响应面法优化鸡肝发酵工艺

采用益生菌对鸡肝进行发酵。从3种菌株(植物乳杆菌LP1、发酵乳杆菌LF1、枯草芽孢杆菌BS1)中选择生长能力和产酸能力最强的植物乳杆菌LP1作为发酵剂,以发酵初始pH值、葡萄糖添加量、接种量、发酵时间和料液比5个因素进行单因素试验。在此基础上,以发酵鸡肝A_(280 nm)为指标,采用响应面分析法进行3因素3水平响应面优化试验,结果表明:各因素对发酵鸡肝A_(280 nm)的影响大小为发酵初始pH值>料液比>接种量,经过优化得到的最佳发酵工艺为:发酵初始pH 5.57、料液比1∶3.55(m/V)、接种量1.5%,最终发酵鸡肝A_(280 nm)为1.537;发酵鸡肝游离氨基酸和必需氨基酸总含量均显著增加(P<0.05),说明发酵能促使蛋白质分解,进一步提升鸡肝的营养价值。     

明胶对鸡肉糜3D打印成型稳定性的影响

采用流变扫描、凝胶强度、核磁共振、扫描电子显微镜等,探究明胶对鸡肉糜3D打印成型稳定性的影响。结果表明,不同明胶添加量（0%、2%、4%、6%、8%,以肉质量计）的鸡肉糜均表现出剪切稀化行为,具备3D打印可行性。明胶增强了体系的黏度和凝胶强度,提高了鸡肉糜3D打印成型稳定性,但过高的明胶添加量会影响物料的挤出,降低打印样品的形状精度。当明胶添加量为4%时,样品表现出良好的精度和成型稳定性,此时打印后形状塌陷率为2.46%。对添加4%明胶的3D打印样品进行蒸煮品质评价,发现3D打印会使样品的蒸煮损失增大,但质构特性得到适当改善。     

基于水平集的炉膛烤鸡色泽满意度模型

为了测量烤箱内烤鸡色泽品质并跟踪其变化过程,提出了一种炉膛烤鸡色泽区域取样方法以及量化检测色泽品质的模型。其中,色泽区域取样是通过基于水平集的自适应能量模型(ABEM),以烤鸡图像的对比度信息和均值为基础,使用水平集方法对炉膛图像进行取样,实现烤鸡色泽区域图像的快速提取。为了验证该方法有效性,采用该方法和距离正则化水平集方法(DRLSE)对炉膛图像进行取样,试验结果表明,ABEM方法可在不损失取样效果的前提下快速获取炉膛烤鸡的前景图像。量化检测色泽品质的模型是通过基于色泽满意度的相对指标模型(CSIM),利用HSV颜色空间中S分量的核心频域,计算烤鸡图像的色泽指标值,并转化为烤鸡相对色泽满意度指标,直观反映烤鸡色泽品质。试验结果表明将ABEM与CSIM相结合,对于监测炉膛烤鸡色泽品质指标是有效的,更为万能蒸烤箱的食品品质测控系统核心算法提供重要借鉴。     

Effect of contamination of foods by Aspergillus flavus on the nutritive value of protein

The effect of aflatoxin was measured on the protein quality of peanut meal (PNM) and fish meal (FM) Total protein efficiency, protein efficiency ratio, net protein utilisation, examination of the histopathology of the liver, ileal digesion of amino acids and plasma amino acid concentration were used as bioassays together with chemical score (CS), dye binding capacity (DBC), essential amino acid index (EAAI), and discriminant computered PER (DC-PER) as chemical methods. In trial 1, aflatoxin-free PNM was compared with infected PNM at graded levels of toxin when fed to chickens and ducklings. In trial 2, various mixtures of PNM and FM at a constant aflatoxin level (280 μg kg^?1) were fed to compare the effects of aflatoxin on proteins of differing quality. Ducks were more sensitive to the toxin than chickens, as indicated by deterioration of protein quality, and the effects on growth and the histological appearance of the liver were magnified on diets of low quality (PNM), but not of high quality (FM). Contamination of PNM resulted in progressive increase in DBC and, to a lesser extent, in DC-PER, while EAAI and CS were not affected. The importance of these findings lies in the problems of mould contamination of animal feedstuffs in humid, tropical conditions, which may affect the more sensitive animals, and may not be detected by chemical methods of measuring protein quality, nor by bioassay on chickens, if the levels of contamination are low.     

