加丽素红在市售鸡蛋中残留情况的研究

目的:加丽素红是一种化学合成类饲料着色剂,主要用于改善家禽皮肤、蛋黄等组织的色泽,被广泛应用在动物养殖业中。本研究为了解饲用着色剂加丽素红在鸡蛋中的残留情况而开展的。方法:以昆明市场上的鲜鸡蛋为研究对象,利用高效液相色谱法对市售鲜鸡蛋中是否含有加丽素红及其含量多少进行研究。结果:64份市售鸡蛋样品中,检出含有加丽素红的样品23份、未检出41份,总体阳性检出率为35.94%;检出的样品中含有加丽素红,含量范围为7.37μg/g≦C≦91.3μg/g,平均值为33.3μg/g。结论:云南省鸡蛋市场上确实有加丽素红残留的鸡蛋存在,且由于鸡蛋品种、来源的不同,加丽素红含量水平有一定差异。     

Effects of egg yolk inclusion,milk replacer feeding rate,and low-starch (pelleted) or high-starch (texturized) starter on Holstein calf performance through 4 months of age

The objectives of this research were to evaluate milk replacer (MR) feeding rates, alternative protein and fat sources in MR, and calf starter starch concentration and their effects on calf performance to 4 mo of age. Male Holstein calves (42.6 ± 1.2 kg of body weight; n = 192) were assigned at 3 d of age to 1 of 8 treatments in a randomized complete block design with a 2 × 2 × 2 factorial arrangement of treatments. Factors tested from d 0 to 56 (nursery) were low or high MR feeding rates, 0 or 10% inclusion of spray-dried egg yolks in MR, and low- or high-starch calf starter. The low MR rate was 0.66 kg of dry matter (DM) fed for 39 d followed by 0.33 kg of DM for 3 d. The high MR rate was 0.87 kg of DM fed for 5 d, 1.08 kg of DM for 37 d, and 0.43 kg of DM for 7 d. The MR contained 27.5% crude protein and 19.6% fat (DM basis) and starters were 21.2% crude protein; low starch was a complete pellet with 10.2% starch, and high starch was textured using whole corn and oats with 43.3% starch. From d 56 to 112 (grower), calves were randomly assigned to pens (4 calves/pen) maintaining MR rate and starch content while stratifying yolk treatments within pen, resulting in a 2 × 2 factorial arrangement. Starter was blended with 5% chopped hay during the grower trial. Fecal scores and medical treatments were recorded daily. In the nursery trial, calves were weighed initially and weekly thereafter. Hip width and body condition score (BCS) were measured initially and every 2 wk thereafter. In the grower trial, body weight, hip width, and BCS were measured on d 56, 84, and 112. Data were analyzed as repeated measures with calf (nursery) or pen (grower) as the experimental unit. Calf average daily gain, hip width, and BCS change were greater for calves fed high versus low MR, 0 versus 10% yolk, and high versus low starch in the nursery. In the grower trial, calves fed low MR and high starch had the greatest average daily gain (1.09 vs. 0.87 kg/d) and hip width change (5.4 vs. 3.9 cm) compared with calves fed low MR and low starch with other treatments intermediate. From 0 to 112 d, calves fed high MR had 9% greater body weight gain and 4% greater hip width change than calves fed low MR, yet nutrient efficiency was similar despite 80% more MR intake than calves fed low MR. Additionally, calves fed high-starch starter achieved 18% greater body weight gain and 17% greater hip width than calves fed low starch starter overall, a more than 2-fold greater response than the effect of MR feeding rate.     

