In Vitro Digestion of caseinate and Tween 20 Emulsions

Food Biophysics - In vitro digestion experiments are set-up with emulsions stabilized either with sodium caseinate and/or Tween 20, in the presence of mucin in the simulated GI fluids. The progress...     

Effect of Sodium Alginate on Staphylococcus aureus During Mild Heating and Freezing

The effects of sodium alginate on Staphyiococcus aureus 196 exposed to mild heating or to freezing at -21 C were studied. The addition of sodium alginate to a diluent appeared to confer some protection of viable cells during mild heating. The effect of the presence of sodium alginate in the suspending media during freezing was less clear. There was a slight trend, not statistically significant, for greater reduction in numbers of viable cells at the low temperature when 4% alginate was present in phosphate buffer. Results indicated that the value of sodium alginate in controlling this food-poisoning microorganism in frozen food is questionable.     

Effect of Soy Soluble Polysaccharide on the Stability of Soy-Stabilised Emulsions During In Vitro Protein Digestion

This study investigated physicochemical properties of soy soluble polysaccharide (SSP) and pectinase-hydrolysed soy soluble polysaccharide (PH-SSP) from okara, the residue from soy milk production, and their influences when used as a fibre source in oil-in-water (o/w) emulsions. Although pectinase hydrolysed only the carbohydrate fraction in SSP, it resulted in the self-association of PH-SSP to the large-size aggregates. When PH-SSP was added to liquid emulsion containing 3.33% (w/v) rice bran oil and 3.75% (w/v) heated soy protein, it regulated the contents of protein in serum phase, sediment phase and at oil–water interface. The types and contents of soy proteins in the serum phase and sediment phase could be manipulated by pre-heating of soy proteins at 80 °C for 30 min and the addition of PH-SSP. The presence of PH-SSP (0–6% w/v) induced different distribution of proteins to the sediment phase and subsequent in vitro protein digestion in the emulsion. Overall, this study proposed the means to design the distributions of proteins in different phases of o/w emulsion for different degrees of oil release, emulsion stability and protein-polysaccharide coacervation during the course of in vitro peptic and tryptic digestion.     

The Effect of Sodium Alginate on the Absorption of Strontium and Calcium in Human Subjects

The effect of sodium alginate on the gastrointestinal absorption of the tracers strontium-85 and calcium-47 was investigated in 19 human subjects. The tracers were administered orally with 100 mg. of a calcium carrier—calcium chloride. At the same time, sodium alginate was given in a commercial jelly. The sevenday per cent retentions of tracers were measured with a whole-body counter. After one month, the experiments were repeated without alginate so that each subject acted as his own control. Fifteen volunteers were given 1.5 g. of alginate, two were given 3.0 g. and two 0.3 g. 1.5 g. of alginate reduced the absorption of strontium by a factor of two with no significant effect on calcium absorption. The smaller dose of alginate (0.3 g.) appeared to have no effect on strontium or calcium absorption and the larger dose (3.0 g.) had no greater effect than the 1.5 g. dose.     

Effect of Sodium Alginate Addition on Physical Properties of Rennet Milk Gels

Effect of addition of sodium alginate (alginate) to milk on the storage modulus (G′), water holding capacity (WHC) and hardness of rennet gels was evaluated as a function of alginate (0–0.25 g/100 g) and fat (0.5–3.0 g/100 g) concentrations. There was a significant effect of alginate addition on ionic calcium in milk and whey (Ca²⁺), and particle size distribution in alginate added milk. Results showed a positive correlation of alginate with WHC; negative correlation of alginate and positive correlation of fat with G′; and negative correlation of interaction of fat and alginate with gel hardness of rennet gels. Hence, the rennet gels with lower fat content and higher added alginate tended to be softer due to the high water holding capacity of the alginate particles.     

Metabolism and Calcium Antagonism of Sodium Alginate Oligosaccharides

Sodium alginate oligosaccharides (NaAOs) consisting of a mixture of eight oligosaccharides have previously been reported to lower blood pressure. We investigated in this study the excretion of NaAOs into the urine or feces, and attempted to elucidate the mechanism for lowering blood pressure by using isolated mesenteric arteries from the rabbit. The recovery rate of P8, which is the main component of NaAOs, was 5.2% and 58.9% over 48 hours in the urine and feces, respectively. The mechanism for lowering blood pressure appeared to be NaAOs having calcium antagonist activity, especially voltage-operated calcium channels. Our results suggest that NaAOs are substantially excreted into the feces, although some of them may be absorbed internally, exerting antagonist activity towards the calcium channels, especially voltage-operated calcium channels.     

