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1.
The effects of gamma irradiation on ruminal dry matter, Neutral Detergent Fiber (NDF) degradation of alfalfa hay were investigated. Alfalfa hay samples were irradiated by gamma irradiator at doses of 50, 100 and 150 kGy under identical conditions of temperature and humidity. Nylon bags of untreated or irradiated samples were suspended in the rumen of three Taleshi bulls for up to 96 h and resulting data were fitted to non-linear degradation model to calculate degradation parameters. Results indicated that the washout fractions of dry matter and NDF increased linearly (p < 0.001) with increasing irradiation dose. The b fraction and the degradation rate of the b fraction (c) of DM and NDF were the highest at 50 kGy dose. Effective degradability of DM and NDF increased linearly with increasing irradiation dose. Gamma irradiation at doses of 50, 100 and 150 kGy increased the effective NDF degradability of alfalfa hay at rumen outflow rate of 0.05 h(-1) by about 8, 11 and 12%, respectively. Gamma irradiation affects on the hydrogenic bonds and with theirs breakdowning causes the wander-valls power weaken, that results in the degradation of cellulose and increasing of DM and NDF degradability.  相似文献   

2.
Early bulking (EB) cassava varieties shorten the growth period from planting to harvesting. Cassava is preferred by farmers to many other crops because of its high-yielding potential and ability to survive a 4- to 6-month dry season. However, the crop in some cases is only able to remain alive during the dry season without further starch accumulation. This and some other factors, such as pest destruction during dry season and inability to use the same land for cultivation of other crops such as vegetables, therefore necessitate the development of EB cassava genotypes. The objective of this study was therefore to identify EB cassava genotypes using the difference in fresh storage root yield (FSRY) at different plant ages. Thirty-four cassava genotypes were evaluated at Umudike and Otobi in Nigeria in two seasons at two plant ages of 7 and 12 months after planting (MAP) for FSRY. The data generated were used to classify the cassava genotypes as EB or late bulking (LB). Cassava genotypes with less than 100% increase in FSRY at 12 MAP over the yield at 7 MAP were regarded as EB, whereas those with more than 100% increase were regarded as LB genotypes. This basis was used considering the fact that root thickening in cassava commences at about 2 MAP; hence, the root yield at 7 and 12 MAP represents accumulation of assimilates for 5 and 10 months, respectively. About 65%, 62%, and 79% of the genotypes were classified as EB genotypes at Otobi, Umudike, and across the two locations, respectively.  相似文献   

3.
马铃薯SSR标记聚丙烯酰胺凝胶电泳分析   总被引：1，自引：0，他引：1  
以马铃薯品种早大白、黄麻子、克新13、荷兰15、大西洋为试验材料,提取基因组DNA,进行SSR标记,并将标记产物进行聚丙烯酰胺凝胶电泳,比较不同电泳参数(聚丙烯酰胺凝胶的浓度、电泳电压、染色方法)对电泳结果的影响。确定了适合马铃薯SSR标记的电泳检测体系,即聚丙烯酰胺凝胶的浓度为12%,电泳电压为170V,染色方法为溴化乙锭染色。  相似文献   

4.
The effects of gamma irradiation on degradation of aflatoxin B1 in wheat, corn, and soybeans and of T-2 toxin in wheat, deoxynivalenol (DON) in soybeans, and zearalenone in corn at 9, 13, and 17% moisture were studied. Radiation doses of 5, 7.5, 10 or 20 kGy were applied to spiked grain samples, and the residual toxins were measured using an enzyme linked immunosorbent assay (ELISA). Irradiation doses of up to 20 kGy did not significantly affect aflatoxin B1 in any of the three grains, but significant reductions occurred in T-2 toxin, DON, and zearalenone concentration at doses of 10 or 20 kGy and in T-2 toxin at the 7.5 kGy dose. Two-way analysis of variance with Tukey's Multiple Range Test showed no significant interaction between radiation dose and grain moisture level. Irradiation of the ground grains at doses higher than 5 kGy resulted in small, but significant, losses of lysine in corn (only at 7.5 kGy), wheat, and soybeans, and methionine was reduced in wheat and corn samples. In some cases, phenylalanine decreased in corn and wheat, and histidine levels in wheat were reduced in samples receiving 7.5 kGy of irradiation. Other essential amino acids were not affected significantly by irradiation.Contribution No. 94-114-J of the Kansas Agricultural Experiment Station.  相似文献   

