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1.
Previous studies suggest that differences in concentrations of natural flavor precursors of the Maillard reaction may affect the odor and flavor of cooked chicken meat. To determine whether such differences occur in the purchased product, chickens from a range of commercial sources were analyzed for selected precursors. These analyses demonstrated that variation occurs both between different commercial sources and between individual chickens from the same source. Coefficients of variation exceeding 30% were observed for inosine 5'-monophosphate, guanosine 5'-monophosphate, and inosine, comparable with those previously determined for reducing sugars and their phosphates. These correspond to concentration ranges of 3-fold and higher, which in some cases may have the potential to affect odor and flavor formation. In contrast, thiamin and amino acids (both protein and nonprotein) show less variation with ranges mainly less than 2-fold. 相似文献
2.
Lantto R Puolanne E Kruus K Buchert J Autio K 《Journal of agricultural and food chemistry》2007,55(4):1248-1255
The effects of Trichoderma reesei tyrosinase-catalyzed cross-linking of isolated chicken breast myofibril proteins as a simplified model system were studied with special emphasis on the thermal stability and gel formation of myofibrillar proteins. In addition, tyrosinase-catalyzed cross-linking was utilized to modify the firmness, water-holding capacity (WHC), and microstructure of cooked chicken breast meat homogenate gels. According to SDS-PAGE, the myosin heavy chain (MHC) and troponin T were the most sensitive proteins to the action of tyrosinase, whereas actin was not affected to the same extent. Calorimetric enthalpy (DeltaH) of the major thermal transition associated with myosin denaturation was reduced and with actin denaturation increased in the presence of tyrosinase. Low-amplitude viscoelastic measurements at constant temperatures of 25 degrees C and 40 degrees C showed that tyrosinase substantially increased the storage modulus (G') of the 4% myofibrillar protein suspension in the 0.35 M NaCl concentration. The effect was the most pronounced with high-enzyme dosages and at 40 degrees C. Without tyrosinase, the G' increase was low. Tyrosinase increased the firmness of the cooked phosphate-free and low-meat chicken breast meat homogenate gels compared to the corresponding controls. Tyrosinase maintained gel firmness at the control level of the low-salt homogenate gel and weakened it when both salt and phosphate levels were low. Tyrosinase improved the WHC of the low-meat and low-salt homogenate gels and maintained it at the level of the corresponding controls of phosphate-free and low-salt/low-phosphate homogenate gels. Microstructural characterization showed that a collagen network was formed in the presence of tyrosinase. Keywords: Chicken myofibrillar proteins; protein modification; cross-linking; tyrosinase; gelation; thermal stability; texture; water-holding capacity; microstructure. 相似文献
3.
Vittayanont M Vega-Warner V Steffe JF Smith DM 《Journal of agricultural and food chemistry》2001,49(3):1587-1594
The denaturation, aggregation, and rheological properties of chicken breast muscle myosin, beta-lactoglobulin (beta-LG), and mixed myosin/beta-LG solutions were studied in 0.6 M NaCl, 0.05 mM sodium phosphate buffer, pH 7.0, during heating. The endotherm of a mixture of myosin and beta-LG was identical to that expected if the endotherm of each protein was overlaid on the same axis. The maximum aggregation rate (AR(max)) increased, and the temperature at the AR(max) (T(max)) and initial aggregation temperature (T(o)) decreased as the concentration of both proteins was increased. The aggregation profile of <0.5% myosin was altered by the presence of 0.25% beta-LG. Addition of 0.5-3.0% beta-LG decreased storage moduli of 1% myosin between 55 and 75 degrees C, but increased storage moduli (G') when heated to 90 degrees C and after cooling. beta-LG had no effect on the gel point of > or =1.0% myosin, but enhanced gel strength when heated to 90 degrees C and after cooling. After cooling, the G' of 1% myosin/2%beta-LG gels was about 1.7 times greater than that of gels prepared from 2% myosin/1% beta-LG. 相似文献
4.
Ultrasonic determination of chicken composition. 总被引：2，自引：0，他引：2
An ultrasonic technique has been developed for measuring the composition of chicken meat. The relationship between the composition and ultrasonic velocity of chicken meat was determined using chicken analogues of different composition, prepared from dried chicken powder, corn oil, and distilled water. The ultrasonic velocity of chicken analogues was measured at temperatures from 5 to 35 degrees C using an ultrasonic spectrometer. The ultrasonic velocity increased with solids-nonfat (SNF) content at all temperatures but had a more complex dependence on fat content. Around 15 degrees C the ultrasonic velocity was independent of fat content; however, at lower temperatures it increased with fat content, and at higher temperatures it decreased. Semiempirical equations were developed to describe the relationship between ultrasonic velocity and chicken composition. To determine the usefulness of these equations, the ultrasonic velocities of various chicken meats were measured. The compositions of the chicken meats predicted on the basis of ultrasonic measurements were in good agreement with those determined by using standard methods (r(2) > 0. 97). The ultrasonic technique could also be used to measure the solid fat content of chicken fat. This study shows that ultrasonic velocity measurements can be used to characterize chicken composition. This method has great potential for application in the food industry because it is simple, fast, nondestructive, and reliable. 相似文献
5.
