3.1.3. Color Analysis

The market value of shrimp depends on the visual appearance of their body color, which is attributed to the presence of astaxanthin [38]. This carotenoid pigment is responsible for orange red tissue pigmentation in shrimp meat. Table 2 shows the color differences of the shrimp. The *L*\* value of shrimp increases from 40.71 when fresh to 63.85 after boiling (*p* < 0.05), which may be due to the increase in heat during boiling, resulting in protein accumulation and an increase in opacity. However, the *L*\* value of the shrimp decreases with more drying (*p* < 0.05). The blackening of dried shrimp is attributed to the Maillard reaction during drying [39]. Moreover, *a*\* and *b*\* exhibit similar trends throughout drying. The *a*\* and *b*\* values of dried shrimp are significantly higher than those of fresh shrimp (*p* < 0.05). The formation of redness upon the exposure of shrimp meat to heat is a result of the release of astaxanthin owing to the breakdown of carotene protein during denaturation. There are slight decreases in *a*\* and *b*\* values in the late drying period, which may be due to a slower drying rate and longer drying time, resulting in the slight damage of astaxanthin from the extension of hot air-drying. Regarding Δ*E* values, the results for Δ*E* > 12 show that the color of shrimp during drying is notably different from that of fresh shrimp.


**Table 2.** Effects of hot air drying on the color of shrimp.

Note: All data are presented as mean ± standard error. Mean values with different letters within each line are significantly different (*p* < 0.05) with respect to processing. "-"represents the blank.
