# A Study of the Dromedary Milk Casein Micelle and its Changes during Acidification

## Introduction

Dromedary milk continues to be drunk fresh because it is not suitable for transformation into dairy products like other types of milk (FARAH; BACHMANN, 1987; MEHAIA et al. 1988; FARAH; ATKINS, 1992; WANGOH et al., 1993; ABU- TARBOUSH, 1994). Difficulties are related concerning the control of the coagulation operation, which is a necessary stage in the development of dairy products. Thus, neither the enzymatic nor the mixed method forms a coagulum with the required qualities to undergo further technological treatment (FARAH, 1993). The information currently available on dromedary milk concerns its general composition (SAWAYA et al., 1984; MEHAIA, 1994), its behaviour during fermentation (ABU TARBOUSH, 1996; ABU TARBOUSH et al., 1998), its aptitude for certain physical separations (MEHAIA, 1996) and its richness in molecules with antibacterial activity (ELAGAMY et al., 1996). Studies concerning its adaptation to technological transformations were limited to studying the feasibility of manufacturing certain products and mentioning the technological difficulties faced (ABU-LEHIA et al., 1989; FARAH et al., 1989; FARAH et al., 1990; MOHAMED et al., 1990; MEHAIA, 1993). However, the acidification and coagulation processes have not been extensively investigated. In these processes, the component playing a dominant role in the formation of the mechanical properties of the gel is the casein fraction. This has already been shown to be the case in cow’s milk (BRULÉ et al., 1997). Therefore, to understand dromedary milk curds, it may be necessary to study the casein structure and composition at the natural milk pH and its changes during pH lowering. This study attempted to investigate this from various approaches: electron microscopy, rheology and physico-chemistry. The results were compared with those of cow’s milk.