Influence of dietary conjugated linoleic acid on volatile profiles, color and lipid oxidation of irradiated raw chicken meat

Forty-eight, 27-week-old White Leghorn hens were fed a diet containing 0, 1.25, 2.5 or 5.0% conjugated linoleic acid (CLA) for 12 weeks. At the end of the 12-week feeding trial, hens were slaughtered, and boneless, skinless breast and leg meats were separated from carcasses. Meats were ground through 9 and 3-mm plates, and patties were prepared. Patties prepared from each dietary treatment were divided into two groups and either vacuum- or aerobic-packaged. Patties were irradiated at 0 or 3.0 kGy using a linear accelerator and stored at 4°C. Samples were analyzed for thiobarbituric acid reactive substances, volatile profiles, color and odor characteristics at 0 and 7 days of storage. Dietary CLA reduced the degree of lipid oxidation in raw chicken meat during storage. The content of hexanal and pentanal in raw chicken meat significantly decreased as dietary CLA level increased. Irradiation accelerated lipid oxidation in meat with aerobic packaging, but irradiation effect was not as significant as that of the packaging. Dietary CLA treatment improved the color stability of chicken patties. Color a*-value of irradiated raw chicken meat was higher than that of the nonirradiated meat. Dietary CLA decreased the content of polyunsaturated fatty acid and increased CLA in chicken muscles, which improved lipid and color stability and reduced volatile production in irradiated and nonirradiated raw chicken meat during storage.     

Effects of Dietary Functional Ingredients and Irradiation on the Quality of Cooked Turkey Breast Meat during Storage

ABSTRACT:  Patties were prepared using the breast meat from 15-wk-old turkeys fed one of the 8 dietary treatments [Con, control; VE, 200 IU/kg vitamin E; Se, 0.3 mg/kg selenium; CLA, 2.5% conjugated linoleic acids; VE + Se, 200 IU/kg vitamin E + 0.3 mg/kg selenium; VE + CLA, 200 IU/kg vitamin E + 2.5% CLA; Se + CLA, 0.3 mg/kg selenium + 2.5% CLA; VE + Se + CLA, 200 IU/kg vitamin E + 0.3 mg/kg selenium + 2.5% CLA] for 4 wk. Patties were vacuum-packaged in oxygen-impermeable bags, and then irradiated with 0 or 1.5 kGy. Irradiated breast meats were cooked and vacuum-packaged or aerobically packaged, and the quality of meat was evaluated after 0 and 7 d of storage at 4 °C. Dietary VE + Se, VE + CLA, Se + CLA, and VE + Se + CLA treatments reduced lipid oxidation of cooked irradiated (1.5 kGy) turkey breast meat by 24%, 29%, 26%, and 40%, respectively, compared to that of the control after 7 d of storage under aerobic conditions. Dietary treatments had no influences on the color of nonirradiated cooked turkey breast. However, dietary VE and Se decreased the internal a * value of irradiated meats in vacuum packaging at days 0 and 7, and the effect was even greater when VE and Se were combined with CLA. Dietary VE, Se, and CLA combinations significantly reduced the production of volatiles, especially those related to lipid oxidation. Dietary VE + Se, VE + CLA, and VE + Se + CLA reduced the difference in sulfur-containing compounds between irradiated and nonirradiated meat. Aerobic packaging was more effective than vacuum packaging in reducing sulfur-containing compounds. Therefore, dietary VE, Se, and CLA combinations plus aerobic packaging were effective in reducing the odor problems induced by irradiation.     

EFFECTS OF BINDING SUBSTRATE, TYPE OF NONMEAT ADDITIVE AND METHOD OF TENDERIZING ON CURED CHICKEN ROLLS

Chicken rolls were manufactured using ground dark fowl meat or mechanically deboned poultry meat as a binding substrate, sodium caseinate or soya isolate and a meat block that was mechanically tenderized or chunked. Effects of these treatments on yield, chemical composition, sensory and texture profile attributes were evaluated in this study. Inclusion of soya isolate increased the cook yield and improved color over sodium caseinate (P < 0.05). Likewise, rolls containing ground-dark fowl meat were lighter in color than those made with mechanically deboned poultry meat. Rolls made with mechanically deboned poultry meat had greater chewiness, while those made with sodium caseinate had greater cohesiveness. Texture profile analysis indicated that mechanical tenderization was the predominant factor in producing a softer and more springy chicken roll. Sensory evaluation revealed that mechanical tenderization decreased chewiness as compared to cubing (P < 0.05).     

