Physico-chemical characterization of milk coagulation with an extract of Calotropis procera - A comparison with chymosin
Résumé
Chymosin is the common enzyme used in cheese making worldwide but other enzymes especially from vegetable origin also exist. In West Africa, an extract of the shrub Calotropis procera, is traditionally used to make a local soft cheese named Wagashi. This cheese, produced and marketed by women, is an interesting source of incomes. The aim of this study was to understand the milk coagulation mechanism by an extract of Calotropis procera leaves in comparison with chymosin. A standard manufacturing process was set up for making both Calotropis procera and chymosin curds. The contents in dry matter, ash and total nitrogen were more important for the curds manufactured using Calotropis procera (310,9; 31,1 and 231,9 g.Kg-1, respectively) compared to those made using chymosin ( 305,7; 25,5 and 207,8 g.Kg-1, respectively). The whey liquid dry matter was also more important when Calotropis procera extract was used. In spite of these composition differences considered as small, both types of curds can be classified as rennet curds strongly mineralized. Analysis by chromatography coupled to tandem mass spectrometry showed an increasing number of peptides coming from -caseins hydrolysis identified in the whey liquids: 96 when using Calotropis procera extract and 47 when using chymosin as coagulant. The proteolysis of this casein molecule explains the milk coagulation observed in both cases. The observation of the two curds by scanning electron microscopy have revealed regular networks with the presence of aggregates of casein micelles. These results support that Calotropis procera extract can be used as effective coagulant in cheese manufacturing with technological adaptations to take in consideration and specific organoleptic and textural specifies.
