Subzero saline chilling with or without prechilling in icy water improved chilling efficiency and meat tenderness of broiler carcasses

Freshly slaughtered carcasses need to be chilled to improve product quality, meat safety, and processing efficiency. This research investigated the effect of subzero saline chilling (SSC) on broiler carcasses with or without prechilling in icy water. Water immersion chilling at 0.5°C (WIC) or SSC at 4% NaCl/-2.41°C (SSC) was a major chilling step. For the combination of pre- and postchilling, the warm water immersion chilling (WWIC) at 10°C was used as prechilling and the WIC as postchilling (WWIC-WIC), and WIC was used as prechilling and the SSC as postchilling (WIC-SSC). The internal temperature of breast fillets was monitored during chilling. Carcasses in a prechiller were transported to a postchiller when their internal temperature reached 15°C. Chilling was completed when the carcass temperature reached 4.4°C or below, and breast fillets were harvested at 3-h postmortem to measure the pH and sarcomere length. Color (L*, a*, and b*) values were evaluated on both breast skin and skinless breast surfaces. Meat tenderness was evaluated using the breast fillets after overnight storage and cooking to an internal temperature of 76°C. The carcasses in the SSC and WIC-SSC showed shorter chilling times (85-91 min) than those (100-144 min) of WIC and WWIC-WIC. A higher chilling yield was observed for the carcasses in WIC-SSC, and a lower cooking yield was seen for the carcasses in WWIC-WIC than other chilling methods (P < 0.05). The breast fillets of broilers in the SSC and WIC-SSC showed lower shear forces and longer sarcomere length than the WIC and WWIC-WIC. No difference was found for L* and a* values, while lower b* value was observed in the SSC than the other chilling methods (P < 0.05). Based on these results, chilling of broiler carcasses in the SSC (4% NaCl/-2.41°C) with or without prechilling in WIC at 0.5°C significantly improved chilling efficiency and meat tenderness, with minor color changes on carcasses.

Effects of broiler chilling methods on the occurrence of pale, soft, exudative (PSE) meat and comparison of detection methods for PSE meat using traditional and Nix colorimeters

The aims of this study were to i) estimate the occurrence of pale, soft, and exudative (PSE) meat in modern commercial Ontario broiler flocks, ii) determine the effects of the chilling method (water vs. air) on PSE meat, and iii) investigate a new inexpensive colorimeter (10% of the price of traditional color meters), the Nix Color Sensor, as an objective color measurement of chicken meat. Between June 2019 to March 2020, a total of 17 different broiler flocks were processed. The color of 1,700 boneless skinless Pectoralis major muscles was randomly measured (100/flock), where 255 samples were also measured for pH, water-holding capacity (WHC), cooking loss, and penetration force. In addition, a traditional Minolta colorimeter was used to measure random 95 samples from a single water-chilled flock and subsequently compared the values obtained with the Nix Color Sensor. Strong correlations of L* values (rho = 0.75; P < 0.001), a* values (rho = 0.72; P < 0.001), and b* values (rho = 0.80; P < 0.001) were observed. When an L* value of 43 was used as the cut-off for the Nix, 12.5% of fillets were classified as PSE meat. Statistical differences (P < 0.05) were observed between the air and water-chill methods for L*, pH, and WHC. However, there were no significant differences observed between the 2 methods for cooking loss and penetration force values. The study indicated that PSE meat is still a challenge in Ontario broilers, and that the L*, pH, and WHC of breast meat (all indicate meat quality) are affected by the chilling method. In addition, the Nix was found to be an affordable, objective, and convenient sensor for measuring chicken meat color.

