The ability of dromedary skim milk to form an acid curd during a lactic acid starter fermentation was investigated. The activity of the starter in dromedary milk was characterized by a longer lag phase ( approximately 5 vs. approximately 1 h) and by an earlier decline phase. This suggests the presence of inhibiting factors. The maximum buffering capacity of dromedary milk as well as its minimum apparent viscosity were obtained at lower pH values. Similarly, its elastic modulus appeared later (pH 5.7 vs. 6.3). Because these rheological and biochemical events took place at lower pH values, dromedary skim milk seems to present a higher physical stability toward the increase of acidity. Determination of the rheological and microscopic characteristics of the dromedary milk coagulum (pH 4.4) did not reveal curd formation but indicated a fragile and heterogeneous structure. This coagulum, which is very different from that of cows' milk, seems to be made up of dispersed casein flakes.

Structural and physicochemical characteristics of dromedary milk fat were investigated and compared with those of cow's milk fat. The fatty acid composition of dromedary milk fat showed the presence of very small amounts of short‐chain fatty acids (C4–C12) and a higher content of 16:1 and 18:0. The microscopic study showed a discontinuous phase of globules with a smaller size but presenting a relatively thicker membrane layer. The rheological and the melting studies showed that dromedary milk fat on the one hand had a relatively higher fusion point, a higher fusion enthalpy and a higher apparent viscosity and on the other hand a relatively lower value of storage modulus (G'). These various characteristics correlated with the results obtained by microscopy and chromatography.

-Biochemical and physical properties of dromedary milk were studied at initial pH and during an acidification with glucono-δ-lactone. In comparison with bovine milk salt, citrate and nitrogen partition between soluble and micellar phases revealed several characteristics. Dromedary milk micelle presented a more important mineral plus citrate charge (~98 mg . g -1 casein). Micellar Mg, P and citrate proportions were higher, about 2/3, 2/3 and 1/3, respectively. During acidification, micellar mineral and citrate release started tardily (~pH 5.8) and the maximum of casein and Pi solubilization took place at lower pH values, 4.9 and 4.8, respectively. Dromedary milk micelle seemed to maintain its integrity until about pH 5.5, below, it underwent extensive biochemical and structural modifications mainly at pH 5.0. At this point, dromedary milk was characterized by a loose microstructure, by a maximum of loss modulus and of micelle hydration and by a minimum of apparent viscosity. The pH 5.0 would be a transition pH between micellar structure and coagulum structure. dromedary milk / micelle / acidification / microscopy / rheology Résumé -Caractérisation de la micelle de caséine du lait de dromadaire et étude de son évolution au cours de l'acidification. Des propriétés biochimiques et physiques du lait de dromadaire ont été étudiées au pH initial et au cours d'une acidification par la glucono-δ-lactone. La déter-mination des répartitions de la fraction minérale, du citrate et de la fraction azotée du lait, entre les phases micellaire et soluble, a révélé de nombreuses particularités par rapport au lait bovin. La micelle du lait camelin présente une charge en minéraux plus citrate relativement plus importante (~98 mg . g -1 caséines). Les proportions en Mg, en P et en citrate micellaires sont plus élevées (respectivement 2/3, 2/3, 1/3). Au cours de l'acidification, la libération des minéraux et du citrate micel

The human Y chromosome is essential for human sex determination and spermatogenesis. The long arm contains the azoospermia factor (AZF) region. Microdeletions in this region are responsible for male infertility. The objective of this study was to determine the frequency of Y microdeletions in Algerian infertile males with azoospermia and oligoasthenoteratozoospermia syndrome (OATS) and to compare the prevalence of these abnormalities with other countries and regions worldwide. A sample of 80 Algerian infertile males with a low sperm count (1-20 × 10⁶ sperms/ml) as well as 20 fertile male controls was screened for Y chromosome microdeletions. 49 men were azoospermic and 31 men had OATS. Genomic DNA was isolated from blood and polymerase chain reaction was carried out with a set of 6 AZFa, AZFb and AZFc STS markers to detect the microdeletions as recommended by the European Academy of Andrology. Among the 80 infertile men screened for microdeletion, 1 subject was found to have microdeletions in the AZFc (sY254 and sY255) region. The deletion was found in azoospermic subjects (1/49, 2%). The overall AZF deletion frequency was low (1/80, 1.3%). AZF microdeletions were observed neither in the OATS group nor in the control group. The frequency of AZF microdeletions in infertile men from Algeria was comparable to those reported in the literature. We suggest analyzing 6 STS in the first step to detect Y microdeletions in our population.

Direct chemical acidification of milk: correlation between the mobility of micellar material and the macro and microstructures of acidified milk.Direct addition of lactic acid was used to follow the behaviour of reconstituted skimmed milk during a chemical acidification. The mobility of the micellar materials: minerals and caseins, was correlated with the change in a range of physicochemical parameters such as buffering capacity and conductivity. It was hypothesized that, for a given pH, the transformations that emerge within milk would be dependent on the biochemical state of: the added lactic acid; the micellar minerals; and of some of the functional groups of caseins. Determination of rheological state equations, calculation of storage and loss moduli and visualization by Scanning Electron Microscopy, allowed the hypothesis to be consolidated and showed the existence of three characteristic points around pH 5.8, 5.4 and 5.0. These results permitted some specificities of rapid and direct chemical acidification to be deduced and allowed their comparison with the situation in slow biological acidification.