Flavour forming abilities and amino acid requirements of Lactococcus lactis strains isolated from artisanal and non-dairy origin

Ayad, Eman H.E.; Verheul, A.; Jong, C. de; Wouters, Jan; Smit, Gerrit

doi:10.1016/s0958-6946(99)00140-5

Cited by 166 publications

(126 citation statements)

References 31 publications

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“…Previously, we analyzed various strains of these species to determine their ability to produce 3-methylbutanal and the presence of the decarboxylase. The results showed that only a limited number of Lactococcus strains are able to produce 3-methylbutanal (5,36,37). It will be interesting to extend this analysis and elucidate whether KdcA-positive strains occur in other lactic acid bacterial species.…”

Section: Homology Of Kdca To Other Tpp-dependent Decarboxylasesmentioning

confidence: 95%

Identification, Cloning, and Characterization of a Lactococcus lactis Branched-Chain α-Keto Acid Decarboxylase Involved in Flavor Formation

Smit

Vlieg

Engels

et al. 2005

Appl Environ Microbiol

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122

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The biochemical pathway for formation of branched-chain aldehydes, which are important flavor compounds derived from proteins in fermented dairy products, consists of a protease, peptidases, a transaminase, and a branched-chain ␣-keto acid decarboxylase (KdcA). The activity of the latter enzyme has been found only in a limited number of Lactococcus lactis strains. By using a random mutagenesis approach, the gene encoding KdcA in L. lactis B1157 was identified. The gene for this enzyme is highly homologous to the gene annotated ipd, which encodes a putative indole pyruvate decarboxylase, in L. lactis IL1403. Strain IL1403 does not produce KdcA, which could be explained by a 270-nucleotide deletion at the 3 terminus of the ipd gene encoding a truncated nonfunctional decarboxylase. The kdcA gene was overexpressed in L. lactis for further characterization of the decarboxylase enzyme. Of all of the potential substrates tested, the highest activity was observed with branchedchain ␣-keto acids. Moreover, the enzyme activity was hardly affected by high salinity, and optimal activity was found at pH 6.3, indicating that the enzyme might be active under cheese ripening conditions.Flavor formation in cheeses is mainly the result of catabolism of milk proteins, sugar, and lipids. Degradation of proteins into amino acids followed by conversion of these amino acids by Lactococcus spp. is very important for flavor formation in semihard types of cheese, like Gouda (for reviews see references 12, 25, 38, and 43). One of the predominant amino acid conversion routes is initiated by transaminases. Transamination of amino acids yields the corresponding ␣-keto acids, which do not have strong flavor properties (12, 13) but are the precursors of various aldehydes, alcohols, acids, and (thio-)esters. The latter compounds generally have much lower odor thresholds and strongly contribute to cheese flavor. This is exemplified by the production of flavor compounds from leucine. Transamination of leucine results in the production of ␣-isocaproic acid (KICA). Interestingly, only a limited number of Lactococcus lactis strains are capable of decarboxylating this ␣-keto acid to 3-methylbutanal (36, 37). The decarboxylating activity is observed mainly in L. lactis strains with nondairy origins, whereas the industrial strains tested hardly showed this activity (36). Subsequently, (de)hydrogenation of 3-methylbutanal results in 3-methylbutanol or 3-methylbutyric acid, which also contributes to the flavor of cheese, but the odor thresholds for these compounds are higher than the odor threshold for 3-methylbutanal (24, 29). The rate-determining step in this route is the decarboxylation of KICA, and therefore, control of this enzyme offers good prospects for the design of starter cultures with tailored flavor production (37, 43).The enzyme performing this reaction has not been identified. A number of thiamine pyrophosphate (TPP)-dependent

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Section: Homology Of Kdca To Other Tpp-dependent Decarboxylasesmentioning

confidence: 95%

Identification, Cloning, and Characterization of a Lactococcus lactis Branched-Chain α-Keto Acid Decarboxylase Involved in Flavor Formation

