The microencapsulated ascorbic acid release<Emphasis Type="Italic">in vitro</Emphasis> and its effect on iron bioavailability

The present study was carried out to examine the stability of microencapsulated ascorbic acid in simulated-gastric and intestinal situation in vitro and the effect of microencapsulated ascorbic acid on iron bioavailability. Coating materials used were polyglycerol monostearate (PGMS) and medium-chain triacylglycerol (MCT), and core materials were L-ascorbic acid and ferric ammonium sulfate. When ascorbic acid was microencapsulated by MCT, the release of ascorbic acid was 6.3% at pH 5 and 1.32% at pH 2 in simulated-gastric fluids during 60 min. When ascorbic acid was microencapsulated by PGMS, the more ascorbic acid was released in the range of 9.5 to 16.0%. Comparatively, ascorbic acid release increased significantly as 94.7% and 83.8% coated by MCT and PGMS, respectively, for 60 min incubation in simulated-intestinal fluid. In the subsequent study, we tested whether ascorbic acid enhanced the iron bioavailability or not. In results, serum iron content and transferring saturation increased dramatically when subjects consumed milks containing both encapsulated iron and encapsulated ascorbic acid, compared with those when consumed uncapsulated iron or encapsulated iron without ascorbic acid. Therefore, the present data indicated that microencapsulated ascorbic acid with both PGMS and MCT were effective means for fortifying ascorbic acid into milk and for enhancing the iron bioavailability.     

Application of microencapsulated isoflavone into milk

This study was designed to develop a microencapsulated, water-soluble isoflavone for application into milk and to examine the hypocholesterolemic effect of such a milk product in a rat diet. The coating material was medium-chain triglyceride (MCT) and the core material was water-soluble isoflavone. The microencapsulation efficiency was 70.2% when the ratio (w/w) of coating material to core material was 15:1. The isoflavone release from the microcapsules was 8% after 3-day storage at 40 degrees C. In in vitro study, 4.0-9.3% of water-soluble isoflavone in simulated gastric fluid was released in the pH range of 2 to 5 after 60 min incubation; however, in simulated intestinal fluid at pH 8, 87.6% of isoflavone was released from the capsules after 40 min incubation time. In sensory analysis, the scores of bitterness, astringency, and off-taste in the encapsulated isoflavone-added milk were slightly, but not significantly, different from those in uncapsulated, isoflavone-added milk. In blood analysis, total cholesterol was significantly decreased in the isoflavone-added group compared with that in the control after 6-week feeding. Therefore, this study confirmed the acceptability of MCT as a coating material in the microencapsulation of water-soluble isoflavone for application into milk, although a slight adverse effect was found in terms of sensory attributes. In addition, blood total cholesterol was lowered in rats which had been fed a cholesterol-reduced and microencapsulated, isoflavone-added milk for 6 weeks.     

Microencapsulation of ascorbic acid: effect of process variables on product characteristics

This study deals with a comparative investigation of the characteristics of ascorbic acid microcapsules prepared by different methods, such as thermal phase separation, melt dispersion, solvent evaporation and spray drying. Scanning electron microscopy (SEM), release tests and size distribution were used for the evaluation of product characteristics. The results show that microencapsulated ascorbic acid could prevent the ascorbic acid colour change, retard its core release rate, and generally mask its acid taste. In the thermal phase separation, molecular weight (Mw) of ethyl cellulose (EC) and the addition of polyisobutylene (PIB) significantly influenced the aggregation and release rate of microcapsules. In the melt dispersion method, spherical particles were prepared by using carnauba. The ascorbic acid release rate was found to be slower in the case of carnauba-encapsulated ascorbic acid than that made by EC using other methods. In the solvent evaporation method, a higher Mw of EC and the addition of plastizer were also found to be important for good encapsulation. In the spray drying method, loss of ascorbic acid was found to be minimum during microencapsulation. Starch and beta-cyclodextrin encapsulated ascorbic acid delayed the degradation of ascorbic acid during storage at 38 degrees C and relative humidity 84.0%.     

