs or wings to see the difference between the 2 methods. The removal of tibia, fibula, humerus, radius, or ulna resulted in formation of a hollow in boneless meat obtained. There was no difference (P > 0.05) between the right and left legs or wings in the weight of residue obtained after deboning as expected. The weight of residue was less (P < 0.05) with the new method compared with the ordinary method in all chicken parts examined. The difference of residue weight between the 2 methods accounted for 10, 12, 14, and 21% of the weight of residue obtained by the ordinary method in thigh, drumstick, drumette, and winglet, respectively. The new method may be useful to deboners at home kitchens as well as the poultry meat industry. The present study also showed the development of a secondary ossification center at the proximal end of the carpometacarpus of chickens. This is, to our knowledge, the first report of development of secondary ossification center in chicken wings.

Antemortem holding temperature and flapping can affect broiler pectoralis major (referred to as p. major) meat quality. The influence of environmental temperature 12 to 14 h before processing and antemortem handling on p. major functional properties and color was tested at multiple processing ages in a 3 × 2 × 5 factorial design study. At 28, 35, 42, 49, and 56 d of age, mixed-sex broilers were crated and held in one of 3 target temperature treatments: heat (30°C), thermoneutral (21°C), or cool (7°C). Following feed withdrawal, birds were transported to a processing facility where either a long (120 s) or short (<10 s) shackling treatment was imposed. Sex was determined at processing. Lightness, redness, and yellowness values were measured at deboning [4.50 to 8.25 h postmortem (PM)] and at 24 h PM. Ultimate pH was measured at 24 h PM. Drip loss, cook loss, and Allo-Kramer shear force were determined at 72 h PM. Ultimate pH was highest in the cool treatment, with no difference between heat and thermoneutral treatments (5.97 vs. 5.87 and 5.90, respectively; P = 0.0004). Ultimate pH correlated negatively with drip loss (r = -0.47; P < 0.0001). Drip loss was lowest in the cool treatment, with no difference between the heat and thermoneutral treatments (2.06 vs. 2.24 and 2.19%, respectively; P = 0.007). The p. major from broilers in the heat treatment had higher Allo-Kramer shear force values than those in both the thermoneutral and cool treatments (4.64 kg/g vs. 4.21 and 4.21 kg/g, respectively; P = 0.023). With the exception of 49 d, broilers subjected to the long shackling treatment had higher redness values at deboning than broilers subjected to the short shackling treatment; by 24 h PM only the 28-d broilers subjected to the long shackling treatment had higher redness values. Higher hue angles at deboning and 24 h PM were observed in the short treatment compared with the long treatment (65.58 vs. 57.46 and 68.48 vs. 63.31, respectively; P < 0.0001), indicating that p. major from long-shackled broilers were redder in appearance. Ultimate pH was lower in female broilers than in male broilers (5.87 vs. 5.96, respectively; P < 0.0001) and subsequent drip loss was higher in females compared with males (2.34 vs. 1.99%, respectively; P < 0.0001). Although temperature and handling before slaughter affected p. major color and texture traits, the differences may not be large enough to have commercial significance. Differences in p. major quality attributable to sex of the bird may have greater commercial significance than previously reported.

Functional and rheological properties of proteins from frozen turkey breast meat with different ultimate pH at 24 h postmortem (pH(24)) have been studied. Sixteen breast fillets from Hybrid Tom turkeys were initially selected based on lightness (L*) values for each color group (pale, normal, and dark), with a total of 48 breast fillets. Further selection of 8 breast samples was made within each class of meat according to the pH(24). The average L* and pH values of the samples were within the following range: pale (L* >52; pH ≤5.7), normal (46 < L* < 52; 5.9 < pH <6.1), and dark (L* <46; pH ≥6.3), referred to as low, normal, and high pH meat, respectively. Ultimate pH did not cause major changes in the emulsifying and foaming properties of the extracted sarcoplasmic and myofibrillar proteins. An SDS-PAGE profile of proteins from low and normal pH meat was similar, which revealed that the extent of protein denaturation was the same. Low pH meat had the lowest water-holding capacity compared with normal and high pH meat as shown by the increase in cooking loss, which can be explained by factors other than protein denaturation. Gel strength analysis and folding test revealed that gel-forming ability was better for high pH meat compared with low and normal pH meat.Dynamic viscoelastic behavior showed that myosin denaturation temperature was independent of pH(24). Normal and high pH meat had similar hardness, springiness, and chewiness values as revealed by texture profile analysis. The results from this study indicate that high pH meat had similar or better functional properties than normal pH meat. Therefore, high pH meat is suitable for further processed products, whereas low pH meat may need additional treatment or ingredient formulations to improve its functionality.