5.
The effect on properties of starch isolated from Ajax and Diamant potatoes freshly harvested and irradiated immediately after harvest and after two weeks with 0.05, 0.10, 0.15, and 0.20 kGy were reported. Changes due to postirradiation storage up to six months at two different conditions (5 C, 90±2% RH and 20 C, 79±5% RH) were also studied. Swelling power (SP) slightly decreased or remained unchanged with different irradiation dose, but the effect of timing of irradiation after harvest was significant. Doses of 0.2 and 0.15 kGy significantly (p≤0.05) increased solubility, particularly at 90 C solubility temperature compared to lower doses. Decrease in viscosity with increasing dose immediately after irradiation was observed in both varieties but was more pronounced in Diamant. However, changes were dependent on variety, irradiation dose, timing of irradiation, and postirradiation storage conditions. Viscoamylograph test showed that 0.2 kGy significantly (p≤0.05) increased transmission temperature (TT) and temperature at maximum viscosity (TMV), but decreased the maximum viscosity immidiately after irradiation. The same trend was established during the post-irradiation storage time, particularly in Ajax starch, regardless of timing of irradiation or storage conditions. Thermoluminescence (TL) glow curves exhibited qualitative differences between irradiated and unirradiated tubers during the entire storage period, but dose estimation could not be determined.  相似文献   

6.
The effects of 60Co gamma-irradiation treatments (2·5, 5·0, 10·0 and 20·0 kGy) on the gluten proteins of two bread wheats and one durum wheat cultivar were investigated. Dough rheological properties of the flour processed from the irradiated wheat were also determined using a computerised micromixograph. Irradiation caused a significant deteriorating effect on all mixogram parameters. There was no observable effect of irradiation on gliadin proteins analysed by polyacrylamide gel electrophoresis. The 50% 1-propanol-insoluble (50 PI) glutenin fraction was highly affected by irradiation. By sodium dodecyl sulfate polyacrylamide gel electrophoresis, reduced 50 PI glutenin showed a noticeable reduction in band intensities of both high (HMW) and low molecular weight (LMW) glutenin subunits (GS) with increasing irradiation dosage greater than 5 kGy. The irradiation effect on 50 PI glutenin was further studied and quantified by reversed-phase high-performance liquid chromatography of glutenin subunits; there was a progressive decrease in the quantity of subunits with increasing irradiation dose level. Compared to non-irradiated wheat, the relative decline in total insoluble glutenin at the 20 kGy dosage level ranged from 34–49% depending on cultivar. Increasing levels of irradiation also progressively reduced the ratio of HMW:LMW-GS up to 13–15% at 20 kGy indicating that irradiation had a greater effect on the largest polymers of glutenin. The observed weakening of dough mixing properties and concomitant decline in the quantity of 50 PI glutenin with increasing levels of gamma-irradiation are consistent with a degradation of glutenin to a lower average molecular size by depolymerisation and/or disaggregation.  相似文献   

7.
The effect of electron beam irradiation at doses of 100, 200 and 300 kGy on ruminal dry matter degradation kinetics of wheat straw was investigated. Samples were irradiated by electron beam irradiator under identical conditions of temperature and humidity. Nylon bags of untreated or irradiated wheat straw were suspended in the rumen of three Taleshi steers for up to 96 h and resulting data were fitted to non-linear degradation model to calculate degradation parameters of dry matter. Results show that the washout fractions of dry matter increased linearly (p<0.001), but potentially degradable fraction and degradation rate decreased linearly (p<0.001) by electron beam irradiation. As a consequence, the effective degradability of dry matter increased linearly (p<0.001) with increasing irradiation dose. Electron beam irradiation at doses of 100, 200 and 300 kGy increased the effective degradability of dry matter at rumen outflow rate of 0.05/h by about 7, 15 and 18%, respectively. In the condition of this study, electron beam irradiation at dose of 200 kGy appeared to be a suitable dose for improving dry matter degradability of wheat straw in the rumen.  相似文献   

