RESUMO
Branched chain aldehyde, 3-methylbutanal is associated as a key flavor compound with many hard and semi-hard cheese varieties. The presence and impact of this flavor compound in bread, meat, and certain beverages has been recently documented, however its presence and consequences regarding cheese flavor were not clearly reported. This paper gives an overview of the role of 3-methylbutanal in cheese, along with the major metabolic pathways and key enzymes leading to its formation. Moreover, different strategies are highlighted for the control of this particular flavor compound in specific cheese types.
Assuntos
Aldeídos/metabolismo , Proteínas de Bactérias/metabolismo , Queijo/análise , Contaminação de Alimentos/prevenção & controle , 3-Metil-2-Oxobutanoato Desidrogenase (Lipoamida)/metabolismo , Aldeídos/análise , Aldeídos/toxicidade , Carboxiliases/metabolismo , Carnobacterium/enzimologia , Carnobacterium/crescimento & desenvolvimento , Carnobacterium/metabolismo , Queijo/microbiologia , Enterococcus/enzimologia , Enterococcus/crescimento & desenvolvimento , Enterococcus/metabolismo , Qualidade dos Alimentos , Glutamato Desidrogenase/metabolismo , Lactobacillus/enzimologia , Lactobacillus/crescimento & desenvolvimento , Lactobacillus/metabolismo , Lactococcus/enzimologia , Lactococcus/crescimento & desenvolvimento , Lactococcus/metabolismo , Controle de Qualidade , Streptococcus/enzimologia , Streptococcus/crescimento & desenvolvimento , Streptococcus/metabolismo , Paladar , Transaminases/metabolismoRESUMO
In Corynebacterium glutamicum, the activity of the 2-oxoglutarate dehydrogenase complex was shown to be controlled by the phosphorylation of a 15-kDa protein OdhI by different serine/threonine protein kinases. In this paper, the phosphorylation status and kinetics of OdhI dephosphorylation were assessed during glutamate producing processes triggered by either a biotin limitation or a temperature upshock from 33 degrees C to 39 degrees C. A dephosphorylation of OdhI in C. glutamicum 2262 was observed during the biotin-limited as well as the temperature-induced glutamate-producing process. Deletion of pknG in C. glutamicum 2262 did not affect the phosphorylation status of OdhI during growth and glutamate production phases triggered by a temperature upshock, though a 40% increase in the specific glutamate production rate was measured. These results suggest that, under the conditions analyzed, PknG is not the kinase responsible for the phosphorylation of OdhI in C. glutamicum 2262. The phosphorylation status of OdhI alone is, as expected, not the only parameter that determines the performance of a specific strain, as no clear relation between the specific glutamate production rate and OdhI phosphorylation level was demonstrated.
