香精包埋技术研究进展

香精包埋是指采用一种保护性壁材以不同过程包覆香精,从而赋予香精在食品中具一定程度抗蒸发,抗反应和抗逸散性质;喷雾干燥、喷雾冷冻或喷雾冷却、挤压、冷冻干燥、凝聚和分子包合都是常用包埋香精方法,选择何种方法进行包埋则取决于产品终端用途和在生产中加工条件。     

Flavour encapsulation and controlled release – a review

Flavours can be among the most valuable ingredients in any food formula. Even small amounts of some aroma substance can be expensive, and because they are usually delicate and volatile, preserving them is often a top concern of food manufacturers. Encapsulation describes different processes to cover an active compound with a protective wall material and it can be employed to treat flavours so as to impart some degree of protection against evaporation, reaction, or migration in a food. Encapsulation of flavours has been attempted and commercialized using many different methods such as spray drying, spray chilling or spray cooling, extrusion, freeze drying, coacervation and molecular inclusion. The choice of appropriate microencapsulation technique depends upon the end use of the product and the processing conditions involved in the manufacturing product. This overview describes each method cited above in terms of the basic chemical and/or physical principles involved and covers mechanisms of flavour release from food matrices.     

Optimization of Microencapsulation of Fish Oil with Gum Arabic/Casein/Beta‐Cyclodextrin Mixtures by Spray Drying

Fish oil was encapsulated with gum arabic/casein/beta‐cyclodextrin mixtures using spray drying. The processing parameters (solids concentration of the barrier solutions, ratio of oil to barrier materials, emulsifying temperature, and air inlet temperature) were optimized based on emulsion viscosity, emulsion stability, encapsulation efficiency, and yield. A suitable viscosity and high emulsion stability could increase encapsulation efficiency and yield. Encapsulation efficiency and yield were significantly affected by all the 4 parameters. Based on the results of orthogonal experiments, encapsulation efficiency and yield reached a maximum of 79.6% and 55.6%, respectively, at the optimal condition: solids concentration of 35%, ratios of oil to barrier materials of 3:7, emulsifying temperature of 55 °C, and air inlet temperature of 220 °C. Scanning electron microscopy analysis showed that fish oil microcapsules were nearly spherical with a smooth surface with droplet size ranging from 1 to 10 μm.     

Double Emulsions Relevant to Food Systems: Preparation,Stability, and Applications

This review describes advances in the preparation of food‐relevant double emulsions (DEs) of the water‐in‐oil‐in‐water (W/O/W) and oil‐in‐water‐in‐oil (O/W/O) types with emphasis on research published within the last decade. The information is assembled and critically evaluated according to the following aspects: the food application area, the range of encapsulated components and emulsion composition, the emulsification preparation methods, the balancing of the osmotic pressure, the stabilization by increased viscosity or gelation, the role of protein–polysaccharide interactions, and the techniques used to estimate DE yield and emulsification efficiency. Particular focus is directed toward the control of encapsulation and release behavior, including strategies that have been employed to improve the retention ability of the inner phase droplets by modifying the outer oil–water interface through mixed ingredient interactions, Pickering stabilization by particles, and biopolymer gelation. We also briefly consider the incorporation of DEs into dried microcapsules and the stability of W/O/W emulsions during eating and digestion. It would appear that 2 outstanding issues are currently preventing full realization of the potential of DEs in food applications: (i) the lack of availability of large‐scale production equipment to ensure efficient nondestructive 2nd‐stage emulsification, and (ii) the limited range of food‐grade ingredients available to successfully replace polyglycerol polyricinoleate as the primary emulsifier in W/O/W formulations.     