The Defeathering Effect by Scalding in Chickens Follows Their Intrinsic Dermal Histologies

This study aimed to delineate the fundamental skin histology and its association with feathers in broilers and native Red-Feather (RF) chickens and further elucidate their thermal alterations in respect to the defeathering effect by scalding. Comparisons of skin thickness between fresh samples and those after dehydration and fixation, as well as their collagen contents and histological differences, suggested that RF chickens had a thicker dermal layer with more collagen deposition and compact architecture, particularly in the neck and abdominal skin, but a thinner hypodermal layer in the back, chest, and abdomen skin. Despite an adolescent age, RF chickens showed a shorter calamus depth of tail feathers but a larger calamus diameter of wing feathers. Within the feather follicle punch, a very intense follicle sheath layer with compact collagenous matrixes to fulfill the space next to the inner feather root sheath was observed in RF chickens. Under both soft and hard scalding, RF chickens showed a lower degree of denaturation on hip skins and were more resistant to structural disintegration, primarily within the epidermal and dermal layer. Accordingly, a much narrower gap space between the feather sheath and surrounding follicle sheath was observed, and the gap expansion was also resistant to thermal changes. These results suggest that the defeathering effect by scalding follows the intrinsic skin histologies in chickens of various breeds and ages, primarily depending on the interaction of the feather calamus with the surrounding follicle sheath and neighboring cutaneous tissues, reflecting their resistance to thermal denaturation, but is irrelevant to the feathers per se.

Proximate Composition, Retained Water, and Bacterial Load for Two Sizes of Hybrid Catfish (Ictalurus furcatus × Ictalurus punctatus) Fillets at Different Process Steps

The catfish processors in the US are required to state the maximum percentage of retained water content (RWC) on the product label. The objectives of our study were to quantify the RWC of processed hybrid catfish fillets from proximate composition and the bacterial load at different processing points. Water content was determined using oven-dry (AOAC950.46,1990) and Near-infrared (NIR) spectroscopy. Protein and fat content were determined by NIR spectrometer. Psychrotrophic (PPC) and Total Coliform (TCC) counts were enumerated using 3MPetrifilm^TM. The fillets' overall baseline water, protein, and fat content were 77.8, 16.7 and 5.7%, respectively. The RWC of final fresh and frozen fillets were ~1.1=/- 2.0% (not significant) and ~4.5%, respectively, and was not fillet size or harvest season dependent. Baseline water content (78.0 vs. 76.0%) was higher (p ≤ 0.05), and fat content (6.0% vs. 8.0%) was lower (p ≤ 0.05) for small (50-150 g) compared to large fillets (150-450 g). Higher (p ≤ 0.05) baseline PPC (~4.2 vs. ~3.0) and TCC (~3.4 vs. ~1.7) were observed for the warm season (April-July) fillets compared to the cold season (Feb-April). This study provides information to processors and others on estimating retained water and microbiological quality of the hybrid catfish fillets over the process line.

Effects of Hard and Soft Scalding on Defeathering and Carcass Quality of Different Breeds of Chickens

Current soft scalding in broilers is not applicable to various strains of chickens with different market weights and ages. This study aimed to examine the effectiveness of soft (57 °C for 120 s) and hard (60 °C for 60 s) scalding on defeathering and carcass quality of the local strain of Red Feather (RF) country chickens and determine age, breed, and body weight factor in accounting for the defeathering effectiveness using adult layers and juvenile broilers as a reference. Results showed no differences between soft and hard scalding in broilers with 60% and 80% of acceptable defeathering scores, respectively, while a significantly better effect by hard scalding was observed in adult layers, young and old RF chickens with more than 70% of birds exhibiting desirable scores and less than 20% by soft scalding. In contrast to soft scalding, hard scalding had no significant effects on breast meat color but impaired skin color in broilers as assessed by L*, a*, and b* value analysis. Interestingly, hard scalding increased breast skin yellowness and lightness in young RF chickens and lightness in old RF chickens, while there were no significant changes in layers. However, hard scalding decreased skin elasticity in layers and old RF chickens. The effectiveness of defeathering by scalding method was governed by the age to reach a certain threshold in the development of dermal architecture and feather richness, irrelevant to body weight. The alteration of carcass color primarily depends on age, body weight/breed, and their interaction. In conclusion, current soft scalding is suitable for broiler chickens for desirable defeathering effect and carcass color, whereas layers and RF chickens scaled at 60 °C for 60 s showed a better defeathering effect without unfavorable changes of breast meat and skin color.

