Cheese flavour development by enzymatic conversions of peptides and amino acids

During ripening of cheese, many biochemical processes take place, which are essential for flavour development. The breakdown of caseins is a prerequis ite for flavour development. A good balance between proteolysis and peptido lysis prevents the formation of bitterness in the cheese. For this reason, it is necessary to focus on starter cultures with highly active peptidases, which should be active in the cheese matrix. Amino-acid-converting enzymes (AACEs) are involved in the degradation of amino acids, which are liberate d during proteolysis. Their activity results in various volatile (flavour) components; most notably the degradation of methionine results in flavour-a ctive sulphur compounds. AACEs involved in degradation of methionine and ot her amino acids were identified and their role in (cheese) flavour formatio n is described. At least two pathways leading to the formation of sulphur c ompounds were identified. Overproduction of one of the enzymes involved, re sults specifically in a higher formation of sulphur compounds. This result, together with the observation that flavour production is highly strain-spe cific amongst Various lactococcal bacteria, offers a new potential for indu strial applications. (C) 2000 Elsevier Science Ltd. All rights reserved.