不同乳化剂对油酸和亚油酸乳状液稳定性的影响

本文以粒径、稳定性和流变为考察指标,利用激光粒度仪、食品稳定性分析仪、流变仪等研究不同种类和添加量的食品乳化剂(阿拉伯胶、酪蛋白酸钠、吐温20)对不饱和脂肪酸(油酸和亚油酸)乳状液的制备及其稳定性的影响。结果表明,三种乳化剂均可制备出稳定性较好的乳状液,不同乳化剂的质量分数不同得到乳状液的稳定性不同。较高质量分数的阿拉伯胶(4%,w/v)乳状液,具有最低的澄清指数并且具有最大粘度(0.30~0.40 Pa·s)。当酪蛋白酸钠的质量分数为2%时,制备出的乳状液较稳定,但粒径较大,贮藏稳定性较差。较低质量分数的吐温20(1%,w/v)的乳状液具有最小粒径(0.20~0.21 μm),经过贮藏后变化程度也最小。本文研究了不同食品乳化剂制备的不饱和脂肪酸乳状液及其稳定性,可为不饱和脂肪酸乳状液的制备和应用提供参考。     

Physical stability of emulsion encapsulated in alginate microgel particles by the impinging aerosol technique

Emulsion filled alginate microgel particles can be applied as carrier systems for lipophilic actives in pharmaceutical and food formulations. In this study, the effects of oil concentration, emulsifier type and oil droplet size on the physical stability of emulsions encapsulated in calcium alginate microgel particles (20–80 μm) produced by a continuous impinging aerosol technique were studied. Oil emulsions emulsified by using either sodium caseinate (SCN) or Tween 80 were encapsulated at different oil concentrations (32.55, 66.66 and 76.68% w/w of total solids content). The emulsions were analysed before and after encapsulation for changes in emulsion size distribution during storage, and compared to unencapsulated emulsions. The size distribution of encapsulated fine emulsion (mean size ~ 0.20 μm) shifted to a larger size distribution range during encapsulation possibly due to the contraction effect of the microgel particles. Coarse emulsion droplets (mean size ~ 18 μm) underwent a size reduction during encapsulation due to the shearing effect of the atomizing nozzle. However, no further size changes in the encapsulated emulsion were detected over four weeks. The type of emulsifier used and emulsion concentration did not significantly affect the emulsion stability. The results suggest that the rigid gel matrix is an effective method for stabilising lipid emulsions and can be used as a carrier for functional ingredients.     

OPTIMIZATION OF EMULSIFICATION AND MICROENCAPSULATION OF EVENING PRIMROSE OIL AND ITS OXIDATIVE STABILITY DURING STORAGE BY RESPONSE SURFACE METHODOLOGY

ABSTRACT

Microencapsulation is a technique by which small droplets of liquid or solid particles are coated with a thin film of wall materials to protect susceptible ingredients in food products to assure their quality or effectiveness. Microencapsulation of liquid lipid into powdery matrixes of wall materials includes two unit operations: emulsification of the lipid with an aqueous solution of wall material and drying of the emulsion. The effects of hydrophile–lipophile balance (HLB) value, emulsifier content and oil content on the evening primrose oil‐in‐water emulsion stability were studied by response surface methodology (RSM). The HLB value, emulsifier content and oil content all had significant effects on the emulsion stability (P < 0.05). Of them, the HLB value and emulsifier content contributed more effects than the oil content. The optimized HLB value, emulsifier content and oil content were used to mix with wall materials: gum arabic (GA), maltodextrin (MD) and/or sodium caseinate (NaC). The oil was encapsulated with these materials individually or in combination by spray‐drying, and their oxidative stability during storage was compared. The microcapsules with a single wall material were relatively susceptible to oxidation than those with multiple wall materials. The most desirable composition of the mixture of GA, MD and NaC by RSM was 17.2, 75 and 7.8%, respectively.