Air chilling of Turkey carcasses: process efficiency and impact in the meat quality traits

The study evaluated the influence of two air-spray chilling systems on the water absorption, cooling time, and the impact of both on the quality traits of the turkey meat. In system A (air/water spray + air) a weight loss of 1.78% (w/w) occurred, while in system B (continuous air/water spray) turkey meat showed a weight gain of 1.82 (w/w). The cooling time in system B was significantly (P < 0.05) shorter. Water retention capacity, the color, and the sarcomere length of turkey meat are significantly influenced (P < 0.05) by the air chilling system. Turkey meat refrigerated in system B showed smaller structural changes. Air chilling with water spray in a continuous process promotes carcass weight gain and reduces processing time, in addition to less impact on the quality traits of turkey meat.

Characterization of Carcass Color Differences Between Hens (Small Birds) and Meat-Type Male Pheasants (Large Birds)

The underlying changes in hen carcass color upon freezing were compared with the color of meat-type male pheasants upon freezing. Chemical and physical assessments of these two pheasant types (n=5) and the effects of different chilling methods on hen carcasses (n=10) were evaluated. The results showed that hen carcasses exhibited more red pigmentation (myoglobin, hemoglobin), as well as significantly higher pH values and redness, than the carcasses from meat-type pheasants. The moisture content was higher in hens than in meat-type pheasants, especially in the skin. The intermediate fiber (IIA) type was the only type found in the pectoralis major muscle, regardless of pheasant type. Chilling method significantly changed the color attributes of the hen carcass. Immersion chilling decreased skin redness (less pigmentation and Commission Internationale de l ́Eclairage [CIE] a*); the breast meat was less red than that from the chilling-in-a-bag condition. The skin had substantially higher levels of red pigmentation than the breast muscles, irrespective of the pheasant type and chilling method (P &lt; 0.05). Our findings suggest that the more intense red appearance may be related to a combination of greater residual hemoglobin levels and higher pH within the skin. The greater moisture content of the skin may have facilitated the development of greater transparency to the darker, more red breast muscle.

Effect of chilling methods on the surface color and water retention of yellow-feathered chickens

This study was conducted to investigate the effects of air chilling (AC), water chilling (WC), combined chilling consisting of WC for 20 min and AC (CO₂₀), and combined chilling consisting of WC for 30 min and AC (CO₃₀) on the microbiological status, surface color, processing yield, and moisture content of yellow-feathered chicken carcasses. After chilling, the carcasses treated by AC exhibited the highest total viable counts (TVC) (4.7 cfu/cm²), followed by those treated by CO₂₀ and CO₃₀, whereas the carcasses treated by WC showed the lowest (P < 0.05) mean log TVC (4.2 cfu/cm²). Based on an instrumental color evaluation and photographs of carcass surfaces, the carcasses treated by AC showed a notable yellow color (P < 0.05), whereas no significant difference (P > 0.05) was found among the carcasses treated by CO₂₀, CO₃₀, and WC. The skin samples of carcass parts treated by WC (breast, thighs, drumsticks, back, neck, and wings) exhibited higher moisture contents than the skin samples of the carcasses treated by AC (P < 0.05), providing evidence that weight gain during WC is due to higher water absorption by the skin. The different parts of the broiler carcasses treated by AC had lower cooking losses than those of carcasses treated by combined chilling or WC (P < 0.05), except for the thighs and claws. In breast and drumstick muscles, the moisture contents of the superficial parts from carcasses treated by WC were higher than those of the carcasses treated by AC, whereas the internal parts were not significantly affected by the chilling methods (P > 0.05). The results of this work can be useful for understanding and improving the chilling process for yellow-feathered chickens.

