提取方式对大米蛋白调控血脂水平作用效果的影响

目的:探讨不同提取方式对大米蛋白调控血脂水平的影响效果。方法:分别给7周龄雄性Wistar幼鼠投喂粗蛋白为20%的酪蛋白及经碱法(RP-A)、酶法(RP-E)提取的大米蛋白14 d后,检测各组实验鼠血浆总胆固醇(TCH)、高密度脂蛋白胆固醇(HDL-C)、非高密度脂蛋白胆固醇(non-HDL-C)、三酰甘油(TG)等血脂水平以及HDL/TG比例和动脉粥样硬化指数(AI)。结果:RP-A和RP-E组实验鼠体重增加量及血浆TCH显著低于酪蛋白组(P<0.05)。实验各组间血浆HDL-C水平差异无统计学意义(P>0.05)。对照酪蛋白,RP-E显著降低了实验鼠AI及血浆TG、non-HDL-C水平(P<0.05),显著提高了HDL/TG比例(P<0.05);而RP-A与酪蛋白组间AI、TG、non-HDL及HDL/TG比例等检测指标差异无统计学意义(P>0.05)。结论:大米蛋白具有调控血脂水平的作用效果,其提取方式是大米蛋白调控血脂水平影响因素之一。     

大米蛋白提取方式对幼鼠生长性能的影响

目的：探讨不同方式提取的大米蛋白对生长性能的调控效果。方法：分别给7周龄雄性Wistar幼鼠投喂粗蛋白质为20％的酪蛋白及经碱法、酶法提取的大米蛋白3w后,检测各组实验鼠生长状况、体重增加量、蛋白质功效、内脏器官（肝脏、脾脏、肾脏）重量及脏器指数。结果：大米蛋白各组实验鼠末体重、总体重增加量、蛋白质功效及肝脏、脾脏、肾脏重量均显著低于酪蛋白组（P〈O．05）,但大米蛋白组幼鼠的日采食量及肝脏指数、脾脏指数、肾脏指数则与酪蛋白组差异无统计学意义（P〉0．05）。结论：提取方式是大米蛋白调控幼鼠体重及生长性能的影响因素之一。酶法提取的大米蛋白调控体重增加量效果优于碱法提取大米蛋白组。     

大麦和燕麦可降低血浆胆固醇

美国农业研究局和威斯康星大学的科研人员从大麦和燕麦中分离出能降低血浆胆固醇浓度的物质。经鉴定 ,这些物质为甘油三酸酯和Ｔｏｃｏｔｒｉｅｎｏｌ。据说 ,这两种成分是在大麦的糊粉层和糊粉下层的高蛋白部分和燕麦的糠皮中发现的。目前 ,这两种可降低胆固醇的物质虽然都没有经过人体试验 ,但对鸡、白鼠和猪的试验效果良好 ,没有副作用。如饲喂含胆固醇抑制剂饲料的鸡 ,其血中有害的低密度脂蛋白比喂玉米为主的鸡降低４０ %,而有益的高密度脂蛋白含量则相当。科学家们认为 ,甘油三酸酯和Ｔｏｃｏｔｉｅｎｏｌ主要具有抑制一些控制胆固醇…     

碱处理对大米蛋白氨基酸组成与含量的影响

选用质量分数0.1%、0.2%、0.3%碱液进行大米蛋白的提取,探讨碱处理对各种氨基酸含量的影响.结果显示,不同质量分数碱液对大米蛋白纯度及提取率无显著影响(P>0.05).随着碱液质量分数的增加,大米蛋白的Arg、Pro、Lys等氨基酸含量呈现下降的趋势,但各组间无显著差异(P>0.05).碱处理降低了大米蛋白Lys/Arg及Lys/Ala比例.说明不同质量分数的碱处理能够影响大米蛋白氨基酸组成与含量,碱处理是影响大米蛋白含硫氨基酸水平的制约因子之一.     