脱盐咸鸭蛋清肽-亚铁螯合物的制备及表征

本文以脱盐咸鸭蛋清肽为原料,Fe Cl₂·4H₂O为铁源,以亚铁的螯合率和螯合物的得率为跟踪指标,对鸭蛋清肽-亚铁螯合物的制备条件进行优化;并采用红外光谱、动态光散射仪、荧光光谱、圆二色谱手段,对肽-亚铁螯合物进行了结构表征。单因素及正交实验结果表明,鸭蛋清肽-亚铁螯合物的最佳螯合反应条件:抗坏血酸（VC）与亚铁盐的质量比为0.2∶1,鸭蛋清肽溶液的浓度为4%,肽与亚铁盐的质量比为3∶1,p H 5.5,反应温度为40℃,反应时间为40 min,乙醇的添加量为反应液体积的7倍,在此条件下亚铁的螯合率为65.15%,螯合物得率为44.46%。红外光谱显示Fe²⁺与肽的氨基端与羧基端相结合;荧光光谱表明随着Fe²⁺的增加,荧光吸收带从3822 nm显著下降为3124.44 nm（p<0.05）;激光粒度仪显示肽与肽-亚铁螯合物的半径分别为（144.23±5.86）nm和（453.66±8.74）nm;圆二色谱显示肽中α螺旋、β折叠的含量为28.66%±1.54%、10.02%±1.04%,而肽-亚铁螯合物中α螺旋、β折叠的含量为16.10%±1.96%、27.33%±1.08%,两者均发生显著变化（p<0.05）。从结构层面证实了肽-亚铁螯合物的形成。      

五香烤鸡的加工

本文详述了五香烤鸡的加工技术和工艺配方及质量要求。     

蛋清蛋白对豌豆淀粉凝胶化及凝胶特性的影响

为探究蛋清蛋白对豌豆淀粉凝胶化及凝胶特性的影响。分别以0%、3%、6%、9%和12%的蛋清蛋白替代豌豆淀粉,研究蛋清蛋白对豌豆淀粉糊化特性、热特性、静态流变、动态流变、凝胶质构及水分子状态的影响。结果表明：蛋清蛋白以浓度依赖的方式影响豌豆淀粉的糊化特性,峰值黏度、谷值黏度、崩解值、最终黏度、回生值均随蛋清蛋白添加量增加而降低,而糊化温度则升高。蛋清蛋白对豌豆淀粉凝胶化温度影响不显著,但降低了淀粉的凝胶化焓值。添加不同量蛋清蛋白的豌豆淀粉糊均表现为假塑性流体特征,Herchel-Bulkley模型能够很好地拟合其静态流变行为,稠度指数和屈服应力均随蛋清蛋白添加量增加而降低。添加蛋清蛋白降低了豌豆淀粉糊体系的黏弹性及凝胶的硬度、强度和可塑性。蛋清蛋白对豌豆淀粉凝胶中自由水含量影响不显著,但使结合水含量增加而不可流动束缚水含量降低。     

黄原胶和魔芋胶抑制碱诱导鸭蛋清凝胶的高温液化

本研究分别将黄原胶和魔芋胶添加至鸭蛋清中制备碱诱导凝胶,以探究亲水胶体对凝胶高温液化的抑制作用,结果表明:与对照组相比,添加亲水胶后的蛋清凝胶黏度、储能模量和损耗模量增大明显(p<0.05),褐变强度增加了7.99%和33.21%;当黄原胶和魔芋胶的浓度由0.50%增加至1.50%,凝胶硬度值提高49.60%和119.56%,穿刺强度提高20.59%和78.42%,持水性提高1.02%和9.47%,且添加黄原胶的蛋清凝胶硬度、穿刺强度和持水性均显著大于魔芋胶(p<0.05)。两种胶的浓度均为1.00%时,蛋清凝胶的感官评分最高。两种亲水胶的加入会改变蛋白质的二级结构及凝胶内部的分子间作用力:黄原胶量的增加显著降低了离子相互作用(p<0.05),无规则卷曲减少了41.23%,α-螺旋增加了81.29%;魔芋胶量的增加显著降低了疏水相互作用(p<0.05),β-折叠减少了34.97%,无规则卷曲和α-螺旋分别增加了68.97%和70.37%;氢键和二硫键均随两种胶浓度的增加而增强。综上所述,添加黄原胶和魔芋胶均能抑制碱诱导蛋清凝胶在高温处理过程中的液化现象,且加入黄原胶所形成的凝胶质构特性和持水性优于魔芋胶,而魔芋胶对于凝胶褐变强度的影响大于黄原胶。     

The assessment of commercial beef and chicken bouillons in terms of heterocyclic aromatic amines and some of their precursors

