Formation of 3-Methylbutanal and 3-Methylbutan-1-ol Recognized as Malty during Fermentation in Swiss Raclette-Type Cheese, Reconstituted Milk, and de Man, Rogosa, and Sharpe Broth

Abstract

This work aimed to determine the formation over time of 3-methylbutanal and 3-methylbutan-1-ol recognized as malty during the manufacture of Raclette-type cheese and the fermention of reconstituted skim milk, and filter-sterilized MRS broth. Using dynamic headspace-vacuum transfer in trap extraction followed by gas chromatography coupled with mass spectrometry− olfactometry (DHS-VTT-GC-MS-O) as a screening method for the malty compounds, five compounds (2-methylpropanal, 2-and 3methylbutanal, and 2-and 3-methylbutan-1-ol) were identified as potential compounds causing the malty aroma in starter culture development and Raclette-type cheeses. Focus on compounds having a predominant sensorial effect (3-methylbutanal and 3methylbutan-1-ol), spikings of leucine, 13 C-labeled leucine, α-ketoisocaproic acid, and α-ketoglutaric acid provided a better understanding of their formation pathway. This study highlighted the discrepancies in the formation of 3-methylbutanal and 3methylbutan-1-ol between the growth media; namely, despite the presence of free leucine available in MRS and the addition of an excess, no increase of the target compounds was observed. The concentration of these compounds in MRS increased only when αketoglutaric acid or α-ketoisocaproic acid was added, and a preference for the pathway to α-hydroxyisocaproic acid instead of 3methylbutanal was shown. In addition, a formation of 3-methylbutanal when the bacteria were not yet active was observed when spiking α-ketoisocaproic acid, which potentially indicates that this part of the metabolism could take place extracellularly. These results could potentially unveil other, not-yet-identified reactants, directly influencing the production of compounds responsible for the malty aroma in Raclette cheese.

Evolution of Volatile Compounds during Ripening and Final Sensory Changes of Traditional Raw Ewe’s Milk Cheese “Torta del Casar” Maturated with Selected Protective Lactic Acid Bacteria

“…In the present work, a significant ( p ≤ 0.05) increase in 3-methylbutanal was observed throughout the ripening process in all the analyzed batches. The 3-methylbutanal, derived from the degradation of amino acid leucine [ 43 , 44 ], is probably a consequence of proteolysis from vegetal rennet and microbial origin. Nevertheless, since no significant differences ( p > 0.05) between batches were detected in 3-methylbutanal in the present work, it seems that the selected L. casei and Lc.…”

Analysis of the Ability to Produce Pleasant Aromas on Sour Whey and Buttermilk By-Products by Mold Galactomyces geotrichum: Identification of Key Odorants

“…Therefore, it has been identified as a key odorants in many food products, such soy sauce, beer, and bakery products such as rye bread and pumpernickel bread [ 5 , 24 , 32 , 37 ]. Both 3-methyl-1-butanol and 3-methylbutanal are formed during the transformation of leucine [ 5 , 32 , 38 ]. 2,3-butanedione is the compound responsible for the strong buttery aroma in samples with buttermilk, where it was present at almost twice the concentration (680 µg/kg) than in the post-fermentation product with sour whey (370 µg/kg).…”

Pivotal role of cheese salting method for the production of 3‐methylbutanal by Lactococcus lactis

“…We, furthermore, saw that the highest concentration of 3‐methylbutanal was obtained in the curd and then during maturation gradually decreased, which is in line with observations made by Meng et al . (2021) for non‐salted Raclette cheese. In addition, we saw that sodium chloride further reduced the 3‐methylbutanal concentration in cheese.…”