巴拉圭茶对高脂血症小鼠血脂的影响

目的:探讨不同剂量巴拉圭茶对高脂血症小鼠血脂的影响。方法:通过高脂日粮建立高脂血症小鼠模型,随机分为模型组、巴拉圭茶低剂量组、巴拉圭茶高剂量组,对照组饲喂基础日粮,模型组饲喂高脂日粮,巴拉圭茶低剂量组、巴拉圭茶高剂量组饲喂高脂日粮并分别灌胃1 g·kg^-1、2 g·kg^-1巴拉圭茶,连续灌胃4周,处死小鼠,测定小鼠血清中总胆固醇、甘油三酯、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇的含量。结果:与模型组相比,低剂量和高剂量巴拉圭茶均可显著降低高脂血症小鼠血清中的总胆固醇、甘油三酯、低密度脂蛋白胆固醇含量(p<0.05),高剂量巴拉圭茶可显著提高小鼠血清中高密度脂蛋白胆固醇含量(p<0.05)。结论:巴拉圭茶对调节高脂血症小鼠血脂代谢具有一定的作用。     

红松松仁中天然产物的研究进展

松仁为松属PinusL.多种植物成熟种子去皮后所得到的种仁的统称,具有软化血管、降低血脂、胆固醇、甘油三脂及防止衰老的功能,具有广阔的应用开发潜力;对红松松仁的营养成分、功能以及天然产物中的蛋白、多糖、油脂的研究进展进行了阐述。     

煮玉米防三高

玉米中含有丰富的不饱和脂肪酸，特别是亚油酸含量高达60％以上，它和玉米胚芽中维生素E协同作用，能有效降低血液胆固醇浓度，并防止其沉积于血管壁。除了新鲜的水煮玉米棒之外，老玉米中糖的含量比普通大米低2．3％，而粗纤维含量几乎是大米的9倍，这些都有利于降低餐后血糖水平。因此，常吃玉米对糖尿病、冠心病、动脉粥样硬化、高脂血症及高血压等疾病都有一定的预防和治疗作用。     

巴拉圭茶对高脂血症小鼠氧化还原状态的影响

探讨不同剂量巴拉圭茶对高脂血症小鼠氧化还原状态的影响。通过高脂日粮建立高脂血脂小鼠模型,随机分为模型组、巴拉圭茶低剂量组、巴拉圭茶高剂量组,对照组饲喂基础日粮,模型组饲喂高脂日粮,巴拉圭茶低剂量组、巴拉圭茶高剂量组饲喂高脂日粮并分别灌胃1 g·kg^-1、2 g·kg^-1巴拉圭茶,连续灌胃4周,处死小鼠,测定小鼠肝脏中活性氧自由基(ROS)水平、超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性、丙二醛(MDA)的含量。与模型组相比,低剂量、高剂量巴拉圭茶可显著降低小鼠肝脏中ROS水平、MDA含量(p<0.05),可显著提高小鼠肝脏中SOD、CAT活性(p<0.05)。巴拉圭茶对高脂血症小鼠氧化应激具有一定的调节作用。     

基于MOA理论消费者绿色农产品溢价支付意愿驱动路径分析——以大米为例

[目的]随着我国人民生活水平的提高,绿色农产品愈发得到消费者的青睐。文章旨在探析消费者绿色农产品意愿溢价水平及其溢价支付意愿的驱动路径,以期为绿色农产品产业的发展提供相应政策启示。[方法]基于MOA理论分析框架,利用结构方程模型和消费者调查数据,该文以主粮大米为例展开分析。[结果]以普通大米5元/kg为基准价格,消费者绿色大米平均意愿溢价水平为125.7%,意愿溢价水平从高到低排序依次是东部地区(145.2%)、中部地区(140.09%)、西部地区(91.82%)。[结论](1)利己动机、利他动机、创新性能力、信息获取能力能够直接作用于消费者绿色农产品溢价支付意愿,而消费机会通过利己动机、利他动机和信息获取能力间接作用于溢价支付意愿;(2)基于多群组结构方程,研究发现个人可支配收入和文化程度能够调节消费者创新性能力、信息获取能力对消费者绿色农产品溢价支付意愿影响;(3)消费者创新性能力和信息获取能力对溢价支付意愿的影响存在地域差异性。     

