Optimal extraction and hydrolysis of Chlorella pyrenoidosa proteins

In this study, for the first time, the applications of two new methods, ionic liquid and low-temperature high-pressure cell breakage methods, to the extraction of whole proteins in Chlorella pyrenoidosa cells were explored. Meanwhile, the comparison with three traditional methods was also made. The results indicated that the extraction rate for ionic liquid is only at moderate level, but the new low-temperature high-pressure cell breakage method can obviously increase the protein extraction rate up to 2- to 15-fold. Subsequently, the hydrolysis of the extracted proteins was conducted with three enzymes (papain, trypsin and alcalase). The data presented that the degree of hydrolysis for each enzyme under the optimal conditions is in the order of: alcalase (18.31%) > papain (14.33%) > trypsin (8.47%), demonstrating the potential of C. pyrenoidosa protein hydrolysates obtained here in nutritional supplement and medical foods.

► For the first time two new methods were applied to whole protein extraction in microalgal cells.
► Two new methods: ionic liquid (IL) and low-temperature high-pressure cell breakage (LTHPCB).
► The newly developed LTHPCB can facilitate the development of Chlorella industry.
► The extracted proteins were hydrolyzed with three enzymes (papain, trypsin and alcalase).
► The obtained protein hydrolysates should be useful in nutritional supplement and medical foods.