Smit

Vlieg

Engels

et al. 2005

Appl Environ Microbiol

Self Cite

122

139

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“…2-Pentanol and the branched chains 2-methyl-1-propanol and 3-methyl-1-butanol, with lower detection thresholds, were also very abundant, and are thus very probably playing an important role in the aroma of this variety. 3-Methyl-1-butanol, as well as 2-methyl-1-propanol, have fruity [23,38], fusel oil, or whisky odours [31] or even chocolate flavour [3,4], according to different authors and maybe depending on their concentration. Coming from amino acid catabolism [10] the production of 3-methyl-1-butanol and 3-methyl-1-butanal could be favoured in La Serena cheeses by the use of the highly proteolytic vegetable rennet.…”

Section: Alcoholsmentioning

confidence: 99%

Evolution of the volatile components of ewe raw milk La Serena cheese during ripening. Correlation with flavour characteristics

Carbonell

Núñez

Fernández-Garcı́a

2002

Lait

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-La Serena cheese is a soft to semi-soft Spanish variety manufactured from Merino ewe raw milk coagulated with an extract of Cynara cardunculus. In the present work a purge and trap extraction procedure coupled to gas chromatography -mass spectrometry was used to study the volatile fraction evolution during ripening of La Serena cheese. A total of 112 compounds were identified. Alcohols were quantitatively the main chemical family in the volatile fraction, increasing significantly during ripening. Ethanol, 1-propanol, 2-propenol, 2-propanol, 2-butanol, 2-pentanol and the branched chain 2-methyl-1-propanol and 3-methyl-1-butanol, were abundant at the end of ripening. Esters, especially ethyl esters of acetic, butanoic, hexanoic and octanoic acids and 3-methyl-1-butanol acetate, were found at high levels in the headspace of La Serena cheese. Concentrations of most esters increased dramatically during ripening, and, given their low perception thresholds, may be considered as key constituents of the aroma of this cheese variety. The principal component analysis of sensory attributes and volatile compounds extracted 3 functions. Linear aldehydes and alcohols, 2-alkanols, branched-chain alcohols, 2-methyl-ketones, alkanes, terpenes and esters other than ethyl esters correlated positively with function 1 (25.8% of the variance explained). Odour and aroma quality, along with the sensory attributes lactic, fruits-flowers, and clean cheese flavour, and the volatiles ethanol and ethyl esters, had a high correlation coefficient with function 2 (14.8% of the variance explained). 2-Butanone and the sensory attributes fishy and putrid had a negative correlation coefficient with this function. Odour and aroma intensity, along with the sensory attributes animal, pungent and fishy, and the volatile compounds branched chain aldehydes, n-alkanols, 2-butanol and esters, were positively correlated with function 3 (11.0% of the variance explained). Terpenes had a negative correlation coefficient with this function. Résumé -Évolution des composés volatils dans le fromage La Serena pendant l'affinage. Corrélation avec les caractéristiques sensorielles. La Serena est un fromage à pâte molle ou demi-dure fabriqué à partir du lait cru de brebis Merino coagulé avec un extrait de Cynara cardunculus. Pour étu-dier la fraction volatile pendant l'affinage du fromage La Serena, un dispositif d'extraction par espace de tête dynamique « purge and trap » couplé à un appareil de CG-SM a été utilisé. Les alcools étaient quantitativement la principale famille chimique dans la fraction volatile, et augmentaient significativement au cours de l'affinage. L'éthanol, le 1-propanol, le 2-propenol, le 2-propanol, le 2-butanol, le 2-pentanol et les alcools ramifiés 2-méthyl-1-propanol et 3-méthyl-1-butanol étaient très abondants en fin d'affinage. Des esters, principalement des esters éthyliques des acides acétique, butanoïque, hexanoïque et octanoïque, ont été trouvés à des niveaux assez élevés dans la fraction volatile du fromage La Serena. Les con...

