Using physical processes to improve physicochemical and structural characteristics of fresh and frozen/thawed sheep milk

摘要

We assessed the impact of stirring (ST), high shear dispersing (HSD) and low (LPH, 3.5 MPa) and high pressure homogenization (HPH, 50 MPa) on physicochemical and structural characteristics of whole and skimmed sheep milk fresh or previously frozen and thawed (FT). Freezing affected the size of the fat globules, their interaction with caseins, reduced calcium solubility (10%) and buffering capacity (5-11%). Amongst the studied processes, HSD was the only one unable to improve the milk stability. The other ones reduced the size of the fat globules and increased fat and casein interactions, favoring milk stability and reducing the creaming occurrence (> 22%). LPH and HPH also reduced the sedimentation in skimmed milk (> 37%). Moreover, all processes recovered the buffering capacity of FT samples. The effectiveness of the processes can be ordered as ST < LPH < HPH, but the final choice will depend on the stability improvement required for milk vs. acquisition and operational equipment costs.