Sampling Methods for Detection of Salmonella in Raw Chicken Carcasses

Detection of Salmonella in thaw water, pericloacal skin and whole carcass rinse samples from naturally contaminated broiler chickens was compared. Of 100 birds tested, 70 were found to contain salmonellae by the three sampling techniques combined; the median level of contamination was 0.27 salmonellae/100g eviscerated carcass weight. Recovery with the whole carcass rinse technique (93%) was significantly greater than that obtained with thaw water (63%) and skin (74%) methods; performance of the latter two methods was not statistically different. Thaw water does not provide a reliable index of Salmonella contamination and therefore is not a suitable method for the nondestructive analysis of poultry carcasses. Selective enrichment in tetrathionate brilliant green broth and plating on bismuth sulfite agar identified the greatest number of contaminated carcasses under all sampling conditions.     

Pre-Chill Spray of Chicken Carcasses to Reduce Salmonella typhimurium

A test chamber was designed and constructed and prechill chicken carcasses inoculated with Salmonella typhimurium were treated in it. They were sprayed with tap water, 0.85% sodium chloride (NaCl), 5% or 10% trisodium phosphate (TSP), 5% or 10% sodium bisulfate (SBS), 0.1% cetylpyridinium chloride (CPC), or 1% lactic acids (LAC) at 207, 345 or 827 kPa pressure for either 30 or 90 sec exposure time. Samples were taken from carcass wash water to determine the most probable number of Salmonella. Compared to tap water spraying, 0.85% NaCl spraying did not significantly reduce Salmonella. The greatest reductions of S. typhimurium, by 10% TSP, 10% SBS, 0.1% CPC or 1% LAC spraying, were 3.7, 2.4, 1.6 or 1.6 log in 90 sec treatments, respectively.     

HXD运行参数与工作段气流初始温度相关性的回归分析

HXD叶丝在线膨胀系统工作段气流初始温度设定值合理与否,与叶丝出料含水率及整个干燥系统运行参数的稳定关系密切。通过分别改变不同工艺参数进行试验,并对试验数据进行回归分析,得出了工作段气流初始温度与进料含水率、物料流量、工艺气流流量、蒸气喷射量等参数的相关方程。利用该方程可以计算出能保证HXD正常运行的参数组合,使其在较短时间内达到叶丝出料含水率的稳定,提高了加工质量。     

Meat Color and Biochemical Characteristics of Unacceptable Dark-colored Broiler Chicken Carcasses

Spectrocolorimetry, pH, TBARS, total pigment and myoglobin were measured in normal and abnormally dark-colored broiler chicken breast muscle. Analyses of L*, a* and b* values revealed that a* values were highly sensitive and specific to differentiate normal from dark-colored carcasses and thus could be used as a potential diagnostic method for carcass classification at slaughter. Color characteristics (L*, a*, and b* values), pH, total pigment, myoglobin, and iron concentrations were all significantly different in dark-colored muscle when compared with normal muscle. TBARS values and percentage moisture for the two groups were not different.     

鸡胴体表面稀释污染物的连续投影-多元线性回归-受试者特性分析检测

建立基于连续投影算法(successive projections algorithm,SPA)-多元线性回归(multiple linear regression,MLR)-受试者特性(receiver operating characteristic,ROC)分析鸡胴体表面稀释污染物识别方法。首先采用高光谱成像系统获取了20个涂有稀释污染物的鸡胴体图像,再利用SPA从1 232个波长中提取出10个特征波长,然后通过MLR方法构建识别函数和特征波长光谱值之间的回归模型,最后通过ROC分析方法,确定出能够获得高真阳性率(true positive rate,TPR)和低假阳性率(false positive rate,FPR)的最佳分类阈值,并据此对鸡胴体表面稀释后的污染物进行检测。结果显示,利用SPA-MLR-ROC分类器检测20个污染鸡胴体样本,检出污染区域的TPR达到98.08%,FPR仅为0.39%,高于波段比算法以及双波段算法检测相同样本的准确率,可见,SPA-MLRROC分类器方法检测鸡胴体表面稀释污染物获得了较好的效果,但由于样本数量有限,还需要具有较大样本量的研究来进一步验证此方法检测结果的稳定性。     