8.
The present study was undertaken to assess the microbiological profile of fresh camel meat and the possibility of improving microbial quality and extending the refrigerated storage life of meat by using low-dose gamma irradiation. Camel meat samples were subjected to 0 (control), 1.5 and 3 kGy doses and stored at 3 +/- 1 degrees C. the microbial and sensory attributes were evaluated. Exposure to 1.5 kGy dose significantly reduced the initial counts of Aerobic Plate Counts (APCs), psychrophilic bacteria, Lactic Acid Bacteria (LAB), molds and yeasts, Staphylococcus aureus, Listeria monocytogenes and Enterococci. Moreover, Pseudomonas, coliforms and Escherichia coli were below the detection levels. Irradiation at 3 kGy significantly reduced the initial counts of APCs LAB and Enterococci by 99.5, 93.5 and 93.9%, respectively. Pseudomonas, coliforms, S. aureus, L. monocytogenes and E. coli were not found at dose of 3 kGy during entire storage period, also psychrophilic bacteria and molds and yeasts were below the detection levels during 6 days of storage. This study shows that irradiation had no significant effects on the sensory attributes of camel meat. Refrigerated shelf-life of the meat irradiated at 1.5 and 3 kGy were 15 and 21 days, respectively, compared to 7 days for non-irradiated controls.  相似文献   

9.
PVDF-CF composite films were prepared using a melt pressing method. The PVDF-CF composite films were cut into rectangular shapes with a gauge length and width of 10 and 5 mm, respectively. The films were drawn using a universal testing machine equipped with a hot chamber. The drawing temperatures and speeds were 50∼150 °C and 100∼000 %/min, respectively. The crystal structure and physical properties of the resulting PVDF-CF films were investigated by wide angle X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis and scanning electron microscopy. The crystal form of the initial films was the 〈alpha〉 phase (non polarity, lamellar structure) of PVDF. The maximum draw ratio was 4.2. The drawn PVDF-CF films prepared at 100 °C were mainly the 〈beta〉 phase (polarity, fibrillar structure) of PVDF. With increasing drawing speeds, the 〈alpha〉 phase became the dominant phase of PVDF in the PVDF-CF films. The thermal properties of the PVDF-CF films improved with increasing drawing temperature, and the dynamic mechanical properties improved with increasing drawing speed.  相似文献   

10.
Irradiation crosslinking of PA6 fibers with and without the presence of triallyl cyanurate (TAC) was investigated. The dose for incipient gel formation was 500 kGy for pristine PA6 fibers and it decreased to 12 kGy when 5 % TAC was incorporated. Changes in structure and properties of irradiated PA6 fibers were analyzed by X-ray diffraction, infrared spectroscopy and thermal gravimetric analysis. Irradiation crosslinking improved the anti-dripping properties of PA6 fibers effectively. Irradiated samples showed an increase of the breaking strength and then a decrease at further doses due to radiolysis effect, the elongation at break decreased during the irradiation process. Irradiation crosslinking had not changed the crystal form and crystallinity decreased first and then increased to some extent. DSC measurement reported that the melting temperature decreased with increasing the dose. The thermal stability decreased after irradiation whereas the amount of nonvolatile residue at 600 °C increased as the irradiation dosage increased. The infrared spectra of irradiated samples were identical with the unirradiated, no new bands were observed.XPS analysis showed that the number of C-C band increased after irradiation which proves that branching and crosslinking has occurred.  相似文献   

11.
Preparation of boron-selective adsorbent was carried out by radiation induced grafting of glycidyl methacrylate (GMA) onto polyethylene-coated polypropylene (PE-PP) nonwoven fabric in emulsion or solvent medium followed by immobilization of N-methyl-D-glucamine (NMDG). Adsorbent precursors with 180 % degree of grafting (DG) were obtained by applying reaction parameters comprising 20 kGy dose, 5 % monomer concentration and 1 h reaction time in emulsion compared to 30 kGy, 10 % and 3 h in solvent medium. A glucamine density of 2.2 mmol/g could be imparted to the obtained adsorbents. The emulsion-mediated grafting was found more efficient and economical for preparation of boron chelating adsorbents.  相似文献   

