## 3 Results and Discussion
### Core Retention  
For a lipid-type core, the overall core losses during microencapsulation by spray drying represent losses from three sources: free core (lipids) at the outer surface of the drying capsule [60], core droplets that reside at the outer surfaces of the drying particle, immediately after the atomization stage, and core droplets that are transported from interior parts of the drying particles to the surface prior to the formation of dry crust [30; 31; 34; 52]. In all but one case, core retention during spray drying was higher than 83% and 50% of the spray-dried CIWEs resulted in a core retention higher than 90% (Table 3). In all cases, core retention was inversely related (\(p<0.05\)) to the concentration of WHPI in the wall solution (Table 3). The extent to which a given wall composition affected core retention varied among systems with different W:C ratio (Table 3). For example, at a W:C ratio of 75:25, core retention decreased by about 29% when the proportion of WHPI in the WS was increased from 2.5 to 10.0%, while in the case of CIWE with a C:W ratio of 50:50, the decrease in core retention with WHPI concentration in the WS was by only 7.3% (Table 3). In all cases, for a given composition of WS, core retention increased (\(p<0.05\)) with the core content of the CIWE (Table 3). The combined influence that the composition of the wall solution and the core load in the CIWE had on core retention could be explained by their combined effects on a multitude of variables that affected the formation and drying: the physico-chemical properties of the CIWE, the formation, drying, and properties the microcapsules during atomization and drying. Among these are the formation of droplets during atomization and their dimensions, the drying properties of the CIWE, the initial spatial distribution of core domains in the atomized droplets, and the severity of the internal mixing in the atomized droplets at early stages of the spray drying [31; 52]. Results (Table 3) clearly indicated that, in all cases, core retention increased (\(p<0.05\)) with the proportion of lactose in WS. The results suggested that increasing the proportion of lactose in the CIWE enhanced the drying rate of the wall matrices and thus results in a shorter constant-drying-rate phase of the drying process [30; 31]. Increasing the lactose content in the CIWE thus enhanced the solidification of wall matrices and the formation of dry crust around the drying droplets spray drying [30; 34]. Results suggested that, overall, the duration of the drying phase during which core droplets could be transported to- and lost from- the outer surface of the drying microcapsules was inversely related to the lactose content in the CIWE. Increasing the proportions  
Figure 2: The typical outer topography (**A,B**) and inner structure (**C,D**) of the investigated spray-dried microcapsules. Microcapsules in (**A–D**) were prepared with CIWE 2.5/17.5/25.75, 5.0/15.0/50:50;2.5/17.5/25:75, and 5.0/15.0/50:50, respectively. of WHPI and core in the CIWEs increased the viscosity of these emulsions to the extent that CIWEs 7.5/12.5/25:75 and 10.0/10.0/25:75 could not be atomized. A higher viscosity of CIWE could have been expected to lower the extent of the internal mixing that governed the transport of core droplets to the outer surface of the drying microcapsule and thus result in a smaller core loss. However, the observed inverse relationship between core retention and WHPI content suggested that the effect of lowering the concentration of lactose in the WS on core retention was more significant and detrimental to core retention than the suggested potential effect of WHPI on the internal mixing. For a given wall composition, the increase in core retention with the core content of the CIWE could be attributed to the decrease in the relative proportion of core (out of the total core content) that resided at the outer surface of the droplets, immediately after atomization.