Effect of Gamma Irradiation of Whole Chicken Carcasses on Bacterial Loads and Fatty Acids

Broiler chickens were irradiated by Cobalt-60 at a commercial irradiation facility at dose levels of 0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 kGy at 3.0°C. Regression analyses indicated more than 99% of the microbial load on the whole carcass was eliminated at doses ranging from 1.5 to 2.0 kGy. Fatty acids were not affected except for palmitic which showed a decrease and oleic acid which showed an increase. Both of those changes were significant. Results indicate gamma irradiation of chicken at 2.0 kGy or more using commercial irradiation substantially reduced bacterial loads.     

高温果汁真空冷却特性

为减小真空冷却中液体飞溅并研究不同条件对降温速率的影响,采用控制变量法,通过改变容器的形状、顶部材料与孔径大小、物料的相对装载量、不同初始温度和冷却终温等条件,测定果汁降温过程的质量和温度变化,根据测试结果计算出不同变量下的无效失水率和降温速率。研究表明,降温速率大且无效失水量小的最佳工艺条件为使用相对装载量23.3%、容器顶盖材料为刚性材料、孔径5 mm的长方形容器,由初始温度80℃降至冷却终温为25℃,此时的无效失水率最小,降温速率最快。     

Modification of the VSV Surface Pasteurizer to Treat the Visceral Cavity and Surfaces of Chicken Carcasses

ABSTRACT: Previous research with the VSV (vacuum/steam/vacuum) surface pasteurizer revealed the visceral cavity of chicken carcasses was not treated as effectively as the outside surface. The processor was modified to specifically treat the cavity by adding a mandrel assembly. Optimum process parameters were determined. Optimum process conditions were: initial vacuum 0.1s, final vacuum 0.5 s, vacuum absolute pressure of 4.1 to 7.1 kPa, steam time 0.1 s, and steam temperature 138 °C. Using carcasses inoculated with Listeria innocua and the whole bird rinse sampling procedure, bacteria kills were statistically significant at 0.7 to 0.8 log cfu/mL. Using deboned chicken breasts inoculated with L. innocua and the whole bird rinse sampling procedure, bacteria kills were statistically significant at 1.0 to 1.3 log cfu/mL.     

不同保水性鸡肉的品质比较和相关性研究

采用聚类分析方法将随机取样的18只白羽肉鸡的胸肉聚为低汁液损失率组(汁液损失率<2%)和高汁液损失率组(汁液损失率≥2%),比较两组鸡肉的蛋白质、肌纤维结构等特点,研究其造成保水性差的原因。结果表明:与低汁液损失率组相比,高汁液损失率组的样品宰后pH值较低,亮度值较高,肌节变短,肌纤维空隙面积变大,总蛋白质溶解性较低。差示扫描量热法(DSC)测定结果显示高汁液损失率组肌球蛋白头部变性温度(T1)和肌球蛋白尾部及肌浆蛋白变性温度(T2)显著低于低汁液损失率组,说明高汁液损失率组的肌球蛋白更易变性。通过相关性分析将鸡肉保水性差的原因归结于低pH值、蛋白质变性和肌纤维结构的变化。     

芳纶纸高温压光过程冷却段的传热模拟研究

经过320℃高温压光的芳纶纸在出压区冷却过程中纸面温度会急剧变化,导致纸幅收缩会对卷曲造成不利影响。为探究芳纶纸出压区后的降温情况,利用牛顿冷却定律和对比参量公式推导出芳纶纸低速热压光过程中的传热方式,借助Matlab软件模拟计算了单辊加热下芳纶纸离开压区后的温度,并与纸张的实际温度测量值进行了对比。结果表明,在压光机车速10 m/min、压光温度320℃条件下,芳纶纸出压区后的热对流形式以自然对流为主;芳纶纸在出压区初期降温较明显,在1 m的特征长度内芳纶纸的温度降至50.2℃,在5 m的假设特征长度内,芳纶纸的温度降至室温。     