Feeding dihydroquercetin to broiler chickens

1. A total of 80 male Ross 308 broilers were used in a study to investigate the effect of dietary dihydroquercetin (DHQ) on growth performance variables, gastrointestinal tract (GIT) and immune organ development, glutathione peroxidase (GPx) and haemoglobin in blood, hepatic vitamin E content, dietary N-corrected metabolisable energy (AMEn) and nutrient retention coefficients when fed to broiler chickens from 7 to 35 d of age.2. Two treatments were used in this study: control (C) and C + 0.5 g/kg extract of Siberian Larch (Larix sibirica) per kg feed, containing 85% DHQ. The diets were fed over 2 feeding phases, a grower phase from 7 to 28 d of age and a finisher phase from 28 to 35 d of age. The birds were reared under the breeder's recommended conditions.3. In general, there were no effects of DHQ on growth performance of broiler chickens. However, the results of this experiment showed that there can be changes in the redness colour of the breast meat when DQH is fed. No negative effects of feeding DHQ at 0.5 g/kg diet were observed in this study.4. Supplementation of poultry diets with DHQ under standard industry-rearing conditions did not improve the performance or any of the studied variables, except an increase of redness index of the breast fillets. Feeding DHQ at different doses and/or under more challenging conditions, e.g. heat stress, may, however, bring positive responses.

Quality parameters of chicken breast meat affected by carcass scalding conditions

Objective

The influence of broiler carcass scalding conditions on chicken breast meat quality parameters was investigated.

Methods

Two hundred and seventy Cobb broiler chickens from 42 to 48 days old were slaughtered according to the standard industry practice and scalded in five temperature/time combinations—T₁, 54°C/210 s; T₂, 55°C/180 s; T₃, 56°C/150 s; T₄, 57°C/120 s; T₅, 58°C/90 s.

Results

Scalding temperature increase resulted in higher values of external and ventral lightness and in protein functionality reduction—determined by emulsification capacity and protein denaturation—in chicken breast fillets 24 h post-mortem. Protein secondary structures had conformational changes, with a decrease of the α-helix and an increase of the β-sheet and β-turn proportions, mainly in T₁ and T₅ samples, determined by Fourier-transform infrared spectroscopy in an attenuated reflectance mode analysis. The chemical composition, pH, water holding capacity and Warner-Bratzler shear force did not differ among the treatments. In the fatty acid profile, the 18:1n-9 was lower in T₅, which suggested that the high scalding-temperature could have caused the lipid oxidation. The values of the polyunsaturated fatty acids (PUFA), such as 22:2, 20:4n-6, and 22:6n-3, were highest in the T₅, thus being related to the phospholipid cellular membrane collapse in this experimental condition and subsequent release of these PUFA.

Conclusion

Intermediate scalding-parameters avoided the negative changes in the chicken meat quality.

Water absorption and dripping of chicken breast and carcasses during pre-cooling in an industrial system

This study aimed to evaluate the parameters that influence the water absorption and drip of chicken carcasses due to the processing and pre-cooling of the meat in an industrial chiller. A total of 1,179 chickens were sampled during industrial processing to evaluate the influence of variables, validate the parameters, and conduct histological analysis. The best parameters for guaranteeing absorption levels and drip tests within acceptable limits on chicken carcasses were total residence time of 60 min (in the pre-chiller, chiller 1, and chiller 2); air pressure of chillers at 0.5 bar; the abdominal opening of carcasses at a maximum of 2 cm. These parameters did not influence the protein content, moisture/protein ratio, pH, or lipid content. The validation of the parameters and the histological analysis performed after each cooling stage showed that the most significant structural changes occurred in the pre-chiller, where the temperature of carcasses and water was higher, which contributes to greater absorption.

Fear responses and postmortem muscle characteristics of turkeys of two genetic lines