Effect of dietary conjugated linoleic acid, irradiation, and packaging conditions on the quality characteristics of raw broiler breast fillets

Skinless breast fillets were harvested from broilers fed with 0, 0.25, 0.5, or 1.0% conjugated linoleic acid (CLA) for 3 weeks. Fillets were either vacuum or aerobically packaged, then irradiated at 0 or 3.0 kGy using a Linear Accelerator. Breast fillets were analyzed for thiobarbituric acid reactive substances (TBARS), volatile profiles, and color at 0 and 7 days of storage at 4°C. Dietary CLA reduced TBARS, but had no effect on volatile profiles and color of breast fillets. Color a* value of breast fillets increased after irradiation. Irradiation also induced production of many volatiles, mainly alkanes and alkenes, which could be the breakdown products of unsaturated fatty acids and amino acids. High amount of dimethyl disulfide was detected in the volatiles of irradiated fillets. Low level of hexanal and pentanal in volatiles, together with low TBARS values, indicated that lipid oxidation of breast fillets after irradiation is not a big concern.     

Effects of nitrite levels,endpoint temperature and storage on pink color development in turkey rolls

The objective of this research was to determine the relationship between minimum nitrite level, endpoint temperature and storage period on pink discoloration of turkey rolls. Rolls were prepared with 0, 3 or 5 parts per million (ppm) NO₂^–, cooked to an endpoint temperature of 75 °C or 85 °C and stored at 4 °C. During the 13-day storage period, on the 0th, 4th, 8th and 13th days cured pigment, total pigment, residual nitrite and color parameters were measured and sensory color was evaluated. At each endpoint temperature, addition of 3 ppm or 5 ppm NO₂^– significantly increased cured pigment and total pigment levels. Cured pigment levels of turkey rolls cooked to 75 °C were higher than rolls cooked to 85 °C, regardless of the NO₂^– level. There was a significant decrease in cured pigment levels at the end of the storage period (13th day). Analysis of residual NO₂^– in all treatment groups showed no detectable amounts. Endpoint temperature and addition of NO₂^– affected L* values: rolls cooked to the 75 °C endpoint had higher L* values. The additon of nitrite with the 75 °C endpoint temperature resulted in higher a* values. a* values also increased during the storage. The higher endpoint temperature (85 °C) resulted in lower a* values. Yellowness was not affected by final cooking temperature. Both the addition of NO₂^– and storage decreased b* values. The panel found no differences in pinkness intensity between the two levels of added nitrite (3 and 5 ppm). Sensory pinkness intensity in nitrite-added samples increased with increasing storage.     

煮制条件对卤鸡肉品质的影响

通过研究90℃和95℃两个温度条件下不同煮制时间对卤鸡肉品质的影响,以期获得卤鸡肉的适宜煮制条件。结果显示,卤煮温度和卤煮时间均显著影响卤鸡腿的品质(p<0.05)。同温下煮制10~120min,卤鸡腿的出品率、汤pH均大体呈现下降趋势,亮度L*、黄度b*、羰基值逐渐增加,红度a*值无明显变化,卤鸡腿pH、嫩度先增后降;煮制相同时间,两温度的出品率除20min外90℃始终高于95℃,亮度L*在30min之前90℃显著低于95℃(p<0.05),40min开始变化不再显著(p>0.05),黄度b*和红度a*无显著差异,剪切力除60min和90min外90℃均高于95℃,pH从60min开始90℃高于95℃,羰基含量在60min之后95℃开始明显高于90℃;60min是两温度在卤煮过程中品质差异显著的时间拐点。      

Effects of Electron Beam Irradiation and Antimicrobials on the Volatiles, Color, and Texture of Ready-to-eat Turkey Breast Roll

ABSTRACT: Breast rolls with 6 antimicrobial additive treatments—no preservatives (control), 0.1% potassium benzoate (PB), 2% sodium lactate (SL), 0.1% potassium benzoate plus 2% sodium lactate (PB + SL), 2% sodium lactate plus 0.1% sodium diacetate (SL + SDA), and 0.1% potassum benzoate, 2% sodium lactate, and 0.1% sodium diacetate (PB + SL + SDA)—were prepared. Samples were irradiated at 0, 1.0, or 2.0 kGy, and then the quality characteristics of turkey rolls were analyzed. Adding 2% SL increased the hardness, springiness, cohesiveness, chewiness, and resilience of breast rolls. Addition of PB or SDA, and irradiation had no significant effect on texture. Adding 2% SL affected color values. The color a * and b * values of turkey rolls with 2% SL added were significantly lower than those of the control, and this difference was maintained after irradiation and during storage. No difference in color and texture was observed between turkey rolls added with SL and those added with SL + PB + SDA. Breast rolls containing antimicrobials had more lipid oxidation than control. Irradiation and storage slightly enhanced lipid oxidation, although the overall lipid oxidation was very low. Irradiation promoted the formation of dimethyl disulfide and dimethyl trisulfide. Adding PB in breast rolls greatly increased the formation of benzene during irradiation, whereas other antimicrobial additives had no significant effects on volatiles.     

