Effect of length and temperature of storage on the ESR signal from various bones in irradiated chicken carcasses

Eighty-four whole, fresh chicken carcasses were randomly allocated to three groups of 28. Half of the carcasses within each group acted as controls (0kGy) and the remainder received an average irradiation dose of 5.27 kGy. The carcasses were then stored at either +20°C, +5°C or -20°C for periods of 1, 3, 7, 14, 21, 28, 56, 84 or 128 days. Bones from four sites within the carcass (tibia, femur, rib and sternum) were removed and prepared for analysis by electron spin resonance (ESR) spectroscopy. The strength of the ESR signal induced in the bones as a result of gamma irradiation was determined by double integration of these signals. The site from which the bone was removed had a highly significant effect on the ESR signal intensity and this response was highly correlated with bone crystallinity. Neither storage time, temperature nor the interaction of these two variables significantly affected the ESR signal strength in the bones from the four sites within the carcass. Nevertheless, there was a tendency for the signal to decrease with time when the samples were stored in dried from at +20°C.     

The effect of post-irradiation cooking on the ESR signal in irradiated chicken drumsticks

Groups of seventy-two, 6-week-old broiler chicken carcasses were either not irradiated and served as controls or were given 2.5 or 5.0 kGy doses of irradiation. Half of each group remained uncooked and half were cooked in a convection oven at 190°C. Pairs of drumsticks were taken from each carcass, the bones excised and the free radical content measured using electron spin resonance (ESR) spectroscopy. The ESR signal strength increased significantly as irradiation dose increased, the value at 5.0 kGy being 96% greater than that at 2.5 kGy. Cooking significantly reduced the free radical concentration of the irradiated bone by approximately 23%.     

An investigation into the effect of sample preparation methods on the resulting ESR signal from irradiated chicken bone

Results are presented giving details of the effect of six different methods of sample preparation on the free radical concentration in irradiated chicken drumsticks. Comparisons were made using electron spin resonance spectroscopy. Freeze drying and grinding was found to be the preferred method of sample preparation.     

Detection of irradiated lamb meat with bone: effect of chilled storage and cooking on esr signal strength

Summary The effect of gamma-irradiation doses of 1, 2, 4 and 5 kGy on ESR signal intensity in pre-packed irradiated lamb meat chunks containing bones was studied. Irradiation-induced a characteristic ESR signal in bone that was not detected in non-irradiated samples and its intensity was proportional to irradiation dose up to 5 kGy. In samples irradiated to 2.5 kGy for shelf-life enhancement, ESR signal intensity was monitored immediately after irradiation and subsequently at weekly intervals during storage at 0–3 °C and after cooking by different methods. Hind leg bones (femur) displayed a higher signal intensity than rib bones. The ESR signal intensity faded by 30 and 42% during 4 weeks at 0–3 °C in hind leg and rib bones, respectively. The magnitude of ESR signal in hind leg bone declined by a maximum of 30% upon pressure cooking (for 15 min), 10% on microwave cooking (for 5 min) and 13% after boiling (for 30 min). However, in the case of rib bones, all cooking methods reduced the ESR signal by about 40%. Storage of irradiated freeze-dried bone powder samples at ambient temperature also resulted in slight reduction in ESR signal intensity. Results point to the suitability of ESR technique for detection of irradiated lamb meat even after storage or cooking, and also in samples that had been stored and then cooked.     

Effect of storage and cooking on the dose response of 2-dodecylcyclobutanone,a potential marker for irradiated chicken

Results are presented indicating a linear relationship between irradiation dose (1–10 kGy) and the amount of 2-dodecylcyclobutanone produced in chicken meat. After storage for 18 days at 4°C this linear relationship with dose persisted although there was a slight decrease in the concentration of the compound. 2-Dodecylcyclobutanone was not generated by cooking and, despite a reduction in the amount of the compound in chicken meat cooked either before or after irradiation, it still proved to be a useful marker for the irradiated product. The compound was not detected in spoiled chicken meat.     

不同的提取工艺对鸡骨素出品率的影响

通过正交试验,研究了不同工艺参数对鸡骨素出品率的影响.结果表明:提取温度为135℃,提取时间为60min,在4min之内将压力从0.32MPa降至0.10MPa,然后继续升温,每35min泄压一次,即在60min的时间内泄压一次半(第二次泄压完后不再升温,直接压抽)时,鸡骨素出品率能够达到最好的水平.     