喷雾干燥法制取宝石鱼油微胶囊技术研究(Ⅰ)

以宝石鱼油微胶囊制品包埋率作为主要评价指标,筛选出喷雾干燥法制取宝石鱼油微胶囊壁材配方组成;通过对五组壁材配方喷雾效果及微胶囊制品特性比较,得出宝石鱼油微胶囊壁材配方组成为:变性淀粉46．75％、酪蛋白酸钠2％、鱼油20％。     

Encapsulation of food ingredients

Microencapsulation is a relatively new technology that is used for protection, stabilization, and slow release of food ingredients. The encapsulating or wall materials used generally consist of starch, starch derivatives, proteins, gums, lipids, or any combination of them. Methods of encapsulation of food ingredients include spraydrying, freeze‐drying, fluidized bed‐coating, extrusion, cocrystallization, molecular inclusion, and coacervation. This paper reviews techniques for preparation of microencapsulated food ingredients and choices of coating material. Characterization of microcapsules, mechanisms of controlled release, and efficiency of protection/ stabilization of encapsulated food ingredients are also presented.     

In-vitro evaluation of hydrocolloid–based encapsulated fish oil

The release behaviour of hydrocolloid-based encapsulated fish oil was carried out to understand its applicability as a controlled release delivery system. A casein-based Maillard reaction product (MRP), [caseinate–glucose-dried glucose syrup, MRP] and its corresponding non-MRP-based encapsulant materials were used to form stable emulsions with fish oil. The emulsion particle size distribution was found to be uniform with 90% of the particles below 1.3 μm. These oil/water emulsions were spray dried to obtain free-flowing fish oil microcapsules. All casein-based microcapsules had a free fat content of <1% and the encapsulation efficiencies were all >97%. A sequential in-vitro release protocol and a method for evaluation of the released oil in simulated gastric and intestinal fluids (SGF/SIF) were developed and tested in this study. A comparative analysis of release behaviour between caseinate and whey protein-based MRP and non-MRP-based encapsulant materials was also obtained. The amount of released oil after subjecting to the sequential in-vitro protocol was found to be <2% and 36% for caseinate and whey protein-based MRP microcapsules respectively.     

Influence of Emulsification Technique and Wall Composition on Physicochemical Properties and Oxidative Stability of Fish Oil Microcapsules Produced by Spray Drying

Encapsulation of fish oil is an effective way to protect it against oxidation and masking its fishy odor. One of the possible ways to produce fish oil microcapsules is to produce an oil-in-water (O/W) emulsion followed by spray drying. This study compares the production of the O/W emulsion by mechanical homogenization (rotor–stator) with membrane emulsification and examines the effect of the type and amount of wall material added before drying. The membrane emulsification process selected for the emulsion production is premix membrane emulsification (ME), which consists of the production of a coarse emulsion by mechanical means followed by droplet breakup when the coarse emulsion is forced through a membrane. The emulsions produced had an oil load of 10 and 20 % and were stabilized using whey protein (isolate and hydrolyzate at 1 or 10 %) and sodium caseinate with concentrations of 2 and 10 %. Regarding the material used to build the microcapsule wall, whey protein, maltodextrin, or combinations of them were used at three different oil/wall ratios (1:1, 1:2, 1:3). The results clearly show that premix ME is a suitable technology for producing O/W emulsions stabilized with proteins, which have a smaller droplet size and are more monodisperse than those produced by rotor–stator emulsification. However, protein concentrations of 10 % are required to reduce the droplet size down to 2–3 μm. Small and monodisperse emulsions have been found to produce microcapsules with lower surface oil content, which increases oil encapsulation efficiency and presents lower levels of oxidation during storage at 30 °C. Of all the possible combinations studied, the one with the highest oil encapsulation efficiency is the production of a 20 % O/W emulsion stabilized with 10 % sodium caseinate followed by the addition of 50 % maltodextrin and drying.     

Formulation and rheological characterization of reduced-calorie food emulsions

Water-in-oil-in-water (W/O/W) double emulsions are systems where a water-in-oil emulsion (W/O) is dispersed in a second aqueous phase. The W/O emulsion exists in the suspending aqueous medium as oil globules containing smaller water droplets.
In this work, a selection of both materials and procedures has been made in order to obtain an optimal formulation of a W/O/W food emulsion for both yield and rheologica] properties.
The rheological properties of W/O/W emulsions have been studied by means of both steady-shear and oscillatory measurements, and appeared to be similar to those of a simple O/W emulsion having the same volume fraction of dispersed phase, but lower oil content.
This is of great interest to the food industry, since producing double emulsions with the same texture as simple ones, but a lower oil content, helps to formulate reduced-calorie foods.     

