眉豆淀粉的研究

本文研究了眉豆淀粉的性质 ,实验采用日立S - 550型电子扫描显微镜拍摄了眉豆淀粉颗粒的形貌 ;用日本OlympusVanoxBHS - 2型多功能光学显微镜观察了其偏光十字 ;用日本理学D/max -IIIA型X -光衍射仪测定了X -光衍射图样及结晶结构 ;用美国Waters公司SugarAnalyerI型高效液相色谱仪测定了其淀粉的重均聚合度、数均聚合度、分子量分布及分散度等 ,并与玉米、马铃薯淀粉进行了比较。在淀粉的应用中 ,糊的性质至关重要 ,实验采用德国Viskograph -E型Brabender连续粘度计对眉豆淀粉在不同乳浓度、pH及蔗糖添加量的情况下测定其粘度曲线 ,研究了不同条件对糊粘度的影响等。将为指导生产和开发眉豆淀粉应用提供理论基础 ,具有重要意义     

豇豆乳酸发酵工艺控制及酸豇豆炒肉末保质初探

豇豆乳酸发酵过程中,以0.5‰双乙酸钠作防腐剂,用米醋调节pH值至4.0～4.5,补充1%冰糖,食盐浓度控制5%对促进乳酸菌迅速形成优势菌群抑制杂菌有利,同时添加0.2%CaCl2可延缓组织软化;对酸豇豆炒肉末商品化生产,酸豇豆先干炒脱水、0.05%山梨酸钾与0.05%苯甲酸钠混合防腐、铝膜复合袋包装、85℃水浴30min间隔24h。两次杀菌可尽量延长产品货架期,确保产品脆度、色泽和风味。     

Effect of sugars on the association between cowpea vicilin (7S storage proteins) and fungal cells

Vicilins (7S storage proteins) found in various legume seeds have been previously shown to interfere with the germination of spores or conidia of phytopathogenic fungi and inhibit yeast growth and glucose stimulated acidification of the medium by yeast cells. In the present work vicilins from cowpea (Vigna unguiculata) seeds were added to the growth medium of Saccharomyces cerevisiae cells and Fusarium oxysporum conidia. Helix pomatia lectin, wheat germ agglutinin and Ulex europaeus lectin were used to identify differences in the binding of the vicilins to the surface of cells of S. cerevisiae and F. oxysporum treated with this protein. After the growth period, the material in suspension (yeast cells) was centrifuged and the final pellet was also treated with different sugar (glucose, sucrose, glucosamine, N-acetyl-glucosamine) concentrations and 0.1 M HCl for extraction of vicilins associated to chitinous structures present in yeast cells. Our results showed that vicilin sub-units were present in the different sugar extracts of yeast cells pretreated with the vicilins and these proteins were eluted by 0.5 M solutions of sugars in the following order of efficiency of elution: N-acetyl-glucosamine, sucrose/glucose and glucosamine.     

Formulation,Evaluation and Optimization of Tortillas Containing Wheat,Cowpea and Peanut Flours Using Mixture Response Surface Methodology1

The performance characteristics of tortillas, prepared with different composite blends of wheat, cowpea and peanut flours, were evaluated by mixture response surface methodology. Optimum wheat flour substitution levels were determined. Results indicated that wheat flour could be successfully replaced with up to 24% cowpea and 46% defatted peanut flours and result in tortillas with quality characteristics comparable to those from 100% wheat. Sensory evaluation indicated that beany flavor was the most limiting attribute. Sensory attributes correlated significantly with physical and compositional measures of tortillas and physical measures of tortilla dough.     

开发和利用我国中草药作为储粮保护剂的研究——2.苦楝(Melia azedarach L.)和使君子(Quisqualis indica L.)对绿豆象和赤拟谷盗的毒杀作用

本文报导了苦楝(Melia azedarach L.)及使君子(Quisqualis indica L.)对绿豆象幼虫、成虫和赤拟谷盗各虫态的毒杀作用。利用喷雾、点滴和拌粮等不同方法处理试虫,结果表明,使君子粉的不同溶剂提取物对绿豆象幼虫、成虫和赤拟谷盗各虫态均无明显毒杀作用。苦楝粉95％乙醇提取物对两种试虫亦无明显毒杀作用。而苦楝油的毒杀效果则比较明显,并对其进行了室内毒力测定。     

Relationship of hydrophobicity and solubility with some functional properties of cowpea (Vigna unguiculata) protein isolate