Raw-meat packaging and storage affect the color and odor of irradiated broiler breast fillets after cooking

Raw breast fillets were divided into two groups and either vacuum or aerobically packaged. The fillets in each group were subdivided equally into two groups and then irradiated at 0 or 3 kGy using a Linear Accelerator. After 0, 3 and 7 days of storage at 4?°C, fillets were cooked in an 85?°C water bath (cook-in-bag) to an internal temperature of 74?°C. Oxidation-reduction potential (ORP) of raw fillets was measured before cooking, and color and sensory characteristics were analyzed after cooking. Irradiation decreased the ORP of meat, but the potential in aerobically packaged fillets increased during storage. After cooking, color a*-value of irradiated fillets was higher than that of the non-irradiated. Irradiation of raw meat also changed color L* and b* values after cooking. Aerobic storage reduced the redness of cooked meat induced by irradiation. Irradiated raw broiler fillets stored for 0 day and 3 day under aerobic conditions before cooking produced a oxidized chicken-like odor. The odor, however, disappeared after 7 days of storage under aerobic conditions before cooking. For raw broiler samples stored under vacuum conditions, significant differences in color and odor between irradiated and non-irradiated fillets remained throughout the 7-day storage period after cooking. Irradiation had only a minor influence on lipid oxidation of raw breast fillets as indicated by low TBARS values. This study indicates that the effect of irradiation on color and odor of broiler breast fillets after cooking can be reduced significantly through shelf-display of raw fillets under aerobic conditions. Storage under vacuum conditions before cooking is not effective in reducing irradiation-induced changes in the color and odor of breast fillet after cooking.     

Conjugated Linoleic Acid Reduces Lipid Oxidation in Aerobically Stored, Cooked Ground Beef Patties

ABSTRACT: The effect of direct addition of conjugated linoleic acid (CLA) on lipid oxidation was studied. CLA and/or fat trim (4% by weight) were added to the lean trim (96%). Thiobarbituric acid reactive substances (TBARS) were determined on days 0, 3, and 7 for cooked or raw patties stored aerobically at 4 °C. Addition of CLA during the grinding process increased CLA isomers in both raw and cooked ground beef and decreased TBARS production ( P < 0.01). CLA caused a greater reduction in TBARS over storage time in cooked patties than in raw patties ( P= 0.006). The concentrations of 18:2n–6 and CLA isomers decreased with storage time. CLA increased 18:2n-6, whereas most fatty acids were decreased by the addition of CLA. CLA did not affect percentages of fat and moisture, cooking loss, or meat color (L*, a *, b *) ( P > 0.60).     

Effects of Irradiation on Properties of Cured Ham

ABSTRACT: The quality characteristics of cured ham, treated with ionizing radiation (4.5 kGy) at different points in the curing process, were compared during a 90-d storage period. Irradiation treatments included irradiation of raw uncured ham, raw-cured ham, cured cooked ham, and a nonirradiated control. Irradiation processing increased lipid oxidation for all treatments. The raw-cured treatment resulted in significantly lower L* values compared with the control regardless of storage period. All treatments except for cured cooked ham had lower b* values over the storage period. Irradiation of cured cooked ham resulted in higher off-odor scores than all other treatments immediately following irradiation thus indicating a change in quality.     

Effects of Carbon Monoxide Packaging on Color and Lipid Stability of Irradiated Ground Beef

ABSTRACT: The effects of packaging atmosphere (aerobic, vacuum, or modified atmosphere with carbon monoxide) on ground beef treated with ionizing radiation were investigated. Measurements of color (CIE L*, a*, b*), lipid oxidation (TBA value), and sensory quality were conducted during 28 d of storage at refrigerated (0 to 2°C) temperatures. Irradiation significantly ( p > 0.001) decreased color scores and increased TBA and off-odor scores. The MAP + CO treatments increased the L* and a* values ( p < 0.001), regardless of irradiation dose. The TBA values for MAP + CO-packaged samples were well below the levels considered "rancid" (about 1.0). In addition, sensory scores indicated minimal production of irradiation off-odors with MAP + CO packaging.     

