Suitability of Different Food Grade Materials for the Encapsulation of Some Functional Foods Well Reported for Their Advantages and Susceptibility

Functional foods find a very important place in the modern era, where different types of cancer, diabetes, cardiovascular diseases, etc. are on a high. Irrespective of the abundance of bioactive components in different fruits and vegetables, their low solubility in aqueous solution, vulnerability to destruction in different environmental and gastrointestinal conditions and a low intestinal absorption becomes a concern. Because it is quite difficult to commercialize non food materials for the food encapsulation purposes due to their safety concerns in the human body, scientists in the recent times have come up with the idea of encapsulating the different bioactive components in different food grade materials that are able to safeguard these bioactive components against the different environmental and gastrointestinal conditions and ensure their safe and targeted delivery at their absorption sites. Different food grade encapsulation materials including various oligosaccharides, polysaccharides (starch, cyclodextrins, alginates, chitosan, gum arabic, and carboxymethyl cellulose) and proteins and their suitability for encapsulating various bioactive components like flavonoids (catechins, rutin, curcumin, hesperetin, and vanillin), nonflavonoids (resveratrol), carotenoids (β-carotene, lycopene, and lutein), and fatty acids (fish oil, flaxseed oil, and olive oil) of high medical and nutritional value are reviewed here.     

Egg yolk: structures,functionalities and processes

Hen egg yolk is an ideal example of natural supramolecular assemblies of lipids and proteins with different organization levels. These assemblies are mainly due to interactions between proteins and phospholipids, and these interactions are essential in understanding and controlling the production of food made with yolk, and particularly emulsions. Furthermore, these assemblies can be modulated by external constraints among which thermo‐mechanical and high‐pressure treatments. This review focuses on multi‐scale structures present in egg yolk, and their modulation by processes, in relation with their emulsifying properties. Egg yolk is mainly composed of two fractions—plasma and granules—which are natural nano‐ and micro‐assemblies. These two fractions possess different composition, structures and functionalities and exhibit specific behaviour under treatments such as high pressure and temperature. Plasma contains a large quantity of lipids structured as lipoproteins (low‐density lipoproteins), whereas granules are mainly composed of proteins aggregated in micrometric assemblies. If plasma is responsible for the important emulsifying properties of yolk, granules bring interesting emulsifying properties when assemblies are in the form of micelles in presence of salts. High‐pressure or thermal treatments, applied before or after emulsion fabrication, alter their functionalities and could be used to commercially exploit these fractions. © 2013 Society of Chemical Industry     

The effect of additives on the treatment of oil-in-water emulsions by vacuum evaporation

A simple batch vacuum evaporation process for the treatment of several oil-in-water (O/W) emulsions is reported. The experiments were carried out with waste emulsions from an industrial copper rolling process and with model emulsions prepared in the laboratory. No detailed information on the formulation of the industrial waste O/W emulsions was available. Several model emulsions were formulated using the same base oil (an 85–15% (w/w) mixture of a synthetic poly-α-olefin and a trimethylol propane trioleate ester, respectively) and one of the three following surfactants: Brij-76 (polyethylene glycol octadecyl ether, non-ionic), CTAB (hexadecyltrimethyl ammonium bromide, cationic), and Oleth-10 (glycolic acid ethoxylate oleyl ether, anionic). Experimental results show a strong influence of operating conditions, such as pressure or bath temperature, on the evaporation performance. As a general trend, the higher the values of these parameters, the higher the pollutant content in the obtained aqueous effluent. The presence of surfactants increase the evaporation rate, especially at low operating vacuum pressures, the solubility of oil molecules in water and the evaporation temperature of model O/W emulsions. Furthermore, COD reductions higher than 99.5% for the treated waste O/W emulsions were achieved.     

Rheological changes during thermal processing of low-fat meat emulsions formulated with different texture-modifying ingredients

The rheological behaviour of high-fat (22%) and low-fat (8%) meat emulsions during thermal processing in the presence (3%) of various texture-modifying non-meat ingredients, namely maltodextrin, starch, wheat flour, egg white and apple fibre, was analysed. Rheological properties of emulsions were assessed using non-destructive measurements (thermal scanning rigidity monitor, TSRM). The lower the fat content, the lower were the rigidity values of meat emulsions throughout the temperature range studied. Emulsions made with maltodextrin proved less rigid. Addition of starch and egg white favoured the formation of more rigid structures in low-fat meat emulsions at temperatures over 55 °C. Low-fat meat batters containing wheat flour and apple fibre exhibited the highest rigidity values over the given temperature range. The presence of wheat flour caused variations in the modulus of rigidity at all stages of the thermal gelation process, very similar to those observed in high-fat emulsions.     

