## 4 Discussion  
### The Physicochemical Properties of Egg Powders  
The effect of the egg yolk to egg white ratio and the addition of sucrose (0%, 5%, and 7.5%), on the physicochemical properties of the dried products obtained by spray-drying was evaluated. The production yields of the dried egg products W, M1:3, and WE5% equated to values of 82 \(\pm\) 2%, 91.2 \(\pm\) 0.6%, and 91 \(\pm\) 1%, respectively. These results are probably due to the air temperatures at the dryer chamber outlet, which were close to the glass transition temperatures reported for whole eggs (59-63 \({}^{\circ}\)C) and egg whites (98-115 \({}^{\circ}\)C). The outlet air temperature was in the range of 74-77 \({}^{\circ}\)C during the drying of W and WE, and in the range of 71-77 \({}^{\circ}\)C during the drying of M1:3, conditions that prevented the development of high material stickiness and, consequently, relatively high production yields [7, 28, 29, 30]. The dried egg products had Aw values lower than 0.3, due to their low moisture contents (below 3.8%) and high compositions of protein and carbohydrates, molecules with a high capacity for binding with water. The W egg product with 0% sucrose had the lowest Aw (0.196 \(\pm\) 0.002) and the highest protein content (80.48%), binding higher amounts of water than do carbohydrates (see Tables 3 and 5) [30]. The low water activity of the egg powder products favors stability during storage. Optimal stability is usually achieved for Aw at between 0.2 and 0.3 [30], which was the range of the Aw in the products obtained in this research. Furthermore, these values of water activities were similar to those reported by [PERSON], et al. [30] for the whole egg, egg yolk, and egg white (0.25, 0.25, and 0.23, respectively). Figure 2: Total amino acid composition of egg powders: whole egg with the addition of 5% sucrose (WE5%); a mixture of 1 part egg yolk and 3 parts egg white (M1:3); and egg white (W). Average data (\(n\) = 2). * Essential amino acids. Bars represent standard deviation. In accordance with the results in Table 3, WE showed an increase of 8.7% in WSI value at 25 \({}^{\circ}\)C when 5% of sucrose was added [14]. In contrast, W and M1:3 showed no WSI increase when sucrose was added. Some of the reasons for this behavior include high protein content in these egg products (see Table 4), as it is believed that the higher protein content in egg powders causes reduced dispersing capacities in water when proteins absorb water and swell, and this phenomenon reduces the ability of the material to progressively disintegrate into particles of smaller sizes [30]. However, under the process conditions studied, WSI values of above 80% were obtained for all powdered egg products. These were higher than those reported by [PERSON] [10] for powdered whole egg, processed in a spray-dryer set with a disk rotating at high speeds to spray the feed liquid. [PERSON] [10] studied a dried mixture composed of 87% unpasteurized liquid whole egg, 12.7% maltodextrin DE 17-20, and 0.33% salt, dried at 180 \({}^{\circ}\)C. The WSI value of the dried product was 75.5 \(\pm\) 0.5%. This could be due to the effect of drying temperatures, the dissolution in water of the liquid mixture, mixture compositions, or particle size, which is dependent on the atomization system and affects the dissolution rate. This is faster with smaller particles because the surface area increases as particle size decreases [8; 19; 30]. The value of lightness and coordinates a* and b* produced numerous variations compared to those reported by [PERSON], et al. [30]. This could be due to the specific characteristics of the feed material and the moderate drying air-temperature conditions (120 \({}^{\circ}\)C) used in this investigation. These could have triggered the color change to brown and caused pigment oxidation [11]. In egg powders, the color results depend on the chemical compositions of liquid eggs, thus influencing liquid color, which may vary from very light yellow to a vivid, dark orange.