Lopez Christelle
UMR Science et Technologie du Lait et de l'Oeuf, INRA-Agrocampus, Rennes, France.
Reprod Nutr Dev. 2005 Jul-Aug;45(4):497-511. doi: 10.1051/rnd:2005034.
Bovine fat is dispersed in raw milk as natural milk fat globules, with an average diameter of 4 microm, which are enveloped in a biological membrane, the milk fat globule membrane (MFGM). However, dairy processes modify the supramolecular structure and the surface composition of milk fat. Thus, milk fat is present in many dairy products under various forms. In this study, we focused on the fact that natural milk fat globules are rarely consumed in their native state, i.e. in fresh raw milk. In most drinking milks, fat globules are homogenised in order to avoid their rising at the surface of the products. Furthermore, fat globules are heat treated to avoid the growth of micro-organisms. As a consequence of the technological process applied, the volume-weighted average diameter of fat globules in drinking milks is in the range 0.2-0.5 microm. Homogenisation of fat globules led to the partial disruption of the MFGM and to the adsorption of milk proteins. Moreover, this study showed that in cheeses, milk fat can be dispersed as (i) fat globules with the MFGM, (ii) aggregates of fat globules, (ii) homogenised fat globules, (iii) free fat and (iv) a combination of different phases and structures. The knowledge of the supramolecular structure of milk fat in dairy products is of primary importance regarding its technological, sensorial and nutritional properties.
牛乳脂肪以天然乳脂肪球的形式分散在原料乳中，其平均直径为4微米，被一层生物膜即乳脂肪球膜（MFGM）所包裹。然而，乳制品加工过程会改变乳脂肪的超分子结构和表面组成。因此，乳脂肪在许多乳制品中以多种形式存在。在本研究中，我们关注的事实是天然乳脂肪球很少以其天然状态被食用，即在新鲜原料乳中。在大多数饮用乳中，脂肪球会进行均质处理以避免其在产品表面上浮。此外，脂肪球会进行热处理以防止微生物生长。由于所应用的工艺过程，饮用乳中脂肪球的体积加权平均直径在0.2 - 0.5微米范围内。脂肪球的均质化导致乳脂肪球膜部分破裂以及乳蛋白的吸附。此外，本研究表明，在奶酪中，乳脂肪可以以以下形式分散：（i）带有乳脂肪球膜的脂肪球，（ii）脂肪球聚集体，（ii）均质化脂肪球，（iii）游离脂肪，以及（iv）不同相和结构的组合。了解乳制品中乳脂肪的超分子结构对于其工艺、感官和营养特性至关重要。