Microencapsulation of ascorbic acid: effect of process variables on product characteristics

This study deals with a comparative investigation of the characteristics of ascorbic acid microcapsules prepared by different methods, such as thermal phase separation, melt dispersion, solvent evaporation and spray drying. Scanning electron microscopy (SEM), release tests and size distribution were used for the evaluation of product characteristics. The results show that microencapsulated ascorbic acid could prevent the ascorbic acid colour change, retard its core release rate, and generally mask its acid taste. In the thermal phase separation, molecular weight (M_w) of ethyl cellulose (EC) and the addition of polyisobutylene (PIB) significantly influenced the aggregation and release rate of microcapsules. In the melt dispersion method, spherical particles were prepared by using carnauba. The ascorbic acid release rate was found to be slower in the case of carnauba-encapsulated ascorbic acid than that made by EC using other methods. In the solvent evaporation method, a higher M_w of EC and the addition of plastizer were also found to be important for good encapsulation. In the spray drying method, loss of ascorbic acid was found to be minimum during microencapsulation. Starch and beta-cyclodextrin encapsulated ascorbic acid delayed the degradation of ascorbic acid during storage at 38°C and relative humidity 84.0%.     

Fast and Selective Assay of l-Ascorbic Acid in Rose Hips by RP-HPLC Coupled with Electrochemical and/or Spectrophotometric Detection

A simple, fast, and selective method for the assay of L-ascorbic acid in rose hips was developed using RP-HPLC. Ascorbic acid was extracted with 2% metaphosphoric acid and sample clean-up was optimized with C18 disposal extraction cartridges. Use of 0.5% metaphosphoric acid as the mobile phase completely suppressed the dissociation of ascorbic acid. Sufficient retention was achieved so that the addition of ion-pairing agents was not necessary. The column effluent was monitored by spectrophotometric (242 nm) and electrochemical detectors (550 mV vs Ag/AgCl); the electrochemical detector was found to be both more selective and more sensitive. By coup-ling the two detectors in series, a true two channel detection with on-line validation was achieved. Reproducible results (r.s.d. 1-4%) were obtained from assays of several commercially available products, as well as from fresh rose hips, and revealed considerable differences in ascorbic acid content, ranging from 0.03 to 1.3%.     

Microencapsulation of water-soluble isoflavone and physico-chemical property in milk

This study was carried out to investigate the addition of water-soluble isoflavone into milk by means of microencapsulation technique. The yield of microencapsulation, sensory attributes, and capsule stability of water-soluble isoflavone microcapsules in milk were measured. Coating materials used was polyglycerol monostearate (PGMS), and core material was water-soluble isoflavone. The encapsulation yield of water-soluble isoflavone with PGMS was 67.2% when the ratio of coating material to core material was 15:1. The rate of water-soluble isoflavone release from capsules was 18, 19, and 25% when stored at 4, 20, and 30 degrees C for 12 days in milk, respectively. In sensory evaluation, beany flavor and color of microencapsuled water-soluble isoflavone added milk were significantly different from uncapsuled water-soluble isoflavone added milk, however, bitterness was not significantly different. In vitro study, micro-capsules of water-soluble isoflavone in simulated gastric fluid with the range of 3 to 6 pHs were released 3.0-15.0%, however, the capsules in simulated intestinal fluid with pH 7 were released 95.7% for 40 min incubation time. In conclusion, this study provided that PGMS as coating materials was suitable for the microencapsulation of water-soluble isoflavone, and the capsule containing milk was almost not affected with sensory attribute.     

Induced synthesis of metallothionein by ascorbic acid in mouse liver

The concentration of metallothionein in mouse tissues after administration of ascorbic acid was determined by the Cd-hem method. The concentration of metallothionein in the liver was increased significantly after an intraperitoneal injection of L-ascorbic acid at the dose of 1000 mg/kg. A simultaneous injection of cycloheximide inhibited the increase of the metallothionein concentration. Mortality of mice injected with a lethal dose of cadmium was decreased significantly by the pre-injection of L-ascorbic acid. All of these results indicate that metallothionein is induced in the liver after the administration of ascorbic acid.     