Increased demand for poultry products has resulted in an increased availability of by-products, such as the neck, back, and frame, that can be processed into mechanically separated poultry meat. The major problems with mechanically separated poultry meat are its high lipid content, color instability, and high susceptibility to lipid oxidation. The present work was undertaken to determine the effect of different concentrations of citric acid and calcium ions on protein yield, color characteristics, and lipid removal from protein isolates prepared using an acid-aided extraction process. Six levels of citric acid (0, 2, 4, 6, 8, and 10 mmol/L) and 2 levels of calcium chloride (0 and 8 mmol/L) were examined. The entire experiment was replicated 3 times, resulting in 36 extractions (3 × 6 × 2). The highest (P < 0.05) protein yield was found for the treatment with 6 mmol/L of citric acid. In general, all the combinations removed an average of 90.8% of the total lipids from mechanically separated turkey meat, ranging from 86.2 to 94.7%. The lowest amount (1.14%) of total lipids obtained was for samples treated with 4 mmol/L of citric acid. Maximum removal of neutral lipids (96.5%) and polar lipids (96.4%) was attained with the addition of 6 and 2 mmol/L of citric acid, respectively. Polar lipid content was found to be significantly (P = 0.0045) affected by the presence of calcium chloride. The isolated proteins were less (P < 0.05) susceptible to lipid oxidation compared with raw mechanically separated turkey meat. The most efficient removal of total heme pigment was obtained with the addition of 6 or 8 mmol/L of citric acid. Addition of calcium chloride had a negative effect on total pigment content. The study revealed that acid extractions with the addition of citric acid resulted in substantial removal of lipids and pigments from mechanically separated turkey meat, improved stability of the recovered proteins against lipid oxidation, and appreciable protein recovery yields.

Textural properties, water-holding capacity, and color characteristics of alkali-extracted chicken dark meat have been studied. Alkali extraction was carried out at 4 different pH values (10.5, 11.0, 11.5, and 12.0). At higher pH of extraction, cooking loss and water loss were found to be significantly decreased (P < 0.05). The lightness (L* value) of the recovered samples treated at higher pH was found to be significantly lower (P < 0.05). Whiteness of uncooked samples also decreased significantly at higher extraction pH values. Protein samples extracted at higher pH values were found to be harder, and the maximum (4,956 g of force) value was shown by samples prepared at pH 11.5. Chewiness values were significantly increased (P < 0.05) for protein samples extracted at pH values of 11.5 and 12.0. Dynamic viscoelastic behavior of samples was assessed in the temperature range of 7 to 100 degrees C. The dynamic viscoelastic behavior of raw chicken dark meat as revealed by storage modulus indicated considerable gel-forming ability. The maximum storage modulus (G') value of 439 kPa was measured at 66.7 degrees C. Storage modulus was found to decrease for the recovered protein samples and be lowest at higher pH values. However, the recovered protein samples did show substantial gel-forming ability when stored with cryoprotectants. Tan delta values denoted 2 clear transitions for raw dark meat; however, only 1 major transition at 50.1 degrees C was evident for pH-treated samples, probably reflecting the loss of collagen in processing. In conclusion, this process of protein recovery may offer the possibility to use the underused poultry resources for preparation of functional foods.