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.     

High-oil-load encapsulation of medium-chain triglycerides and D-limonene mixture in modified starch by spray drying

Oil mixtures of medium-chain triglycerides (MCT) and D-limonene in mixing ratios from 10 to 100 wt% were encapsulated in modified starch (wall material) by spray drying to produce oil-rich powders. The oil load (mass ratio of oil mixture to wall material) of the infeed emulsion markedly influenced the properties of the infeed liquid and the characteristics of the resulting powder. The viscosity of the infeed liquid and the particle size of the powder exponentially decreased with increasing oil load, while the emulsion droplet size in the infeed liquid increased. In addition, retention of D-limonene during spray drying also decreased markedly with increasing oil load. Irrespective of the different oil loads and concentrations of the wall material, D-limonene retention was well correlated with the emulsion droplet diameter of the infeed liquid. The encapsulation efficiency of the oil mixture exhibited a maximum value (almost 100%) at an oil load between 0.5 and 1.0, before decreasing at higher oil loads. At an oil load of 2.0, the encapsulation efficiency of D-limonene was reduced to almost zero, while around 40% of the initial MCT was encapsulated in the powder. The increase in oil load also led to increased amounts of surface oil of MCT and D-limonene in the resulting powder due to the increasing emulsion droplet diameter of the infeed liquids. PRACTICAL APPLICATION: This study proposes the microencapsulation of medium-chain triglycerides under high-oil-load conditions by spray drying. The powders prepared by this process provide significant benefits in terms of rapid energy conversion after consumption without accumulation in the body. Important quality factors of the powder products such as the encapsulation efficiency and the amount of surface oil were examined to understand the optimum process conditions for spray drying.     

Encapsulation of Fish Oil by an Enzymatic Gelation Process Using Transglutaminase Cross-linked Proteins

ABSTRACT To improve the storage stability and achieve controlled release, fish oil containing docosahexaenoic acid was encapsulated using double emulsification and subsequent enzymatic gelation method, using microbial transglutaminase cross-linked proteins. Isolated soy protein was selected as a wall material because it showed better emulsion stability and higher reactivity with MTGase than other proteins. Microcapsules prepared by this method showed a high stability against oxygen and a low water solubility, which subsequently resulted in sustained release of fish oil. Results indicate that this microencapsulation process is suitable for preparing protein-based microcapsules containing sensitive ingredients for controlled release and stability improvement.     

Cheese fortification using water-in-oil-in-water double emulsions as carrier for water soluble nutrients

Encapsulation of vitamin B₁₂ in water-in-oil-in-water double emulsions was optimized to produce functional cream for cheese milk standardization. The effect of encapsulation on vitamin B₁₂ release during in vitro gastric digestion and on retention during cheese making was determined. Primary water-in-oil emulsions were prepared from vitamin B₁₂ (0.2%, w/v) solution and butter oil containing 8% (w/w) polyglycerol polyricinoleate, and dispersed in skim milk or sodium caseinate solution using a dispersing tool or a valve homogenizer. Encapsulation of vitamin B₁₂ in double emulsions exhibited greater than 96% efficiency and prevented vitamin losses during in vitro gastric digestion. Less than 5% of the encapsulated vitamin B₁₂ was released from double emulsion stabilized with sodium caseinate. Compared with non-encapsulated vitamin B₁₂, encapsulation in double emulsions reduced vitamin B₁₂ losses in whey and increased retention in cheese from 6.3 to more than 90%.     