Effect of ginseng polysaccharide on the stability of lactic acid bacteria during freeze-drying process and storage

Lactic acid bacteria (LAB) quickly attenuate or are killed during the freeze-drying process and storage. The effect of some natural polysaccharides, which are known as potent antitumor and immunomodulating substances, on the viability of the LAB, Lactobacillus acidophilus and Bifidobacterium breve, on freeze-drying and storage were investigated. Among the polysaccharides tested, red ginseng polysaccharide (RGP) and chitosan significantly inhibited the cell death of the LAB during freeze-drying, and fucoidan and RGP most potently protected the cell death of the LAB during storage. The stabilities of the LAB on the addition of RGP and fucoidan were comparable to that of skimmed milk. However, white ginseng polysaccharide (WGP) did not promote storage stability. When 5% skimmed milk/5% RGP treated LAB were freeze-dried and stored, their viabilities were found to be significantly higher those treated with 5% or 10% RGP. The stabilizing effect of 5% RGP/5% skimmed milk during LAB freeze-drying and storage stability was comparable to that of treatment with 10% skimmed milk. Based on these findings, we believe that RGP beneficially improves the stability of LAB during the freeze-dry process and storage.     

Association of the time course of pulmonary arterial hypertension with changes in oxidative stress in the left ventricle

1. This study investigates the time course of pulmonary arterial hypertension (PAH) due to monocrotaline (MCT) and its association with cardiac function and oxidative stress markers in the left ventricle (LV). 2. Male Wistar rats were divided into six groups: 7 days, 21 days, and 31 days for both control and MCT groups. Following echocardiographic analysis, the heart was removed. The LV was separated and homogenized to analyze oxidized-to-total glutathione ratio and thioredoxin reductase (TrxR) activity as well as hydrogen peroxide (H(2) O(2) ) and ascorbic acid levels. 3. There was significant (P < 0.01) cardiac and right ventricle (RV) hypertrophy and pulmonary congestion in the MCT 21 day and 31 day groups. Echocardiography showed a change in the flow wave of the pulmonary artery at 21 days after MCT treatment. There was an increase in the LV ejection time (P < 0.05) at 31 days after MCT. The LV H(2)O(2) concentration was increased (P < 0.05) in the MCT 21 day and MCT 31 day groups compared with controls. There was a reduction (P < 0.05) in the LV ascorbic acid concentration and an increase (P < 0.05) in TrxR activity in the MCT 31 day rats. 4. Our findings showed RV changes due to pulmonary hypertension at 21 days after MCT injection. There was a correlation between the degree of dysfunction and the morphometry of the heart chambers, along with impairment of the antioxidant/pro-oxidant balance in the LV 31 days after the beginning of the protocol. This study suggests that LV changes follow RV dysfunction subsequent to pulmonary hypertension.     

Studies on reaction of formaldehyde with naturally occurring thiol compounds and ascorbic acid

To gain insight into possible cellular protective mechanisms against the insult of formaldehyde, we have investigated this molecule's reactivity with both naturally occurring thiol compounds including glutathione and L-ascorbic acid. By UV measurements, formaldehyde was found to rapidly react with glutathione forming an S-hydroxymethyl covalent adduct. The adduct which was confirmed by NMR is transiently stable. Formaldehyde is also significantly reactive with L-ascorbic acid in a reaction which was observed to be dissimilar to its reaction with dimedone. The reaction of formaldehyde with glutathione was reduced by 40% in the presence of an excess amount of L-ascorbic acid, due to the trapping of formaldehyde by L-ascorbic acid. The data suggest that L-ascorbic acid may have a possiblein vivo role in the metabolism of formaldehyde, thereby protecting cellular glutathione from possible depletion.     

Influence of microwave-microencapsulated citric acid on some sensory properties of chewing gum

Over the past few decades, microwave processing and its high potential capabilities have attracted food scientists. Application of microwave for microencapsulation is an innovative and new method in which the shell, due to having different dielectric constant, can fuse and cover core. In this research, the citric acid powder at various size ranges was microencapsulated by casein and inulin, using a domestic microwave oven. Then, for sensory evaluation purposes, they along with uncoated citric acid and commercial microcapsules were incorporated in chewing gum formulation. The qualitative and quantitative evaluations revealed the potential capability of this technique at micronized scales. Moreover, findings on some sensory characteristics showed practical and efficient applicability of inulin-coated microcapsules in chewing gum where its sensory scores were competitive and even much better than commercial ones. In addition, these observations elucidate a new approach for producing functional, nutritional and dietetic chewing gums.     