A RESEARCH NOTE EFFECTS OF AMMONIA EXPOSURE ON FRESH PORK: A DISTINCT PINK COLOR AFTER COOKING

Exposure of raw pork loin chops to ammonia results in the development of a distinct pink color throughout, after cooking to 80C as indicated by visual observations and CIE L*a*b* values. While some of the color development is apparently due to the pH shift caused by the ammonia, experiments suggest that other factors are involved in the formation of the distinct pink color. Samples cooked and then exposed to ammonia failed to develop the pink color. CIE a* values were higher (P < 0.05) for all cooked ammonia treated samples than the cooked control. Distinctly different absorbance spectra (400–700 nm) were observed between cooked, treated samples and either the cooked untreated control, raw fresh pork, or nitrosohemochrome samples. These data suggest that exposure of raw pork to ammonia will influence formation of an undercooked color in fully cooked pork.     

Use of calcium lactate with salt-phosphate and alginate-calcium gels in restructured pork rolls

The study was carried out to evaluate restructured pork rolls (RPR) prepared by using salt-phosphate and alginate-calcium gels with or without calcium lactate. Five types of RPR were prepared with: (1) 1.75% sodium chloride+0.3 phosphate (SP); (2) 1.75% sodium chloride+0.3% phosphate+0.3% calcium lactate (SPL); (3) 0.7% sodium alginate+0.125% calcium carbonate (AC); (4) 0.7% sodium alginate+0.3% calcium lactate (AL); and (5) 0.7% sodium alginate+0.125% calcium carbonate+0.3% calcium lactate (ACL). Cooking yield and cooked binding strength were significantly (P<0.05) higher in RPR containing salt and phosphate whereas pH and raw binding strength were significantly (P<0.05) higher in RPR containing alginate and calcium. Texture profile analysis indicated significantly (P<0.05) higher firmness and cohesiveness in RPR containing SPL and ACL. Sensory scores were significantly (P<0.05) higher in SP, SPL and ACL than AC and AL treatments. Results of storage studies indicated significant (P<0.05) increases in pH, TBARS numbers, metmyoglobin and microbial counts with storage in all the treatments. The results suggest that quality characteristics of raw product were better when RPR were prepared with alginate-calcium whereas quality characteristics of cooked product were better when rolls were prepared with salt-phosphate. Further, addition of calcium lactate improved sensory characteristics and shelf life of both alginate-calcium and salt-phosphate restructured pork rolls.     

Quality characteristics of irradiated turkey breast rolls formulated with plum extract

The effects of adding 1%, 2% and 3% plum extract on the quality characteristics of vacuum-packaged, irradiated ready-to-eat turkey breast rolls were determined. Turkey breast rolls were sliced, packaged and irradiated at 0 or 3 kGy using a Linear Accelerator. Lipid oxidation, volatile profiles, color, texture, proximate analysis and sensory characteristics of sliced turkey breast rolls were determined at 0 and 7 days of storage. Addition of plum extract had no detectable effect on the proximate analysis of turkey breast rolls. Plum extract increased a* and b* values, and decreased L* value of turkey breast rolls due to the original color of plum extract. Addition of >2% plum extract to turkey breast rolls was effective in controlling lipid oxidation of irradiated meat and the production of aldehydes (hexanal, heptanal, octanal, and nonanal) in non-irradiated meat at Day 0. Texture of turkey breast rolls was not influenced, but juiciness was increased by plum extract. Therefore, addition of 3% or higher of plum extract is recommended to improve mouth-feel and antioxidant effect in irradiated turkey breast rolls. However, the color of turkey breast rolls with 3% plum extract was dark and might not be appealing to consumers.     

低钠复合盐对盐焗鸡贮藏期品质的影响

以低钠复合盐（含52%（质量分数,后同）氯化钠、30%氯化钾、8%乳酸钙、10%酵母抽提物）制作的盐焗鸡为低钠组,以100%氯化钠制作的盐焗鸡为对照组,结合理化指标及微生物情况探究低钠复合盐对盐焗鸡贮藏期品质的影响。结果表明,随贮藏时间延长,盐焗鸡pH值先上升后下降,总巯基含量及模糊数学感官评分下降,总挥发性盐基氮（total volatile basic nitrogen,TVB-N）值、硫代巴比妥酸反应物（thiobarbituric reactive substances,TBARS）值及菌落总数上升,大肠菌群数及致病菌数符合GB 2726—2016《食品安全国家标准 熟肉制品》规定,而第30天时盐焗鸡的菌落总数均超过国家标准。低钠组pH值、TVB-N值、TBARS值及菌落总数始终高于对照组,脂肪及蛋白质氧化程度低于对照组,而a*、b*值及模糊数学感官评分总体与对照组没有显著差异（P＞0.05）。高通量测序结果表明,盐焗鸡主要优势菌门为厚壁菌门,低钠组及对照组主要优势菌属分别为沙雷氏菌属、Paeniclostridium。综上,低钠复合盐对盐焗鸡的颜色及感官品质没有显著影响且能抑制盐焗鸡的脂肪及蛋白质氧化,对盐焗鸡的安全性没有负面影响,贮藏20 d后两组盐焗鸡均不宜食用。     

