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1.
To investigate the effect of ultrasonic treatment on the properties of sweet potato starch and sweet potato starch-based films, the complexing index, thermograms and diffractograms of the sweet potato starch-lauric acid composite were tested, and light transmission, microstructure, and mechanical and moisture barrier properties of the films were measured. The results indicated that the low power density ultrasound was beneficial to the formation of an inclusion complex. In thermograms, the gelatinization enthalpies of the ultrasonically treated starches were lower than those of the untreated sample. With the ultrasonic amplitude increased from 40% to 70%, the melting enthalpy (ΔH) of the inclusion complex gradually decreased. X-ray diffraction revealed that the diffraction intensity of the untreated samples was weaker than that of the ultrasonically treated samples. When the ultrasonic amplitude was above 40%, the diffraction intensity and relative crystallinity of inclusion complex gradually decreased. The scanning electronic microscope showed that the surface of the composite films became smooth after being treated by ultrasonication. Ultrasonication led to a reduction in film surface roughness under atomic force microscopy analysis. The films with ultrasonic treatment exhibited higher light transmission, lower elongation at break, higher tensile strength and better moisture barrier property than those without ultrasonic treatment.  相似文献   
2.
Non‐targeted nuclear magnetic resonance (NMR)‐based metabolic profiling was applied to potato leaves to survey metabolic changes associated with late blight resistance under field conditions. Potato plants were grown in an experimental field, and the compound leaves with no visible symptoms were collected from 20 cultivars/lines at two sampling time points: (i) the time of initial presentation of symptoms in susceptible cultivars and (ii) 12 days before this initiation. 1H NMR spectra of the foliar metabolites soluble in deuterium oxide‐ or methanol‐d4‐based buffers were measured and used for multivariate analysis. Principal component analysis for six cultivars at symptom initiation showed a class separation corresponding to their levels of late blight resistance. This separation was primarily explained by higher levels of malic acid, methanol, and rutin and a lower level of sucrose in the resistant cultivars than in the susceptible ones. Partial least squares regression revealed that the levels of these metabolites were strongly associated with the disease severity measured in this study under field conditions. These associations were observed only for the leaves harvested at the symptom initiation stage, but not for those collected 12 days beforehand. Subsequently, a simple, alternative enzymatic assay for l ‐malic acid was used to estimate late blight resistance, as a model for applying the potential metabolic marker obtained. This study demonstrated the potential of metabolomics for field‐grown plants in combination with targeted methods for quantifying marker levels, moving towards marker‐assisted screening of new cultivars with durable late blight resistance. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
3.
The present paper deals with the speciation of selenium in potatoes (enriched or not in selenium). The study was carried out by using differential pulse cathodic stripping voltammetry (DPCSV) for quantifying selenium. Results obtained provide evidence that the selenium content in the protein fraction is rather independent from the selenium added to the plants during their growth. On the contrary, the amount of Se in the non-protein fraction (water and starch) in Se-enriched sample is significantly higher than in non-enriched one, suggesting that it is the main selenium-storing site. In this fraction the Se(VI)/Se(IV) ratio seems independent from selenium application but it may be related to the redox conditions. The accumulation of selenium in the non-protein fraction is tentatively ascribed to the “Se–starch interaction” that should be able to modulate both the Se absorption into proteins and, possibly, its toxic effect for the plant itself.  相似文献   
4.
In order to explore the potential application of combined physical treatment in producing highly lipophilic modified starch, the effects of ultrasound combined with freeze-thaw treatment on the microstructure and physicochemical properties of potato starch were investigated. The samples treated by combined treatment had the roughest structure and the oil adsorptive capacity value increased from 59.62% (native starch, NS) to 80.2% (7 cycles of ultrasound-freeze-thaw treatment starch, 7UT-FTS). Compared to NS, the crystalline type and chemical groups of modified starches did not change, but the relative crystallinity, enthalpy change, and paste viscosity decreased to varying degrees, while the gelatinization temperature increased. The digestibility of raw modified starch was higher than that of NS, but this phenomenon disappeared after gelatinization. 7UT-FTS showed better resist-digestibility than NS after encapsulating oil. Hence, this would be an efficient and environmentally friendly way to produce modified starch with safety, highly lipophilic and heat resistance.  相似文献   
5.
Effect of heating of the potato starch on damages of its structure was investigated by quantitative electron paramagnetic resonance (EPR) spectroscopy, X‐ray diffraction and determination of the molecular weight distribution. The measurements were performed in the temperature range commonly used for starch modifications optimizing properties important for industrial applications. Upon thermal treatment, because of breaking of the polymer chains, diminishing of the average molecular weights occurred, which significantly influences generation of radicals, evidenced by EPR. For the relatively mild conditions, with heating parameters not exceeding temperature 230 °C and time of heating equal to 30 min a moderate changes of both the number of thermally generated radicals and the mean molecular weight of the starch were observed. After more drastic thermal treatment (e.g. 2 h at 230 °C), a rapid increase in the radical amount occurred, which was accompanied by significant reduction of the starch molecular size and crystallinity. Experimentally established threshold values of heating parameters should not be exceeded in order to avoid excessive damages of the starch structure accompanied by the formation of the redundant amount of radicals. This requirement is important for industrial applications, because significant destruction of the starch matrix might annihilate the positive influence of the previously performed intentional starch modification. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
6.