微波杀菌白切鸡的工业化生产工艺要点

介绍了采用微波杀菌的白切鸡工业化生产工艺要点以及各工序之间的关系,归纳了影响白切鸡品质的关键控制点,并指出了今后相关的研究方向。     

卷烟常规化学成分与焦油的线性回归分析

对某种牌号卷烟的焦油量与其烟丝中的总糖、总氮和总氯的检测数据进行了回归分析,建立了根据烟丝中总糖、总氮和总氯的检测数据预测卷烟焦油量的线性回归方程,用得到的线性回归方程进行了预测,并将卷烟焦油预测值与实测值作了比较,结果表明,大部分数据的相对预测偏差都小于5%。     

新疆大盘鸡炒制过程中香气形成与品质的关联性分析

以新疆大盘鸡为研究对象,分析炒制过程中色泽、嫩度、水分含量3个品质指标变化与香气成分变化的相关性。结果表明:新疆大盘鸡亮度值(L*)、白度(W)和嫩度随炒制时间的延长先增加后减少,水分含量和红度值(a*)则呈相反变化趋势;采用气相色谱-质谱法测定炒制过程挥发性风味化合物,检出45种化合物随着炒制时间的延长而变化,其中醇类、醛类、酮类和酯类含量与水分含量和嫩度变化相关性较大,与水分含量呈正相关,与嫩度呈负相关;1-辛烯-3-醇、正辛醇、松油烯含量与L*、W呈正相关,十六烷、乙酸桃金娘烯酯、甲氧基苯基肟含量与L*、W呈显著负相关,与a*呈负相关。可以通过在线检测色泽、嫩度及水分含量变化预测新疆大盘鸡香气成分种类及含量变化。     

蛋鸡与肉鸡原料在盐鸡翅加工中的品质比较

针对由于蛋鸡原料生产周期长而造成的盐鸡生产受到制约的现状,采用感官评定与质构分析(TPA)相结合的方法,参考含水量等指标,研究盐煽工艺对不同鸡翅原料食用品质的影响,探讨使用肉鸡原料代替蛋鸡原料进行盐鸡翅生产的方法.结果表明:以蛋鸡为原料所得鸡肉品质高,鸡肉弹性好、肉质紧密、盐风味浓郁;以内鸡为原料所得鸡肉采用干燥处理后...     

多元回归分析在绸厂工序质量管理中的应用

通过对多元回归分析方法在07双绉捻度控制点应用过程和效果的阐述,证实该法在绸厂工序质量管理中具有可操作性,从而可推动科学管理,提高管理水平。     

The Microbiological Status of Carcasses of Goats Slaughtered in an Inadequate Facility

The microbiological contamination of goat carcasses slaughtered on a slaughter line under controlled conditions and in inadequate facilities was measured by determining the total number of aerobic mesophilic bacteria, Enterobacteriaceae and Salmonella spp. Wet swabs were taken from the carcasses of goats (in slaughterhouses n = 115 and in inadequate facilities n = 80). Test results showed that the total number of aerobic mesophilic bacteria and Enterobacteriaceae were mostly within satisfactory and acceptable categories. Salmonella spp. was not isolated from any of the goat carcasses.     

鸡汤烹制工艺优化与辐照保藏技术研究

以扬州地产草鸡为原料加工鸡汤,经L9(33)正交试验设计,优选出鸡汤最优烹制工艺为鸡汤原料肉、食盐与水配比50:1:110,先115℃加热20min,后80℃保温80min。将该鸡汤加工成包装制品,经60Coγ射线辐照处理,置于25±1℃条件下做保藏试验,得出鸡汤的适宜辐照剂量为9KGy,保藏期为28d,其细菌总数低于国家标准限量,感官品质良好。