Physical Chemistry of Milk Fat Globules

Many properties of milk and dairy products are determined by the behaviour and physical chemistry of milk fat globules. Allowed to stand, raw milk quickly separates into fat-enriched and fat-depleted phases, i.e. cream and skim milk, respectively. This is partly due to simple density differences between the emulsified fat globules and milk serum, but gravitational separation occurs at a rate ultimately determined by a complex series of colloidal interactions mediated by the milk fat globule membrane (MFGM) that lead to aggregation of fat globules, particularly at low temperatures (i.e. so-called cold agglutination). Creaming properties of milk differ between mammalian species, and processing of milk can profoundly alter the creaming properties of bovine milk, particularly homogenization and centrifugal separation, but also heat treatment. In this chapter, the principal physical properties of bovine milk fat globules are discussed, along with methods for their analysis and the impact of common dairy processes on their stability

Discovering lactic acid bacteria by genomics

This review summarizes a collection of lactic acid bacteria that are now undergoing genomic sequencing and analysis. Summaries are presented on twenty different species, with each overview discussing the organisms fundamental and practical significance, environmental habitat, and its role in fermentation, bioprocessing, or probiotics. For those projects where genome sequence data were available by March 2002, summaries include a listing of key statistics and interesting genomic features. These efforts will revolutionize our molecular view of Gram-positive bacteria, as up to 15 genomes from the low GC content lactic acid bacteria are expected to be available in the public domain by the end of 2003. Our collective view of the lactic acid bacteria will be fundamentally changed as we rediscover the relationships and capabilities of these organisms through genomics.