Application of ESR spectroscopy to identify and estimate original dose in irradiated cumin and white pepper

Feature changes in the ESR spectrum and the relationship between ESR intensity and irradiation dose ranging between 0 and 15.0 kGy were studied to detect irradiated cumin and white pepper by ESR spectroscopy. The absorbed irradiation doses of two samples were assessed using the dose-additive method. The ESR signal intensities of irradiated cumin and white pepper increased with increasing absorbed radiation dose. Even after 220 days, the ESR method could still be used to identify whether or not cumin and white pepper had been irradiated. The dose-additive method can be used to reliably evaluate the absorbed doses of cumin and white pepper. The 3rd polynomial function can be used to fit the data. Long-term decay of the radiation-induced radical has a marked influence on dose assessment and leads to an underestimation of the dose.     

Development of a method based on ESR spectroscopy for the identification of irradiated beef,pork, and chicken meats

The electron spin resonance (ESR) spintrapping method for the detection of irradiated beef, pork, and chicken was studied using a α-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) spin trapper in the dose of 0.5–7 kGy. Irradiation caused a significant increase in the ESR signal intensity of samples with hyperfine coupling constants of a ^N=1.57 mT and a ^H=0.25 mT, which correspond to lipid-derived radicals. In contrast, un-irradiated samples exhibited a weak ESR signal with no hyperfine coupling constants. The irradiation-induced lipid radical stability vs. temperature was also studied at room temperature, −4 and −18°C using 3 kGy irradiated beef. Temperature did not affect ESR signal intensity or the hyperfine coupling constants. To investigate the applicability of the proposed procedure for pork and chicken, a comparison of the spectra at the hyperfine coupling constants confirmed the presence of lipid-derived radicals in the samples.     

不同加工和贮藏条件对鸡肉制品颜色的影响

研究了腌制剂(食盐、亚硝酸盐)、天然抗氧化剂(维生素C、茶多酚)、其他加工(热处理)和贮藏条件(温度、光线、氧气)对鸡肉制品颜色的影响.在鲜鸡胸肉中按4种处理添加食盐(2%)、亚硝酸盐(0.02%)、茶多酚(0.02%)、维生素C(0.05%),每种处理在不同的加工和贮藏条件(蒸煮与否、温度、抽真空与否、有光与否)的组合下放置120h,每24h用色差仪客观测定样品a*值.结果表明,亚硝酸盐、维生素C和茶多酚配合使用既能促进鸡肉制品发色,又能有效保护鸡肉制品颜色;但其发色和护色的效果仍然受温度、光线、氧气、蒸煮加热与否等加工或贮藏条件的显著影响.因此,在实践中使用天然抗氧化剂可能会降低亚硝酸盐的用量,但为保证鸡肉制品的颜色采用低温、避光、真空等措施是非常必要的.     

添加超细粉碎盐煸鸡骨泥对鸡肉肠品质的影响

在鸡肉肠中添加一定比例的超细粉碎盐焗鸡骨泥会增加肉肠的风味和营养,但添加后可能会对鸡肉肠凝胶的质构带来不利影响。以普通鸡肉肠的加工为基础,分别添加4%、8%、12%、16%(按干基计)的骨泥,通过采用单因素实验,根据色泽和质构特性测定,并结合感官评定分析,探讨了盐焗鸡骨泥对鸡肉肠品质特性的影响。当骨泥添加量增加,鸡肉肠和鸡肉糜的L*值下降,b*值上升;鸡肉肠的凝胶强度、硬度、咀嚼性均下降,弹性先下降(0%～8%骨泥添加量)后上升(8%～16%骨泥添加量);鸡肉肠的感官得分先上升后下降。当骨泥添加量为12%时,鸡肉肠的感官接受度最高,为最佳盐焗鸡骨泥添加量。     

Changes in structure and color characteristics of irradiated chicken breasts as a function of dosage and storage time

Structural change and color characteristics of chicken breasts as a function of irradiation dose and subsequent storage process were investigated by visible spectroscopy and HunterLab measurement. Ratios of R(1)=A(485 nm)/A(560 nm) and R(2)=A(635 nm)/A(560 nm,) which are related to absorbances of the visible bands at 485 nm (metmyoglobin), 560 nm (oxymyoglobin), and 635 nm (sulfmyoglobin), suggested that relative amount of oxymyoglobin either increases as a result of irradiation, or decreases with the storage process. The plot of R(1) and R(2) versus storage time showed that the increments of both R(1) and R(2) are dose-dependent and that the relative amount of oxymyoglobin species in irradiated meats begins to decompose 7-12 days later than raw meats. In addition, R(1) and R(2) values were correlated with color index E(?) of chicken breasts.     

