Measurement and targeting of thermophysical properties of carrot and meat based alginate particles for thermal processing applications

The objective of the study was to investigate the thermo-physical properties of meat and carrot based alginate particles as influenced by the formulation variables. A response surface methodology (RSM) was used to study the effect of sodium alginate concentration, calcium chloride concentration and dipping time in the calcium chloride solution, at five levels each, on the thermo-physical properties of the fabricated particles (9 mm in diameter and 9 mm in height). Density was similar for all conditions. Increasing sodium alginate concentration resulted in a significant decrease in the heat capacity and thermal conductivity values. These changes were primarily attributed to the lowering of moisture content of the particles resulting from the treatment. Using RSM, optimum conditions for fabricating particles having similar thermo-physical properties to real foods were obtained as 5.3% and 4.9% sodium alginate, 2.2% calcium chloride and 14.2 and 36.0 h immersion in the calcium chloride solution for meat and carrot alginate particles, respectively.     

Synthesis and inclusion property of α-cyclodextrin-linked alginate

The inclusion ability on alginate, a hydrogel forming polysaccharide, has been introduced by covalently linking α-cyclodextrin (α-CD). The secondary hydroxyl groups of sodium alginate were activated with cyanogen bromide and subsequently reacted with 6-amino-α-CD. The degree of substitution (DS) of the resulting α-CD linked alginate was 0.05-1.58 depending on reaction condition and the ratio of 6-amino-α-CD and alginate. Using p-nitrophenol as a model compound in UV-vis and circular dichroism spectroscopic examination, the modified polysaccharide showed an ability to form a host-guest complex. Furthermore, the α-CD linked alginate found to be provided the spherical beads by treating with a calcium chloride solution.     

Removal of zirconium from spent fuel solution by alginate gel polymer

The uptake behaviour of zirconium (Zr) in alginate gel polymer and removal of Zr from spent fuel solution have been studied by the batch and column methods. As a first step, alginate gel polymer was synthesized and conditioned. The uptakes of Zr were examined in several concentrations of HNO₃ solution (from 0.01 M to 9 M HNO₃) by a batch method. Stronger affinity of Zr was shown than strontium (Sr), cobalt (Co), uranium (U) and iron (Fe) in 1 M HNO₃. It has been reported that cation binding was stronger with ions of higher charge in the alginate gel polymer. In contrast, the free aqueous ion, Zr⁴⁺, is the dominant form of the Zr species in very acidic solution. Therefore, the strong affinity of Zr is explained. The uptake rate of Zr was also evaluated in 2.6 M HNO₃ solution, which was close to the HNO₃ concentration in actual HLLW from fuel reprocessing. The uptake of Zr reached equilibrium within 2 h. For the column experiment, fission products (FPs) solution containing rare earth elements (REEs), platinum group metals, alkaline metals, alkaline earth metals and the other elements was prepared from actual spent fuel and the concentration of HNO₃ was adjusted to 2.6 M. In the column experiment, the alginate gel polymer was packed into a column, and then a chromatographic experiment was performed using the FPs solution prepared from actual spent fuel. As a result, over 95% of the Zr was removed from the FPs solution. Molybdenum (Mo), technetium (Tc), yttrium (Y), palladium (Pd), tellurium (Te), cesium (Cs) and REEs were eluted by the successive use of H₂O, and 1 M and 3 M HNO₃.     

Alginate block fractions and their effects on membrane fouling

Alginate has been commonly used as a model foulant in studies of membrane organic fouling. As a complex polymer, alginate is composed of two different monomers, namely M ((1 → 4) linked β-D-mannopyranuronic acid) and G ((1 → 4) linked α-L-gulopyranuronic acid) which are randomly arranged into MG-, MM- and GG-blocks. So far, little information is available about fouling propensity of each block in microfiltration. In this study, microfiltration experiments were conducted respectively with MG-, MM- and GG-blocks separated from alginate under defined conditions. Results showed the severest fouling in the filtration of MG-block, and the least flux decline in the filtration of MM-block. The initial pore blocking was found to be responsible for the fouling observed in MG-block filtration, while the cake layer formed on membrane surface during the MM-block filtration could serve as a pre-filter that prevented membrane from further pore blocking. In order to look into fouling mechanisms, the effects of transparent exopolymeric particles (TEP) on membrane fouling were also studied. TEP were found to form through aggregation or cross-link of alginate blocks. As TEP were bigger than original alginate blocks, they could facilitate the formation of cake layer on membrane surface. It was observed that more TEP were produced from MM-blocks than from MG-blocks in solutions. This in turn explained why cake resistance was dominant in the filtration of MM-blocks as compared to MG-blocks. The analysis by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory further revealed that MM-blocks had lowest cohesive interaction energy among all three alginate blocks, which favoured aggregation of MM-blocks, and ultimately leading to the formation of more TEP. This study provided insights into the roles of different alginate blocks in development of membrane fouling, and suggested that the membrane fouling would be related to molecular structure of alginate.     

Encapsulation of lipid by alginate beads reduces bio-accessibility: An in vivoC breath test and MRI study

This paper describes an in vivo study of the use of encapsulation to alter lipid bio-accessibility in the gastro-intestinal (GI) tract. The hypothesis that encapsulation would delay the accessibility of lipid in the GI tract was tested using subjects (N = 11) who consumed either 30 g of ¹³C-labelled sunflower oil encapsulated within 70 g alginate gel particles, or unencapsulated ‘free’ sunflower oil and alginate-only particles (control). Lipid accessibility was determined by the appearance of the ¹³C label in breath carbon-dioxide (CO₂), and the particles behaviour in the GI tract was investigated using non-invasive magnetic resonance imaging (MRI).     

