SPME-GC-MS分析皖西白鹅蛋挥发性成分

以皖西白鹅蛋的熟蛋清和熟蛋黄为研究对象,采用顶空固相微萃取-气相色谱-质谱联用技术对皖西白鹅蛋的挥发性化合物进行测定和分析。结果表明,从皖西白鹅蛋的熟蛋清、熟蛋黄中分别检测出48种、24种挥发性化合物,鉴定到的挥发性物质主要包括烷烃类、烯烃类、醇类、酮类、酯类、含硫化合物、杂环类及硅化物等。研究结果为鹅蛋的品质和风味提供了重要的信息,也为鹅蛋的生产加工方式提供一定的参考。     

北部湾海鸭蛋蛋黄色泽与5种天然色素含量的关联分析

目的：建立高效液相色谱法同时测定北部湾海鸭蛋蛋黄中虾青素、叶黄素、玉米黄素、角黄素和β-胡萝卜素5种天然类胡萝卜素含量,同时对比罗氏比色扇法测定结果,合理分析出天然类胡萝卜素总含量与蛋黄色泽两者之间的关联。方法：样品经皂化后用复合溶剂[石油醚+乙醚=1+1(V/V)]提取,用水洗涤去碱性,旋蒸干后用乙腈复溶,Athena C30 HPLC Column(250 mm×4.6 mm,5μm)色谱柱分离,以甲醇+1%磷酸水+叔丁基甲醚作为流动相进行梯度洗脱,流速1.0 mL·min^-1,DAD二极管阵列检测器,检测波长474 nm。结果：5种类胡萝卜素可以良好分离,相关系数r2均在0.997以上,样品在3个浓度水平的加标回收率为86.7%～98.4%(n=8),精密度为1.59%～3.78%。结论：该方法快速实用,测定的色素总量结果与采用罗氏比色扇法测定色度结果具有明显的关联,色素总量越高,其色度值也越高,可以作为海鸭蛋中天然色素的有效检测方法,克服了罗氏法易受个人主观性影响的缺陷,具有更科学、更准确的优点。     

Interaction Effects among Labeled Attributes for Eggs in the United States

New labels for food products continue to be introduced in the United States. This paper estimates interaction effects among labeled attributes for eggs to investigate cases where affixing labels of “premium” attributes would indeed gain additional premiums in the U.S. market. A latent class analysis identified four consumer segments (Attribute Seekers, Price Checkers, Local Supporters, and Combination Responders). Several interaction effects were sufficiently large in magnitude to neutralize the main effects, but differently for each segment. While the combination of certified-organic with cage-free or local label yielded negative premiums in certain segments, the premium Attribute Seekers were willing to pay were considerable. Across all segments, preferences for locally produced products were robust singly or in combinations. Consideration of interaction effects and consumer segments are recommended for effective labeling strategies.     

中国—新西兰部分农产品贸易竞争与合作研究

本文运用显示性比较优势指数分析了中新两国在农业中的园艺产品和乳制品及蛋类这两大类产品中的竞争与合作关系,并对双方的互补性产品进行了贸易强度分析,结果表明两国互补性产品的贸易关系不够紧密,尚存贸易进一步开拓的空间;基于此,本文对中新自由贸易区的建立提出了相应的对策建议。     

土鸡蛋中添加剂斑蝥黄的色谱质谱联用检测方法研究

本实验对土鸡蛋中斑蝥黄添加剂色谱质谱联用检测方法进行了研究,利用操作简便的液液萃取净化方法,使用Waters公司BEH C18反相色谱柱结合ACQUITY UPLC超高效液相色谱串联三重四极杆质谱联用仪对目标化合物进行分析测试,实验结果表明,在10~200 ng·mL^-1的浓度范围内,线性相关系数大于0.99,斑蝥黄的检出限为5.00 ng·mL^-1,定量限为10.0 ng·mL^-1,在10~200 ng·mL^-1的不同添加水平下,回收率为90%~105%,RSD≤5(n=6),方法快速准确可靠,灵敏度高,操作简便,可满足对土鸡蛋中添加剂斑蝥黄的检测工作需求。     

Consumers' willingness to pay for food quality - The case of eggs

The aim of this paper is to introduce an approach to estimating the marginal willingness to pay (WTP) for food quality and safety using data on actual consumer purchases. Marginal WTP for specific food product varieties can be derived from estimated demand functions by inverting the relations, thereby expressing the prices consumers are willing to pay as functions of quantity demanded. The task addressed in the paper is isolation of the WTP for quality attributes embedded in the varieties. Two models based on the AIDS-specification are proposed and discussed. To illustrate the applicability of the models, the case of five varieties of eggs is presented. It is found that Danish consumers are willing to pay a relatively high premium for improved animal welfare and organic production methods and somewhat less for food safety.     

Are Local and Organic Claims Complements or Substitutes? A Consumer Preferences Study for Eggs

This paper provides an analysis of consumer preferences for product claims, specifically about origin and production methods. In particular, it addresses two important questions: i) whether consumers are willing to pay a premium for food products carrying these claims; and ii) whether local and organic claims are complements or substitutes. A choice experiment designed to estimate two‐way interactions was undertaken in Spain for eggs. The findings show first, that consumers are willing to pay a positive premium price for an enhanced method of production (that of barn, free‐range and/or organic instead of cage produced eggs) as well as for the proximity of production (local, regional and national over imported). Second, the findings show that consumer preferences for the claims are heterogeneous with two consumer segments being identified: “origin preference”, the larger segment, and the “production method preference”. Results show that organic and local claims were complements for the larger first segment but that free‐range and local/regional claims were substitutes for the second smaller segment. These results provide the marketing chains with insights applicable for pricing strategies.     

民国时期商检新政的推行与贸易危机应对--以出口蛋品为考察中心

商品检验是国际贸易中不可或缺的重要环节。20世纪初,我国蛋品出口数量迅速增长,由此引发的商品纠纷也愈加频繁,而检验环节几乎缺失。1928年南京国民政府颁布《商品出口检验暂行规则》,次年成立官方机构,开始实施自主检验。其中包括对蛋品建立出口标准,科学严格地执行检验;深入蛋品生产加工环节进行改良指导;主导实施蛋业救济等。这一过程不仅有效地提高了蛋品质量,减少贸易失利因素,而且对新旧变革期的蛋业及相关行业发展,增加我国对外贸易中的话语权都有重要作用。但由于战争和检验本身的不足,南京国民政府的检政实践最终未能完全化解蛋业危机。     

鸡蛋的抗氧化活性研究进展

目前普遍认为通过饮食摄入抗氧化剂对减少机体细胞的氧化损伤,促进人体的健康有十分重要的意义。本文阐述了鸡蛋的营养成分、鸡蛋中各种抗氧化剂的抗氧化机理以及加工、贮存条件和消化代谢过程对鸡蛋抗氧化剂的影响,为鸡蛋抗氧化功能的研究提供参考。     

基于支持向量机的鸡蛋供应链中价格预警研究

鸡蛋价格的大幅波动对鸡蛋供应链中生产者、经营者和消费者产生严重的影v向,因此鸡蛋供应链中的价格预警问题亟待研究。支持向量机是一种建立在统计学习理论基础上的机器学习方法,能够较好地解决小样本、非线性和局部极小点等问题。文中基于支持向量机方法建立鸡蛋价格预警模型,运用libsvm软件对样本集进行参数寻优、训练和测试。结果表明模型预警结果与实际情况相符,模型可以帮助鸡蛋供应链中的各主体在采购、生产、仓储、销售等方面更好地决策。