基于冠层光谱和BP神经网络的水稻叶片氮素浓度估算模型

[目的]快速、准确地诊断水稻叶片氮素营养状况,为水稻氮肥精准管理提供依据。[方法]以江西省农科院8种不同施肥处理的晚稻为研究对象,于主要生育期同步测定了水稻冠层光谱反射率及叶片全氮浓度(Leaf Nitrogen Concentration,LNC),系统分析了原始光谱反射率、一阶微分光谱、"三边"参数以及由350～1 350nm两两波段组合的差值(SD (Rλ1,Rλ2))、比值(SR (Rλ1,Rλ2))及归一化(ND(Rλ1,Rλ2))光谱指数与水稻LNC的相关关系,筛选出敏感参数,并以之为自变量构建了水稻LNC的传统预测模型,另外构建不同指标个数的多元线性与BP神经网络模型,并对模型进行验证。[结果](1)水稻LNC与一阶微分光谱在751nm处的相关性最高(r=0. 822);(2)"三边"参数中的红边面积SDr与LNC的相关性较高(r=0. 687);(3) 750nm附近的红边波段与近红外波段差值组合、550nm附近的绿光波段与近红外波段的比值及归一化差值组合与水稻LNC的相关性较高,以SD (R752,R751)、SR (R534,R1 350)和ND (R534,R1 349)表现最好,相关系数分别为0. 827、-0. 790和0. 788;(4)传统回归模型中以SD(R752,R751)构建的一元线性模型最佳(RC2=0. 665、RV2=0. 750、RMSEV=0. 4%、RPD=2. 034);(5)利用5个指标((R'751、SDr、SD (R752,R751)、SR (R534,R1 350)、ND (R534,R1 349))经逐步回归筛选出的2个指标SD ((R752,R751)和SR (R534,R1 350))构建预测水稻氮素的BP神经网络模型,预测效果最佳,其验证参数值分别为R2=0. 859、RMSEV=0. 302%和RPD=2. 669。[结论]基于单指标构建的传统线性模型计算过程简单但精度略低,而基于2个指标(SD (R752,R751)、SR (R534,R1 350))构建的BP神经网络模型预测精度高于该2指标构建的多元线性模型,表明在指标适合的情况下,BP神经网络对氮素具有较好的预测能力,是一种快速准确估算水稻叶片全氮浓度的方法。     

Armington Elasticities and Tariff Regime: An Application to European Union Rice Imports

The European Union’s (EU) import sources for rice include developing countries and least developed countries (LDCs). The EU has made a commitment to allow duty‐free and quota‐free access to rice imports originating in the LDCs from September 2009 onward. The purpose of this article is to answer two questions: (1) does the inclusion of import tariffs lead to different estimated Armington elasticities? (2) when a discriminating tariff is introduced, what happens to the market share of large rice exporters to the EU, especially of poor countries? We present the Armington model, derived from a constant elasticity of substitution (CES) utility function, and a non‐homothetic CES utility functional form, which is more flexible. We then estimate the Armington model, with and without the inclusion of a tariff, and we compare the elasticities. Lastly, we model five scenarios with different discriminated import tariff rates to calculate the changes in the market access of large rice exporters to the EU. Our empirical results show the importance of non‐homothetic preferences and import tariffs. Ignoring import tariffs and the non‐homothetic parameter may produce results which are biased and of uncertain validity. Furthermore, the simulation findings demonstrate that, in spite of a large difference between import tariff rate of Suriname and other countries (scenario V), its market access would not change greatly. This may be caused by supply side problems like poor infrastructures, weak technology and small capacity production in LDCs.     

Consumer Demand for Genetically Modified Rice in Urban China

We investigate consumer demand for genetically modified (GM) rice in urban China, using a relatively large survey of urban consumers in 2013 and the contingent valuation method. Our results show that respondents discount their WTP for first, second and third generation of GM rice by 31%, 34% and 36%, respectively, compared with non‐GM rice, indicating substantial aversion to GM rice by Chinese consumers. The level of consumers’ subjective knowledge of GM rice has a significantly negative impact on their WTP for GM rice, implying that GM rice in China has become a ‘special food’ with an unreliable image.     

Yield Effects of Tissue Culture Bananas in Kenya: Accounting for Selection Bias and the Role of Complementary Inputs

We analyse yield effects of tissue culture (TC) banana technology in the Kenyan small farm sector, using recent survey data and an endogenous switching regression approach. TC banana plantlets, which are free from pests and diseases, have been introduced in East Africa since the late 1990s. Although field experiments show significant yield advantages over traditional banana suckers, a rigorous assessment of impacts in farmers’ fields is still outstanding. A comparison of mean yield levels between TC adopters and non‐adopters in our sample shows no significant difference. However, we find evidence of negative selection bias, indicating that farmers with lower than average yields are more likely to adopt TC. Controlling for this bias results in a positive and significant TC net yield gain of 7%. We also find that TC technology is more knowledge intensive and more responsive to irrigation than traditional bananas. Simulations show that improving access to irrigation could lift TC productivity gains to above 20%. The analytical approach developed and applied here and the finding of negative selection bias may also be relevant for the evaluation of other agricultural technologies.     