布洛芬L-抗坏血酸酯的合成及镇痛活性

布洛芬和L-抗坏血酸在叔丁醇中,用Novozym 435固定化脂肪酶催化制得布洛芬L-抗坏血酸酯,收率30%,纯度大丁98%.热板试验和乙酸扭体试验的结果表明,与布洛芬和布洛芬精氨酸盐相比,布洛芬L-抗坏血酸酯镇痛作用显著.     

Ascorbic acid safety: analysis of factors affecting iron absorption

The potential for excessive iron absorption by subjects ingesting ascorbic acid doses above the recommended dietary allowance (60 mg) was evaluated by examining published literature (24 studies, 1412 subjects) in which ascorbic acid was part of a test meal given to determine effects on iron absorption. Three parameters associated with iron absorption were identified: (1) a relatively shallow slope for the dose-response curve relating ascorbic acid dosage (1-1000 mg) and percent iron absorption; (2) no significant effect of ascorbic acid on the absorption of high (60 mg) iron doses; and (3) an inverse relationship between iron absorption and plasma transferrin saturation. Ascorbic acid did not increase the incidence of 'high' iron absorbers (greater than 2 SD from population mean) above control levels; limited data for ascorbic acid doses greater than 100 mg/d indicated no change in the distribution of iron absorption values.     

Preparation,characterisation and thermal properties of calcium alginate/n-nonadecane microcapsules fabricated by electro-coextrusion for thermo-regulating textiles

Abstract

The objective of this study is to develop a new technique for producing a phase change material (PCM) loaded biopolymer capsule for thermo-regulating textiles. Electro-coextrusion process fabricated a series of microencapsulated phase change material (MEPCM) based on n-nonadecane core and alginate shell. The influence of the flow rate ratio of the shell/core on the formation, encapsulation efficiency and thermal behaviour of a microencapsulated PCM has been investigated. The MEPCM was characterised using optical microscopy and differential scanning calorimetry (DCS). The size and the encapsulation efficiency of a capsule decreased as the flow rate ratio of the shell/core increased. The PCM microcapsules contained 56–84% n-nonadecane and the size range from 200 to 400?µm, as evaluated by DSC and optical microscopy, respectively. The experimental results show that the electro-coextrusion method has a potential technology for the encapsulation of PCMs for thermal storage.     

缓释安息香酸微型胶囊的制备研究

以明胶为包囊材料,用滴制法使安息香酸等药物微囊化,并研究微囊的形成条件。安息香酸微囊化后,具有明显缓释作用,6h内仅释放72％,而其粉末在40min内即释放82.6％。     

Influence of microwave-microencapsulated citric acid on some sensory properties of chewing gum

Abstract

Over the past few decades, microwave processing and its high potential capabilities have attracted food scientists. Application of microwave for microencapsulation is an innovative and new method in which the shell, due to having different dielectric constant, can fuse and cover core. In this research, the citric acid powder at various size ranges was microencapsulated by casein and inulin, using a domestic microwave oven. Then, for sensory evaluation purposes, they along with uncoated citric acid and commercial microcapsules were incorporated in chewing gum formulation. The qualitative and quantitative evaluations revealed the potential capability of this technique at micronized scales. Moreover, findings on some sensory characteristics showed practical and efficient applicability of inulin-coated microcapsules in chewing gum where its sensory scores were competitive and even much better than commercial ones. In addition, these observations elucidate a new approach for producing functional, nutritional and dietetic chewing gums.     

Development and Evaluation of Oral Controlled Release Chlorpheniramine-Ion Exchange Resinate Suspension

An oral controlled release suspension of chlorpheniramine maleate was prepared using ion-exchange resin technology. A strong cation exchange resin Indion 244 was utilized for the sorption of the drug and the drug resinates was evaluated for various physical and chemical parameters. The drug-resinate complex was microencapsulated with a polymer Eudragit RS 100 to further retard the release characteristics. Both the drug-resinate complex and microencapsulated drug resinate were suspended in a palatable aqueous suspension base and were evaluated for controlled release characteristic. Stability study indicated that elevated temperature did not alter the sustained release nature of the dosage form indicating that polymer membrane surrounding the core material remained intact throughout the storage period.     