Lipid,Fatty Acid and Energy Density Profiles of White Sharks: Insights into the Feeding Ecology and Ecophysiology of a Complex Top Predator

Lipids are major sources of metabolic energy in sharks and are closely linked to environmental conditions and biological cycles, such as those related to diet, reproduction and migration. In this study, we report for the first time, the total lipid content, lipid class composition and fatty acid profiles of muscle and liver tissue of white sharks, Carcharodon carcharias, of various lengths (1.5–3.9 m), sampled at two geographically separate areas off southern and eastern Australia. Muscle tissue was low in total lipid content (<0.9% wet mass, wm) and was dominated by phospholipids (>90% of total lipid) and polyunsaturated fatty acids (34±12% of total fatty acids). In contrast, liver was high in total lipid which varied between 51–81% wm and was dominated by triacylglycerols (>93%) and monounsaturated fatty acids (36±12%). With knowledge of total lipid and dry tissue mass, we estimated the energy density of muscle (18.4±0.1 kJ g⁻¹ dm) and liver (34.1±3.2 kJ g⁻¹ dm), demonstrating that white sharks have very high energetic requirements. High among-individual variation in these biochemical parameters and related trophic markers were observed, but were not related to any one biological or environmental factor. Signature fatty acid profiles suggest that white sharks over the size range examined are generalist predators with fish, elasmobranchs and mammalian blubber all contributing to the diet. The ecological applications and physiological influences of lipids in white sharks are discussed along with recommendations for future research, including the use of non-lethal sampling to examine the nutritional condition, energetics and dietary relationships among and between individuals. Such knowledge is fundamental to better understand the implications of environmental perturbations on this iconic and threatened species.     

海藻酸钠与十二烷基聚氧乙烯醚硫酸钠复配体系泡沫及流变性能的研究

采用罗氏泡沫仪和流变仪对海藻酸钠(NaAlg)/十二烷基聚氧乙烯醚硫酸钠(AES)复配体系的起泡稳泡性能及流变行为进行研究,以探索NaAlg对AES起泡稳定性的影响及作用机理。泡沫性能试验显示,NaAlg的加入,提高了AES溶液的起泡能力及泡沫稳定性,溶液的pH值由7.0降到5.0,混合体系的起泡稳泡性明显增加。流变性研究展示,随着NaAlg浓度的增加,溶液的粘度呈增大的趋势,溶液总体呈现牛顿流体性质,当NaAlg浓度大于0.5%时,低剪切速率区,溶液仍呈现牛顿流体性质,而在高剪切速率区,有剪切变稀的现象出现。总体来看,各试液的G’相似文献   

负载维生素D3的海藻酸纳米粒抗佝偻病作用研究

目的:观察负载维生素D3海藻酸纳米粒和维生素D3的抗佝偻病作用.方法:36只SD大鼠随机分组为正常对照组、佝偻痛模型组、负载VD3的自组装海藻酸钠纳米粒(sSAN-VD3)低剂量组(1.70 mg·kg-1·d-1含VD315.0μg)、sSAN-VD3高剂量组(4.2 mg·kg-1·d-1含VD337.5μg)、VD3低剂量组(15.0μg·kg-1·d-1)、VD3高剂量组(37.5μg·kg-1·d-1)6组,每组6只.正常对照组大鼠在通光条件下用正常饲料饲养,其余各组大鼠置于暗室中,并喂养缺乏维生素D3的饲料,同时各预防给药组按剂量连续灌胃给药35天.观察记录大鼠的体重变化,检测大鼠血清中25羟基维生素D3(25-(OH)VD3)、血清骨碱性磷酸酶(Bone Alkaline Phosphatase,BAP)活性及股骨骨密度(Bone Mineral Density BMD).结果佝偻病模型组大鼠喂养5周后体重明显低于正常对照组,血清BAP活性明显增高,血清25-(OH)VD3含量及股骨BMD则显著降低(P<0.05);与佝偻病模型组大鼠比较,各预防给药组大鼠体重及股骨BMD均有所增加,sSAN-VD3高、低剂量组和VD3高剂量组大鼠血清BAP活性降低,25-(OH)VD3水平明显升高,与模型组差异显著(P<0.05);与同剂量的VD3低剂量组比较,sSAN-VD3低剂量组大鼠的血清BAP、25-(OH)VD3及股骨BMD等三项指标均显示出更明显的抗佝偻痛作用(P<0.05).结论:负载维生素D3海藻酸纳米粒和维生素D3均具有良好的抗佝偻病作用,以前者作用较强.     