12.
Thermoplastic films from wheat proteins   总被引：1，自引：0，他引：1  
We show that the wheat proteins gluten, gliadin and glutenin can be compression molded into thermoplastic films with good tensile strength and water stability. Wheat gluten is inexpensive, abundantly available, derived from renewable resource and therefore widely studied for potential thermoplastic applications. However, previous reports on developing thermoplastics from wheat proteins have used high amounts of glycerol (30-40%) and low molding temperature (90-120 °C) resulting in thermoplastics with poor tensile properties and water stability making them unsuitable for most thermoplastic applications. In this research, we have developed thermoplastic films from wheat gluten, gliadin and glutenin using low glycerol concentration (15%) but high molding temperatures (100-150 °C). Our research shows that wheat protein films with good tensile strength (up to 6.7 MPa) and films that were stable in water can be obtained by choosing appropriate compression molding conditions. Among the wheat proteins, wheat gluten has high strength and elongation whereas glutenin with and without starch had high strength and modulus but relatively low elongation. Gliadin imparts good extensibility but decreased the water stability of gluten films. Gliadin films had strength of 2.2 MPa and good elongation of 46% but the films were unstable in water. Although the tensile properties of wheat protein films are inferior compared to synthetic thermoplastic films, the type of wheat proteins and compression molding conditions can be chosen to obtain wheat protein films with properties suitable for various applications.  相似文献   

13.
In the present research effects of gamma irradiation (5–20 kGy) on the physicochemical, antioxidant and thermal properties of brown rice starch were studied. Scanning electron microscopy displayed mostly polyhedral shapes with no surface fractures. XRD displayed characteristic A type pattern and decrease in per cent crystallinity (22.53–20.41%) was observed as the dose increased from 5 to 20 kGy. DPPH % inhibition and FRAP values were increased in a dose dependent manner. Pasting properties (peak, final and setback viscosity) decreased with irradiation. Pasting temperature also significantly decreased with irradiation for all the irradiated starches. The transition temperatures, enthalpy of gelatinization, pH and apparent amylose content of starch decreased significantly with increase in irradiation dose.  相似文献   

14.
Chemical and nutritional characteristics of irradiated and nonirradiated cowpea bean at 0.2 kGy submitted to several thermal treatments were studied. The cowpea bean flours irradiated at 0.2 kGy were superior to those non-irradiated concerning digestibility and the flours submitted to microwave oven were superior to those cooked under low pressure, autoclaved or even raw from the nutritional point of view. As to the presence of anti-nutritional factors, the results showed that the variety of cowpea bean under research presented neither trypsin inhibitor nor haemagglutinin activity, however, regarding tannin, a 0.006% content was found and considered negligible.  相似文献   

15.
Poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP) films were prepared using either a melt pressing or solution casting methods. The resulting PVDF-HFP films were drawn uniaxially at various drawing temperatures and speeds. The mp-PVDF-HFP films were more transparent and had more drawability than the sc-PVDF-HFP films. The crystal form of the initial films was the alpha-phase (non polarity) of PVDF. The maximum draw ratio was 7.6. The mp-PVDF-HFP films were prepared at a drawing speed of 2500 %/min at 100 °C. With increasing drawing speed, the beta-phase (polarity) became the dominant phase of PVDF in mp-PVDF-HFP films. The thermal properties of the resulting PVDF-HFP films improved with increasing drawing temperature.  相似文献   

