Buttermilk, a potential material used to produce milk fat globule membrane (MFGM), is obtained as a byproduct of butter making from milk whole cream and cheese whey cream. This study investigated the effects of rennet and acid coagulation on the protein profiles of buttermilk rennet-coagulated whey (BRW) and buttermilk acid-coagulated whey (BAW). They were compared to those of whey cream buttermilk (WCB). Rennet coagulation was more efficient in removing casein, while retaining more IgG and lactoferrin than acid coagulation. BRW had more MFGM than BAW. Butyrophilin, xanthine dehydrogenase, and mucin1 were significantly higher (P < 0.05) in BRW, while fatty acid-binding protein 3 was enriched in BAW. KEGG analysis showed that complement and coagulation cascades had the greatest differences, and the abundance of proteins involved in this signaling pathway in BRW and BAW was higher, suggesting their potential anticoagulant and anti-inflammatory activity. BAW had higher apolipoprotein A4 and transcobalamin 2, which are essential carriers for transporting long-chain fatty acids and vitamin B12 from the intestine to the blood. Therefore, BAW intake might improve lipids and vitamin B12 absorption. This study can help deepen the understanding of protein composition of MFGM-enriched whey and facilitate the production of MFGM proteins for infants and old-aged populations.

Thermoviscoelastic and biochemical properties of Afuega\'l Pitu cheese blancu (B) and roxu (R), a Spanish acid-curd cheese made from cow\'s milk, were determined at 3, 15, 30 and 60 days of ripening. The contents of fat (>45 g/100 g total solids, TS) and NaCl (<3 g/100 g TS) were similar between varieties and did not change with ripening. Total solids, pH, nitrogen fractions and fat acidity increased with ripening time in B and R samples. Lactose content was higher in B than in R cheeses at 3 d, was degraded gradually throughout ripening but did not disappear totally in both cheeses at 60 d. Viscoelastic parameters were determined in the linear viscoelastic region (LVER) by stress sweeps (6.3 rad/s, 20 °C): the stress amplitude (σmax) and complex modulus (G*) increased, while strain amplitude (γmax) decreased up to 60 d. Mechanical spectra were also determined, in the LVER, at 20 °C, 50 °C and 75 °C, showing that all samples behaved as \"true gels\" (elastic modulus, G\' > viscous modulus, G\'\'), irrespective of temperature. The best gel properties (low values of loss factor, tanδ = G\'\'/G\', and minor frequency dependence, i.e., low n\', n\'\' exponents), were observed at 20 °C for B30 and R30. The viscoelastic parameters (G0\' and G0\'\') increased with ripening time, irrespective of the temperature, and for a fixed ripening time they were lower at higher temperature. At 75 °C, all samples exhibited notable frequency dependence (n\'\' ≫ n\'), resulting in shear-induced gelation at low frequencies (high oscillation times) which was consistent with data in thermal profiles from 70 °C to 90 °C.

The rheological properties of acid-induced coagulation of camel and cow milk gels following the addition of calcium chloride (CaCl2) and hydrogen phosphate dehydrate (Na2HPO4*2H2O) were investigated using a dynamic low amplitude oscillatory rheology. For a considered condition, the final values of storage modulus (G\') and loss modulus (G″) of camel milk gels were significantly lower than those of cow milk gels. The increase of the added CaCl2 levels improved significantly the gelation properties of camel and cow milk gels, since a reduction in the gelation time and an increase in the gel firmness were observed. Following the addition of Na2HPO4*2H2O at 10 and 20 mM, no significant effect on the gelation rate and the firmness of camel milk gels was observed, while, a significant decrease in the gelation rate and firmness were observed for cow milk gels.