The effect of crude protease from Pacific white shrimp hepatopancreas at different levels and various hydrolysis times on the recovery of carotenoprotein from Pacific white shrimp shells is shown in Fig. 1A. At the same hydrolysis time, the recovery of carotenoproteins increased with increasing protease levels (p0.05). The limited amount of protein substrate for hydrolysis reaction by crude protease most likely contributed to the plateau observed when crude protease above 20 units/g shrimp shells was used. The results indicated that the addition of crude protease from Pacific white shrimp hepatopancreas was effective in increasing the recovery of carotenoproteins from shrimp shell. For all protease levels used, the rapid hydrolysis of protein was observed within the first 60 min. Thereafter, a slower rate of hydrolysis was found up to 120 min. No differences in protein recovery were observed after 120 min (p>0.05). This was in accordance with the slower rate of hydrolysis after 60 min. This typical curve was also reported by Klomklao et al. (2009) when trypsin from bluefish was used for recovery of carotenoproteins from black tiger shrimp shells. Furthermore, the increase in trypsin concentration (0–1.2 units/g shrimp shells) resulted in an increase in recovered proteins ( Klomklao et al., 2009). Trypsin was used to extract carotenoprotein from brown shrimp shell waste and showed the maximum recovery (55%) of carotenoid pigment in 4 h at (28±2 °C). Pepsin and papain yielded 50% recovery when the same hydrolysis time was used ( Chakrabarti, 2002). Armenta and Guerrero-Legarreta (2009) reported that fermented carotenoproteins from Pacific white shrimp waste were hydrolysed with a combination of protease and lipase. Protein recovery was used as an indicator for the cleavage of peptide bond, and the release of the carotenoprotein