Effects of conjugated linoleic acid on color and lipid oxidation of beef patties during cold storage

The effects of conjugated linoleic acid (CLA) on color and lipid oxidation of beef patties were investigated. Ground beef was divided into three batches. The control patties were prepared with 90% lean meat and 10% tallow. The second treatment consisted of 90% lean meat with 9.5% tallow+0.5% CLA sources. The third treatment consisted of 90% lean meat with 8% tallow+2% CLA sources. The patties were wrap-packaged and then stored at 4° for 14 days. The CLA concentration significantly increased (P<0.05) by substituting CLA sources for fat. Storage of the patties did not alter the CLA concentration in beef patties. The treatment substituted with CLA sources had significantly lower TBARS (2-thiobarbituric acid-reactive substances) values (P<0.05) than the control. For oxymyoglobin contents and a* value, substituted CLA sources treatments had significantly higher values than the control. However, L* value significantly increased by substituting CLA sources for fat.     

Physicochemical characteristics of pork fed palm oil and conjugated linoleic acid supplements

The experiment was conducted to determine chemical and physical characteristics of pork fed palm oil in the diets and with two levels of CLA (0.5% and 1.0%) supplementation. Chemical compositions and CLA contents were analyzed from raw loins and ham portions. Color and shear force values were measured in raw and cooked meats. The pork fed CLA supplements contained higher (P<0.05) moisture, less fat, and lower MUFA:SFA, PUFA:SFA and n-6:n-3 ratios. Fatty acid compositions were noticeably changed in the loin meats when palm oil was supplemented with CLA in the pig diets, but not in the hams. The CLA contents of meats increased (P<0.05) with increasing amounts of CLA in the diets, with the c9,t11 CLA isomer was the highest concentration. The loins from pigs fed CLA supplements had lighter (P<0.05) color while the ham portions showed darker color. Cooked loins from pigs fed CLA supplements gave higher (P<0.05) shear forces compared with that fed palm oil only, while cooked hams had lower forces in spite of higher forces were observed in raw state.     

Functional properties of raw and cooked pork patties with added irradiated, freeze-dried green tea leaf extract powder during storage at 4 °C

Functional and sensory properties of raw and cooked pork patties with added irradiated freeze-dried green tea leaf extract powder were studied. Components of green tea were extracted by 70% ethanol, and the extract was irradiated to obtain a bright color. The irradiated green tea extract was freeze-dried and the powdered sample (0.1%) was added to the pork patties (Trt C). Pork patties without any ingredient (Trt A) and with nonirradiated, freeze-dried green tea extract powder (Trt B) were also prepared for comparison. Lipid oxidation, radical scavenging effect, color, and sensory properties of pork patties with treatments were analyzed at 5-day intervals for 15 days with storage at 4?°C. The lipid oxidation had a lower (P<0.05) and radical scavenging effect was greater (P<0.05) in the raw and cooked pork patties with added Trt B and Trt C, than those of Trt A (control). The pork patties with Trt B and Trt C had a higher Hunter color a*-value and less cooking loss than that of Trt A. Sensory panelists preferred the odor of the raw pork patties and color of the cooked pork patties of Trt C (P<0.05). Generally, no significant difference between Trt B and Trt C was found. Therefore, irradiated, freeze-dried green tea extract powder can be used for producing functionally-improved meat products.     

Effect of microbial transglutaminase and sodium caseinate on quality of chicken döner kebab

The effect of microbial transglutaminase (MTGase) and sodium caseinate on the quality of chicken d?ner kebab was investigated. Yield, color, pH, SDS-polyacrylamide gel electrophoresis (SDS-PAGE), texture, and sensory evaluations were measured. The results of SDS-PAGE showed that addition of MTGase with or without sodium caseinate created cross-linking between meat proteins. Texture measurements indicated that the effect of the enzyme on binding properties of chicken meat is more effective if it is used with sodium caseinate (P<0.05). Sensory evaluation was not significantly different statistically among treatments.