雪莲果系列制品的研制

为提高雪莲果的利用价值和开发新的功能性食品,以新鲜雪莲果为原料,榨汁后滤液喷雾干燥制备雪莲果汁粉,滤渣制备雪莲果渣粉。考察了护色剂对雪莲果汁粉及出粉率的影响,并对产品中低聚果糖的含量进行了测定。再以玉米胚芽油为芯材,雪莲果汁及其他材料为壁材,采用微胶囊技术研发新型的功能性雪莲果汁粉末油脂。结果表明:0.20%的柠檬酸护色效果较好,制备的雪莲果汁粉末油脂表面油含量2.11%,包埋率92.6%,冲溶后的乳状液有雪莲果香且稳定性好。     

Review on the Stability Mechanism and Application of Water‐in‐Oil Emulsions Encapsulating Various Additives

Water‐in‐oil (W/O) emulsions can be used to encapsulate and control the release of bioactive compounds for nutrition fortification in fat‐based food products. However, long‐term stabilization of W/O emulsions remains a challenging task in food science and thereby limits their potential application in the food industry. To develop high‐quality emulsion‐based food products, it is essential to better understand the factors that affect the emulsions’ stability. In real food system, the stability situation of W/O emulsions is more complicated by the fact that various additives are contained in the products, such as NaCl, sugar, and other large molecular additives. The potential stability issues of W/O emulsions caused by these encapsulated additives are a current concern, and special attention should be given to the relevant theoretical knowledge. This article presents several commonly used methods for the preparation of W/O emulsions, and the roles of different additives (water‐ and oil‐soluble types) in stabilizing W/O emulsions are mainly discussed and illustrated to gain new insights into the stability mechanism of emulsion systems. In addition, the review provides a comprehensive and state‐of‐art overview of the potential applications of W/O emulsions in food systems, for example, as fat replacers, controlled‐release platforms of nutrients, and delivery carrier systems of water‐soluble bioactive compounds. The information may be useful for optimizing the formulation of W/O emulsions for utilization in commercial functional food products.     

乳液粒径对橙皮精油微胶囊物理性质和氧化稳定性的影响

本文以橙皮精油为芯材,变性淀粉和麦芽糊精为壁材,通过高压(1000、2500、3500和22000 psi)均质制备了不同粒径橙油乳液,从而探讨乳液粒径对喷雾干燥橙油微胶囊平均粒径、包埋率、总油量、含水量、微观形貌以及重组乳液粒径分布的影响。同时以柠檬烯氧化程度评价微胶囊稳定性并预测其货架期。结果表明,均质压力越高,乳液粒径越小。乳液粒径对微胶囊的总油量(1.5 g/20 g)、包埋率(>95%)和含水量(<4%)没有明显影响,但会影响微胶囊的平均粒径、微观形貌以及重组乳液的粒径分布。乳液粒径越小,微胶囊平均粒径越小,表面越光滑,重组乳液也具有更窄的粒径分布。微胶囊在37 ℃贮藏5周,经零级动力学方程拟合氧化柠檬烯/柠檬烯(mg/g)变化的结果表明,以22000 psi制备的微胶囊货架期可长达11周左右,是其余微胶囊货架期的2.97~4.63倍。研究结果可为喷雾干燥精油微胶囊的工艺优化及质量控制提供理论参考。     

Stability of Anthocyanin‐Rich W/O/W‐Emulsions Designed for Intestinal Release in Gastrointestinal Environment

