Use of non-growing Lactococcus lactis cell suspensions for production of volatile metabolites with direct relevance for flavour formation during dairy fermentations

Table 3 Amino acid dependent flavour production

	Methionine	Leucine	Phenylalanine	Tyrosine	aa-mix	Reference
2-methylpropanal	1.0 × 10⁸	9.5 × 10⁷	1.2 × 10⁷	2.2 × 10⁷	5.7 × 10⁹	n.d.^a
2-methylpropanol	n.d	n.d.	n.d.	n.d.	1.2 × 10⁸	n.d
3-methylbutanal	4.3 × 10⁸	4.0 × 10⁹	1.3 × 10⁸	1.3 × 10⁸	2.2 × 10⁹	n.d.
2-methylbutanal	2.5 × 10⁸	5.2 × 10⁸	4.6 × 10⁷	6.0 × 10⁷	1.5 × 10⁹	n.d.
DMDS	8.3 × 10⁷	n.d.	n.d.	n.d.	n.d.	n.d.
3-methylpentanal	n.d.	3.8 × 10⁷	n.d.	n.d.	n.d.	n.d.
Methional	5.2 × 10⁸	n.d.	n.d.	n.d.	n.d.	n.d.
2,6-nonadienal	n.d.	4.1 × 10⁸	n.d.	n.d.	5.7 × 10⁷	n.d.
DMTS	1.1 × 10⁷	n.d.	n.d.	n.d.	n.d.	n.d.
Benzaldehyde	n.d.	n.d.	3.2 × 10⁸	n.d.	n.d.	n.d.
Phenylacetaldehyde	n.d.	n.d.	3.1 × 10⁹	n.d.	5.8 × 10⁸	n.d.
3-methylbutylvalerate	n.d.	9.5 × 10⁷	n.d.	n.d.	1.4 × 10⁷	n.d.
5-methyl-2-isopropyl-2-hexenal	n.d.	2.0 × 10⁹	n.d.	n.d.	3.8 × 10⁷	n.d.

Volatile compound production (GCMS-peak area^a) of incubations of L. lactis 1157 in a buffer system containing 100 mM sodium phosphate, pH 6.0, 2 mM NADH, 10 mM α-ketoglutarate, 0.1 mM pyridoxal phosphate, 10 mM methionine, 10 mM tyrosine, 10 mM phenylalanine, 10 mM leucine or 18 amino acids where 13 volatiles are presented (AA-mix).
^an.d, not detected.
The reference is the complete incubation mixture without amino acids.

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