Protein hydrolysates from the alga Chlorella vulgaris 87/1 with potentialities in immunonutrition
Abstract
Chlorella vulgaris (Chlorophyta, Chlorophyceae) has received a particular attention in the programmes of microalgae utilisation in biotechnology. Enzymatic hydrolysis of cell proteins represents a very promising method to increase protein digestibility and thus, for obtaining hydrolysates with improved nutritional and functional properties. However, this technology has been little approached and the biological evaluation of hydrolysates has had a strictly nutritional nature. The design of hydrolysis conditions that combined for the first time, the use of C.vulgaris 87/1 treated with ethanol and pancreatin at pH values of 7.5-8.0, led to a product with a degree of hydrolysis of 20-22% and yields of 50-55%, characterised by a high digestibility (97.2%) and nitrogen solubility over a wide pH range (2.0- 10.0). Hydrolysis curves were fitted to an exponential model, common to many food proteins. The bulk of the product dry matter consists of soluble peptides and free amino acids (47.7%) with three main peptides of molecular masses between 2 and 5 kDa. The oral administration of Chlorella hydrolysate (500 mg/kg) to undernourished Balb/c mice provided benefits in terms of liver protein metabolism and the induction of anabolic processes in gut mucosa. The hydrolysate also enhanced the immunological recovery, as judged by the stimulation of haemopoiesis, monocyte-macrophage system activation, as well as humoral and cell mediated immune functions, like T-dependent antibody response and the reconstitution of delayed-type hypersensitivity (DTH) response. These results represent the first findings in the world concerning the immunomodulating effects of a microalgae protein hydrolysate.