Abstract: Anthocyanins belong to the most important hydrophilic plant pigments. Outside their natural environment, these molecules are extremely unstable. Encapsulating them in submicron‐sized containers is one possibility to stabilize them for the use in bioactivity studies or functional foods. The containers have to be designed for a target release in the human gastrointestinal system. In this contribution, an anthocyanin‐rich bilberry extract was encapsulated in the inner aqueous phase of water‐in‐oil‐in‐water‐double emulsions. The physical stability as well as the release of free fatty acids and encapsulated, bioactive substances from the emulsions during an in vitro gastrointestinal passage were investigated. The focus was on the influence of emulsion microstructural parameters (for example, inner and outer droplet size, disperse phase content) and required additives (emulsifier systems), respectively. It could be shown that it is possible to stabilize anthocyanins in the inner phase of double emulsions. The release rate of free fatty acids during incubation was independent of the emulsifier used. However, the exterior (O/W)‐emulsifier has an impact on the stability of multiple emulsions in gastrointestinal environment and, thus, the location of release. Long‐chained emulsifiers like whey proteins are most suitable to transport a maximum amount of bioactive substances to the effective location, being the small intestine for anthocyanins. In addition, it was shown that the dominating release mechanism for entrapped matter was coalescence of the interior W₁‐droplets with the surrounding W₂‐phase. Practical Application: Microencapsulation of phytochemicals and bioactives is in the focus of functional food development. Here, the influence of matrix material, formulation, and structural parameters on stabilization and release of the molecules encapsulated has to be known for target product and process design. As the results are representative for hydrophilic active ingredients encapsulated in double emulsion systems a cross‐sectoral use in the pharmaceutical sector is possible.     

The loss of OSA‐modified starch emulsifier property during the high‐pressure homogeniser and encapsulation of multi‐flavour bergamot oil by spray drying

The encapsulation of bergamot oil by spray drying was investigated by using octenyl succinylated waxy maize starch as wall material and bergamot oil as core. The bergamot oil is majorly composed of d‐limonene, linalool and linalyl acetate. High‐speed and high‐pressure homogenisers were used as major tools of emulsification process. The results indicated that some chemical functional groups were lost during the high‐pressure homogenisation. Moreover, larger emulsion droplet size (5–10 μm) was observed when emulsion passed through high‐pressure homogeniser. Meanwhile, the saturation of carrier solution before preparing the emulsion was also important to produce the encapsulated flavour powder by spray drying. The optimal value of air inlet temperature at 160 °C to give the highest flavour retention and the lowest surface oil content was observed. Furthermore, the retention of linalool after spray drying was higher than 100%. The transformation of each flavour might occur.     

丁香油微胶囊的制备及表征

以明胶和海藻酸钠为壁材,采用复凝聚法对丁香油进行包覆,通过喷雾干燥法得到干燥的微胶囊产物,研究pH、明胶和海藻酸钠质量比、芯壁质量比、壁材用量、搅拌转速对微胶囊形成的影响,并对微胶囊的缓释性进行研究,采用红外、TG、SEM对优选实验条件下制备得到的微胶囊进行表征.结果表明:经过微胶囊化的丁香油挥发性明显降低,热稳定性大...     

Pea (<Emphasis Type="Italic">Pisum sativum,L.</Emphasis>) Protein Isolate Stabilized Emulsions: A Novel System for Microencapsulation of Lipophilic Ingredients by Spray Drying

Oil-in-water emulsions can be considered as an important delivery system for lipophilic food molecules. In this study, pea protein isolate (PPI) was studied for its emulsifying capacity at various pH values and pH 7 was selected to prepare emulsions for the production of dry microcapsules. Emulsions stabilized by PPI just enough to cover oil droplets were mixed with solutions of starch hydrolysates of various dextrose equivalent (DE) and subsequently spray dried to yield powders with 30 wt% oil. Effects of DE (6, 12, 19, and 28) on feed emulsion properties and on the characteristics of the spray-dried powders were examined. Reconstituted emulsion oil droplet size and stability were affected by DE in all cases. Microencapsulation efficiency of dried emulsions increased significantly with increasing DE. The scanning electron microscope results showed that lower maltodextrins DE microcapsules are shallow and presented rough surfaces or invaginations. However, higher carbohydrates DE microcapsules were circular and uniform showing minimum cracks and dents on the surface confirming these DE to be efficient encapsulating materials. The formation of the drying matrix seems control the destabilization of pea protein-coated oil droplets during spray drying. In systems where the matrix is formed in a uniform manner, the interfacial protein film is less affected by the drying process. Thus the functionalities of pea protein can be protected during drying by using high DE carbohydrates.