## 3 Major Pre-Treatments for Sea Cucumber Processing
### Boiling/Heating
Due to the low heating, the meat becomes tender because of the action of proteolytic enzymes, reduction in fibrils, and solubilization of collagen [8]. Cathepsin L is a lysosomal protease, and one kind of endopeptidase, as well as other proteolytic enzymes, becomes activated during the autolysis of sea cucumbers below 80 \({}^{\circ}\)C while these enzymes become deactivated above this temperature [8]. Therefore, boiling time and temperature are crucial factors for retaining the chemical composition of the sea cucumbers, but it relies on the body wall thickness as well as softness. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Species**} & \multirow{2}{*}{**Pre-Treatment**} & \multicolumn{6}{c}{**Proximate Compounds**} & \multicolumn{6}{c}{**Biactive Compounds**} & \multirow{2}{*}{**Ref.**} \\ \cline{2-2} \cline{5-10}  & **Protein** & **Lipid** & **Carb.** & **Phenolics** & **Saponin** & **Polysac.** & **Collagen** & **Ref.** \\ \hline _Cucumaria fundus (BW)_ & Boiling at 100 \({}^{\circ}\)C for 30 min vs. steaming & 11.8\% I & - & - & - & - & - & - & [58] \\ \hline _Apostichopsis japonicus_ (BW) & Boiling at 100 \({}^{\circ}\)C for 10 min, & & & & & & & & \\ (BW) & then vacuum cooking at 95 \({}^{\circ}\)C & 9.95\% I & 0.59\% I & 1.64\% I & - & - & 1.5\% I & - & [37] \\ \hline _Stichopsis japonicus_ (BW) & Infrared radiation & 51.8\% I & - & - & - & 0.07\% I & 6.25\% I & - & [60] \\ \hline _Apostichopsis japonicus_ (BW) & Boiling at 100 \({}^{\circ}\)C for 10 min & 11.5\% D & - & 33\% D & - & 41\% D & - & - & [47] \\ \hline _Cucumaria fundus_ (IO) & HPP (200, 400, and 600 MPa for 5, 10, and 15 min) & - & - & - & 32.59\% I & - & - & - & [7] \\ \hline _Cucumaria fundus_ (BW) & HPP (200, 400, and 600 MPa for 5, 10, and 15 min) & & & & 29.21\% I & & & [7] \\ \hline _Cucumaria fundus_ Flower & HPP (600 MPa for 10 min) & & & & \multicolumn{2}{c}{241.38 mg} & & & [61] \\ \hline _Holethuris schema_ (BW) & Brining with 15 g/100 mL & - & - & - & - & - & 14.28\% D & [23] \\ \hline _Holethuris schema_ (BW) & Kenching for 24 h & - & - & - & - & - & - & 18.49\% D & [23] \\ \hline _Holethuris schema_ (BW) & Smoking & - & - & - & - & - & - & 12.50\% D & [23] \\ \hline _Holethuris schema_ (BW) & Boiling at 80–90 \({}^{\circ}\)C & - & - & - & - & - & - & 69.81\% D & [23] \\ \hline _Holethuris schema_ (BW) & Boiling at 80–90 \({}^{\circ}\)C and salted for 48 h & - & - & - & - & - & - & 38.41\% D & [23] \\ \hline _Sticapus japonicus_ (BW) & Atmospheric pressure boiling at 100 \({}^{\circ}\)C for 1 h & 14.8\% D & - & - & - & - & - & [62] \\ \hline _Sticopus japonicus_ (BW) & Atmospheric pressure steaming at 100 \({}^{\circ}\)C for 1 h & 13.0\% D & - & - & - & - & - & [62] \\ \hline _Sticopus japonicus_ (BW) & High-pressure steaming at 121 \({}^{\circ}\)C for 10 min under 11.6\% D & - & - & - & - & - & - & [62] \\ \hline _Apostichopsis japonicus_ & Vacuum cooking at 95 \({}^{\circ}\)C for 3 h under \(-\)0.04 MPa & 9.95\% I & 0.59\% I & 1.64\% I & - & - & 1.5\% I & - & [37] \\ \hline _Apostichopsis japonicus_ & Vacuum cooking at 95 \({}^{\circ}\)C for 3 h under \(-\)0.04 MPa then soaking at 4\({}^{\circ}\)C water for 12 h & 1.33\% I & 0.04\% D & 0.28\% D & - & - & 0.33\% I & - & [37] \\ \hline \multicolumn{10}{c}{HPP + high-pressure processing, I = increased and D =decreased than when found in control without any treatments.} \\ \multicolumn{10}{c}{BW = body wall; IO = internal organ; GAE= gallic acid equivalents; Carb. = carbohydrates; Polysac. = polysaccharides.} \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Different pre-treatments on the proximate and bioactive compounds of sea cucumbers.