Vittayanont M Steffe JF Flegler SL Smith DM 《Journal of agricultural and food chemistry》2003,51(3):760-765
Thermal, rheological, and microstructural properties of myosin (1 and 2% protein) were compared to mixtures of 1% myosin and 1% heat-denatured beta-lactoglobulin aggregates (myosin/HDLG) and 1% myosin and 1% native beta-lactoglobulin (myosin/beta-LG) in 0.6 M NaCl and 0.05 M sodium phosphate buffer, pH 6.0, 6.5, and 7.0 during heating to 71 degrees C. Thermal denaturation patterns of myosin and myosin/HDLG were similar except for the appearance of an endothermic peak at 54-56 degrees C in the mixed system. At pH 7.0, 2% myosin began to gel at 48 degrees C and had a storage modulus (G') of 500 Pa upon cooling. Myosin/HDLG (2% total protein) had a gel point of 48 degrees C and a G' of 650 Pa, whereas myosin/beta-LG had a gel point of 49 degrees C but the G' was lower (180 Pa). As the pH was decreased, the gel points of myosin and myosin/HDLG decreased and the G' after cooling increased. The HDLG was incorporated within the myosin gel network, whereas beta-LG remained soluble. 相似文献
6.
鸡、猪BPI氨基端的基因克隆和鉴定 总被引：1，自引：0，他引：1
为了克隆杀菌/通透性增加蛋白(BP I)N端cDNA,构建重组体pM D 18-T-BP I,并进行序列鉴定,应用RT-PCR技术,参照G enB ank报道的预测序列,从鸡多形核白细胞(PM N)mRNA中扩增出杀菌/通透性增加蛋白(BP I)氨基端95个氨基酸的基因片段,并与pM D 18-T连接,构建BP I氨基端的基因重组体,进行酶切鉴定和序列测定;从猪PM N的总mRNA中扩增出BP I氨基端48个氨基酸的基因片段,进行测序鉴定。获得鸡BP I N端长度为285 bp的基因片段。序列分析证实该片段中有3个点突变,但均不在活性中心;获得猪BP IN端长度为146 bp的基因片段。成功克隆出BP I N端基因,经序列测定,确认为BP I基因,为进一步表达该基因奠定了基础。 相似文献
7.
利用以UASB和接触氧化法技术为核心的工程处理设施和生物综合治理两项关键技术,分别对肉鸡屠宰场废水及下脚料进行综合治理研究。结果表明:工程处理设施可使屠宰场废水及下脚料的COD、BOD_5、SS和油类去除率分别达96．8％、99．6％、99．6％和99．4％。各项指标均达到GB8978-1996《污水综合排放标准》一级和GB13457-92《肉类加工工业水污染物排放标准》禽类屠宰加工一级标准,减少处理费25％。通过生物综合治理措施处理后的水质也达到上述标准,处理费用可以减少85％。 相似文献
8.
该文利用以UASB和接触氧化法技术为核心的工程处理设施和生物综合治理两项关键技术，分别对肉鸡屠宰场废水及下脚料进行综合治理研究。结果表明：工程处理设施可使屠宰场废水及下脚料的COD、BOD5、SS和油类去除率分别达96.8%、99.6%、99.6%和99.4%。各项指标均达到GB8978-1996《污水综合排放标准》一级和GB13457-92《肉类加工工业水污染物排放标准》禽类屠宰加工一级标准，减少处理费25%。通过生物综合治理措施处理后的水质也达到上述标准，处理费用可以减少85%。 相似文献
9.
鸡只粪便的性状是反映鸡只健康状况的重要特征之一,不同性状的鸡便往往与特定的疾病相关联。针对鸡只粪便性状主要依靠人工监测,存在速度慢且易发生交叉感染等问题,该研究提出一种基于可见-近红外光谱技术的鸡只粪便分类判别模型。首先,通过扫描4类典型的鸡只粪便样本（正常粪便、红血丝粪便、绿色粪便和饲料粪便）在400～900 nm波段范围的光谱数据,对每一类别的鸡便样本按随机性原则以3∶1划分为校正集和测试集。其次,分别采用多元散射校正、SG卷积平滑和标准差标准化进行数据预处理,并建立偏最小二乘判别分析模型,根据模型评价指标确定最优预处理方法。然后,使用主成分分析、竞争性自适应重加权采样、改进的混合蛙跳3种方法对预处理后的样本进行数据降维,并最终建立分类判别模型。结果表明：基于模型评价指标确定最优数据预处理方法后,再采用改进后的混合蛙跳降维方法建立的判别模型区分正常粪便、红血丝粪便、绿色粪便表现最优,测试集判别准确率分别为92.27%、92.59%、100%;而对于饲料粪便,所选3种降维方法建立的判别模型,其测试集准确率均可达100%。因此,通过可见-近红外光谱检测手段,结合特征波长优选与偏最小二乘判别分析,可以有效判别不同类型的鸡只粪便,为实现鸡病智能化监测提供技术支持。 相似文献
10.
Poultry feathers are renewable resources, inexpensive and abundantly available, but have limited applications. Although keratin extracted from feathers has been chemically modified, there are no reports on the chemical modification or development of thermoplastics from poultry feathers. Acetylation is an inexpensive and environmentally friendly approach to make biopolymers thermoplastic. Several biopolymers have been acetylated and used to produce fibers, films, and extrudates. In this research, chicken feathers were acetylated, and the structure and properties of the acetylated feathers were studied. Acetylation conditions such as concentration of chemicals and catalyst and time and temperature of acetylation were optimized. Acetylation of feathers was confirmed using Fourier transform infrared (FTIR) and pyrolysis-gas chromatography-mass spectrometry (P-GC-MS). The acetylated feathers were analyzed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to understand their thermal behavior. Acetylated feathers were thermoplastic and could be compression molded to form transparent films despite the relatively low percentage of acetyl content. 相似文献