Chicken dark meat has been considered as a major underused commodity due to the increasing demand for further-processed breast meat products. One option to increase the utilization of chicken dark meat is to extract myofibrillar proteins and separate them from fat and pigments to enhance their application for the preparation of further-processed meat products. The objective of the current study was to determine the effect of pH, in the range of 10.5 to 12.0, on the alkaline solubilization process of chicken dark meat. Aspects studied were the effect of the alkali-aided process on protein content, lipid composition, lipid oxidation, and color characteristics of the extracted meat. Each experiment and each assay were done at least in triplicate. Lipid content of the extracted meat showed a 50% reduction compared with the chicken dark meat. Neutral lipids were reduced by 61.51%, whereas polar lipids were not affected by the alkali treatments. There was a higher amount of TBA reactive substances observed in the extracted meat compared with chicken dark meat, indicating that extracted meat was more susceptible to oxidation. Long-chain polyunsaturated fatty acids (22:4n-6, 20:3n-3, 20:5n-3, 22:5n-3, and 22:6n-3), which were detected only in the polar lipids, were responsible for increasing lipid oxidation susceptibility of extracted meat compared with chicken dark meat. Alkali-aided extraction of chicken dark meat lightened the color of the meat. The redness, yellowness, and total heme pigments in extracted meat significantly decreased by 83, 11, and 53%, respectively, compared with chicken dark meat. Even though this process did not remove polar lipids, based on our early findings, the extracted meat had considerable physicochemical and textural properties for product preparation compared with those of raw dark meat. Hence, alkali recovery of protein can be considered a potentially useful method to increase the utilization of dark chicken meat.

The influence of vitamin E and selenomethionine (SeMet) on lipid oxidation in frozen-raw and cooked omega-3 enriched dark chicken meat was evaluated. Feed was supplemented with 2 levels of vitamin E (250 and 50 IU/kg of feed) and selenium (0.1 mg of sodium selenite/kg of feed and 0.3 mg of SeMet/kg of feed). An extruded linseed product was used as the alpha-linolenic acid source. Fatty acid (FA) profile, oxysterols, and thiobarbituric reactive acid substances (TBARs) were analyzed in frozen-raw, boiled, pan-fried, and roasted meat. After 6 mo of storage, oxysterols in frozen-raw meat remained stable with either high or low levels of dietary antioxidants. During cooking, high levels of vitamin E reduced oxysterol formation, whereas high levels of SeMet were inconsistent and even increased oxysterols during roasting. TBARs in frozen-raw meat stored for 6 mo were inhibited by high levels of either antioxidant. Conversely, no protective effect during cooking was observed at this time of storage. After 12 mo at -30 degrees C no antioxidant protection was observed.

Consumers are becoming more aware of the effect of the food they eat on their health. One of the ways they hope to reduce their risk of cardiovascular disease is by consuming more foods enriched with n-3 polyunsaturated fatty acids (PUFA). Due to the high content of alpha-linolenic acid (LNA), dietary flaxseed is a good source for increasing n-3 PUFA in poultry meat. A study was conducted with 2 primary objectives: to establish the distribution of n-3 PUFA between triacylglycerol (TAG) and phospholipid of broiler chicken breast and thigh meat and to determine the duration of dietary flaxseed supplementation required to ensure a level of n-3 PUFA of 300 mg per 100 g of meat necessary to label meat as a source of n-3 PUFA. This experiment was conducted as a 2 x 8 factorial, with 2 dietary levels of ground flaxseed (10 and 17%) and 8 durations of dietary flaxseed before processing [0 (control), 4, 8, 12, 16, 20, 24, and 35 d]. A total of 128 Ross x Ross 308 mixed-sex broilers were evaluated to 35 d of age. Breast and thigh meat fatty acid composition was analyzed on duplicate samples of ground meat pooled from 8 birds per treatment. Broken-stick analysis was used to estimate the duration required to achieve 300 mg of n-3 PUFA per 100 g of breast meat. Results clearly indicated that LNA was mainly deposited in the TAG fraction of both breast and thigh meat. Enriching the chicken breast meat with 300 mg of n-3 PUFA per 100 g of meat was achieved in 11.3 and 26.2 d with a 17 and 10% level of flaxseed in diet, respectively. Although a significant increase of n-3 long-chain PUFA (20:5n-3, 22:5n-3, and 22:6n-3) was found in the phospholipid and TAG fraction of both tissues, the concentration of these functional components was low. More than 95% of n-3 PUFA enrichment was due to LNA.