Vitamin C metabolism and the common cold

Summary Male and female university students at the commencement of common cold symptoms were given a single dose of 500 mg of vitamin C. Plasma and leucocyte ascorbic acid concentrations were then measured for six hours. Symptom severity was recorded. The test was repeated twenty-three days after the last symptom had disappeared. The ascorbic acid blood response curve had then returned to normal. Significant and similar elevations of plasma ascorbic acid occurred in both sexes in the cold and post-cold tests. The leucocyte response was significantly reduced in the males but was unaffected in the females in the cold test. The regression coefficients between leucocyte and plasma values (P/L regressions) confirmed that ascorbic acid metabolism was less deranged in females than males during the cold test. Administration of ascorbic acid was associated with increases in blood ascorbic acid concentrations during the post-cold period but not during colds. A single dose of 1000 mg raised blood ascorbic acid concentrations in both sexes during their colds. The elevation was higher, and maintained for two hours longer in the females.In vitro incubation of leucocytes in ascorbic acid confirmed that their ascorbic acid load could be increased by approximately 100% while cold symptoms were present. A significant association between cold symptoms and the state of ascorbic acid metabolism was demonstrated by correlating the ratio of toxic to catarrhal symptoms with P/L regressions during colds. When catarrhal symptoms are severe, ascorbic acid passes from the leucocytes into the plasma, and thence into the inflamed respiratory membranes. When toxic symptoms are relatively more severe, ascorbic acid is retained in the cells. The beneficial effect of vitamin C on the common cold is associated with its influence on ascorbic acid metabolism. A sex-linked difference in ascorbic acid metabolism is manifested during the common cold which affects assessment of the effects of vitamin C on the common cold.     

Metabolism of [14C]monocrotaline by isolated perfused rat liver.

The metabolism of the pyrrolizidine alkaloid [14C]monocrotaline [( 14C]MCT) was examined using the in situ isolated perfused rat liver. Hepatic tissue was perfused in a recirculatory fashion for 90 min and the distribution of metabolites between the bile and perfusate was analyzed. Monocrotalic acid (MCA) was found to be the major acidic metabolite of [14C]MCT, with trace amounts of 1-formyl-7-hydroxy-6,7-dihydro-5H-pyrrolizine, 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP), and 1-hydroxymethyl-7-oxo-6,7-dihydro-5H-pyrrolizine (tentative assignment) being identified in the perfusates using GC/MS. MCT N-oxide was also identified but represented less than 4% of the perfusate 14C. The simple necine base retronecine was not present at detectable levels in the perfusion medium. A large portion of the 14C recovered from both the bile and perfusate was not extractable, under acidic or basic conditions, into organic solvents. Using fast atom bombardment MS/MS, a portion of this material was identified as a glutathione conjugate of DHP. In addition, this nonextractable material retained a portion of the radioactivity that was equivalent to the acidic fraction. Given these findings and the absence of retronecine, the major pathway for the metabolism of MCT could potentially involve the production of MCT pyrrole, which subsequently reacts with cellular nucleophiles producing MCA in addition to highly water-soluble conjugated pyrroles and possibly macromolecular adducts.     

Role of Ascorbic Acid in Stratum Corneum Lipid Models Exposed to UV Irradiation

Purpose. The effects of ascorbic acid on Stratum corneum lipid models following ultraviolet irradiation were studied adding iron ions as transition metal catalysts. Methods. Lipid peroxidation was quantified by the thiobarbituric acid assay. The qualitative changes were studied on a molecular level by mass spectrometry. To elucidate the nature of free radical involvement we carried out electron paramagnetic resonance studies. The influence of ascorbic acid on the concentration of hydroxyl radicals was examined using the spin trapping technique. Moreover, we checked the vitamin's ability to react with stable radicals. Results. Ascorbic acid was found to have prooxidative effects in all lipid systems in a concentration dependent manner. The degradation products of ascorbic acid after its prooxidative action were detected. The concentration of the hydroxyl radicals in the Fenton assay was decreased by ascorbic acid. The quantification assay of 2,2-diphenyl-1-picrylhydrazyl hydrate showed reduced concentration levels of the stable radical caused by ascorbic acid. Conclusions. Considering human skin and its constant exposure to UV light and oxygen, an increased pool of iron ions in irradiated skin and the depletion of co-antioxidants, the administration of ascorbic acid in cosmetic formulations or in sunscreens could unfold adverse effects among the Stratum corneum lipids.