PRACTICAL APPLICATIONS

Response surface methodology (RSM) provided a valuable means to help us understand the relative or interactive effects of three important parameters: HLB value, emulsifier content and oil content on the emulsion stability of the oil‐in‐water (o/w) system. The information obtained would be useful for the preparation of similar o/w emulsion system as needed in some product development for foods. In addition, the effects of gum arabic, maltodextrin and sodium caseinate on the oxidative stability of microencapsulated oil were also studied by RSM. The results revealed the relative or interactive effects of these materials and gave the optimal conditions in minimizing the oxidative instability in this study. Since these wall materials are readily available and widely used in a variety of products, the information provided by this study would be useful for product‐developing professionals to use these materials more efficiently in terms of obtaining optimal microencapsulated products against lipid oxidation and cost effectiveness.     

Formulation of monodisperse oil‐in‐water emulsions loaded with ergocalciferol and cholecalciferol by microchannel emulsification: insights of production characteristics and stability

Nutritional deficiencies of ergocalciferol (VD₂) and cholecalciferol (VD₃) cause skeletal deformations. The primary aim of this study was to encapsulate VD₂ and VD₃ in food‐grade oil‐in‐water (O/W) emulsions by using microchannel emulsification (MCE). Silicon asymmetric straight‐through microchannel (MC) array consisting of 10 313 channels, each having an 11 × 104 μm microslot connected to a 10 μm circular microholes. 1% (w/w) sodium cholate or Tween 20 in water was used as the continuous phase, while 0.5% (w/w) of each VD₂ and VD₃ in different oils served as the dispersed phase. Monodisperse O/W emulsions with Sauter mean diameters of 28 to 32 μm and relative span factor widths below 0.3 were formulated via an asymmetric straight‐through MC array under appropriate operating conditions. The monodisperse O/W emulsions stabilised with Tween 20 remained stable for >30 days with encapsulation efficiencies (EEs) of VD₂ and VD₃ of above 70% at 4 and 25 °C. In contrast, those stabilised with sodium cholate had stability of >30 days with their EEs of over 70% only at 25 °C.     

Light stability of spray-dried bixin encapsulated with different edible polysaccharide preparations

Bixin was encapsulated by spray-drying with gum arabic or maltodextrin, and the stability was evaluated in aqueous solution both under illumination or in the dark at 21 °C. The microcapsules containing emulsifier, such as gum arabic or maltodextrin + Tween 80, showed the highest encapsulation efficiency, respectively 86% and 75%, less superficial imperfections and higher stability than bixin encapsulated with maltodextrin alone or blended with sucrose. The kinetic behavior of bixin photodegradation in all encapsulated systems was composed by two first-order decays, due to the presence of bixin outside and inside the microcapsules. Bixin encapsulated with gum arabic was 3 to 4 times more stable than that encapsulated with maltodextrin. In all systems, greater bixin stability (<two orders of magnitude) was observed in the dark than under illuminated conditions. In addition, 10 times greater bixin stability was observed for encapsulated solutions as compared to the non-encapsulated systems in the absence of light.     

The influence of sodium caseinate on the physical properties of spray‐dried honey

The aim of this work was to spray dry honey (rape and buckwheat varieties) with Arabic gum (AG) as a carrier alone or in combination with sodium caseinate (1% and 2% w/w NaCas) as a drying aid. Powder recovery ranged from 66.2 ± 0.7% to 75.8 ± 4.9%, and the values were significantly higher for samples containing NaCas. Powders were characterised by good flowability, the addition of NaCas had positive impact on this factor. However, the hygroscopicity of protein‐containing powders was higher, especially at 2% w/w of NaCas. Powders hygroscopicity was related to particle size: AG powder of the smallest particle size was the most hygroscopic, while the particle size did not affected flowability, which was strongly related to the feed solution composition. Based on the obtained results, it was concluded that the addition of 1% w/w of NaCas as a drying aid during buckwheat and rape honey spray drying with Arabic gum as a carrier is favourable, while the further increase of protein content does not give additional benefits.     

