Presence of Electrostatically Adsorbed Polysaccharides Improves Spray Drying of Liposomes

Spray drying of liposomes with conventional wall materials such as maltodextrins often yields nonfunctional powders, that is, liposomes break down during drying and rehydration. Electrostatically coating the surface of liposomes with a charged polymer prior to spray drying may help solve this problem. Anionic lecithin liposomes (approximately 400 nm) were coated with lower (approximately 500 kDa, LMW‐C) or higher (approximately 900 kDa, HMW‐C) molecular weight cationic chitosan using the layer‐by‐layer depositing method. Low (DE20, LMW‐MD) or high molecular weight (DE2, HMW‐MD) maltodextrin was added as wall material to facilitate spray drying. If surfaces of liposomes (1%) were completely covered with chitosan (0.4%), no bridging or depletion flocculation would occur, and mean particle diameters would be approximately 500 nm. If maltodextrins (20%) were added to uncoated liposomes, extensive liposomal breakdown would occur making the system unsuitable for spray drying. No such aggregation or breakdown was observed when maltodextrin was added to chitosan‐coated liposomes. Size changed little or even decreased slightly depending on the molecular weight of maltodextrin added. Scanning electron microscopy images of powders containing chitosan‐coated liposomes revealed that their morphologies depended on the type of maltodextrin added. Powders prepared with LMW‐MD contained mostly spherical particles while HMW‐MD powders contained particles with concavities and dents. Upon redispersion, coated liposomes yielded back dispersions with particle size distributions similar to the original ones, except for LMW‐C coated samples that had been spray dried with HMW‐MD which yielded aggregates (approximately 30 μm). Results show that coating of liposomes with an absorbing polymer allows them to be spray dried with conventional maltodextrin wall materials. Practical Application : Liposomes have attracted considerable attention in the food and agricultural, biomedical industries for the delivery of functional components. However, maintaining their stability in aqueous dispersion represents a challenge for their commercialization. Spray drying may promise a solution to that problem. However, prior to this study spray drying of liposomes often led to the loss of structural integrity. Results of this study suggest that spray drying might be used to produce commercially feasible liposomal powders if proper combinations of adsorbing and nonadsorbing polymers are used in the liquid precursor system.     

Densitometric determination of zinc bacitracin and nystatin in animal feed

BACKGROUND: The European Union has forbidden the use of antibiotics as additives in animal feed. Zn‐bacitracin (Zn‐BC) and nystatin (NYS) were frequently used for their growth‐promoting effects and for feed conversion in poultry, pigs and cattle. An HPTLC method has been developed for separating Zn‐BC and NYS in the mixture, for routine quality control. RESULTS: The separation was obtained using RP‐18 F_254S coated HPTLC plates with acetonitrile/methanol (equal volumes):toluene:KH₂PO₄/KOH (buffer, pH 6.8) = 57:3:40 (v/v/v), adjusted with HCl to pH 8.2, as a mobile phase. The densitograms were monitored at 192, 215 and 305 nm and both antibiotics were assayed at 215 nm. The method was shown to be specific, accurate (recoveries were 98.7 ± 0.5% and 104.8 ± 0.7% for Zn‐BC and NYS, respectively), linear over the tested range (correlation coefficients, 0.9982 and 0.9884), and precise (intermediate precision RSD below 2.2% for both analytes) with efficient separation (R_s = 3.5). CONCLUSION: The method was applied for determining Zn‐BC and NYS as additives in spiked matrices of commercial animal feedstuffs. According to LOD values for each antibiotic, the minimum detectable amount in feed is 4.5 and 5.5 ppm of Zn‐BC and NYS, respectively. Copyright © 2008 Society of Chemical Industry     

