Spray flavor retention

Dried flavoring wall material development conducted in this study was completed in two separate phases. Firstly, a water-dispersable starch polymer which 1) exhibited good flavor retention potential during spray drying and 2) was able to form a stable flavor-incorporated aqueous emulsion was examined. 

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) ... 

In order then to determine what influences flavor retention during drying, one must focus attention on the very early stages of dehydration. In fact, it has been shown that the major fraction of total volatiles lost during nozzle-atomized spray drying occurs within ten centimeters of the pressure nozzle (17, 33, 35). 

While the infeed solids content of the infeed material has an unquestionably greater influence on the retention of volatile flavors than does the type of carrier used, carrier type does influence flavor retention during spray drying (4, 16, 31, 3Z. ... 

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. 

The emulsifiers and emnlsifying techniques to produce nanoparticle encapsulated powders (Jafari et al., 2007a). In the case of fish oil encapsulated in maltodextrin combined with modified starch or whey protein concentrate, spray-dried powders were obtained from nanoemulsions (210-280 nm) prepared by microfluidization, with a good efficiency (Jafari, 2009). And the satnration of the carrier solution of wall materials influenced the flavor retention and surface oil content (Penbundiktul et al., 2012). 

Baranauskiene R., Bylaite E., Zukauskaite J., and Venskutonis R.P., 2007. Flavor retention of peppermint essential oil spray-dried in modified starches during encapsulation and storage. Journal of Agricultural and Food Chemistry, 55, 3027-3036. 

Freeze drying is a special case of drying under vacuum at a temperature below the triple point of water here water (ice) sublimes directly into water vapor. Although the heat required for sublimation is severalfold lower than for evaporation, vacuum operation is expensive. Freeze drying of coffee, for example, costs two to three times more than spray drying. On the other hand, the product quality and flavor retention are better. 

In the following sections, encapsulation of flavor by means of spray drying will be discussed. We will focus on flavor retention during spray drying, stability of the encapsulated flavor on the basis of emulsion properties, and on the release and oxidation rates in the spray-dried powder. 

The selective diffusion theory has been well formulated mathematically and solved by numerical calculations. On the basis of such calculations, flavor retention during spray drying increases with the increase in solids content in the feed, inlet gas temperature and inlet gas flow rate, as well as with the decrease in inlet gas humidity, see Fig. 6.20. All of these conditions favor the early formation of a dry skin on the surface of the droplet (Furuta et ol., 1984). 

Risch, S. J., Reineccius, G. A., 1988. Spray-dried orange oil Effect of emulsion size on flavor retention and shelf stability, in Fhvor encapsulation (eds S. J. Risch, G. A. Reineccius). American Chemical Society, Washington DC, USA, pp. 67-77. 

Flavor carrier choice has been shown to influence volatile retention during spray drying by numerous authors [19,62-66]. This influence can be indirect in the sense that some carrier materials become very viscous at relatively low solids contents. For example, Dronen [67] has shown that a soy protein concentrate infeed is limited to ca. 15% infeed solids or its viscosity prohibits effective atomization. Low solids means poor flavor retention. Dronen [67] found an average retention of a model volatile mixture to be only 13.1% when spray dried in a soy concentrate but 24.7% when dried in a whey protein isolate carrier (30% infeed solids). We assume that the two proteins would act reasonably similarly in terms of retaining volatiles and the difference in retention is primarily due to the low infeed solids of the soy protein infeed. 

Once a carrier (or blend of carriers) has been selected, it (or they) must be rehydrated in water. It is desirable to use a particular infeed solids level that is optimum for each carrier or combination of carriers. Research has shown that infeed solids level is the most important determinant of flavor retention during spray drying (Figure 13.9). While most research has suggested that one should use as high an infeed soUds level as possible, other work has shown that there is an optimum infeed solids level for each carrier system [68]. The existence of an optimum in solids content may be due to either the possibiUty that adding solids beyond their solubility... 

Dryer Operating Parameters Having considered the formulation and preparation of the material to be spray dried, one must now consider the effect of spray drier operating variables on flavor retention. One needs to choose operating temperatures, air flow rates, inlet air dehumidiiication etc. 

Risch, S.J., G.A. Reineccius, Effect of emulsion size on flavor retention and shelf-stability of spray dried orange oil, in Flavor Encapsulation, S.J. Risch, G.A. Reineccius, Eds., Amer. Chem. Soc., Washington, D.C., 1988, p. 67. 

Example 1.3-7 Flavor retention When food products are spray-dried, they lose a lot of flavor. However, they lose less than would be expected on the basis of the relative vapor pressures of water and the flavor compounds. The reason apparently is that the drying food often forms a tight gellike skin across which diffusion of the flavor compounds is inhibited. What diffusion model should you use to study this effect ... 

Possibly the most important, and least understood, aspect of spray-dried flavorings manufacture is the role the wall material plays in this process. The polymers utilized for this product are controlled by FDA constraints, cost, finished product labelling considerations and compatability, functionality and historical usage. Given these considerations, polymers selected for the retention and maintenance of labile flavors and aromas in industrial spray dried, food grade systems include both carbohydrate (hydrolyzed starches, "lipophilic starches, plant exudates) and protein. The importance of these wall materials should not be underestimated. 

Viability of Starch Derivatives as Flavoring Encapsulants. The capillary GC vapor phase flux term (defined by a percent external standard or ZEStD flux) previously described (34) was used to screen starch derivatives (oxidized, dextrinized and/or covalent amino acid linkage) as to their flavor encapsulation potential. The samples were prepared as previously described (34) with the exception of an added reduced pressure deaeration step, thus allowing the use of the headspace diffusivity versus retention standard curves to predict volatile lemon oil retention following spray drying. 

Following preliminary hypochlorite treatments, a coherent process path was identified and implemented. Corn starch was oxidized with 6.4% (w/w) hypochlorite for two hours and given a combined base-heat gelatinization process (Method A). This base material exhibited excellent physical characteristics (i.e., stable emulsion with 20% db lemon oil incorporation into an aqueous dispersion, low lemon oil vapor phase flux (low headspace content), lack of inherent flavor and aroma) and when finally tested for spray dried lemon oil (20% db) retention efficiency in a lab-scale mini-dryer, the viability of this polymer was ascertained. Nearly 70% of the added lemon oil was retained following the drying of this DE 1.45 starch, a measure of functionality matched only by gum arabic (34). 

Starch octenylsuccinates offer excellent emulsifying properties, flavor oil retention and good oxidation resistance versus gum arabic. They can be made on a variety of starch bases, dextrins or fluidities which provide versatility and improved spray-drying costs. Starch octenylsuccinate are low in cost, domestically produced and are not subject to the market fluctuations that gum arabic encounters. 

The process parameters which have been stated as influencing the retention of volatile flavor compounds during spray drying are (36) ... 

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