Emulsification properties of sodium caseinate‐based conjugates with selected polysaccharides

Sodium caseinate (SC) was conjugated with polysaccharides, viz. maltodextrin (MD), pectin (P) and gum arabic (GA) at protein:polysaccharide weight ratio of 1:2, 1:1 and 2:1. The emulsifying properties and other relevant chemical properties of these conjugates were compared. The visible colour change, SDS‐PAGE analysis and available reducing groups confirmed greater conjugation in SC‐MD conjugate than the SC‐GA and SC‐P conjugates. SC‐P conjugate at the weight ratio of 1:2 exhibited the best emulsifying properties (emulsifying activity – 46.7%, emulsion stability – 7 days at 5 ± 1 °C storage) and had better solubility (33.5%) near the iso‐electric pH.     

Nanoencapsulation of EPA/DHA with sodium caseinate–gum arabic complex and its usage in the enrichment of fruit juice

In this study, encapsulating fish oil, as a source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), with multi-layered interfacial membranes using electrostatic attraction between sodium caseinate and gum arabic and its usage in the enrichment of fruit juice was investigated. Initially, optimum conditions for forming a stable complex between sodium caseinate and gum arabic were determined at pH 4 and at a concentration of 0.1 g/100 ml sodium caseinate-0.2 g/100 ml gum arabic. This complex was utilized for nanoencapsulation of fish oil. Encapsulation efficiency and particle size were obtained as 78.88 ± 2.89%, 232.3 nm, respectively. Fish oil nanocomplex containing 40–50–60 mg EPA + DHA were used in the enrichment of 100 ml fruit juice. After in vitro digestion, the bioaccessibility of EPA, DHA and EPA + DHA were found as 56.16 ± 6.39, 36.25 ± 5.38 and 47.37 ± 10.65 percent, respectively (p < 0.05). This study indicates that stable protein–polysaccharide complexes can be used for nanoencapsulating hydrophobic compounds such EPA and DHA, useful for enrichment of non- or low-fat beverages.     

The interplay between diverse oil body extracts and exogenous biopolymers or surfactants

Hazelnuts, sesame seeds and soybeans were selected as three diverse sources of oil bodies. Application of aqueous extraction and centrifugation steps resulted in concentrated oil body creams that were studied for their physical stability after dilution to a series of 5.0 wt.% oil-in-water emulsions incorporating sodium caseinate (1.0 wt.%), Tween 80 (1.0 wt.%) or xanthan gum (0.1 wt.%). In terms of aggregation/coalescence and creaming, the stability of the oil body based emulsions was ruled to a large extent by the initial natural oil droplet size and the presence of co-extracted exogenous proteins and secondarily by the added biopolymers and the surfactant. More specifically, soybean oil bodies exhibited the highest physical stability, even though incorporation of Tween 80 into all three oil body emulsions improved the stability against aggregation/coalescence, while xanthan gum was an effective stabilizer against creaming.     

Interfacial activity of phenolic-rich extracts from avocado fruit waste: Influence on the colloidal and oxidative stability of emulsions and nanoemulsions

The effects of phenolic-rich extracts from avocado peels (AP) and seeds (AS) on the colloidal and the lipid oxidative stability of oil-in-water (O/W) emulsions/nanoemulsions were evaluated. For this purpose, the interfacial tension (IFT) of avocado oil droplets in the presence of extracts and surfactants (low methoxyl pectin, LMP; Tween 80, T80), individually or combined, was assessed. Individually, T80 led to the lowest IFT values (4.25 ± 0.02 mN/m), followed by AS and AP extracts (9.27 ± 0.86 mN/m and 12.31 ± 0.10 mN/m, respectively) and LMP (14.88 ± 0.05 mN/m). Regarding particle size, the emulsions containing AP and AS extracts were smaller (1.45 ± 0.10 μm and 1.11 ± 0.03 μm, respectively), and stabler, than blank emulsions (4.05 ± 0.51 μm). Conversely, the extracts, especially AS extract, reduced the stability of nanoemulsions causing a 24-fold particle size increase. Nevertheless, AP and AS extracts reduced the formation of secondary oxidation products in emulsions/nanoemulsions. These findings provide novel insights into the potential use of avocado waste.     