对产蛋鸡实用日粮中铜、铁、锌、锰平衡供应方案的探讨

探讨蛋鸡铜、铁、锌、锰的补充方案.试验1选用420只19周龄罗曼褐壳蛋鸡,随机分为4处理,每处理7重复,每重复15只.试验2选用360只39周龄罗曼褐壳蛋鸡,随机分为4处理,每处理6重复,每重复15只.以基础饲粮铜、铁、锌、锰的实测值为基础,结合1994年NRC逐步平衡饲粮4种元素.结果显示,两试验基础日粮配方相似,但铜、铁、锌、锰含量差异较大.试验1依次添加锌、铜、锰提高产蛋率,不影响铜、铁、锌的表观利用率,显著影响锰的表观利用率.试验2依次补充锰、铜、锌降低产蛋率和4种元素的表观利用率.从生产性能考虑,1994年NRC中铜、铁、锌、锰的比例不适宜作为微量元素的最佳平衡比,典型蛋鸡饲粮中锌是产蛋性能的限制性因素.     

Comparison and Characterization of Compounds with Antioxidant Activity in Lycium barbarum Using High‐Performance Thin Layer Chromatography Coupled with DPPH Bioautography and Tandem Mass Spectrometry

Methanol extracts from 50 batches of Lycium barbarum (L. barbarum, wolfberry) in China were compared and characterized using high‐performance thin‐layer chromatography coupled with 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) bioautography (HPTLC‐DPPH) and electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry (ESI‐Q‐TOF‐MS/MS), respectively. Results showed that similar components occupying the major antioxidant activity existed in L. barbarum collected from different origins. However, the average antioxidant capacities of methanol extracts of L. barbarum collected in Ningxia were significantly higher than those of Qinghai, Xinjiang, Inner Mongolia, and Gansu, which may contribute to rational use of L. barbarum in China. Furthermore, the chemical structure of compound with the highest antioxidant capacity was tentatively identified as 2‐O‐β‐d ‐glucopyranosyl‐l ‐ascorbic acid using ESI‐Q‐TOF‐MS/MS analysis, which possessed high potentials to be used as an antioxidant biomarker for the quality control of L. barbarum. Results are helpful for the bioactivity‐based quality control of L. barbarum, and beneficial for the improvement of their performance in functional/health foods area, suggesting that HPTLC‐DPPH bioautography with ESI‐Q‐TOF‐MS/MS could be used as a routine approach for quality control of antioxidant components in L. barbarum.     

Composition, microstructure, and surface barrier layer development during brine salting

The goal of this study was to characterize the changes in chemical composition, porosity, and structure that occur at the surface of a block of brine-salted cheese and their relationship to the rate at which salt is taken up from the brine. To create a difference in composition, salt uptake, and barrier layer properties, identical blocks of Ragusano cheese were placed in saturated and 18% salt brine at 18°C for 12 d. The overall moisture content and porosity decreased, whereas salt and salt in moisture content increased near the surface of blocks of brine-salted Ragusano cheese for all treatments. The general appearance of the microstructure of the surface of the blocks of brine-salted cheese was much more compact than the microstructure 1 mm inside the block at both brine concentrations. Large differences in porosity of the barrier layer were produced by brine-salting cheese in 18% vs. saturated brine, with cheese in saturated brine having much lower porosity at the surface and taking up much less salt during brining. The macro network of water channels within the microstructure of the cheese was less open near the surface of the block for cheese in both saturated and 18% brine after 4 d. However, no large differences in the size of the macro channels in the cheese structure due to the difference in brine concentration were observed by scanning electron microscopy. It is possible that the shrinkage of the much smaller pore structure within the casein matrix of the cheese is more important and will become more limiting to the rate of salt diffusion. Further microstructure work at higher resolution is needed to answer this question. The calculated decrease in porosity at the exterior 1-mm portion of the block was 50.8 and 29.2% for cheeses that had been in saturated vs. 18% brine for 12 d, respectively. The difference in brine concentration had a very large impact on the salt in moisture content of the cheese. The exterior of the cheese in 18% brine reached a salt in moisture content almost identical to that of the brine very quickly (17.3% at 4 d), whereas the salt in moisture content at the surface of the cheese block in saturated brine was only 11.9% at 4 d. There appears to be some critical concentration of salt in brine above which there is a large negative impact on salt uptake due to the creation of a barrier layer at the surface of the block of cheese.     