Effect of processing and storage conditions on the generation of acrylamide in precooked breaded chicken products

The generation of acrylamide was determined during frying and cold storage of breaded chicken products. The role of the batter crust on acrylamide formation also was evaluated. The effect of storage under a modified atmosphere on the fate of acrylamide was investigated during a 23-day storage period under refrigeration. Acrylamide was analyzed by using normal phase high-performance liquid chromatography according to a previously developed methodology that allows for dual identity verification as acrylamide and acrylic acid and determination of concentrations as low as 10 microg liter(-1), which corresponds to 20 microg kg(-1) of solid sample. For the total 28 commercial precooked samples analyzed, initial acrylamide concentrations ranged between 0.91 and 0.97 mg kg(-1) and were attributed to the combined effect of batter and meat. In all cases, acrylamide concentrations increased during storage, attaining a maximum (1.36 to 1.80 mg kg(-1)) between day 15 and day 19. The maximum value was observed in samples packaged under air, and the minimum value was observed under a modified atmosphere mixture of 60% CO2-40% N2. In this group, the maximum acrylamide concentration was reached after 19 days of storage. These data indicate that there is a high concentration of acrylamide in precooked, battered protein foods and that the concentration changes considerably during storage, which may lead to almost twice the initial amounts when air is present within the package.     

Detection of irradiation in scampi tails — effects of sample preparation, irradiation dose and storage on ESR response in the cuticle

This paper describes the potential of using ESR spectroscopy for the identification of irradiated scampi (Norway lobster) using the signal induced in the cuticle at 349.5 mT. Freeze-drying the cuticle gave a larger signal than air-drying, and peak height was found to be a more reliable method of quantification than double integration of the peak. There was a linear response with increasing irradiation dose. Samples were stored intact at –20°C and +5°C and as dry shell at room temperature for up to 84 d and it was observed that signal intensity was reduced with increased storage time and higher temperature, especially at the higher doses. Thus ESR spectroscopy can be used to detect irradiation in scampi cuticle and has potential for the estimation of irradiation dose.     

Determination of hydrogen in irradiated frozen chicken

A headspace analyser based on a hydrogen-specific electronic sensor has been developed and applied to the determination of hydrogen in ice and in frozen chicken. The loss of hydrogen during storage of samples at — 18°C has been monitored; it has been demonstrated that the hydrogen generated during the irradiation of frozen chicken at 5 kGy can be determined for up to at least 6 months. It is concluded that hydrogen is a promising marker for distinguishing between irradiated and unirradiated frozen food; it could provide a rapid screening test, complementing other chemical, physical and microbiological procedures. Positive detection of hydrogen provides conclusive evidence of irradiation; however, no definite conclusions can be drawn from a failure to detect hydrogen.     

鸡蛋壳暗斑对鸡蛋贮藏性能的影响

文章探讨了鸡蛋壳具有0%,10%,30%,60%的暗斑覆盖率对贮藏中鸡蛋失重率、相对密度、蛋黄指数、蛋清pH值、哈夫单位等新鲜度指标及菌落总数、大肠菌群、霉菌、沙门氏菌等微生物的影响。结果表明,在鸡蛋存放期间,暗斑鸡蛋新鲜度指标的变化速度以及菌落总数、霉菌等微生物的增长速度均较无斑鸡蛋快,且随着鸡蛋壳暗斑覆盖率的增加,鸡蛋新鲜度下降越快,菌落总数、霉菌等微生物的增长也越快。鸡蛋壳暗斑的存在对鸡蛋品质具有不良影响,可使鸡蛋贮藏期缩短。     

不同冻藏温度对鸡胸肉电阻抗特性的影响

为研究不同冻藏温度条件下鸡胸肉的阻抗特性差异,将白羽鸡鸡胸肉在-10、-20与-30℃的条件下分别冻藏3、6、9、12个月,相应的冻藏时间取20块鸡胸肉解冻,在0.05²00 k Hz的频率范围内,选取6个频率点进行电阻抗特性的分析,检测鸡胸肉的阻抗幅值与阻抗相对变化值（Q值）以及理化品质指标。结果表明:相同冻藏时间内,冻藏温度越高,鸡肉的解冻汁液流失率、脂肪氧化程度、剪切力越大（p<0.05）,蛋白质溶解度越小（p<0.05）。随着检测频率的上升,不同冻藏温度鸡胸肉的阻抗幅值均呈下降趋势。在50 Hz频率时,各个冻藏时间的鸡胸肉在不同冻藏温度条件下的阻抗幅值均存在差异（p<0.05）;在200 k Hz频率时,-10℃处理组的阻抗幅值在冻藏3个月与6个月时显著低于其它处理组（p<0.05）。在冻藏过程中,-10℃冻藏组的Q值均显著高于-30℃处理组的Q值（p<0.05）。冻藏温度对解冻鸡胸肉的阻抗幅值与Q值产生影响,阻抗特性的差异能够反映冷冻鸡胸肉品质的差异,不同冻藏温度鸡肉的电阻抗特性差异为阻抗技术在冻肉品质检测中的应用提供了基础。      