基于改进鸡群优化算法的质子交换膜燃料电池模型参数辨识

针对当前大部分智能算法在求解质子交换膜燃料电池模型参数辨识问题时易陷入局部最优,导致参数辨识精度低、模型泛化能力差等问题,提出一种基于改进鸡群优化算法的质子交换膜燃料电池模型参数辨识方法。首先,引入Tent映射策略初始化种群,提高种群的均匀性和遍历性;其次,设计基于个体进食速度的自适应惯性权重,改善母鸡个体寻优效率,平衡算法的开发与探索能力;然后,利用Levy飞行策略的长短跳跃特点对小鸡位置进行随机更新,增强算法的全局最优搜索能力。最后,通过4组测试函数验证了该算法的优越性,并将算法应用于H-12电堆的参数辨识问题中。结果表明：相比于鲸鱼优化算法、花卉授粉算法等算法,该算法具有更高的参数辨识精度,所辨识出的模型具有更强的泛化能力。     

Synthesis and Evaluation of a Molecularly Imprinted Polymer for Solid Phase Extraction of Ethopabate from Chicken Tissue

In this paper the development and evaluation of a molecularly imprinted polymer (MIP) for ethopabate is described. Ethopabate (ETP), 4-acetamido-2-ethoxybenzoic acid methyl ester, is one of the antibiotics which is used as coccidiostat in poultry feeds. In the present study, two widely used functional monomers, methacrylic acid (MAA) and 4-vinylpyridine (4-VP) were compared theoretically and experimentally as the candidates for MIP preparation. Hyperchem software was employed to estimate binding energies between ETP and functional monomers and batch rebinding experiments were performed to study the binding characteristics of the polymers. The results showed that MAA is a better functional monomer to prepare MIP. UV/Vis and NMR spectroscopy were used as two common tools to study the interactions between ETP and MAA in the pre-polymerization mixture. Liquid chromatography experiments showed that the prepared MIP has recognition capability toward ETP in comparison with other structurally related compounds. The ETP-imprinted polymer was further applied for selective solid phase extraction (SPE) of ETP from a chicken tissue sample. The extraction yield of ETP was found to be quantitative (87 ± 3%) and the LOD and LOQ based on 3 and 10 times of the noise of HPLC profile were 0.05 and 0.32 ng ml^?1, respectively. It was confirmed that the binding ability of the prepared MIP for ETP was essentially sufficient in the presence of other compounds coexisting in tissue sample. Therefore, as a selective and efficient solid phase material, ETP-imprinted polymer has a high potential application in the analysis of residues of this antibiotic in chicken tissue samples.     

Comparison of the stability of palm olein and a palm olein/canola oil blend during deep‐fat frying of chicken nuggets and French fries

Stability of palm olein (PO) and a blend 50% palm olein/50% canola oil (POC) during deep‐fat frying at 180 °C of French fries (FF) or chicken nuggets (CN) was studied through the determination of physical and chemical parameters in the fresh and used oils. Degradation at the end of the study resulted in total polar compounds of 12–13.5% for PO and 11.5–14.5% for POC and viscosity of 65–123.3 cP for PO and 63–72.8 cP for POC. Lower peroxide values (5.33–6.32) were obtained for the blend (PO had 5.21–8.55). Food type affected colour parameters and p‐anisidine value of the oils. For CN, the lowest fat content and higher hardness were obtained when they were fried in PO. CN caused a faster deterioration in the oils, in comparison with FF, especially in POC. Gas chromatography allowed to observe differences in fatty acids composition for both used oils.     

A method for the determination of total and reduced methimazole in various biological samples

A simple, rapid, reproducible and sensitive method based on HPLC with ultraviolet detection was developed for the determination of methimazole (MMI) in animal tissues and plasma samples. Under the optimum experimental conditions, the calibration curves for MMI were linear in the tested range 0.5–20 mg kg^?1 tissue sample (mg l^?1 plasma) with correlation coefficients better than 0.99. The performance of the proposed method was tested for the determination of MMI levels in brain, liver, thyroid gland and plasma of MMI-treated hens, as well as in their eggs and embryos. The proposed method reduces time and simplifies the sample preparation procedure.     

Direct and mediated impacts of product and process characteristics on consumers’ choice of organic vs. conventional chicken

There is a lack of research into why consumers value process characteristics. In this study, we test the hypothesis that the impact of process characteristics such as organic and free-range on consumers’ choices of food products is at least partly mediated through expected eating quality or taste expectations. In other words, the process characteristics partly function as cues to (eating) quality. Using a traditional metric conjoint approach based on an additive model, four product characteristics (production method, price, size and information about farmer and rearing conditions) were varied in a fractional factorial conjoint design, creating nine profiles of whole chickens. 384 Respondents rated the nine different chickens in terms of taste expectations and willingness to buy. Since the nine records for each respondent are not independent, we used linear mixed modelling for the mediation analysis. We find that, as expected, taste expectations are a strong predictor of willingness to buy. As hypothesised, the impact of both product and process characteristics on willingness to buy is at least partly mediated through taste expectations. Hence, the study shows that process characteristics are important for consumers, not only in and off themselves, but partly because consumers make inferences about eating quality from knowledge about such process characteristics.