脂肪乳剂理化性质和稳定性的影响因素浅析

静脉注射脂肪乳剂是由两种互不相溶的液体(油相和水相)混合而成,是水不溶性药物的良好栽体,可以提高易水解药物的稳定性并且减少各种毒副作用.脂肪乳荆属于热力学不稳定体系,其会表现出各种不稳定的现象如聚集,絮凝,聚结等,最终可能出现相分离.本文就处方、工艺及包装等影响脂肪乳剂理化性质及稳定性的主要因素进行综述.     

Studies of Inhibition of Intestinal Absorption of Radioactive Strontium: IV. Estimation of the Suppressant Effect of Sodium Alginate

A method is reported which permits selective suppression of absorption of radioactive strontium from ingested food material, allowing calcium to be available to the body. Studies were carried out on the inhibitory effect of various amounts of sodium alginate and the dose-response relationship of Sr⁸⁹ and bone uptake. The results obtained indicated that under laboratory conditions sodium alginate effectively reduces Sr⁸⁹ uptake in a constant proportion. This effect was observed at the three levels of administration of 1.4%, 12% and 24% of sodium alginate. The linear relationship between the dosage of the radioisotope and the bone uptake in the presence of sodium alginate suggests that the same proportion is maintained at the lower levels of intake of radioactive strontium.Previous studies with small constant doses of sodium alginate were extended in rats to a period corresponding approximately to three years of human life span. Low doses were sufficient to reduce appreciably bone uptake of radiostrontium.     

Effect of Tween Emulsifiers on the Shear Stability of Partially Crystalline Oil-in-Water Emulsions Stabilized By Sodium Caseinate

We investigated the effects of Tween emulsifier fatty acid chain length on the shear stability and crystallization behavior of 35 wt% partially crystalline oil-in-water emulsions prepared with and without 1 wt% sodium caseinate. Emulsions containing sodium caseinate and Tween 20, 40, 60 or 80 varied in shear stability, degree of supercooling and crystallization behavior depending on the type and concentration of Tween as well as the presence of protein. Generally, emulsions containing the unsaturated emulsifier Tween 80 were the most shear sensitive followed by the saturated emulsifiers Tween 20, 40 and 60 in order of increasing fatty acid chain length. Long chain saturated Tween emulsifiers (40 and 60) improved shear stability regardless of whether sodium caseinate was present indicating that alone, these emulsifiers form more robust interfacial films compared to the saturated short chain length Tween 20 and Tween 80. In emulsions prepared with sodium caseinate, the degree of supercooling decreased and the crystallization rate diminished with increasing saturated fatty acid chain length but only negligible changes were found without sodium caseinate. Together, these findings indicate that long chain saturated Tween emulsifiers provide better emulsion stability regardless of the presence of sodium caseinate but with sodium caseinate, stability may also be affected by changes to fat crystallization. These novel findings provide guidance on how combinations of proteins and emulsifiers can be used to modify and control the stability of partially crystalline oil-in-water emulsions through their combined effects on the properties of the interfacial film and fat crystallization.     