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“…The origin of linear aldehydes is not clear. Certain strains of lactococci can produce branched chain aldehydes, 2-methyl-1-propanal, 2-methyl-1-butanal and 3-methyl-1-butanal, from valine, isoleucine and leucine, respectively, through several enzymatic pathways [1,2,7]. 2-Propenal (acrolein) is derived from 3-hydroxypropanal, through the action of some lactic acid bacteria such as Lactobacillus brevis and Lb.…”

Section: Carbonyl Compoundsmentioning

confidence: 99%

Seasonal variation of volatile compounds in ewe raw milk La Serena cheese

Carbonell

Núñez

Fernández-Garcı́a

2002

Lait

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-La Serena cheese is a soft to semi-soft variety made in Extremadura (western Spain) from Merino ewe raw milk using an extract of Cynara cardunculus as milk coagulant. A purge and trap apparatus coupled to a GC-MS was used to study the seasonal variation of the volatile fraction of La Serena cheeses made at four artisan dairies. Alcohols and esters were the main chemical families found in La Serena cheese. Most volatile compounds were detected in cheeses made during the whole year, although at different concentrations. Abundances of hydrocarbons, primary alcohols, secondary alcohols of an uneven number of carbon atoms, terpenes, 2,3-butanedione, free fatty acids, nitrogen compounds and aromatic compounds were generally higher in cheeses made during spring. Aldehydes reached the highest levels in spring and summer cheeses. Ethanol and ethyl esters were more abundant in spring and autumn cheeses, while branched chain alcohols and branched chain alkyl esters were more abundant in summer cheeses. Cheeses made in winter showed a lower abundance of most volatile compounds, except dimethyl sulphide and dimethyl disulphide. Cheeses made in spring received the highest scores for odour and aroma quality, and cheeses made in winter received the lowest scores. High amounts of 2,3-butanedione, medium concentrations of most terpenes and alcohols, low levels of methyl ketones, especially of 2-butanone, and very low concentrations of 2-butanol were generally recorded for cheeses with the highest quality scores in sensory evaluation. Concentrations of most ethyl esters and branched chain alkyl esters in the highest scored cheeses were above the mean values in cheeses made during the whole year. However, levels of propyl esters and ethyl esters of branched chain acids were lower in the highest scored cheeses.Volatile compound / ewe raw milk / La Serena cheese / seasonal variation Résumé -Variation saisonnière des composés volatils dans le fromage La Serena au lait cru de brebis. La Serena est un fromage à pâte molle ou demi-dure d'appellation d'origine contrôlée fait en Extremadura, à l'ouest de l'Espagne, avec du lait cru de brebis Merino et un extrait de Cynara cardunculus comme coagulant du lait. Un dispositif de « purge and trap » couplé à un appareil de CG-SM a été utilisé pour étudier la variation saisonnière de la fraction volatile des fromages de La Serena fabriqués dans quatre usines pendant une année. Les familles chimiques majoritaires étaient des alcools et des esters. La plupart des composés volatils ont été détectés dans les fromages fabriqués pendant les quatre saisons de l'année, mais à des concentrations différentes. Les concentrations des hydrocarbures, des alcools primaires, des alcools secondaires à nombre impair d'atomes de carbone, terpènes, 2,3-butanedione, acides gras libres, composés azotés et composés aromatiques étaient en général plus élevées dans les fromages de printemps. Les aldéhydes étaient en concentration maximale dans les fromages de printemps et d'été. L'éthanol et les esters éthyliqu...

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Flavour forming abilities and amino acid requirements of Lactococcus lactis strains isolated from artisanal and non-dairy origin

Cited by 166 publications

References 31 publications

Identification, Cloning, and Characterization of a Lactococcus lactis Branched-Chain α-Keto Acid Decarboxylase Involved in Flavor Formation

Identification, Cloning, and Characterization of a Lactococcus lactis Branched-Chain α-Keto Acid Decarboxylase Involved in Flavor Formation

Evolution of the volatile components of ewe raw milk La Serena cheese during ripening. Correlation with flavour characteristics

Seasonal variation of volatile compounds in ewe raw milk La Serena cheese

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