乳清蛋白微凝胶颗粒的制备及其对油脂消化性的抑制作用

针对高脂肪摄入带来的高血脂、高血压、高血糖等疾病风险,定向设计高脂肪食品的乳液结构,调控其与胃肠液的相互作用,从而减少食物中油脂的消化吸收,是实现饮食健康且不降低食物感官品质的有效途径。探究了不同pH值条件下,由乳清浓缩蛋白(WPC)通过湿热-均质组合方法制备的乳清蛋白微凝胶颗粒(WPMP)的理化性质(粒径分布、热力学性质、流变学性质等),并测定了加入WPMP的油脂乳液在消化道中的稳定性、游离脂肪酸(FFA)的释放率。结果表明:在pH值为5.5时,制备的WPMP具有相对较小的中位粒径6.63μm、较高的热稳定性、较小的流体指数(n=0.06)和较好的触变性(SR=0.42)。加入WPMP的油脂乳液的油滴粒径显著小于加入WPC的油脂乳液(P<0.05),且加入在pH值为5.5时制备的WPMP,可获得油滴粒径最小(13.28μm)的油脂乳液。相较于加入WPC制得的油脂乳液,WPMP油脂乳液在模拟胃肠消化液中具有更高的稳定性和更低的FFA释放率,且不同pH值条件下制备的WPMP油脂乳液具有不同的FFA释放率。研究证实,WPMP对消化道内胆盐界面取代、脂肪酶-辅脂酶界面吸附具有一定阻隔作用,因此,WPMP对油脂乳液的消化吸收具有一定的抑制作用,且受WPMP界面结构调控。希望研究结果可为定向设计乳液结构从而抑制油脂消化提供参考。     

Breakup of non-newtonian emulsion jets

The breakup of non-Newtonian emulsion jets into drops was experimentally studied by ejecting both O/W and W/O emulsions vertically downward into stagnant air through nozzles. Breakup lengths of non-Newtonian emulsion jets were found to be almost equivalent to those of Newtonian jets. Experimental breakup data establish that the static surface tension of the oil phase can be used as the surface tension of W/O emulsion jets, whereas the dynamic surface tension of aqueous surfactant solutions is used as that of O/W emulsion jets. Diameters of drops formed from non-Newtonian emulsion jets are in good agreement with the prediction from the stability theory previously developed by the authors. When the rheological index in a power law model is appreciably smaller than unity and the Ohnesorge number is significantly large, however, drop sizes are larger than the prediction because of the profile relaxation in jets. The critical velocity of emulsion jets, either O/W or W/O emulsion, is significantly lower than that of homogeneous Newtonian jets.     

面筋蛋白粒子-黄原胶Pickering乳液的制备及其表征

制备黄原胶与面筋蛋白纳米粒协同稳的Pickering乳液,表征Pickering乳液的物理化学性能和微观结构。结果显示：通过黄原胶与面筋蛋白纳米粒协同作用,可制备出稳定性较好的Pickering乳液。低质量分数的黄原胶（0.2%）会促进乳析;当黄原胶质量分数不小于0.3%时,乳液于4 ℃贮存30 d仍无乳析现象;当黄原胶质量分数为1%时,贮存30 d乳液出现析油的现象。不同乳化顺序得到乳液的稳定性不同。乳液M-WG-XG（面筋蛋白纳米粒与玉米油乳化得粗乳液,然后加入黄原胶二次分散）的稳定性最好,同时乳液的平均粒径最小（21.4±0.314）μm。黄原胶的加入增大了乳液的净电荷,乳液的稳定性提高。共聚焦显微镜结果表明,乳液M-WG-XG液滴分布均匀,界面层呈现出多层结构。相比于其他方式制备的乳液,乳液M-WG-XG有更好的黏弹性和离子稳定性。