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。     

氢化物原子荧光光谱法检测富硒稻米中硒含量的方法研究

采用氢化物原子荧光光谱法测定富硒大米和大米中的硒含量,分别从微波消解程序、样品称样量、消解加硝酸量、仪器参数条件(灯电流、负高压)等方面进行方法优化,选出最优参数,并通过实际样品检测结果及优化改进后的方法、质控样和加标回收率进行了方法验证。该方法的线性良好(R=1.000 0),方法的检出限为0.010 6 mg·kg^-1,定量限为0.035 3 mg·kg^-1,3个不同梯度水平的加标回收率在85.23%～98.48%,该方法称样量和加硝酸量少、微波消解程序简单,极大地提高了检测效率,可以很好地满足粮食检测行业的需求。     

全自动固相萃取-超高效液相色谱-串联质谱法同时测定大米中香兰素、甲基香兰素、乙基香兰素、香豆素

建立全自动固相萃取-超高效液相色谱-串联质谱法同时测定大米中4种香精的分析方法。选用甲醇作为提取溶剂,经涡旋振荡和超声提取后,上清液加一级水稀释通过亲水亲脂平衡型固相萃取柱HLB净化,氮吹近干后补液过膜上机,使用Atlantis T3色谱柱分离,以甲醇-0.1%甲酸水为流动相。结果表明,4种香精在质量浓度为1～500 ng·mL-1时线性关系良好,相关系数R均大于0.999,平均加标回收率在80.1%～89.3%,RSD为1.7%～3.9%。该方法具有前处理简便、自动化、检测速度快等优点,适用于大米的批量检测。     

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。     

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.     

Impact of land fragmentation and resource ownership on productivity and efficiency: The case of rice producers in Bangladesh

The paper analyzes the impact of land fragmentation and ownership of resources on productivity and technical efficiency in rice production in Bangladesh using farm level survey data. Results reveal that land fragmentation has a significant detrimental effect on productivity and efficiency as expected. The elasticity estimates of land fragmentation reveal that a 1% increase in land fragmentation reduces rice output by 0.05% and efficiency by 0.03%. On the other hand, ownership of key resources (land, family labour, and draft animals) significantly increases efficiency. The mean elasticity estimates reveal that a 1% increase in family labour and owned draft animal improve technical efficiency by 0.04% and 0.03%, respectively. Also, a 1% increase in the adoption of modern technology improves efficiency by 0.04%. The mean technical efficiency in rice production is estimated at 0.91 indicating little scope to improve rice production per se using existing varieties. Policy implications include addressing structural causes of land fragmentation (e.g., law of inheritance and political economy of agrarian structure), building of physical capital (e.g., land and livestock resources), improvements in extension services and adoption of modern rice technology.