Interfacial adsorption and shear flow properties of gum arabic-sodium caseinate mixtures

This work discusses rheological and physicochemical properties of sodium caseinate and gum arabic, in aqueous media (25 °C). All the systems showed low viscosity values and Newtonian behaviour in the shear rate range studied. From particle size distribution, a limited thermodynamic compatibility was observed since hydrocolloids mixtures showed particles size between the values from the systems alone. Interfacial tension measurements at equilibrium at the air-water interface, revealed that the binding affinity of arabic to the air water interface is very low compared to that of caseinate. The adsorption critical concentration could be deduced as a function of aqueous solutions composition. In competitive adsorption experiments involving simultaneous adsorption of the hydrocolloids from a bulk mixture, sodium caseinate displaced gum arabic from the interface at both polysaccharide concentrations, changing the adsorption critical concentration.     

Temperature-dependent complexation between sodium caseinate and gum arabic

Complex formation between sodium caseinate and gum arabic as a function of temperature was investigated using dynamic light scattering, fluorescence and NMR. At neutral pH, the turbidity and the particle size increased when sodium caseinate and gum arabic mixtures were heated in situ at temperatures above a critical temperature. The increases in turbidity and particle size were reversible. This effect was considered to be due to hydrophobic interactions, leading to the formation of a complex between sodium caseinate and gum arabic. ¹H NMR spectroscopy showed that ANS, which bound to caseinate at low temperatures in caseinate solution or a caseinate-gum arabic mixture, was released at high temperatures upon formation of a caseinate or caseinate-gum arabic complex. This supported changes observed in the fluorescence of 8-anilino-1-naphthalene sulfonate upon binding to caseinate, which decreased at high temperatures for caseinate alone or when sodium caseinate was mixed with gum arabic. Light-scattering (turbidity) and dynamic light-scattering studies show that the temperature-dependent complexation between sodium caseinate and gum arabic was sensitive to the mass ratio of protein to gum arabic (greater complexation at a 1:5 ratio than a 1:1 ratio) and the pH (maximum complexation at pH 6.5).     

添加玉米低聚肽的紫苏籽油乳状液及其微胶囊的制备

为制备含玉米低聚肽的紫苏籽油微胶囊,选择阿拉伯胶、可溶性大豆多糖、辛烯基琥珀酸淀粉钠（HI-CAP 100）、酪蛋白酸钠和大豆分离蛋白5 种乳化剂,并添加不同质量分数的玉米低聚肽制备紫苏籽油乳状液,筛选出制备紫苏籽油乳状液的最适乳化剂及最佳的玉米低聚肽添加比例;进而采用喷雾干燥法制备高载油量的玉米低聚肽紫苏籽油微胶囊,筛选和评价高载油量玉米低聚肽紫苏籽油微胶囊的壁材。结果显示：HI-CAP 100制备的紫苏籽油乳状液的液滴粒径主要分布在0.1～2 μm之间,并且玉米低聚肽添加量为5%时,乳状液的不稳定性指数为0.275,粒径为（0.76±0.02）μm;以HI-CAP 100为壁材经喷雾干燥制成的目标微胶囊（载油量≥50%）表面油含量为3%,表明HI-CAP 100对紫苏籽油的包埋效果较好,并且微胶囊粒径分布均匀,表面较光滑适合作为高载油量玉米低聚肽紫苏籽油微胶囊的壁材;通过加速贮藏实验证明玉米低聚肽与茶多酚棕榈酸酯复配,能提高紫苏籽油微胶囊的抗氧化性。     

Influence of emulsifier type on in vitro digestibility of lipid droplets by pancreatic lipase

The objective of this study was to investigate the influence of interfacial composition on the in vitro digestion of emulsified lipids coated by various emulsifiers by pancreatic lipase. Sodium caseinate, whey protein isolate (WPI), lecithin and Tween 20 were used to prepare corn oil-in-water emulsions (3 wt% oil). Pancreatic lipase (1.6 mg/mL) and/or bile extract (5.0 mg/mL) were added to each emulsion and the particle charge, droplet aggregation, microstructure and free fatty acids released were measured. In the absence of bile extract, the amount of free fatty acids released per unit volume of emulsion was much lower for lipid droplets coated by Tween 20 (13 ± 16 μmol ml⁻¹) than those coated by lecithin (75 ± 20 μmol ml⁻¹), sodium caseinate (220 ± 24 μmol ml⁻¹) or WPI (212 ± 6 μmol ml⁻¹). In the presence of bile extract, there was an appreciable increase in the amount of free fatty acids released in all the emulsions, with the most appreciable effects being observed in the Tween 20-stabilized emulsions. The stability of the emulsions to droplet flocculation and coalescence during hydrolysis was also strongly dependent on emulsifier type, with the WPI emulsions being the least stable and the Tween 20 emulsions being the most stable. Our results suggest that the access of pancreatic lipase to emulsified fats decreases in the following order: proteins (caseinate and WPI) > phospholipids (lecithin) > non-ionic surfactants (Tween 20). These results may have important consequences for the design of foods with either increased or decreased lipid bioavailability.     