高效液相色谱法对粉条中甲醛含量的快速检测   总被引:1,自引:0,他引:1  
建立了Nash试剂柱前衍生高效液相色谱法快速测定土豆粉条样品中甲醛含量的分析方法.考察了衍生试剂、衍生反应条件及衍生物的稳定性.Nash试剂柱前衍生,产物经Agilent Zorbax Eclipse XDB-C18(4.6mm× 250 mm,5μm)柱分离,采用可变波长扫描紫外检测器(VWD)检测,检测波长412 ...  相似文献   
7.
A potential bacterial carrier for bioremediation   总被引:1,自引:0,他引:1  
One of the limiting factors to the effectiveness of biostimulation and bioremediation is the loss of inoculated material from the site. This can occur by a number of pathways, but is particularly problematic in open water systems where the inoculated material is simply lost in the water. It is desirable to develop new material, a matrix, within which bacteria and/or biostimulants can be incorporated. We have investigated the basic physical properties of insoluble potato starch to eventually evaluate its use as such a matrix. Insoluble starch fibers were prepared from white potato (Solanum tuberosum) and sweet potato (Ipomoea batatas) and were compared for their melting temperature by DSC and their ability to bind/aggregate bacteria. The DSC curves for white and sweet potato showed that the melting temperature is 127.34 and 133.05°C for white and sweet potato fibers, respectively. The TG curves for white and sweet potato starches exhibited one main mass loss step corresponding to the DTG peak temperature at 323.39 and 346.93°C, respectively. The two types of fibers, however, showed different binding/aggregation capacities for bacteria, with white potato approximately twice as many cells of Burkholderia cepacia (22.6 billion/g) as cells of Pseudomonas putida. The reverse was true for fibers from sweet potato, binding twice as many cells of Pseudomonas putida (23 billion/g) as cells of Burkholderia cepacia.  相似文献   
8.
叶菜型甘薯茎尖中微量元素和氨基酸的含量分析   总被引:4,自引:0,他引:4  
采用等离子体发射光谱法测定了叶菜型甘薯茎尖中K、Ca、Mg、Fe、Zn、Cu、Se等7种微量元素的含量,氨基酸分析仪测定了18种氨基酸的含量。结果表明,与其它12种叶菜类蔬菜相比较,叶菜型甘薯茎尖中K、Ca、Se含量较高;含有18种氨基酸,人体必需的氨基酸种类齐全,含量较高的氨基酸是天冬氨酸、谷氨酸、亮氨酸;高Se是叶菜型甘薯茎尖的显著特点。为探讨叶菜型甘薯茎尖中微量元素和氨基酸与保健功能之间的关系提供了有用的数据。  相似文献   
9.
A non‐denatured SDS‐PAGE followed by in‐gel activity staining using embedded glycol chitin as a substrate was used to identify the proteins with chitinolyitc activities from sweet potato leaf extract. At least two chitinase activity zones can be clearly identified on the gel at positions with estimated molecular weights of 54.1~55.6 kDa and 39.6 kDa. Furthermore, our data also indicate that the activity of the larger one can withstand the standard SDS‐PAGE sample preparation. Both of these chitinases, however, are different from that of the previously identified chitinase in sweet potato leaves, which has a molecular weight of 16 kDa. By using an embedded substrate, our method has superior sensitivity in detecting chitinases with higher molecular weights. It is a simple, affordable way and may aid in the future discovery of new chitinases.  相似文献   
10.
Cyclodextrins (CDs) are cyclic oligasaccharides composed by d-glucose monomers joined by α-1,4-d glicosidic linkages. The main types of CDs are α-, β- and γ-CDs consisting of cycles of six, seven, and eight glucose monomers, respectively. Their ability to form inclusion complexes is the most important characteristic, allowing their wide industrial application. The physical property of the CD-complexed compound can be altered to improve stability, volatility, solubility, or bio-availability. The cyclomaltodextrin glucanotransferase (CGTase, EC 2.4.1.19) is an enzyme capable of converting starch into CD molecules. In this work, the CGTase produced by Bacillus clausii strain E16 was used to produce CD from maltodextrin and different starches (commercial soluble starch, corn, cassava, sweet potato, and waxy corn starches) as substrates. It was observed that the substrate sources influence the kind of CD obtained and that this CGTase displays a β-CGTase action, presenting a better conversion of soluble starch at 1.0%, of which 80% was converted in CDs. The ratio of total CD produced was 0:0.89:0.11 for α/β/γ. It was also observed that root and tuber starches were more accessible to CGTase action than seed starch under the studied conditions.  相似文献   
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