The relationship of hydrophobicity and solubility with some functional properties of cowpea protein isolate was determined. Cowpea protein isolate was prepared by alkali extraction followed by precipitation at pH 4.5. The precipitated proteins were then neutralized to pH 7. Heating of the protein isolate to 100°C for 10 min followed by cooling to room temperature resulted in a significant (P ≦ 0.05) decrease in aromatic hydrophobicity (ARH) when compared to the native protein isolate. The inclusion of sodium dodecyl sulfate (SDS) during heating gave a significant (P ≦ 0-05) 1.7-fold increase while inclusion of mercaptoethanol (ME) gave a significant (P ≦ 0.05) 2.5-fold increase in ARH of the cooled protein solution. Protein solubility (PS), foam expansion (FE) and emulsification activity index (EAI) of the isolate generally increased significantly (P ≦ 0.05) upon heating or treatment with urea or SDS or a combination of SDS and ME. Backward stepwise multiple regression was used to obtain equations for predicting emulsifying and foaming properties of the protein isolate from solubility and hydrophobicity parameters. PS, ARH and aliphatic hydrophobicity (ALH) were important in predicting foam stability and emulsion stability, while PS and ALH were important for predicting FE. ALH alone was important for predicting EAI.     

Simultaneous Records of Methane and Nitrous Oxide Emissions in Rice-Based Cropping Systems under Rainfed Conditions

Rainfed rice (Oryza sativa L.)-based cropping systems are characterized by alternate wetting and drying cycles as monsoonal rains come and go. The potential for accumulation and denitrification of NO₃ ^– is high in these systems as is the production and emission of CH₄ during the monsoon rice season. Simultaneous measurements of CH₄ and N₂O emissions using automated closed chamber methods have been reported in irrigated rice fields but not in rainfed rice systems. In this field study at the International Rice Research Institute, Philippines, simultaneous and continuous measurements of CH₄ and N₂O were made from the 1994 wet season to the 1996 dry season. During the rice-growing seasons, CH₄ fluxes were observed, with the highest emissions being in organic residue-amended plots. Nitrous oxide fluxes, on the other hand, were generally nonexistent, except after fertilization events where low N₂O fluxes were observed. Slow-release N fertilizer further reduced the already low N₂O emissions compared with prilled urea in the first rice season. During the dry seasons, when the field was planted to the upland crops cowpea [Vigna unguiculata (L.) Walp] and wheat (Triticum aestivum L.), positive CH₄ fluxes were low and insignificant except after the imposition of a permanent flood where high CH₄ fluxes appeared. Evidences of CH₄ uptake were apparent in the first dry season, especially in cowpea plots, indicating that rainfed lowland rice soils can act as sink for CH₄ during the upland crop cycle. Large N₂O fluxes were observed shortly after rainfall events due to denitrification of accumulated NO₃ ^–. Cumulative CH₄ and N₂O fluxes observed during this study in rainfed conditions were lower compared with previous studies on irrigated rice fields.     

自然发酵酸豆角中优势乳酸菌的分离鉴定和生长特性研究

在自然发酵的酸豆角中筛选优势乳酸菌,并对其生长特性进行研究.在自然发酵酸豆角中筛选得到一株明串珠菌.该菌株在温度为20℃～45℃,氯化钠浓度为0%～7%,蔗糖浓度为0%～5%情况下生长良好;其代谢产物具有明显的抑菌作用.     

Antioxidant and apoptotic potential of protein isolates derived from Vigna unguiculata (L.) Walp

Projected mortalities from cancer are expected to continue escalating, with conventional chemotherapeutic regimens having extensive side effects, hence the need for therapeutics capable of terminating cancer cells selectively, through apoptosis. Therapeutic protein isolates bind specifically to target proteins inducing cell death in vitro and in vivo in various cancer cells. Therefore, this study aimed at observing the antioxidant and anticancer potential of protein isolates from five cowpea cultivars (Glenda, Embu buff, Makhatini, Veg Cowpea 2 and Veg Cowpea 3). Cytotoxicity was conducted on cancerous and non-cancerous cell lines. Apoptosis was quantified using flow cytometry, and caspase-3/7 activity was determined. Cytotoxicity assays revealed that Embu buff was the pre-eminent inhibitor of cancerous cells, while also acting as a protecting mediator in a stressed non-cancerous cell line by causing a reversal in apoptotic activity. Therefore, cowpea isolates show high potential as candidates for the therapeutic intrusion of cancer.     

Mineral Loss in Cowpeas [Vigna unguiculata (L.) Walp] by Pressure Heating in Water

White Acre cowpeas of four maturity levels were heated in water at 35 kPa for 0–40 min. As the cowpeas increased in maturity, Zn, Cu, Mn, Mg, and K increased, Fe decreased and Ca did not change. All minerals analyzed decreased with heating: Cu, Ca and Mg (p < 0.001), Zn, Fe and K (p <0.01) and Mn (P<0.05). Minerals leached from the cowpeas at different magnitudes and rates. For example, K lowered 70–80% within 10 min; others lowered 20% or less. Loss of minerals across maturity stages was not uniform. This method reduced loss of certain minerals when compared to published values for the boiling water method.