Current enzymatic milk fermentation procedures

Aside from bacteria, yeasts and moulds, enzymes from animal, vegetal and microbial sources are increasingly utilized for milk fermentation providing a broad spectrum of innovative product conceptions. In order to alter texture and flavour or to improve the nutritional value of milk-based products from different animal milks, microbial and enzymatic fermentation procedures are traditionally established worldwide. To date, genomic and proteomic approaches enable new selection strategies for precise enzymes for modern product applications. Hereby, generating beneficial health ingredients from milk is a main aspect. New insights into the biochemical mechanisms of enzymatic digestion and genetic engineering lead to enzymes with exact defined functions for explicit ripening flavour development or the improvement of texture of fermented milk products. The ability to synthesize complex exo-polysaccharides or to release bioactive peptides by accurate proteolytic activities of enzymes or to enzymatically cross-link the protein matrix in order to modify the texture characteristics of fermented milk products is a raising facet, especially for specific pharma- or nutraceutical applications. This review aimed at discussing the recent research activities on milk fermentative enzymes, with focus on the broad spectrum of enzyme origins and current aspects of genetic engineering. New approaches on proteolytic, lipolytic, glycolytic as well as milk clotting and protein cross-linking enzymatic activities are examined and associated with possible product applications. From technical prospective, advantages and disadvantages of immobilized enzymes within milk fermentation processes are critically discussed.