Herein, the assessment of commercial beef and chicken bouillons in terms of heterocyclic aromatic amines (HAAs) and some of their precursors was evaluated. Creatine and creatinine levels were ranged between 0.57–0.80 and 0.28–0.94 mg g⁻¹, respectively. Glutamic acid was found to be the most abundant amino acid in both bouillons. 2-amino-3,7,8-trimethylimidazo[4,5-ƒ]quinoxaline (7,8-DiMeIQx, up to 0.03 ng g⁻¹) was the only quantified analyte in beef bouillons, whereas it (up to 0.08 ng g⁻¹) was determined in addition to 2-amino-3-methylimidazo[4,5-ƒ]quinoxaline (IQx, up to 0.08 ng g⁻¹) in chicken bouillons. Creatine, creatinine and free amino acid composition did not have the capacity to initiate the formation of HAAs. Therefore, bouillons do not pose risk in terms of HAAs. However, it should be noted that multiple factors, such as the substrate amount and production conditions, may affect the results. Glutamic acid content is remarkable in commercial bouillons sold in Turkey.     

双抗体夹心酶联免疫吸附法检测鱼糜制品中鸡蛋卵白蛋白

目的 建立双抗体夹心酶联免疫吸附(sandwich enzyme linked immunosorbent assay, sELISA)法检测鸡蛋卵白蛋白(ovalbumin, OVA)的方法,组装定量检测鱼糜制品中OVA含量的ELISA检测试剂盒。方法 确定各步骤反应时间,使用棋盘法确定捕获抗体和检测抗体的最佳工作浓度,建立检测方法并对其性能进行评价。结果 反应最佳条件为:抗原孵育20 min,检测抗体孵育20min,酶促反应显色10 min。兔抗OVA抗体为捕获抗体,工作质量浓度为1μg/mL,辣根过氧化物酶(horseradish peroxidase, HRP)标记兔抗OVA抗体为检测抗体, 1:5000 (V:V)稀释。采用四参数逻辑曲线拟合标准曲线,所建立sELISA方法的检测范围为8.5～200.0 ng/mL,检出限为3.5 ng/mL,定量限为8.5 ng/mL。批次内和批次间的变异系数分别为2.31%～4.58%和6.06%～12.23%;鱼糜基质中的回收率为80%～130%;测得28种常见食物样品中4种样品的交叉反应率小于0.002%;试剂盒在4℃保存6个月期间,...     

Egg yolk: structures,functionalities and processes

Hen egg yolk is an ideal example of natural supramolecular assemblies of lipids and proteins with different organization levels. These assemblies are mainly due to interactions between proteins and phospholipids, and these interactions are essential in understanding and controlling the production of food made with yolk, and particularly emulsions. Furthermore, these assemblies can be modulated by external constraints among which thermo‐mechanical and high‐pressure treatments. This review focuses on multi‐scale structures present in egg yolk, and their modulation by processes, in relation with their emulsifying properties. Egg yolk is mainly composed of two fractions—plasma and granules—which are natural nano‐ and micro‐assemblies. These two fractions possess different composition, structures and functionalities and exhibit specific behaviour under treatments such as high pressure and temperature. Plasma contains a large quantity of lipids structured as lipoproteins (low‐density lipoproteins), whereas granules are mainly composed of proteins aggregated in micrometric assemblies. If plasma is responsible for the important emulsifying properties of yolk, granules bring interesting emulsifying properties when assemblies are in the form of micelles in presence of salts. High‐pressure or thermal treatments, applied before or after emulsion fabrication, alter their functionalities and could be used to commercially exploit these fractions. © 2013 Society of Chemical Industry     

Fat and Water Composition Affects Residual Catalatic Activity in Chicken Breast Heated to Specific End-point Temperatures

Fat and water contents of meat tissues strongly influence their thermo-physical properties. Seven groups of ground chicken breast meat containing varying amounts of fat and water were prepared for this investigation. Each group was heated to end-point temperatures (EPTs) of 69.0 to 71.0°C at 0.5°C intervals. Severity of heat treatments was evaluated by the total process lethality calculated using the General Method. The fat and water contents affected the heating time to reach specific EPTs and the residual catalatic activity at EPTs of 69.0, 69.5 and 70.0°C, but did not affect total process lethality. The variation of the catalase method for determining EPT was related to the sample composition.