Spray-drying, encapsulation method

This methodology includes the one-step method, and the spray-drying encapsulation. None of these techniques are capable to produce microcapsules smaller than 100 pm. ... 

Spray-drying is an economical effective method widely used for flavour encapsulation [22-27]. The technology has been used in the food industry since the late 1950s to provide protection of aroma chemicals against oxidation or degradation and to convert liquids into free-flowing solids. The main limitations... 

A very recent development is encapsulation of actives in colloidosomes [16, 41]. The method is analogous to liposome entrapment. Selectively permeable capsules are formed by surface-tension-driven deposition of solid colloidal particles onto the surface of an inner phase or active ingredient in a water-in-oil or an oil-in-water emulsion composed of colloidal particles. Initially synthetic polymer microparticles were used but more recently a natural alternative has been described based on small starch particles. After spray-drying, redispersible emulsions can be formed. 

The most common method to simultaneously dry and encapsulate flavours is the spray-drying technique (Fig. 21.11). For this technology, carrier materials like maltodextrin, starch and gum arabic are dissolved in water. As a next step, the liquid flavour raw material is emulsified in this slurry. Also non-volatile flavour components can be added. The slurry is atomised and dried in a spraydrying facility. 

Emulsions of lemon oil stabilized with gum arabic, a conventional starch dextrin and a low viscosity starch octenylsuccinate were spray-dried and evaluated for encapsulating efficiencies. Oil retentions and surface oil determinations were made according to the Materials and Methods section. TABLE 3 demonstrates the superiority of the starch octenylsuccinate in flavor retention and surface oil to gum arabic and a starch dextrin (5) ... 

Spray drying is one of the most cost effective and widely used methods of flavor encapsulation. While the process of spray drying is fairly straight forward, there are many variables relative to both sample preparation and actual drying conditions. 

Spray drying is the most widely used, least expensive and favored route among the methods available for encapsulation (2) Various theories of volatile retention in spray drying have been proposed and reviewed (3). In addition to the nature of flavor compounds, flavor retention is governed by type of carriers, infeed composition, solids concentration (4), dryer inlet/exit air temperature, air velocity and humidity, feeding rate and atomization characteristics. In addition to flavor retention,the stability of the encapsulated product, as mentioned earlier, is also of importance and is governed by nearly the same parameters. However,the effect and mechanics of each individual factor are much less understood. 

In a spray-drying method of encapsulation, Zhao and Whistler (1994) suspended starch to a concentration of 30% in water containing 0.1-1.0% gelatin or any of a number of polysaccharide bonding agents the suspension was forced through an orifice (2 mm diameter) under 80-100 psig at an inlet temperature of 120°C and outlet temperature of 76°C. Porous 10-40-nm-diameter spherical capsules were obtained that were then immersed in peppermint oil. After diffusion of the peppermint oil into the capsules, the spheres were rinsed free of oil and coated in a fluidized bed with a 3%... 

Spray drying is the most commonly used method in the food industry. Bioactive ingredients microencapsulated by this method include fats and oils, flavours, essential oils and other oil-soluble bioactives. Water-soluble bioactives can also be encapsulated by spray drying, where the encapsulant forms a matrix structure rather than a film surrounding the core. This process typically involves the dispersion of the core material into a solution of the encapsulant (e.g., protein, carbohydrate) and atomization of the mixture into the drying chamber. This leads to evaporation of the solvent... 

Spray Drying and Other Methods for Encapsulation of Flavourings... 

Spray dried flavourings have satisfied the demands of the food industry for quite some time. However, manufacturing technologies and application forms for food continue to develop. Modem flavourings have to keep up with these changes and with other special requirements put forward by producers. This has resulted in some further developments in the manufacture of encapsulated flavourings - the so-called complementary procedures - which have come into use in recent years. Complementary procedures are refinements, later developments of the spray drying technique. These methods are dealt with later in this section [1-3],... 

These few examples may demonstrate how differently flavours can be released, either at the point of processing the food or at the point of consumption. No single encapsulation method can satisfy all these different requirements. Hence methods other than spray drying, i.e. spray chilling, compacting, agglomerating and fluidised spray drying, as described below, have been developed. 

PLGA microspheres containing encapsulated DNA vaccines are usually prepared using double-emulsion methods or by spray-drying, resulting in more or less even distribution of DNA throughout the bulk of the microspheres. These micro-spheres have been evaluated extensively in vitro and in cell culture to study DNA release and uptake by immune cells (see Refs. [40, 41]). In vivo studies of this system have also been conducted in animal models [42 14] and in human trials for... 

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