采用碱提酸沉与淀粉酶解复合法制备小麦胚芽蛋白的试验研究

为了改善小麦胚芽蛋白质的提取效果，建立了“碱提+α-淀粉酶水解+酸沉淀”分离小麦胚芽蛋白的新方法。与传统的碱溶酸沉淀法相比，该方法明显地提高了小麦胚芽蛋白的纯度和得率，其数值分别达到94.5%和81.36%。用高效毛细管电泳定性测定了小麦胚芽蛋白的纯度，结果进一步证明该方法得到的小麦胚芽蛋白纯度较高。用SDS-PAGE电泳测定了小麦胚芽蛋白的分子量，结果表明小麦胚芽蛋白的分子量主要由35kDa和55kDa组成。     

尿素包接法预浓缩α-维生素E的试验研究

豆油脱臭馏出物含有丰富的维生素E和大量的游离脂肪酸,是浓缩天然维生素E的优质原料,但由于游离脂肪酸和维生素E在超临界CO₂中具有相似的溶解度,用超临界CO₂萃取难以提高维生素E的浓度。尿素包接可除去脱臭馏出物中的大部分饱和游离脂肪酸,为超临界CO₂萃取提供良好原料。试验结果表明,尿素包接法预浓缩维生素E的效能主要和脱臭馏出物与尿素的摩尔比、溶解尿素的甲醇或乙醇的浓度有关,两种试剂溶解尿素表现了相似的包接效果,回流时间和温度对包接效果基本无影响。包接的最佳条件为,豆油脱臭馏出物与尿素的摩尔比为1∶15,溶剂为95%的乙醇,60℃回流10min,1～2℃静置6～8h,过滤除去包接物。尿素包接可使剩余物中α-维生素E的浓度从原料的0.57%上升到1.62%,包接物中含有较多与维生素E有相似溶解度的游离脂肪酸,而α-维生素E的浓度仅为0.1%～0.2%。以剩余物为原料,利用超临界CO₂萃取可将α-维生素E的浓度提高到5.6%以上。     

脱脂米糠中脉冲超声辅助提取蛋白和多糖动力学模型

为建立脱脂米糠中蛋白和多糖脉冲超声辅助提取的动力学模型,通过试验测定了脱脂米糠脉冲超声辅助提取液中蛋白和多糖质量浓度随提取时间和提取温度的变化.根据试验数据,分别建立了脱脂米糠中蛋白和多糖脉冲超声辅助提取的二级动力学模型.结果分析发现,提取温度是影响米糠中蛋白和多糖溶出的重要因素,当提取温度提高到45℃和50℃时提取液中蛋白和多糖的质量浓度分别出现显著上升;随着提取温度的升高,米糠提取液中蛋白的平衡质量浓度线性上升,多糖的平衡质量浓度45℃之后才显著上升,蛋白和多糖的起始提取速率均表现为先下降后上升的变化趋势.     

食品加工机械与设备课程教学方法的改革与实践

分析了食品加工机械与设备课程需要改革的必要性,较为系统地研究了该课程的重点、理论教学存在的难点,针对每一个难点提出了较为全面的解决方案;针对实践性教学存在的不足,对重点环节进行了探索,并从多个方面大胆实践。从完善课程教学内容、充分利用学校相关资源、强化课程群建设和培养自学能力4方面,论述了不断完善课程教学方案、积极创新教学方法的思路。     

In vitro identification and verification of inflammatory biomarkers in swine

Currently there are no non-steroidal anti-inflammatory drugs (NSAIDs) approved for the control of inflammation in swine due to a lack of validated animal models and suitable biomarkers to assess drug efficacy. This study investigates the differential expression of genes altered in response to Escherichia coli lipopolysaccharide (LPS) induced inflammation which may serve as indicators of NSAID efficacy. Unstimulated whole blood from swine was mixed with tissue culture media, stimulated with LPS, and RNA extracted at the following time points 0 h, 1 h, 3 h, 24 h and 48 h. Total RNA was extracted and analyzed using a commercial swine DNA microarray. The DNA microarray was utilized as a screen to determine potential biomarkers, focusing on the genes that exhibited the greatest degree of differential expression. A master list of 57 genes was formed based on the differential expression as a result of the stimulation. Following analysis, 12 genes whose expressions were significantly altered (8 up- and 4 down-regulated) were chosen for verification via quantitative RT-PCR (qRT-PCR). The qRT-PCR analysis confirmed the differential expression of 11 of the 12 genes chosen via the microarray analyses. Specifically, traditional genes such as SAA, G-CSF, and IL-10 were up-regulated, while CD4 was down-regulated; all of the genes were altered by 24 h or 48 h post-stimulation. We demonstrate here that expression of these 11 genes is altered as a direct result of LPS stimulation and consequently inflammation.     

