Microbial communities and volatile profile of Queijo de Azeitão PDO cheese, a traditional Mediterranean thistle-curdled cheese from Portugal

Abstract

The production of ovine or caprine milk cheeses with thistle rennet is a common practice in the Mediterranean basin, especially in the Iberian and Italian Peninsulas. In these latter geographical areas, numerous Designation of Origin (PDO) or Protected Geographical Indications (PGI) cheeses are traditionally manufactured, including Queijo de Azeitão PDO cheese, produced in Portugal. The aim of the present study was to obtain information on bacteria and yeast communities harboured in Queijo de Azeitão PDO cheese through viable counting and, for the first time, via metataxonomic analyses.Moreover, solid phase microextraction (SPME) technique was applied to characterize Queijo de Azeitão PDO cheese volatile compounds. Cheese wheels were collected from three different artisan producers located in Portugal. Concerning microbiota, a simple composition was shared by the three producers, whose cheese manufactures were dominated by the presence of Leuconostoc mesenteroides, Lactococcus lactis, Lacticaseibacillus zeae, Lentilactobacillus kefiri, Serratia spp., Lactiplantibacillus plantarum, and Lactilactobacillus sakei. The mycobiota composition showed the neat dominance of Yarrowia lipolytica, followed by Candida ethanolica, Kurtzmaniella zeylanoides, Geotrichum candidum, Galactomyces geotrichum, Kluyveromyces lactis, and Geotrichum silvicola. The volatile profile analysis allowed to identify 24 different compounds: 7 acids (acetic acid, isobutyric acid, butanoic acid, 3-methylbutanoic acid, 2methylbutanoic acid, 4-Methyl-2-oxovaleric acid, and hexanoic acid), 7 esters (butyl acetate, ethyl butyrate, propyl butyrate, ethyl exanoate, isopentyl isobutyrate, 2-nonanone, and ethyl octanoate), 4 alcohols (n-propanol, 2-pentanol, 3-Methyl-1-butanol, and 2-heptanol), 3 ketones (2-butanone, 2-pentanone, and 2-heptanone), 2 aromatic hydrocarbons (benzene and toluene), 1 aldehydes (3-methyl-butanal). The most represented volatile organic compounds (VOCs) were 2-butanone, butanoic acid and hexanoic acid. A positive correlation between Lent. kefiri and hexanoic acid and isopentyl isobutyrate was observed. Whereas Y. lipolytica displayed the highest number of positive correlations with 3-methylbutanal, 2-pentanone and 2-pentanol. It is noteworthy that, to the authors' knowledge, this is the very first detection of Lent. kefiri in raw ewe's milk cheese coagulated with vegetable rennet. The presence of Lent. kefiri in Queijo de Azeitão PDO cheese deserves a further in depth, since in kefir, this species, together with L. kefiranofaciens, L. kefirgranum, and L. parakefiri, contributes to the production of health-promoting exopolysaccharides with acknowledged antioxidant, antitumor, antimicrobial, cholesterol reducing and immune-modulating properties. The detection of Lent. kefiri in Queijo de Azeitão PDO cheese represents an absolute novelty, which suggests that this cheese could have still unknown beneficial effects on the health of consumers. Further research is needed to study the dynamics of microbial communities during manufactur...

Serra da Estrela PDO Cheese Microbiome as Revealed by Next Generation Sequencing

“…The microbiological characterization of SEC samples revealed the presence of almost 500 genera (138 of bacteria and 338 of fungi— Table S5 of supplementary material ). A composition that is in general, analogous to previous SEC characterizations [ 3 , 5 , 6 , 7 , 8 , 79 ], other ovine milk cheeses [ 18 , 21 , 79 , 80 , 81 , 82 , 83 , 84 ], and cheese in general [ 54 , 62 , 77 ].…”

“…This is in contrast with previous characterizations, that have shown a limited contribution of these species, in particular to the overall microbial composition of SEC [ 5 , 6 ]. However, recent publications concerning other ovine milk cheeses show a high prevalence of L. mesenteroides and L. lactis , namely Azeitão from Portugal [ 80 ], Krčki, Istrian and Paski from Croatia [ 18 ], Feta from Greece [ 84 ] and Fiore Sardo from Italy [ 82 ].…”

“…As expected, SEC shared a higher number of core taxa with REM than with cardoon—18 vs. 11—and only 9 were shared between all matrices. L. lactis , one of the most prevalent species in SEC, is one of the most important LAB species in the dairy industry [ 80 ]. Its presence in SEC derives predominantly from REM (accounting up to 12% of total counts) and rarely from cardoon (≤0.5% of total counts).…”

Organoleptic Chemical Markers of Serpa PDO Cheese Specificity

“…This indicator does not show significant differences concerning the cheese quality, which can be explained by the fact that it is mainly related to primary proteolysis, essentially caused by the coagulating enzymes, native milk proteinases and less related to direct or indirect microbial activity [48]. The microbial activity generally shows a more significant relationship with the quality of the cheese, mainly aroma and flavour, and can, in a way, be evaluated by indicators such as FAAs and compounds resulting from their catabolism (e.g., organic acids, FFAs and volatile compounds) or also by the ratio NPN/TN [8,9,22,[45][46][47][49][50][51]. In our study, we did not find significant differences for this indicator, probably due to the great variability expressed by the high standard deviation for "bad" and "excellent" quality cheeses.…”

Aroma Clouds of Foods: A Step Forward to Unveil Food Aroma Complexity Using GC × GC

“…The DVB/CAR/PDMS coating contains both adsorbents that are layered to extend the molecular weight range of analytes extracted with one SPME fiber and the combination with the PDMS, an absorptive-type fiber that also confers a bipolar character ( Shirey, 2012 ; Godage and Gionfriddo, 2019 ; Carriço et al, 2020 ). This arrangement explains the high performance of the DVB/CAR/PDMS fiber for a wide range of chemical species and the fact that it is extensively used for profiling of volatile molecules released from various food items, such as table and fortified wine ( Perestrelo et al, 2011 ; Santos et al, 2013 ; Welke et al, 2014 ; Whitener et al, 2016 ; Rocha et al, 2021 ), beer ( Sterckx et al, 2010 ; Rodriguez-Bencomo et al, 2012 ; Romero-Medina et al, 2020 ), sea salt ( Donadio et al, 2011 ; Silva et al, 2015 ), pear ( Wang et al, 2019 ; Fonseca et al, 2020 ), distilled beverages ( Thibaud et al, 2020 ), coffee ( Ongo et al, 2020 ; Lopes et al, 2021 ), elderberry ( Salvador et al, 2016 ), hazelnut ( Cordero et al, 2010 ; Rosso et al, 2020 ), honey ( Čajka et al, 2007 ; Siegmund et al, 2018 ), dairy products ( Cardinali et al, 2021 ; Székelyhidi et al, 2021 ; Liu et al, 2022 ), virgin olive oil ( Purcaro et al, 2014 ; Ros et al, 2019 ), and cereals ( Buśko et al, 2010 ). Indeed, DVB/CAR/PDMS fiber exhibited the highest sorption capacity for a wide range of VOCs released from honey, comparing with six other fiber coatings ( Čajka et al, 2007 ).…”