海藻酸钾对原发性高血压人群的影响研究

目的了解海藻酸钾对原发性高血压(EH)人群的影响。方法将102例EH患者随机分为海藻酸钾组和对照组。原服用降压药物不变,海藻酸钾组每天服用含海藻酸钾的奶粉50g(含海藻酸钾3.5g),对照组服用普通奶粉,连续50d。对每位受试者进行血压、血常规、肝功能、肾功能、血糖、血脂测定,同时对临床症状、不良反应等进行问卷调查。结果海藻酸钾组血压随服用时间逐步下降,自第21d开始显著降低(P0.05),服用海藻酸钾50d后,海藻酸钾组收缩压、舒张压平均下降13.89、10.15mmHg,降压有效率为60.78%。主要临床症状积分显著降低(P0.05),头痛、眩晕、心悸、耳鸣、失眠、腰膝酸软6项临床症状改善有效率及改善总有效率与对照组比较差异显著(P0.05),改善总有效率达76.47%。结论海藻酸钾可有效辅助降压药物降低EH人群血压值,缓解临床症状。     

STRESS RELAXATION BEHAVIOR OF MICROWAVE-VACUUM-DRIED ALGINATE GELS

Swelling of alginate polymer matrix in water involves a build up of network pressure due to an elastic extension of the polymeric matrix. When this network pressure undergoes relaxation by means of dehydration, shrinkage may take place. Three different types of wet alginate gels were prepared and dried using microwave‐vacuum‐drying technique. Dried alginate gel solids had a porous structure. To understand the stress relaxation behavior of alginate gel‐based porous solid structures, uniaxial compressive relaxation studies were performed at selected strain rates, preloads and relaxation times Experimental relaxation curves were normalized and fitted to an empirical relationship, and relaxation behavior was explained. Stress relaxation data were also fitted to another empirical model. All three types of gels had similar elastic components. At lower strain rate, all samples had more resistance to elastic deformation. Stress relaxation information of the dried gel was related to its microstructure. Type 2 gel had more stiffness than type 1 and type 3 gels. The mechanism involved in stress relaxation was entanglement coupling of larger polymer chains in covalently cross‐linked alginate gels.     

Two placebo-controlled crossover studies in healthy subjects to evaluate gastric acid neutralization by an alginate–antacid formulation (Gaviscon Double Action)

Objective: To investigate the intragastric acid neutralization activity of a combined alginate-antacid formulation.

Significance: Published studies have investigated the reflux-suppressing alginate component of Gaviscon Double Action (Gaviscon DA; RB, UK) but intragastric acid neutralization activity of the antacid component has not been evaluated in vivo.

Methods: Intragastric pH monitoring, using a custom-made 10-electrode catheter, was evaluated in a two-part exploratory study in healthy subjects; Part I (n?=?6) tested suitability of the catheter using antacid tablets (Rennie; Bayer, Germany); Part II (n?=?12) evaluated gastric acid neutralization activity of Gaviscon DA liquid (20?ml) versus placebo in fasted subjects using a randomized, open-label, crossover design. The primary endpoint was the percentage of time that intragastric pH ≥4 was measured during 30?min post-treatment. A confirmatory study of identical design was subsequently conducted (n?=?20).

Results: Monitoring pH using the multielectrode catheter was a viable approach, directly detecting changes in intragastric pH following a single dose of antacid tablets. In the exploratory study, the percentage of time that pH ≥4 during 30?minutes post-treatment was 46.8% with Gaviscon DA liquid versus 4.7% with placebo (p?=?0.0004). These findings were supported by the confirmatory study, where pH ≥4 was recorded 50.8% of the time with Gaviscon DA versus 3.5% with placebo (p?=?0.0051). In this study, Gaviscon DA was safe and well tolerated.

Conclusions: These studies demonstrate the effective acid neutralizing capacity of Gaviscon DA versus placebo in healthy, fasted subjects. This adds to the evidence base for the combination of alginates and antacids.     

海藻酸纤维在医用敷料中的应用

近年来,由海藻酸纤维制成的非织造布在医用敷料上得到了广泛的应用,比起传统的棉纱布,海藻酸纱布吸湿性高,止血性能好,并能在潮湿的伤口表面形成一层水凝胶,这层水凝胶体既能给伤口提供一个良好的愈合环境,又能在伤口复愈后无疼痛地去除,从而使海藻酸纱布拥有其独特的伤口保护性能。本文介绍了海藻酸纤维的制造工艺及物化性能,并对海藻酸纱布的临床应用作了一些描述。     

Evaluation of in vitro enzymatic degradation of various thiomers and cross-linked thiomers

The aim of this study was to examine the biodegradability of thiomers and cross-linked thiomers in comparison with unmodified polymers. Disulfide-cross-linked conjugates were prepared by air oxidation at room temperature. Thiomers were investigated by viscosity measurements and spectrophotometric assays. The influence of different factors on the hydrolysis rate, such as the degree of modification of thiomers, structure of the conjugates, pH value of the reaction medium, and the impact of the process of cross-linking were evaluated. Due to the modification, thiolated chitosans degraded 12.9-24.7% less than unmodified chitosan in the framework of viscosity measurements. In addition, the hydrolysis degree of thiolated alginates and modified carboxymethylcelluloses was 25.6-32.4% and 18.4-27.0% lower, respectively, in comparison to the corresponding unmodified polymers. Conjugates with higher coupling rate of thiol groups were degraded even more slowly. Moreover, the cross-linking process via disulfide bonds additionally reduced the rate of thiomer degradation. The range of degradation rates achieved in vitro could be modified by alterations of the contents of thiol and disulfide groups, as well as by suitable design of the polymer structure and ligands used.

These results represent helpful basic information for the development of mucoadhesive drug delivery systems, implantable delivery systems and tissue engineering constructs.