Genetic evaluation of Ethiopian Boran cattle and their crosses with Holstein Friesian for growth performance in central Ethiopia

Breed additive and non-additive effects, and heritabilities of birth weight (BWT), weaning weight (WWT), 6 months weight (SMWT), yearling weight (YWT), eighteen months weight (EWT), 2 years weight (TWT) and average daily weight gain from birth to 6 months (ADG1) and from 6 months to 2 years (ADG2) were estimated in Ethiopian Boran (B) cattle and their crosses with Holstein Friesian (F) in central Ethiopia. The data analysed were spread over 15 years. Ethiopian Boran were consistently lighter (p < 0.01) than the B-F crosses at all ages. Ethiopian Boran also gained lower weight than all the crosses. At birth, 50% F crosses were significantly (p < 0.01) lighter than all the other crosses. However, the differences in SMWT, YWT, EWT, TWT, ADG1 and ADG2 were all non-significant among the crosses. The individual additive breed differences between B and F breeds were positive and significant (p < 0.01) for all traits. The individual heterosis effects were significant (p < 0.05) for all traits except WWT for which the effect was non-significant. The maternal heterosis effects were significant (p < 0.01) for BWT (2.5 kg) and WWT (-3.0 kg). The heritability estimates for all traits in B and crosses were generally moderate to high indicating that there is scope for genetic improvement through selection. Selection within B and crossbreeding should be the strategy to enhance the growth performance under such production systems.     

Heterogeneity in land resources and diversity in farming practices in Tigray,Ethiopia

The management of soils is an important issue for policy makers in Ethiopia. However, most of the interventions designed to conserve the soil resources have fallen short of the expectations, performing impressively in the short run, but proving unsustainable on a long-term basis. There are no simple explanations for the failure of these interventions to reverse soil degradation, but it has been evident for some time that there is an uneasy connection between ‘objective’ assessments of the state of the land and the way this information is used in the policy-making processes. It is now widely accepted that understanding the processes of the soil degradation is not simply a matter of analysing changes in the stock of physical and nutrient capital. While studies of nutrient balances are an important component of research in soil erosion and land degradation, their results need to be considered in the context of social, cultural and political factors.     

Haplotype analysis of molecular markers linked to stem rust resistance genes in Ethiopian improved durum wheat varieties and tetraploid wheat landraces

The recent emergence of wheat stem rust race Ug99 (TTKSK) and related strains threaten Ethiopian as well as world wheat production because they overcome widely used resistance genes that had been effective for many years. The major cause which aggravates the ineffectiveness of Ethiopian wheat varieties against stem rust is the narrow genetic base on which the breeding for resistance has been founded, however, little is known about the resistance genotypes of Ethiopian durum wheat varieties and tetraploid wheat landraces. The objective of the study was to identify stem rust resistance genes that are present in the Ethiopian tetraploid wheat landraces and improved durum wheat varieties using molecular markers and assess which genes are effective for current Ethiopian stem rust races of Puccinia graminis f. sp. tritici including Ug99. The investigated 58 tetraploid wheat accessions consisted of 32 (Triticum durum s.l. incl. Triticum aethiopicum Jakubz., Triticum polonicum) landraces and 22 registered T. durum varieties released in Ethiopia between 1966 and 2009 and four T. durum varieties from ICARDA. A total of 17 molecular markers (SSR, EST and InDel) linked or diagnostic for stem rust resistance genes Sr2, Sr13, Sr22 and Sr35 were used for genotyping. Haplotype analysis indicated that only few of the Ethiopian durum wheat varieties carried Sr13. The resistant variety ‘Sebatel’ showed a haplotype for Sr2 and Sr22 and variety ‘Boohai’ for Sr22, however further evaluation is needed for the diagnostic value of these haplotypes. This study is the first report on the presence of stem rust resistance (Sr) genes in Ethiopian durum wheat varieties and tetraploid wheat landraces based on linked or associated molecular markers. Thus it might help in the identification of varieties carrying resistant alleles that provide valuable genetic material for the development of new improved varieties in further breeding programmes.     

超临界CO2萃取小麦胚芽油的试验研究

测定并分析了小麦胚芽的粒度、含水量、萃取温度、压力和CO₂流量对小麦胚芽油的超临界CO₂萃取率及产物品质(包括脂肪酸构成、VE含量、酸价和色泽)的影响。     

采用MECC在线堆积同步检测茶叶中七种残留农药

为解决茶叶中的痕量农药残留的快速检测问题,建立了一种基于胶束毛细管电泳在线堆积技术的茶叶中7种拟除虫菊酯类农药痕量残留的一次进样同步检测方法.通过参数优化,得到最优的柱上在线堆积浓缩操作工艺:以15%异丙醇、20%乙腈、60 mmol/L十二烷基硫酸钠(SDS)和50 mmol/L tris的混合物为背景缓冲溶液(BGS).茶叶的浸提液经过固相萃取净化吹干后,用1 mmol.L SDS溶解溶液残渣.进样100 s后施加反向电压,进行农药反向在线堆积,当电流恢复至正常分离时的95%时改变电压方向,进行正常分离.经过在线堆积浓缩,7种拟除虫菊酯类农药痕量残留堆积因子均高于17,回收率在82%以上,检测下限分别达到:功夫菊酯0.05 mg/kg、联苯菊酯0.05 mg/kg、百树菊酯0.05 mg/kg、高效氯氰菊酯0.05 mg/kg、溴氰菊酯0.2 mg/kg、二氯菊酯0.05 mg/kg、氰戊菊酯0.05 mg/kg,满足了2006年欧盟茶叶中拟除虫菊酯类农药残留的最低标准.