Milk fat globule fractions recovered by disc stack centrifugal separation of camel milk: Process-induced fat balance, microstructure and lipid composition as a function of size

In recent years, camel milk has become the focus of growing interest in different parts of the world due to its nutritional significance, sustainability, and promising opportunities for dairy product processing. The objectives of this study were to increase knowledge about the size-based fractionation of camel milk fat globules (CMFGs) occurring during conventional centrifugal separation, to calculate the fat balance, to determine the fatty acid, cholesterol and polar lipid compositions as a function of CMFG size, and to examine the microstructure of the CMFG membrane. A comparative analysis with bovine milk was performed. Centrifugal separation of camel milks induced the recovery of CMFG-enriched creams (317.8 ± 12.1 g/kg of fat; mean diameter: 3.2 μm), and of semi-skim milks containing 16.7 ± 1.2 g/kg of fat dispersed in small CMFGs of 0.5 μm in diameter. The fat balance revealed that a high amount of camel milk fat was recovered in the aqueous phase, i.e. 47 %wt versus 53 %wt recovered in the cream. Small CMFGs contained a greater amount of membrane polar lipids than larger ones: 37.4 ± 2.4 vs. 13.6 ± 0.4 mg/g fat. CMFGs contained 41 g sphingomyelin per 100g polar lipids, corresponding to 15.3 ± 0.8 mg/g fat in small CMFGs and 7.4 ± 0.7 mg/g fat in whole milks, which is of nutritional interest. The microscopic observations of the CMFG membrane revealed a heterogeneous distribution of proteins and polar lipids with circular lipid microdomains rich in sphingomyelin and possibly cholesterol. This study opens perspectives for the valorization of the semi-skim milk fraction recovered as a co-product of camel cream preparation. • Centrifugal separation of camel milk leads to size-based fractionation of fat globule • A high fat content of 16 g/kg (47 % of total milk fat) is recovered in the high density aqueous phase • Small milk fat globules (MFG) of 0.5 μm diameter are recovered in the semi-skim milk fraction • The camel MFG membrane contains a high proportion of sphingomyelin with 41 % of polar lipids • This study opens perspectives for the valorization of the co-product of camel cream preparation