Commercial turkey production has increased greatly in recent decades. Along with increased production, problems with turkey meat quality have also increased. Research with other species has demonstrated that differences in meat quality exist among pigs and cattle differing in characteristics such as fearfulness. However, associations between fear responses and postmortem (PM) muscle characteristics related to the meat quality of turkeys have not been examined. This study evaluated the test-retest repeatability of responses of male commercial (COMM) and randombred (RB) turkeys in an open field (OF) test, which is used to assess fear and activity levels of poultry. Another objective of this study was to evaluate the relationship between behavioral OF responses and PM breast muscle characteristics (pH and R-value) that are related to meat quality. Thirdly, this study evaluated differences in pH and R-value between the turkey lines. Male COMM and RB turkeys were each housed in groups in 4 pens. Turkeys were individually tested in an OF (2.74×2.74 m, divided into 81 squares) at 1, 4, and 11 wk (COMM N=27; RB N=33). Turkeys were then grouped into clusters based on a cluster analysis of OF behavior. Turkeys were processed and meat quality characteristics were evaluated at 15-17 wk for COMM and 20-21 wk for RB turkeys. Results were analyzed using a mixed model (SAS 9.4). Breast muscle pH and R-value did not differ between genetic lines, and there were no differences in pH and R-value among clusters within genetic lines. These findings suggest that OF responses measured during rearing are not related to PM breast muscle pH and R-value, which ultimately affect meat quality. Further research is needed to assess whether other types of fear responses are associated with meat quality and whether differences in R-value between genetic lines are associated with differences in other meat quality characteristics.

Impact of broiler processing scalding and chilling profiles on carcass and breast meat yield

The effect of scalding and chilling procedures was evaluated on carcass and breast meat weight and yield in broilers. On 4 separate weeks (trials), broilers were subjected to feed withdrawal, weighed, and then stunned and bled in 4 sequential batches (n = 16 broilers/batch, 64 broilers/trial). In addition, breast skin was collected before scalding, after scalding, and after defeathering for proximate analysis. Each batch of 16 carcasses was subjected to either hard (60.0°C for 1.5 min) or soft (52.8°C for 3 min) immersion scalding. Following defeathering and evisceration, 8 carcasses/batch were air-chilled (0.5°C, 120 min, 86% RH) and 8 carcasses/batch were immersion water-chilled (water and ice 0.5°C, 40 min). Carcasses were reweighed individually following evisceration and following chilling. Breast meat was removed from the carcass and weighed within 4 h postmortem. There were significant (P < 0.05) differences among the trials for all weights and yields; however, postfeed withdrawal shackle weight and postscald-defeathered eviscerated weights did not differ between the scalding and chilling treatments. During air-chilling all carcasses lost weight, resulting in postchill carcass yield of 73.0% for soft-scalded and 71.3% for hard-scalded carcasses, a difference of 1.7%. During water-chilling all carcasses gained weight, resulting in heavier postchill carcass weights (2,031 g) than for air-chilled carcasses (1,899 g). Postchill carcass yields were correspondingly higher for water-chilled carcasses, 78.2% for soft-scalded and 76.1% for hard-scalded carcasses, a difference of 2.1%. Only in trials 1 and 4 was breast meat yield significantly lower for hard-scalded, air-chilled carcasses (16.1 and 17.5%) than the other treatments. Proximate analysis of skin sampled after scalding or defeathering did not differ significantly in moisture (P = 0.2530) or lipid (P = 0.6412) content compared with skin sampled before scalding. Skin protein content was significantly higher (P < 0.05) for prescald and soft-scalded skin samples than for hard-scalded or soft or hard-scalded skin samples after defeathering. The hard-scalding method used in this experiment did not result in increased skin lipid loss either before or after defeathering.

Combination of muscle tension and crust-freeze-air-chilling improved efficacy of air chilling and quality of broiler fillets

The objective of this study was to evaluate the effects of water immersion chilling (WIC), air chilling (AC), and crust-freeze-air-chilling (CFAC) on the efficacy of broiler chilling and quality of breast fillets with and without muscle tension (MT), restraining both wings behind the carcass. In each of 3 replications, 66 birds were purchased locally and processed at the Michigan State University meat laboratory. After evisceration, one-half of the birds were subjected to MT and the remaining birds received no MT. Twenty-two birds (11 with and 11 without MT) per chilling were randomly assigned to WIC (ice/water slurry at 0.2°C), AC (air at 1°C/1.5 m/s), or CFAC (air at -12°C/1.5 m/s). After chilling and aging for 3 h postmortem (PM), all breast fillets were deboned, one-half of which were immediately quick-frozen or cooked, whereas the remaining half were further aged on ice for 24 h PM. All left fillets were used for pH, R-value, and sarcomere measurements, whereas all right fillets were used for shear force. During chilling, breast temperature was reduced from 40 to 4°C in an average of 62, 68, and 140 min for WIC, CFAC, and AC, respectively. The birds at 3 h PM had higher pH and shear force than those of birds at 24 h PM except the CFAC with no MT (P < 0.05). Breast fillets with MT showed lower shear force than the fillets without MT at 24 h PM (P < 0.05) in AC and CFAC. Based on these findings, the combination of CFAC and MT appears to improve both air chilling efficacy and breast fillet quality.

