Flavor retention

Viscosity. Viscosity and solubility may be the two most important characteristics of an encapsulation matrix ingredient. The increase in solids to the dryer at a constant solids/flavor ratio can greatly increase the economic efficiency of an operation. Most processing systems have a maximum viscosity at which they can operate. Proper atomization may also affect the flavor retention (Reineccius and Bangs 1985). The low viscosity of maltodextrins and corn syrup solids is shown in Figure 2. The viscosity of these products... 

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. ... 

Dryer air humidity can be controlled by dehumidifying the inlet air. This would favor rapid drying and flavor retention. Dehumidification typically is cost prohibitive and, therefore, is seldom done. 

Thijssen stated that dryer infeed temperature should be elevated such that higher infeed solids (i.e. greater solubility) may be used. The higher infeed solids would result in better flavor retention. 

The role of particle size of the atomized droplets in determining flavor retention is also controversial. Several workers have reported that larger particle sizes result in improved flavor retentions (2, 9, 23, 24, 43). To the contrary,... 

Previous work has shown that flavor retention increases with increasing inlet air temperature until internal steam is formed in the drying droplet (12). The higher inlet air temperatures produce a more rapid drying which thereby results in a shorter time until the formation of a high solids "skin" around the drying droplet. This "skin" acts as a semipermeable membrane which retains the larger (relative to water) flavor molecules. 

Previous work (12) has also demonstrated that higher exit air temperatures result in improved flavor retention. It has been postulated that higher exit air temperatures result in more rapid drying, thereby providing better retention of volatiles. We do not observe this relationship in this study. 

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. 

AT values are thus divided into two major groups flavor components which were found to possess a high AT (greater than 1.0, the value for water), and those with low AT (less than 1.0). High AT components tend to get hotter in the microwave oven and therefore can be used most effectively in "reaction"-type flavors where browning and caramelization is desirable. Conversely, low AT values reflect the reduced heat absorbance of flavor components within the microwave oven. They are less prone to microwave-related "modifications" or "flashing-off" and are therefore likely to have superior flavor retention. Experimental data for chemical combinations, essential oils, and flavor systems will appear in a future publication. 

The solubility of flavor ingredients influences the retention of flavors. Retentions of several esters in GA encapsulation were studied (Rosenberg et al., 1990). Retentions of partially water-soluble esters, such as ethyl propionate and ethyl butyrate (EB), were less than those of esters having lower solubility (ethyl caproate). A similar trend was also reported by Liu et al. (2001) and Soottitantawat et al. (2003). A higher retention of o-limonene (insoluble flavor) was observed compared to that of EB (moderate solubility). 

Flavor retention is dependent not only on the solubility of the flavor but also on the emulsion size. For example, the retention of o-limonene was found to decrease with an increase in the emulsion size, as illustrated in Figure 1.4 (Soottitantawat et al., 2003). The increased loss of esters at small emulsion sizes was due to the larger surface areas of the fine emulsions the increase in surface areas of emulsion droplets would result in an accelerated dissolution of the flavor in the carrier solution, and loss... 

Kllengode ANR, Hanna MA. 1997. Cyclodextrin complexed flavors retention in extruded starches. Journal of Food Science 62 1057-1060. 

Reineccius GA, Coulter ST. 1969. Flavor retention during drying. Journal of Dairy Science 52(8) 1219-1223. 

The relative merits of sucrose, dextrose, and corn sirup as a food preservative from the standpoint of color and flavor retention have been investigated by several workers. Using frozen peach slices (18, 118, 116), strawberry preserves (110), and frozen blackberries and raspberries (17), the following results were observed (1) Replacement of part of the sucrose by dextrose resulted in poorer color of frozen peaches and (2) replacement of 25 to 50% of the sucrose with corn sirup produced detectable changes in flavor in all the cited foods. 

---