Water‐dispersible microparticles of polyunsaturated oils

Health benefits of polyunsaturated oils are well known; nevertheless, incorporating these oils into food/feed products is not possible due to their chemical instability. Here purified fish oil with 32% (w/w) polyunsaturated fatty acids is co‐encapsulated with the antioxidant butylhydroxyanisole, into 1.0 ± 0.7 μm cellulose‐based microspheres by solvent precipitation method, at the fish oil loading content of 41% and encapsulation efficiency of 81%. Aqueous suspension of the encapsulated fish oil particles shows significantly improved oxidative stability, thermal stability, photostability and shelf‐life stability. Dry powder of the fish oil particles shows excellent shelf‐life stability. Double bond functionality of the encapsulated oil can tolerate high production temperature such as the shrimp feed production process (95 °C for 10 min) or spray dry process (outlet temperature of 120 °C). This encapsulation strategy using biocompatible cellulose polymer should enable effective and versatile applications of polyunsaturated oils in foods, feeds and cosmetics.     

三种乳化剂对橄榄油乳液稳定性的影响

乳化剂因亲水亲油平衡值的不同对油脂乳化效果表现出固有的差异,但这种差异会因加入辅助剂的影响而发生改变。以非离子型表面活性剂单甘酯、蔗糖酯和吐温20为乳化剂,以白果直链淀粉及阿拉伯胶(质量比1∶1)为辅助剂,对橄榄油进行乳化,考察了辅助剂加入前后在不同制备方法(先油后水和先水后油工艺)和乳化剂添加量下乳液的稳定性。结果表明:单独使用乳化剂时,经外观观察,在三种乳化剂添加量相同时,吐温20的橄榄油乳液稳定性较好,其次为蔗糖酯、单甘酯;加入辅助剂后,乳液的乳化状态较单一加入乳化剂的好,乳液黏度、粒径和浑浊度均随着乳化剂添加量的增大呈先减小后增加趋势,且在相同添加量下,由蔗糖酯制备的橄榄油乳液黏度较低,粒径和浑浊度较小,稳定性较好,吐温20及单甘酯次之;辅助剂加入前后,先油后水工艺制备的橄榄油乳液的稳定性总体优于先水后油工艺的。     

Effect of Aqueous Phase Composition on Stability of Sodium Caseinate/Sunflower oil Emulsions

The aim of the present work was to investigate the effect of aqueous phase composition on the stability of emulsions formulated with 10 wt% sunflower oil as fat phase. Aqueous phase was formulated with 0.5, 2, or 5 wt% sodium caseinate, or sodium caseinate with the addition of two different hydrocolloids, xanthan gum or locust bean gum, both at 0.3 or 0.5 wt% level or sodium caseinate or with addition of 20 wt% sucrose. Emulsions were processed by Ultra-Turrax and then further homogenized by ultrasound. Creaming and flocculation kinetics were quantified by analyzing the samples with a Turbiscan MA 2000. Emulsions were also analyzed for particle size distribution, microstructure, viscosity, and dynamic surface properties. The most stable systems of all selected in the present work were the 0.3 or 0.5 wt% XG or 0.5 wt% LBG/0.5 wt% NaCas coarse emulsion and the 20 wt% sucrose/5 wt% NaCas fine emulsion. Surprisingly, coarse emulsions with the lower concentration of NaCas, which had greater D _4,3, were more stable than fine emulsions when the aqueous phase contained XG or LBG. In these conditions, the overall effect was less negative bulk interactions between hydrocolloids and sodium caseinate, which led to stability. Sugar interacted in a positive way, both in bulk and at the interface sites, producing more stable systems for small-droplet high-protein-concentration emulsions. This study shows the relevance of components interactions in microstructure and stability of caseinate emulsions.     