表里换层组织织物的设计与试织

以涤/棉混纺纱为原料,进行表里换层组织织物即条格表里换层组织(AB型、ABBA型)、ACCA单双层联合组织、ABC多层混合组织的设计及试织。通过组织结构的差异赋予织物不同风格,为这类组织的产业用纺织品应用开发提供参考。     

Self‐Assembled Carbohydrate Polymers for Food Applications: A Review

The self‐assembled natural and synthetic polymers are booming. However, natural polymers obtained from native or modified carbohydrate polymers (CPs), such as celluloses, chitosan, glucans, gums, pectins, and starches, have had special attention as raw material in the manufacture of self‐assembled polymer composite materials having several forms: films, hydrogels, micelles, and particles. The easy manipulation of the architecture of the CPs, as well as their high availability in nature, low cost, and being sustainable and green polymers have been the main positive points in the use of them for different applications. CPs have been used as building blocks for composite structures, and their easy orientation and ordering has given rise to self‐assembled CPs (SCPs). These macromolecules have been little studied for food applications. Nonetheless, their research has grown mainly in the last 5 years as encapsulated food additive wall materials, food coatings, and edible films. The multifaceted properties (systems sensitive to pH, temperature, ionic strength, types of ions, mechanical force, and enzymes) of these devices are leading to the development of advanced food materials. This review article focused on the analysis of SCPs for food applications in order to encourage other research groups for their preparation and implementation.     

Effects of Roxarsone on Performance,Toxicity, Tissue Accumulation and Residue of Eggs and Excreta in Laying Hens

In this study, we examined the effects of a high dosage of roxarsone in the diet on the performance, liver function, and its residue in liver, eggs and excreta of laying hens. Seventy-five 32-week-old layers were selected and randomly allocated into five dietary treatments with three replications for each treatment. Feeding periods were 4 weeks with an additional week for withdrawal. The experimental diets included 0, 11, 22, 44 or 88 mg kg^-1 arsenic from roxarsone, respectively. Dietary arsenic above 44 mg kg^-1 significantly decreased the egg production and feed intake of the layer (P < 0·05). Layers ceased to produce eggs after two weeks of feeding the 88 mg kg^-1 arsenic supplement diet. Where the enzyme activities in the serum, aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) significantly increased. Also, the liver weight did not only significantly decrease (P < 0·05), but was also damaged on histological examination. Moreover, arsenic residues in the liver, eggs and the excreta significantly increased as dietary arsenic level was increased (P < 0·05). The serum enzyme activities of AST, LDH, CK returns to normal after a week of the drug withdrawal. Arsenic residues in liver, egg and excreta also significantly declined in the withdrawal period (P < 0·05). Furthermore, the hepatic cells were vacuolised from layers treated with 88 mg kg^-1 of arsenic. © 1997 SCI.     

二种酵母多糖的纯化、鉴定及抗氧化性质分析

以热带假丝酵母和八孢裂殖酵母为材料，通过化学抽提法得到水溶性提取物Mb与Mc：经薄层层析分析表明：Mb主要含有甘露糖，Mc含有甘露糖和半乳糖：经检测，Mb和Mc含有蛋白质，为蛋白多糖：Mb和Mc中氨基酸种类丰富，其中含有7种必需氨基酸和9种非必需氨基酸：邻苯三酚自氧化法发现多糖能够抑制邻苯三酚自氧化，具有体外抗氧化能力。     

荞麦黄酮类化合物的提取分离及结构鉴定

采用正交设计对荞麦黄酮提取工艺条件进行筛选得到荞麦的最佳提取条件为65%的乙醇、物料比1∶15在50～55℃温度下提取6h。在最佳提取条件下进行不同荞麦原料提取显示,苦荞粉黄酮得率最高为2.5%,其次为苦荞壳,甜荞粉得率最低。对荞麦黄酮提取浓缩液进行薄层分离,得到与芦丁和懈皮素结构相近的两种黄酮类物质;定性显色结果显示荞麦中的黄酮类物质包括黄酮醇、5-羟基黄酮或2-羟基黄酮等化合物。