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21.
The catalytic role of various inert solid supports on acceleration of alcohol fermentation by Saccharomyces cerevisiae was investigated. The enhanced rate of alcohol production was dependent on the nature of the support as well as on the amount
used. Among all the tested supports, chitosan flakes showed the maximum yield of alcohol (93% of theoretical yield). This
higher rate of alcohol production was associated with the twofold increase in the activity of alcohol dehydrogenase over control.
Our results suggest that the addition of a small fraction of solids in submerged fermentations to facilitate cell anchorage
for enhanced metabolic activity is easier and more economical compared to cell immobilization processes.
IICT Communication No. 4266. Some of the results in this article are covered under a patent. 相似文献
22.
Nancy M. Edwards Donatella Peressini James E. Dexter Steven J. Mulvaney 《Rheologica Acta》2001,40(2):142-153
Linear viscoelastic properties (LVP) were determined for five durum wheat doughs and five common wheat doughs (representing
four different classes of Canadian common wheat) of different strength using creep testing. A creep time of 10,000 s was sufficient
to reach a state of steady state flow for all of the doughs. Creep compliances were analyzed in terms of a Burgers model.
For the durum doughs, the entire elastic compliance curve was shifted to higher values as the strength of the dough (as measured
by extensigraph) decreased, while the steady state viscosity increased with strength. For common wheat doughs, the elastic
compliance curves were steeper and the steady state viscosities were lower than for durum doughs of comparable extensigraph
strength. The retardation strengths associated with a maximum in the retardation spectra were lower for the stronger durum
doughs than for common wheat doughs of comparable strength. Differences in the LVP between durum and common wheat doughs of
similar extensigraph strength were interpreted in the context of physical gels with crosslinks and entanglements, whose contributions
to material properties are difficult to distinguish in short-time creep or dynamic measurements. The increased extensibility
of common wheat doughs relative to durum doughs of comparable extensigraph strength was attributed to a higher molecular weight
fraction in the polypeptide chains, similar in some respects to end-linked bimodal polymer networks. The idea of considering
these doughs as physical gels was supported by their stress relaxation behavior.
Received: 6 February 2000 Accepted: 22 August 2000 相似文献
23.
Giovanni Dinelli Antonio Segura Carretero Raffaella Di Silvestro Ilaria Marotti Shaoping Fu Stefano Benedettelli Lisetta Ghiselli Alberto Fernández Gutiérrez 《Journal of chromatography. A》2009,1216(43):7229-7240
An evaluation of the grain functional components of Italian durum wheat cultivars was conducted. The raw material was obtained from the field trial performed in 2006–2007 at the Experimental Farm of the University of Bologna, (Bologna, Italy). The aim of this study was to define the phytochemical profile of ten varieties, comprised of old and modern durum wheat genotypes, including quantitative and qualitative phenolic and flavonoid content (free and bound forms). The results showed that mean values of total phenolic compound and total flavonoid content in old wheat varieties (878.2 ± 19.0 μmol gallic acid equivalent/100 g of grain and 122.6 ± 25.4 μmol catechin equivalent/100 g of grain, respectively) did not differ significantly from those detected in modern genotypes (865.9 ± 128.9 μmol gallic acid equivalent/100 g and 123.5 ± 20.6 μmol catechin equivalent/100 g, respectively). However, the HPLC–ESI-TOF-MS analysis highlighted remarkable differences between modern and old cultivars. The interpretation of the mass spectra allowed the identification of 70 phenolic compounds, including coumarins, phenolic acids, anthocyanins, flavones, isoflavones, proanthocyanidins, stilbenes and lignans. The free extracts of ancient wheat varieties showed the presence of a mean number of phenolic compounds and isomer forms (8.7 ± 2.5 and 7.7 ± 4.7 respectively) significantly higher than in modern genotypes (4.4 ± 2.9 and 2.0 ± 2.4, respectively). A similar trend was observed also for the bound phenolic fraction. Moreover, the phytochemical profiles showed the presence of unique phenolic compounds in both free and bound fractions of some of the investigated wheat genotypes. Results highlighted that investigated old wheat cultivars may offer unique nutraceutical values for their peculiar contents in bioactive phytochemicals, suggesting their uses into a wide range of regular and specialty products naturally enriched with health-promoting compounds. 相似文献
24.