Microstructural design to reduce lipid oxidation in oil-inwater emulsions

The influence of emulsifier type (Tween 20 and sodium caseinate (CAS)) and oil phase volume fraction (5% and 30%) on emulsion oxidative stability was investigated. The primary and secondary lipid oxidation products of emulsions stored at 40 °C were measured over 7 days. The results indicated that the oxidative stability of samples stabilised with CAS was significantly higher compared with emulsions stabilised with Tween 20. We propose that this is due to iron binding ability of CAS. Moreover, the impacts of Pickering emulsions (Silica particles) on lipid oxidation were studied and compared with Tween 20 stabilised emulsions. The results showed that silica particles could increase the oxidative stability of 20% sunflower oil-in-water emulsions by acting as a physical barrier between pro-oxidants located in continuous phase and hydroperxide at droplet interface.     

Fabrication of chia (Salvia hispanica L.) seed oil nanoemulsions using different emulsifiers

In this study, the quality of spiral cold press chia seed oil was evaluated and four types of O/W chia seed oil nanoemlusion systems were prepared, including chia seed oil nanoemulsion stabilized with Tween 80 and Span 80 by spontaneous emulsification and microfluidization, sodium caseinate by microfluidization, and sucrose monopalmitate by microfluidization. All these optimized samples exhibited good storage stability for at least two weeks when stored at 4 °C or ambient temperature. The nanoemulsion stabilized with sodium caseinate was labeling friendly, and enough energy‐input facilitated the achievement of small particle size around 160 nm. The chia seed oil nanoemulsion fabricated with sucrose monopalmitate could get best transparency with smallest droplet diameter (around 47 nm). Chia seed oil nanoemulsion stabilized with Tween 80 and Span 80, as one model case diluted 500× into water system, had constant transparency after fortnight's storage.

Practical applications

Consumers are increasingly aware of nutrition as well as sensory properties of food products. Chia seed oil is a good source of n‐3 polyunsaturated fatty acids, yet difficult to be added directly into water‐based liquid food or beverages. The information given in this work might be useful for designing O/W chia seed oil nanoemulsion delivery system, facilitating the further application of chia seed oil in beverages and functional food industry which required only slightly turbid or even transparent appearance.     

高压微射流制备岩藻黄素纳米乳液的影响因素及其理化分析

采用高压微射流制备岩藻黄素纳米乳液（fucoxanthin nanoemulsion,FCNE）,研究均质条件、乳化剂类型和质量分数、乳化温度、助乳化剂（甘油）对FCNE理化性质的影响。结果表明：FCNE粒径和多分散指数（polydispersity index,PDI）随均质压强和次数的增加而减小,压强120 MPa、均质4 次后FCNE粒径基本达到最小（154 nm,PDI=0.19）。不同乳化剂（吐温80、十二烷基硫酸钠（sodium dodecyl sulfate,SDS）、酪蛋白酸钠）制备的FCNE粒径大小为：SDS＜吐温80＜酪蛋白酸钠,且随着乳化剂质量分数和乳化温度的升高,FCNE粒径显著减小（P＜0.05）。此外,添加不同质量分数的甘油后,吐温80和SDS制备的FCNE粒径显著减小（P＜0.05）,而酪蛋白酸钠制备的FCNE粒径变化较小,表明SDS和吐温80制备的FCNE比酪蛋白酸钠制备的FCNE对水相黏度变化更敏感。在不同的pH值条件下,吐温80制备的FCNE可稳定存在,表面电荷基本不变;而SDS和酪蛋白酸钠制备的FCNE在酸性条件下稳定性较差,且pH值从7变化至3时,其粒径变化显著（P＜0.05）。在37 ℃条件下储存30 d后,纳米乳液中岩藻黄素残留量明显高于有机相,表明将岩藻黄素制成FCNE显著提高了岩藻黄素的储存稳定性。