Effect of Aluminium on Lipid Peroxidation of Human High Density Lipoproteins

We investigated the effect of aluminium (Al 3+ ) on lipid peroxidation and physico-chemical properties of high density lipoproteins (HDL) isolated from human plasma. Our results demonstrated that Al 3+ enhances lipid peroxidation of human HDL as shown by the significant increase in lipid hydroperoxides in Al-treated HDL with respect to control HDL. The oxidative effect was higher at acid pH (pH 5.5) with respect to pH 7.4. Moreover, a stimulating effect of Al 3+ on iron-induced lipid peroxidation of HDL was demonstrated. The study of the effect of Al 3+ on the physico-chemical properties of HDL, using the fluorescence polarization (Pf) of the probes TMA-DPH (1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene iodide) and DPH (1,6-diphenyl-1,3,5-hexatriene), showed a significant decrease of Pf in Al-treated HDL with respect to control. These results suggest that Al 3+ induces a decrease of molecular order at the lipoprotein surface. Moreover, the study of tryptophan (Trp) fluorescence demonstrated that aluminium induces structural modifications of HDL apoproteins and on HDL physico-chemical properties. The effect of Al 3+ on lipid peroxidation of HDL was observed at aluminium concentrations similar to those observed in the brain of patients affected by neurological diseases. Aluminium-induced oxidative damage of HDL could be involved in the development of neurological diseases.     

Reversibility of the Stabilization Effect of Sodium Molybdate on Uterine Estrogen and Progesterone Receptors of the Vervet Monkey

Abstract

Sodium molybdate affected the stability of vervet monkey (Cercopithecus aethiops pygerythrus) uterine estrogen (ER) and progesterone (PR) receptors. Yields of receptors were invariably higher (20 - 40 %) when cytosols were prepared in the presence of 10mM sodium molybdate. No changes were observed in the binding affinities for the natural ligands as reflected in dissociation at 0°C and 20°C was not affected in the presence or absence of molybdate. Stability studies at 37°C indicated both receptors to be more resistant to inactivation in the presence of molybdate. Dissociation of ER and PR was biphasic, indicating the existence of slow (SDC), as well as fast dissociating (FDC) complexes. Rate constants of dissociation were significantly affected by the presence of sodium molybdate Although no significant changes in the sedimentation coefficeints were observed, marked differences in the actual gradient profiles could be illustrated in the presence or absence of sodium molybdate. Observed effects could only be partially reversed in sedimentation dialysis experiments. Proteolytic inhibitors phenlymethylsulfonylfluoride (PMSF) and leupeptin had no inhibitive effect on the molybdate stabilization of ER and PR.     

臭氧与海藻酸钠涂膜对葡萄的保鲜效果及其贮藏生理特性的影响

以采后"红地球"葡萄果实为试材,分别设置对照(CK)、250μL/L臭氧处理(O3)、0.3%海藻酸钠涂膜处理(M)、250μL/L臭氧+0.3%海藻酸钠涂膜处理(O3+M),在(0±0.5)℃条件下贮藏,通过测定贮藏过程中葡萄可溶性固形物含量、可滴定酸含量、呼吸强度、硬度、过氧化物酶(POD)、超氧化物歧化酶(SOD)、几丁质酶(CHI)、β-1,3-葡聚糖酶(GLU)的活性以及膜脂过氧化物质丙二醛(MDA)和总酚含量等的变化,统计果实失重率与腐烂率情况,观察各处理对葡萄保藏效果的影响。结果表明:与对照相比,250μL/L臭氧处理、0.3%海藻酸钠涂膜及250μL/L臭氧+0.3%海藻酸钠涂膜复合处理均能显著降低葡萄果实的失重率和腐烂率,抑制葡萄果实的呼吸上升,延缓硬度下降,提高果实抗性相关酶(POD、SOD、GLU、CHI)的活性,减少膜脂的过氧化程度,延缓果实总酚含量下降,有效改善葡萄的贮藏品质,并以250μL/L臭氧+0.3%海藻酸钠涂膜复合处理对葡萄果实保鲜效果最佳。     

An Analytic Study on the Effect of Alginate on the Velocity Profiles of Blood in Rectangular Microchannels Using Microparticle Image Velocimetry

It is desired to understand the effect of alginic acid sodium salt from brown algae (alginate) as a viscosity modifier on the behavior of blood in vitro using a micro-particle image velocimetry (µPIV) system. The effect of alginate on the shape of the velocity profile, the flow rate and the maximum velocity achieved in rectangular microchannels channels are measured. The channels were constructed of polydimethylsiloxane (PDMS), a biocompatible silicone. Porcine blood cells suspended in saline was used as the working fluid at twenty percent hematocrit (H = 20). While alginate was only found to have minimal effect on the maximum velocity and the flow rate achieved, it was found to significantly affect the shear rate at the wall by between eight to a hundred percent.