Valorisation de co-produits de la sole tropicale (Cynoglossus senegalensis) par hydrolyse enzymatique : Application en nutrition avicole

This scope of work relates to the valorization of the tongue sole (Cynoglossus senegalensis) by-products resulting from the processing chain in Senegal by the implementation of enzymatic hydrolysis in order to obtain high value proteins. The by-products (viscera and heads) of tongue sole, were hydrolized with the Protamex® enzyme. Degrees of hydrolysis of 25% and 19% were obtained respectively with 40°C and 50°C.The results also showed that the proteins contained in these by-products are solubilized by the action of this protease at the end of 180 minutes of hydrolysis. The biochemical characterization showed that these hydrolysates are rich in proteins (61%) and minerals (10%). However, the hydrolysates contain peptides of lower molecular sizes 1760 Dalton. For the optimization of hydrolysis conditions, the effectiveness of four different water ratio to hydrolyze sole by-products by using Protamex® were compared. It was found that by changing the hydrolysis conditions it was possible to produce hydrolysates with the same proportion of proteins (60%). Lastly, these hydrolysates have high nutritional value in order to set up table fowls because they have in big quantity nine (9) essential amino acids for the animal feed. Finally, trials were carried out on 1200 chickens (cobb 500) since 14 days of age. The results showed that high nutritional value by-products proteins increase the growth of the birds. So, the live weights at 6 weeks are 2369.60 G (batch 1), 2189.60 G (batch 2), 2298.05 G (batch 3) against 2158.20 G (witness batch), with respective average GMQ of 78.20 G, 66.72 G, 69.89 G and 68.30 G. The carcass weights are 2112.43 G (batch 1), 1994.67 G (batch 2), 2081.75 G (batch 3) and 1989.22 G (witness batch). Food consumption seems little influenced by the level and the nature of proteins. However, their presence decreased the consumption index during the end of the study; it is 2.30 (batch 1), 2.07 (batch 2), 2.05 (batch 3) and 20.8 (witness batch). To identify the future application of hydrolysates in human food, a sensory analysis was carried out. The sensory profile was performed with a jury of 14 specialized judges.11 profiles were found by this panel of tasting. In addition, the aromatic characterization revealed that 57 molecules are responsible for these odours described in sensory analysis. The description of these aromatic compounds opens potential way of valorization of these hydrolysates in human consumption.