Consumers are becoming more aware of the impact on their health of the food they eat. One of the ways they hope to reduce their risk of cardiovascular disease is by consuming more foods enriched with polyunsaturated fatty acids (PUFA), particularly n-3 fatty acids. Flaxseed is a good source for increasing the n-3 PUFA in poultry meat because of the high content of alpha-linolenic acid. A study was conducted to identify an optimal process to enrich of broiler diets with n-3 PUFA by using 2 levels of flaxseed fed for various times before processing. The acceptability of broiler meat functional properties was tested to ensure that further processing efficiencies would not be compromised by the enrichment strategy. This experiment was conducted as a 2 x 8 factorial, with 2 dietary levels of ground flaxseed (10 and 17%) fed for 8 lengths of time before processing [0 (control), 4, 8, 12, 16, 20, 24, and 35 d]. Of 650 Ross x Ross 308 mixed-sex broilers reared in this study, 128 were used to evaluate breast and thigh meat functional properties, oxidative stability, and sensory analysis. No statistical interactions were found between treatments for chicken breast meat quality traits. The duration of feeding flaxseed strongly affected meat quality parameters. In particular, feeding flaxseed for 16 d resulted in a final pH of 5.65, compared with 5.93 in the control. The lower ultimate pH found in animals fed flaxseed affected meat cooking loss, drip loss, and shear value (P < 0.0001). Shear value significantly increased after 16 d of feeding flaxseed (P < 0.0001). Susceptibility to oxidation increased in both breast and thigh broiler meat with the duration of feeding flaxseed. Enriching the diet for less than 16 d did not result in perceivable sensory defects. Duration of flaxseed feeding significantly affected the color characteristics, functional properties, and oxidative stability of broiler meat.

Consumer awareness of the health benefits of n-3 fatty acids is growing and is driving consumer demand for enriched food products. Enrichment of meat with n-3 fatty acids is an opportunity for the broiler production sector to add value to their product, but enrichment can increase the cost of production. A study was conducted to determine an optimal production strategy for n-3 enrichment of broiler meat using ground full-fat flaxseed. Low and high levels of dietary flaxseed (10 and 17%, respectively) were fed to broilers for 8 lengths of time (0, 4, 8, 12, 16, 20, 24, or 35 d) before processing at 35 d. Increasing the level or duration decreased feed intake, BW, and the percentage yield of carcass and breast. Flaxseed level and duration of feeding increased feed conversion ratios and the cost of production. Feeding flaxseed at 10 and 17% increased breast n-3 fatty acid levels by 7.65 and 13.70 mg/100 g of meat per day, respectively. In breast meat, the threshold level of 300 mg/g, required in Canada for labeling foods as a source of n-3 fatty acids, was reached at 12.1 and 24.1 d in the high and low flaxseed treatments, respectively. This was due primarily to a tripling of alpha-linolenic acid (18:3n-3) levels in the breast meat. Levels of the long-chain n-3 fatty acid eicosapentaenoic acid increased significantly in the breast meat with increased level and duration of flax feeding, indicating that birds were able to desaturate and elongate alpha-linolenic acid to eicosapentaenoic acid. To minimize cost, while achieving adequate breast meat n-3 enrichment, carcass weight, and meat yield, feeding 10% flaxseed for 24.1 d before processing is recommended as an optimal breast meat n-3 enrichment strategy. The optimal thigh meat n-3 enrichment strategy was to feed 10% flaxseed for 4.54 d before processing.