Microbial and sensory quality of marinated and irradiated chicken

Chicken legs were subjected to two pretreatments (packaged in air or marinated in natural plant extracts and then packaged in air) followed by irradiation (0, 3, or 5 kGy). The control and irradiated chicken legs were stored at 4 degrees C and underwent microbial analysis (mesophilic aerobic plate counts and Salmonella detection) and sensory evaluation at predetermined intervals. Microbial analysis indicated that irradiation had a significant effect (P < or = 0.05) on the mesophilic aerobic plate counts of the poultry. For each treatment, the bacterial growth decreased with an increase of irradiation dose. The marinade had an additive effect with irradiation in reducing bacterial growth and controlling proliferation during storage at 4 +/- 1 degree C. No Salmonella was observed until day 12 in marinated chicken irradiated at 3 kGy and for all experiments with chicken legs stored under air or marinated at 5 kGy. However, Salmonella was found in chicken legs irradiated at 3 kGy in air and in nonirradiated samples. The sensory evaluation indicated a significant (P < or = 0.05) difference in odor and flavor intensities between the irradiated chicken at 5 kGy and the control. No significant difference was found (P > 0.05) between the marinated chicken irradiated at 5 kGy and the control.     

Studies on chicken actomyosin. I. Effect of storage on muscle enzymic and physico-chemical properties

Experiments were conducted to study the effect of storing broiler chicken muscle at 25°C on certain properties of actomyosin of the pectoralis major. Storage for 3 h or more resulted in the Mg²⁺-activated ATPase of actomyosin becoming less sensitive to inhibition by increasing concentrations of KCl and in an increased rate of superprecipitation of the complex. The analytical ultra-centrifuge pattern of the actomyosin of stored muscle differed from that of fresh muscle. Some evidence was obtained for the observed changes being partly dependent upon the pH of the muscle used as the source of actomyosin.     

Effect of natural antioxidant combinations on lipid oxidation in cooked chicken meat during refrigerated storage

The effect of combinations of sage, oregano and honey on lipid oxidation in cooked chicken meat during refrigeration at 4°C for 96h was determined. Chicken samples (thigh and breast) were then separated into five groups: control; butylated hydroxytoluene; oregano+sage; oregano+sage+5%honey and oregano+sage+10%honey. Quantitative measurements of thiobarbituric acid reactive substances, conjugated dienes, hexanal, fatty acids, cholesterol and cholesterol oxides were used as indicators of lipid oxidation. Acceptability and preference were also evaluated. The effectiveness of the natural antioxidants for reducing the velocity of lipid oxidation in cooked chicken thigh and breast was demonstrated after 48 and 96h of refrigeration at 4°C. The treatments that presented the lowest hexanal values after 96h of refrigeration were oregano+sage+5%honey and oregano+sage+10%honey. Only traces of free cholesterol oxides were found (25-OH, 7-k, 7α-OH and 7β-OH). The natural antioxidants protected cooked chicken meat from oxidation processes and resulted in great acceptability.     

Factors influencing the yield of free radicals in irradiated chicken bones

The exposure of foodstuffs containing bone or other calcified tissue to a dose of ionizing radiation results in the formation of long lived free radicals which give rise to characteristic ESR signals. The presence of this signal provides clear evidence that the sample has been irradiated. In order to determine the radiation dose by post-irradiation calibration, it is necessary to consider factors that might influence the radical yield and to allow for the stability of the radicals under likely conditions of storage. Using chicken bone we have shown that the yield is influenced by the nature of the bone, temperature of irradiation, and gaseous atmosphere, although not by dose rate, water content, or type of radiation. Cooking before irradiation greatly enhances the subsequent yield of radicals, while cooking after irradiation causes little or no destruction of the radiation-induced radicals, which also appear to be unaffected by length and conditions of storage.