Cold-batter mincing of hot-boned and crust-freezing air-chilled turkey breast improved meat turnover time and product quality

The purpose of this research was to evaluate the combined effects of turkey hot-boning and cold-batter mincing technology on acceleration of meat turnover and meat quality improvement. For each of 3 replications, 15 turkeys were slaughtered and eviscerated. Three of the eviscerated carcasses were randomly assigned to water-immersion chilling for chill-boning (CB) and the remaining were immediately hot-boned (HB), half of which were used without chilling whereas the remaining were subjected to crust-freezing air chilling (CFAC) in an air-freezing room (1.0 m/s, -12°C) with/without 1/4; sectioning (HB-1/4;CFAC, HB-CFAC). As a result, CB and HB breasts were minced using 1 of 5 treatments: (1) CB and traditional mincing (CB-T), (2) HB and mincing with no chilling (HB-NC), (3) HB and mincing with CO2 (HB-CO2), (4) HB and mincing after CFAC (HB-CFAC), and (5) HB and mincing after quarter sectioning and CFAC (HB-1/4;CFAC). Traditional water-immersion chilling took an average of 5.5 h to reduce the breast temperature to 4°C, whereas HB-CFAC and HB-1/4;CFAC took 1.5 and 1 h, respectively. The breast of HB-CFAC and HB-1/4;CFAC showed significantly higher pH (6.0-6.1), higher fragmentation index (196-198), and lower R-value (1.0-1.1; P < 0.05) than those of the CB controls. No significant differences (P > 0.05) in sarcomere length were seen between CB-T and HB-CFAC filets regardless of quarter sectioning. When muscle was minced, the batter pH (5.9) of CB-T was significantly lower (P < 0.05) than those (6.1-6.3) of HB-NC, HB-CO2, and HB-1/4;CFAC, with the intermediate pH (6.0) seen for the HB-CFAC. When meat batters were cooked, higher cooking yield (90 - 91%; P < 0.05) was found in HB-CFAC, HB-1/4;CFAC, and HB-CO2, followed by HB-NC (90%) and finally CB-T (86%). Stress values (47-51 kPa) of HB-CFAC gels were significantly higher (P < 0.05) than those of CB-T (30 kPa) and HB-NC (36 kPa). A similar trend was found in strain values.

Microbiological quality of water immersion-chilled and air-chilled broilers

Carcass chilling during broiler processing is a critical step in preventing growth of pathogenic and spoilage bacteria. The objective of this study was to compare the microbiological quality of air- and water-chilled broiler carcasses processed at the same commercial facility. For each of four replications, 15 broilers were collected from the same commercial processing line after evisceration, after spraying with cetylpyridinium chloride (a cationic disinfectant), and after air chilling or water immersion chilling (WIC). All carcasses were quantitatively examined for mesophilic aerobic bacteria, Escherichia coli, coliforms, and Campylobacter as well as for the presence of Salmonella and Campylobacter. No significant differences (P > 0.05) were seen between air and water chilling for E. coli or coliforms or for the incidence of Salmonella and Campylobacter. Lower numbers of Campylobacter were recovered from WIC than from air-chilled carcasses (P < 0.05), but the incidence of Campylobacter on WIC carcasses was similar, suggesting that some Campylobacter organisms were injured rather than killed during WIC. In-line spraying with the disinfectant effectively decreased the incidence of Salmonella and Campylobacter on prechilled carcasses; however, cells presumably injured by the sanitizer recovered during chilling. Therefore, on-farm intervention strategies remain critically important in minimizing the spread of microbial contaminants during processing.