Lacto-fermented garlic handcrafted in the Lower Silesia Region (Poland): Microbial diversity, morpho-textural traits, and volatile compounds.

The aim of the present study was to provide a first characterization of lacto-fermented garlic manufactured by local small-scale artisanal producers in the Lower Silesia Region (Poland). The lacto-fermented garlic samples showed high nutritional features in terms of antioxidant activity. A total of 86 compounds, belonging to various chemical classes, were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC/MS). Most of these compounds belonged to six main classes, being sulfur compounds, esters and acetates, oxygenated monoterpenes, monoterpene hydrocarbons, and alcohols. Aldehydes, acids, ketones, furans, and phenols were also identified. In the analyzed samples, counts up to 8 log cfu g-1 were observed for lactic acid bacteria. Metataxonomic analysis revealed the presence of Levilactobacillus, Lactiplantibacillus, Latilactobacillus, Secundilactobacillus, Weissella, Leuconostoc, Lactococcus, Pediococcus, and Lacticaseibacillus among the major taxa. These results were confirmed by the isolation and characterization of viable lactic acid bacteria. Indeed, the presence of the closest relatives to Lacticaseibacillus casei group, Pediococcus parvulus, Levilactobacillus brevis, Levilactobacillus parabrevis, and Lactiplantibacillus plantarum group was observed. A good acidification performance in salty garlic-based medium was observed for all the isolates that, between 8 and 15 days of fermentation, reached pH values comprised between 4 and 3.5, depending on the tested species. Of note, 15 out of the 37 lactic acid bacteria isolates (Levilactobacillus parabrevis, Pediococcus parvulus, Lactiplantibacillus plantarum group, and Lacticaseibacillus casei group) showed the presence of the hdcA gene of Gram-positive bacteria encoding for histidine decarboxylase. Furthermore, for 8 out of the 37 isolates the in-vitro exopolysaccharides production was observed. No isolate showed inhibitory activity against the three Listeria innocua strains used as surrogate for Listeria monocytogenes.

Impact of Refrigerated Storage on Microbial Growth, Color Stability, and pH of Turkey Thigh Muscles.

The quality of poultry meat offered to the consumer depends mainly on the level of hygiene during all stages of its production, storage time, and temperature. This study investigated the effect of refrigerated storage on the microbiological contamination, color, and pH of turkey thigh muscles stored at 1 °C over six days. Microbial growth, including total mesophilic aerobes, presumptive lactic acid bacteria, and Enterobacteriaceae, significantly increased, impacting the meat's sensory attributes and safety. On the 6th day of meat storage, the content of total mesophilic aerobes, presumptive lactic acid bacteria, and Enterobacteriaceae was 1.82 × 107 CFU/g, 1.00 × 104 CFU/g, and 1.87 × 105 CFU/g, respectively. The stability of color was assessed by quantifying the total heme pigments, comparing myoglobin, oxymyoglobin, and metmyoglobin concentrations, analyzing color parameters L*, a*, b*, and the sensory assessment of surface color, showing a decline in total heme pigments, three myoglobin forms, redness (a*) and lightness (L*). In contrast, yellowness (b*) increased. These changes were correlated with the growth of spoilage microorganisms that influenced the meat's pigmentation and pH, with a notable rise in pH associated with microbial metabolization. Based on the conducted research, it was found that the maximum storage time of turkey thigh muscles at a temperature of 1 °C is 4 days. On the 4th day of storage, the total mesophilic aerobe content was 3.5 × 105 CFU/g. This study underscores the critical need for maintaining controlled refrigeration conditions to mitigate spoilage, ensuring food safety, and preserving turkey meat's sensory and nutritional qualities. There is a need for further research to improve turkey meat storage techniques under specific temperature conditions by studying the impact of using varying packaging materials (with different barrier properties) or the application of natural preservatives. Additionally, future studies could focus on evaluating the effectiveness of cold chain management practices to ensure the quality and safety of turkey products during storage. By addressing these research gaps, practitioners and researchers can contribute to developing more efficient and sustainable turkey meat supply chains, which may help mitigate food wastage by safeguarding the quality and safety of the meat.

Technological and Enzymatic Characterization of Autochthonous Lactic Acid Bacteria Isolated from Viili Natural Starters.