16.
Influence of irradiation (0.05–0.20 kGy) and germination (24–120 hours) in distilled and tap water on phytate, protein and amino acids of soybean, was studied. Phytate values significantly decreased with increasing germination period and irradiation dose (P<0.01). Irradiation independently decreased the original phytate (212.0 mg/100 g) to a range value of 205.0–190.0 mg/100 g depending upon dose level. Germination of unirradiated seeds for 120 hours in distilled and tap water lowered the phytate to 55.0 and 94.9 mg/100 g (74.1 and 55.2% reduction) respectively. Maximum destruction of phytate to levels of 20.5 and 50.9 mg/100 g (90.3 and 76.0% reduction) occurred during germination of 0.20 kGy samples for 120 hours in distilled and tap water respectively. Total protein content significantly increased during germination (P<0.05) and the increase was more in tap than distilled water. Germination for 120 hours of untreated seeds in tap water increased the essential and decreased non-essential amino acids while in the 0.10 kGy sample, increases in both cases were observed.  相似文献   

17.
Biosynthesis of ascorbic acid in irradiated and unirradiated germinating rapeseed cultivars was studied at ambient room temperature (20–35 °C). Appreciable quantities of ascorbic acid (19.8–24.1 mg/100 g) were detected in the seeds and synthesis of this vitamin increased significantly (three fold) with increasing germination time depending upon rapeseed cultivars (p<0.05). Soaking of seeds in tap water (1:2) for 24 hours resulted in the decrease of the vitamin in each case. Among the radiation treatments (0.05–0.20 kGy), maximum amounts of ascorbic acid were found in 0.10 kGy (342.1 mg/100 g dry weight) and 0.15 kGy (113.8 mg/100 g wet weight) samples after 96 hours of germination. An overall significant linear relation (r=0.96) was observed between vitamin biosynthesis and germination time upto 96 hours in rapeseed.  相似文献   

18.
This study evaluated the starch digestibility, physicochemical properties and cooking characteristics of polished rice (varieties IRGA417 and IAC202) subjected to the doses of 0 (as the control), 1, 2 and 5 kGy of gamma radiation. The highest dose decreased the apparent amylose content, peak viscosity, water absorption and volume expansion. Irradiation increased the solid loss by 119% and 187% for IAC202 and IRGA417, respectively, when comparing the higher dose with the control. For IAC202, irradiation decreased the rapidly digestible starch and increased the slowly digestible starch (SDS) and resistant starch (RS). IRGA417 showed an elevation of SDS and a reduction in RS. And 1 kGy dose of gamma radiation generated the highest level of RS for both the two varieties and presented the smallest changes in other physicochemical and cooking properties.  相似文献   

19.
In this study, α-polylysine was used to enhance the cross-linking effect of TGase on gluten and its effects on properties of gluten films were investigated. The amount of free ammonia released from the cross-linking reaction of gluten induced by TGase at the presence of α-polylysine obviously increased, and more polymers with higher molecular weight were formed from the SDS-PAGE results, which indicated that the TGase-mediated cross-linking reaction ability of gluten was strengthened with the incorporation of α-polylysine. The tensile strength of the films from gluten modified with TGase (20 units/g wheat gluten) and 2% α-polylysine (g/g gluten) for 3 h increased from 4.02 ± 0.09 MPa to 5.28 ± 0.14 MPa, which was more effective than that treated with TGase alone (in which the tensile strength of the films was 4.49 ± 0.10 MPa). The TGase treatment with α-polylysine of gluten improved the water stability of the films much more than that treated with TGase alone. A rougher surface and a more compact cross-section structure were observed by SEM for the films from TGase-α-polylysine treated gluten. The contact angles between the gluten films surface and a water droplet increased because of TGase-mediated cross-linking modification.  相似文献   

20.
王岳飞 《茶叶科学》1999,19(2):151-155
利用荧光探针溴化乙啶研究了茶( 包括绿茶、红茶、乌龙茶和花茶) 与DNA 的相互作用及维生素C、咖啡因对其影响。结果表明: 各种茶类的茶液对EB DNA 荧光强度均有压低作用;不同茶类影响状况不同, 压低作用同这些茶类所含的茶多酚量密切相关, 但红茶的作用强于绿茶; 茶叶中的其它成分对荧光强度会有一定的影响。维生素C与茶多酚(TP) 在压低EB DNA荧光强度的效果上存在协同增效作用。茶叶中另一成分咖啡因可增强TP对EB DNA 荧光强度的压低作用, 而其本身对荧光强度没有影响。  相似文献   

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