Flavour formation by lactic acid bacteria and biochemical flavour profiling of cheese products

Abstract

Flavour development in dairy fermentations, most notably cheeses, results from a series of (bio)chemical processes in which the starter cultures provide the enzymes. Particularly the enzymatic degradation of proteins (caseins) leads to the formation of key-flavour components, which contribute to the sensory perception of dairy products. More specifically, caseins are degraded into peptides and amino acids and the latter are major precursors for volatile aroma compounds. In particular, the conversion of methionine, the aromatic and the branched-chain amino acids are crucial. A lot of research has focused on the degradation of caseins into peptides and free amino acids, and more recently, enzymes involved in the conversion of amino acids were identified. Most data are generated on Lactococcus lactis, which is the predominant organism in starter cultures used for cheese-making, but also Lactobacillus, Streptococcus, Propionibacterium and species used for surface ripening of cheeses are characterised in their flavour-forming capacity. In this paper, various enzymes and pathways involved in flavour formation will be highlighted and the impact of these findings for the development of industrial starter cultures will be discussed.

Insights into the microbial diversity and community dynamics of Chinese traditional fermented foods from using high-throughput sequencing approaches

“…In the complex microbial diversity of fermented foods, there are a number of technically important microbial strains which impart useful properties to food, like aroma and flavor (Smit et al, 2005). It is well known that the performance of a microbe during fermentation can be understood by its gene expression.…”

Branched-chain alcohol formation by thermophilic bacteria within the genera of Thermoanaerobacter and Caldanaerobacter

“…These studies have often focused on the formation of compounds that contribute to the flavor profile of foods and beverages (branched-chain and aromatic aldehydes, alcohols, and acids) (Smit et al 2005(Smit et al , 2009. Recently, some studies have focused on the production of branched-chain alcohols from protein-rich waste using genetically engineered Escherichia coli and Bacillus subtilis with the main focus being that BCOHs are promising biofuel candidates (Huo et al 2011;Choi et al 2014).…”

Evaluation of technological properties of Enterococcus faecium CECT 8849, a strain isolated from human milk, for the dairy industry

“…Alcohols, ketones, and carboxylic and fatty acids were the most abundant volatile compounds found in the experimental cheeses manufactured in this study. Unfortunately, their exact impact on the flavor perception of the product cannot be assessed at the moment because it depends not only on the concentration and threshold concentration of the flavor compounds but also on possible interactions between taste, aroma, and structure components in the cheese (Smit et al 2005). The screening of bacterial strains from natural niches, and their combination with industrial strains if required, has been claimed as an interesting possibility for the development of custom-made starter cultures because they have been found to produce unusual flavor components and/or profiles (Ayad Smit et al 2005).…”

“…Unfortunately, their exact impact on the flavor perception of the product cannot be assessed at the moment because it depends not only on the concentration and threshold concentration of the flavor compounds but also on possible interactions between taste, aroma, and structure components in the cheese (Smit et al 2005). The screening of bacterial strains from natural niches, and their combination with industrial strains if required, has been claimed as an interesting possibility for the development of custom-made starter cultures because they have been found to produce unusual flavor components and/or profiles (Ayad Smit et al 2005). In this sense, cheese manufactured with E. faecium CECT 8849 did not have a high concentration of the primary alcohol 3-methyl-1-butanol, which is present in relatively large quantities in cheeses giving alcoholic and floral notes, in contrast with that elaborated with L. lactis ESI 153; on the other hand, E. faecium CECT 8849 increased fivefold the concentration of acetoin and tenfold that of ethanol, a fact that could lead to cheese with buttery, alcoholic, and floral notes (Molimard and Spinnler 1996).…”