Ultrasound technology was used to treat rice bran protein (RBP), and the structural and functional properties of ultrasonically treated RBP (URBP) and its chlorogenic acid (CA) complex were studied. When ultrasonic power of 200 W was applied for 10 min, the maximum emission peak λmax of the URBP-CA complex in the fluorescence spectrum was red-shifted by 3.6 nm compared to that of the untreated complex. The atomic force microscope (AFM) analysis indicated that the surface roughness of the complex was minimized (3.89 nm) at the ultrasonic power of 200 W and treatment time of 10 min. Under these conditions, the surface hydrophobicity (H0) was 1730, the contents of the α-helix and β-sheet in the complex were 2.97% and 6.17% lower than those in the untreated sample, respectively, the particle size decreased from 106 nm to 18.2 nm, and the absolute value of the zeta-potential increased by 11.0 mV. Therefore, ultrasonic treatment and the addition of CA changed the structural and functional properties of RBP. Moreover, when ultrasonic power of 200 W was applied for 10 min, the solubility, emulsifying activity index (EAI), and emulsion stability index (ESI) were 68%, 126 m2/g, and 37 min, respectively. 相似文献
25.
纯化小麦液泡膜H -ATPase,测定了纯化的小麦液泡膜H -ATPase 受Mg2 和Ca2 双重激活的特性及两种激活状态下酶的特性. Mg2 激活时酶水解活性受DCCD的抑制,受磷脂酰丝氨酸(PS)影响明显,ATP水解和泵质子活性相偶联.而在Ca2 激活时酶水解活性不受DCCD抑制,受PS影响微弱,Ca2 激活时ATP水解与泵质子活性解偶联. Mg2 和Ca2 对小麦液泡膜H -ATPase的激活作用不具有叠加效应. 相似文献
26.
27.
Nodule-like structures (para-nodules) can be induced in wheat roots by low concentrationsof 2,4-dichlorophenoxyacetic acid (2,4-D), a synthetic analogue of the plant growth hor-mone indole-acetic acid. Growth of nodulated wheat plants was not affected by 2,4-D treat-ment. Infection of these?para-nodules by adding oxygen-tolerant Azorhizobium caulinodans isolat-ed from stem nodules of the tropical legume Sesbania rostrata resulted in massive prolifera-tion of bacterial cells in the intercellular spaces as well as inside the para-nodular cells.Para-nodules colonized by Azorhizobium coulinodans not only reduced acetylene, but alsotransferred fixed nitrogen to the plant, contributing up to 16--23% of the nitrogen budgetof infected wheat. 相似文献
28.
The purpose of this study was to examine the efficiency with which rice bran (treated or untreated) removes heavy metals, especially Cr(III) and Hg(II), from acidic solution. Sorption assays were done in shaken flasks in the presence of rice bran. Different experimental conditions such as pH, volume of solution, bran weight, particle size, exchange time and stirring time were improved. The efficiency of bran was studied before and after treatments. For treatment, solutions of acid, alkali and salt were used. The results show that after treating with 4 M sodium chloride solution, its efficiency in removal of Cr(III) and Hg(II) was improved. Kinetic measurements of chromium and mercury removal by bran have revealed that sorption equilibrium was obtained after 10 min of contact. Sorption experiments done with various granulometric fractions of rice bran have shown that this sorbent has the same efficiencies in meshes higher than 20. Further research is necessary in order to determine a mechanism for cations removal by the bran. It is mentioned that the process of making polished rice from brown rice discharges rice bran; therefore, it is very inexpensive, with a cost of 1/50 ? 1/40 of that of synthetic sorbent, and thus its use would significantly lower the cost of wastewater treatment. 相似文献
29.
氮离子束注入对新疆春小麦M1代生物学效应的影响 总被引:3,自引:0,他引:3
为了探索离子束诱变育种的合适剂量,用5种剂量处理2个品种,对两个品种的出苗率、分蘖率、小穗数、穗粒数、千粒重、有效分蘖率进行了分析,结果表明剂量为2~4×1016N+/cm2处理对新疆春小麦适宜. 相似文献
30.
Umar Asghar Mehvish Iram Zile Huma Rubina Nelofer Muhammad Nadeem 《Natural product research》2015,29(2):125-131
This study was conducted to analyse structural changes through scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) after alkaline pretreatment of wheat straw for optimum steaming period. During the study, 2 mm size of substrate was soaked in 2.5% NaOH for 1 h at room temperature and then autoclaved at 121°C for various steaming time (30, 60, 90 and 120 min). Results revealed that residence time of 90 min at 121°C has strong effect on substrate, achieving a maximum cellulose content of 83%, delignification of 81% and hemicellulose content of 10.5%. Further SEM and FTIR spectroscopy confirmed structural modification caused by alkaline pretreatment in substrate. Maximum saccharification yield of 52.93% was achieved with 0.5% enzyme concentration using 2.5% substrate concentration for 8 h of incubation at 50°C. This result indicates that the above-mentioned pretreatment conditions create accessible areas for enzymatic hydrolysis. 相似文献