Estimating the Potential Benefits of New Health Claims in Canada: The Case of Soluble Fiber and Soy Protein

Growing awareness of the link between diet and health has spurred growth in the functional food sector. Health Canada regulates allowable health claims on food products, and in recent years has approved health claims linking the consumption of soluble fiber from barley (2012) and psyllium (2011) to reduced/lower low‐density lipoprotein (LDL)‐cholesterol levels, a major risk factor for heart disease. A health claim linking consumption of soy protein to reduced risk of coronary heart disease (CHD) is still under consideration. Using a cost‐of‐illness approach, this paper estimates the potential economic benefits of allowing health claims for soluble fiber and soy protein in terms of reductions in the direct and indirect costs of CHD. Parameters for the economic analysis are drawn from a meta‐analysis of scientific studies examining the effect of soluble fiber and soy protein on LDL‐cholesterol levels, as well as other scientific literature. While a barley soluble fiber health claim yields nontrivial benefits in a base case scenario equal to CAD$105 million annually and ranging from $42 million to $238 million in low and high scenarios, the potential benefits of a soy protein health claim appear to be several magnitudes larger at $549 million annually in the base case and ranging from $220 million to $1.25 billion in low/high scenarios. Given the relatively slow regulatory approval process for new health claims, there may be value in using economic estimates of potential gains to help prioritize health claims approval processes.     

Are small‐scale rice farmers in eastern India really inefficient? Examining the effects of microtopography on technical efficiency estimates

The article analyzes how controlling for differences in land types (defined by position on a low‐scale toposequence) affects estimates of farm technical efficiency for rice farms in eastern India. Contrasting previous research, we find that farms are considerably more technically efficient when efficiency estimates are carried out at the plot level and control for plot characteristics rather than at the farm level without such controls. Estimates show farms cultivating modern varieties are technically efficient and plots planted with traditional varieties on less productive lands (upland and midupland) operate close to the production frontier. Significant technical inefficiency is found on more productive lands (medium and lowland plots) planted with traditional rice varieties. The finding that these smallholder rain‐fed rice farms are efficient cultivators on some plots contrasts with previous findings of farm‐level inefficiency (i.e., rejects overarching explanations linked to farm operator ignorance or lack of motivation) and suggests more complex explanations are required to address the inefficiency that is present.     

Modern Rice Technologies and Productivity in the Philippines: Disentangling Technology from Managerial Gaps

Using cross‐sectional farm‐level data from 3,164 rice‐farming households in the Philippines, we measure the impact of modern rice technologies on farm productivity while disentangling technology gaps (the distance between production frontiers) from managerial gaps (differences in technical efficiency). To do so, we combine a recently developed stochastic production frontier framework with impact evaluation techniques to control for biases stemming from observables and unobservables. First, we find an adequate control group using propensity score matching to mitigate the effect of biases from observable variables. Then, we test for biases that might arise from unobserved variables using a stochastic frontier framework corrected for self‐selection. Finally, we estimate meta‐frontiers to assess productivity differences between adopters and non‐adopters. The analysis shows that the adoption of certified seeds has a significant and positive impact on productivity, efficiency and net income in rice farming.     

中国循环农业发展评估——政策回顾与对辽中县的调研案例

循环农业涉及农业废弃物的循环性利用和资源保护等方面,在中国获得了越来越多的关注。当前对循环农业的政府干预手段较多,但目的和手段都不尽相同。因此,有必要对这些政策系统化,并进行深入了解,提出具体建议,以促进循环农业发展。研究总结中国有关循环农业发展的现行政策,揭示影响其发展的关键因素,选择辽宁省沈阳市辽中县为案例,通过比较分析循环农业和非循环农业的农业管理方式差异,揭示农民培训的重要性。研究结果表明,循环农业生产者使用农家肥的比例(38%)明显高于非循环农业生产者(6%),使用化肥的比例(90%)低于非循环农业生产者(98%)。每种作物的U-STAT和模式都显示循环农业生产者比非循环农业生产者使用更少的农家肥和化肥。循环农业生产者玉米的产量明显高于非循环农业生产者。许多循环农业生产者使用化肥,其数量与非循环农业生产者使用的并没有很大的区别。因此,为了推动循环农业发展,传授循环农业技术,开展具体技术培训和信息服务比简单的宣传更为重要。