Tropicultura (Jan 2006)
Mise en évidence d'un agent coagulant utilisable en fromagerie dans les fruits de Balanites aegyptiaca
Abstract
Study of a Suitable Cheese Making Milk-clotting Agent from Balanites aegyptiaca Fruits. As slaughtering of zebu (Bos indicus) calves in Cameroon is forbidden, calf abomasa are rare on markets so it is diffi cult to prepare rennet. The aim of this study was to look for other sources of milk clotting extracts, especially from Balanites aegyptiaca fruits. B. aegyptiaca is a widespread tree in northern Cameroon. Its fruit is pulpy with a thin and hard epicarp, a dark brown mesocarp and a hard endocarp enclosing an oil seed. The fruits of B. aegyptiaca were harvested at Pitoa (9°23' N, 13°32 E). Milk clotting, determined by the Berridge method, was only obtained with mesocarp extracts. The experimental design of the extraction was a split-plot (5 4 4) with 5 mesocarp concentrations, 4 temperatures and 4 maceration times. Optimum extraction was performed when macerating 50 g mesocarp in 100 ml water at 4 °C during 9 h. Protein content (91 14 mg. ml-1) was determined by bicinchoninic acid assay. Five proteins of respective molecular masses 27, 30, 42, 44 and 90 kg.mole-1 were observed by SDS-PAGE under reducing conditions. The force of the extract was determined by comparing its milk clotting time to that obtained with rennet. Proteolytic activity of the extract was measured by hydrolysis of bovine haemoglobin and titration of free NH2 using l'ophthaldialdehyde reagent. Counting of coliforms was carried out on DCL gelose, that of the total aerobic mesophil fl ora on PCA and that of the sulfi to-reducing fl ora on TSN. The extract only contained coliforms and aerobic mesophil fl ora. Fresh cheese was made with zebu milk using rennet or B. aegyptiaca mesocarp extract. Indemnes of Specifi que Pathogen Organism mice were fed with these cheeses then with crude B. aegyptiaca mesocarp extract. No abnormality, nor toxicity were observed on mice. A panel was allowed to appreciate these cheeses. Statistical analysis was conducted using SASsoftware. It was concluded that B. aegyptiaca mesocarp extract is suitable for cheese manufacture.