In recent years, demand for white meat products has resulted in excess supplies and depressed prices of leg meat in the United States. One approach to increasing the utilization of dark meat is to extract the pigments and fat to make the resulting product more acceptable for the production of further-processed meat products. To date, such technologies have been inefficient (low yields) or have resulted in products of limited use. Three replicate trials were conducted to determine the effects of extraction pH and precipitation pH on the wet and dry extract yields of boneless, skinless broiler leg meat. Broiler leg meat was chopped with added water and extracted by adjusting the pH to 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, and 12.0 while mixing. After determination of extraction yields, each extraction was adjusted to pH 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, and 5.2 to determine the effect of precipitate pH on total wet and dry yields. Dry yield increased with extraction pH and precipitation pH. However, the greatest yields, over 70%, were at extraction pH values above 10.5, which have been associated with the production of potentially harmful by-products. Combinations of extraction pH values between 9 and 10.5 and precipitation pH values above 4.4 resulted in dry yields of approximately 65%. These results indicate that pH extraction and precipitation may result in economically viable yields. Further research is needed to determine the optimal conditions of yield, composition, and functionality.

The variation in broiler breast meat color (CIE values L*a*b*) that normally occurs during processing was evaluated on 6,997 broiler breast fillets (pectoralis major muscles) from 79 flocks using a Minolta Chroma Meter. The samples were randomly collected at 3 to 6 h postmortem from the deboning line at a single major Italian processing plant. In addition, 216 fillets were selected based on lightness (L*) values as being dark (L* < 50), normal (50 < or = L* < or = 56), or pale (L* > 56), and were analyzed for ultimate pH, intact and ground meat cooking loss, and shear value. The overall range in measured lightness (L*) was considerable and varied from 40 (dark) to 66 (pale), indicating that high breast meat color variation during processing could exist. Broiler breast meat during summer was found to be paler (+1.7 L* unit), less red (-1.0 a* unit), and less yellow (-0.7 b* unit) than breast meat samples collected during the winter, confirming that the incidence of pale meat is greater during summer as indicated by nonscientific observations of plant personnel. It was also determined that paler (L* > 56) breast meat is associated with lower ultimate pH and poorer water-holding capacity, whereas darker (L* < 50) breast meat is associated with higher muscle pH and cooking yield.

The influence of vitamin E and selenomethionine (SeMet) on lipid oxidation in frozen–raw and cooked ω-3 enriched dark chicken meat was evaluated. Feed was supplemented with 2 levels of vitamin E (250 and 50 IU/kg of feed) and selenium (0.1 mg of sodium selenite/kg of feed and 0.3 mg of SeMet/kg of feed). An extruded linseed product was used as the α-linolenic acid source. Fatty acid (FA) profile, oxysterols, and thiobarbituric reactive acid substances (TBARs) were analyzed in frozen–raw, boiled, pan-fried, and roasted meat. After 6 mo of storage, oxysterols in frozen–raw meat remained stable with either high or low levels of dietary antioxidants. During cooking, high levels of vitamin E reduced oxysterol formation, whereas high levels of SeMet were inconsistent and even increased oxysterols during roasting. TBARs in frozen–raw meat stored for 6 mo were inhibited by high levels of either antioxidant. Conversely, no protective effect during cooking was observed at this time of storage. After 12 mo at −30 °C no antioxidant protection was observed. [ABSTRACT FROM AUTHOR]

Abstract: Meat produced in vitro has been proposed as a humane, safe and environmentally beneficial alternative to slaughtered animal flesh as a source of nutritional muscle tissue. The basic methodology of an in vitro meat production system (IMPS) involves culturing muscle tissue in a liquid medium on a large scale. Each component of the system offers an array of options which are described taking into account recent advances in relevant research. A major advantage of an IMPS is that the conditions are controlled and manipulatable. Limitations discussed include meeting nutritional requirements and large scale operation. The direction of further research and prospects regarding the future of in vitro meat production will be speculated. Industrial relevance: The development of an alternative meat production system is driven by the growing demand for meat and the shrinking resources available to produce it by current methods. Implementation of an in vitro meat production system (IMPS) to complement existing meat production practices creates the opportunity for meat products of different characteristics to be put onto the market. In vitro produced meat products resembling the processed and comminuted meat products of today will be sooner to develop than those resembling traditional cuts of meat. While widening the scope of the meat industry in practices and products, the IMPS will reduce the need for agricultural resources to produce meat. [Copyright &y& Elsevier]