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

Resumo

We acessed the efficacy of stirring (ST), high shear dispersion (HSD) and low (LPH) and high (HPH) pressure homogenization to improves the stability of fresh or frozen/ thawed sheep milk (whole and skimmed). After each process, milk samples were evaluated for color, buffering capacity, soluble calcium, pH, particle size distribution and near infrared backscaterring. From the results obtained, we observed that freezing changed the buffering capacity and particle size distribution of whole milk and the buffering capacity, sedimentation and soluble calcium in skimmed one. The physical processes caused changes in milk (mainly in the whole one) and most of them (except HSD) was able to reduced, at least partially, the defects caused by the freezing of the milk, improving the product stability. In addition, the HPH and LPH also improved the stability of fresh milk. In respect to their effectiveness, the processes can be ordered as HPH> LHP> ST. Although less effective, the ST can be an interesting alternative to process previously frozen sheep milk, since it is a cheap, simple and easy to operate technology.