Viili, a Finnish ropy fermented milk, is traditionally manufactured through spontaneous fermentation, by mesophilic lactic acid bacteria and yeast-like fungi, or back-slopping. This study evaluated four natural viili starters as sources of lactic acid bacteria for dairy production. Back-slopping activation of the studied viili samples was monitored through pH and titratable acidity measurements and enumeration of mesophilic lactic acid bacteria. Sixty lactic acid bacteria isolates were collected, molecularly identified, and assayed for acidification performance, enzymatic activities, production of exopolysaccharides (EPSs), presence of the histidine decarboxylase (hdcA) gene of Gram-positive bacteria, and production of bacteriocins. A neat predominance of Lactococcus lactis emerged among the isolates, followed by Enterococcus faecalis, Enterococcus faecium, Enterococcus durans, Enterococcus lactis, and Lactococcus cremoris. Most isolates exhibited proteolytic activity, whereas only a few enterococci showed lipase activity. Five isolates identified as L. cremoris, L. lactis, and E. faecalis showed a good acidification performance. Most of the isolates tested positive for leucine arylamidase, whereas only one E. durans and two L. lactis isolates were positive for valine arylamidase. A few isolates also showed a positive reaction for beta-galactosidase and alpha- and beta-glucosidase. None of the isolates produced EPSs or bacteriocins. The hdcA gene was detected in five isolates identified as L. lactis and E. faecium. A few L. cremoris and L. lactis isolates for potential use as starter or adjunct cultures for dairy processing were finally identified.

Spontaneous fermentation of Marastina wines: The correlation between autochthonous mycobiota and phenolic compounds.

Understanding fungal community dynamics during fermentation is important for assessing their influence on wine's phenolic content. The present study represents the first effort to explore the correlation between the autochthonous mycobiota of Marastina grapes collected from Dalmatian winegrowing sub-regions in Croatia and the phenolic composition, as well as the physicochemical parameters of wines produced through spontaneous fermentation. The metataxonomic approach revealed Metschnikowia pulcherrima, Metschnikowia fructicola and Hanseniaspora uvarum as the core mycobiota detected at the initial phase of fermentation. By contrast, Saccharomyces cerevisiae took over the dominance starting from the middle stage of fermentation. The wine's phenolic compounds were revealed by high-performance liquid chromatography, with tyrosol being the most abundant. Rhodotorula babjevae and Botrytis cinerea showed a positive correlation with p-hydroxybenzoic acid, gentisic acid, caffeic acid and cinnamic acid, while demonstrating a negative correlation with protocatechuic acid and chlorogenic acid. Heterophoma novae-verbascicola exhibited the opposite behaviour regarding the same phenolic compounds. The concentration of lactic acid was positively correlated with B. cinerea and negatively correlated with Het. novae-verbascicola. These findings serve as a foundation for in-depth investigations into the role of autochthonous grape mycobiota in phenolic transformation during spontaneous fermentation, potentially leading to the production of high-quality wines with unique terroir characteristics. Future studies should aim to explore the specific role played by individual yeast isolates in the formation of phenolic compounds.

Exploitation of Black Olive (Olea europaea L. cv. Piantone di Mogliano) Pomace for the Production of High-Value Bread.

In this study, the morpho-textural features, total phenolic content (TPC), and antioxidant capacity (AOC) of bread fortified with olive (Olea europaea L.) pomace were evaluated. Fresh olive pomace was subjected to microbiological and chemical (TPC, AOC, and fiber) analyses; then, the same olive pomace was analyzed during 1 to 6 months of storage at 4 °C or -20 °C. All olive pomace samples were used in 10%, 15%, or 20% amounts to produce type 0 soft wheat (Triticum aestivum) and whole wheat bread samples. The volatile organic compounds (VOCs) in the bread samples were also analyzed to assess the effect of the addition of the olive pomace on the flavor profile of the baked products. The TPC and AOC evaluation of olive pomace showed no differences among the analyzed samples (fresh, refrigerated, or frozen). Regarding the bread containing olive pomace, the specific volume was not affected by the amount or the storage methods of the added pomace. Bread samples produced with soft wheat flour showed the lowest hardness values relative to those produced with whole wheat flour, irrespective of the amount or storage method of the olive pomace. Regarding color, the crust and crumb of the bread samples containing 20% olive pomace were significantly darker. The bread samples containing 20% olive pomace had the highest TPC. The bread samples with fresh olive pomace were characterized by terpenoids, ketones, and aldehydes, whereas the bread samples containing refrigerated olive pomace were characterized by alcohols (mainly ethanol), acids, esters, and acetate. Finally, the bread samples with frozen olive pomace showed a volatile profile similar to that of bread produced with fresh olive pomace. Olive pomace was shown to be a suitable ingredient for producing bread with high nutritional value.

Search for carbapenem-resistant bacteria and carbapenem resistance genes along swine food chains in Central Italy.

The presence of carbapenem-resistant bacteria and carbapenem resistance genes (CRGs) in livestock is increasing. To evaluate the presence of carbapenemase-producing Enterobacteriaceae (CPE) and the main CRGs along swine food chains of the Marche Region (Central Italy), samples of faeces, feed, and animal-food derived products were collected from seven small/medium, medium, and large-scale pig farms. A total of 191 samples were analysed using a culture-dependent method, with the aim of isolating CPE. Isolates were analysed for their resistance to carbapenems using a modified Hodge test and the microdilution method for the minimum inhibitory concentration (MIC) determination. Moreover, the extraction of microbial DNA from each sample was performed to directly detect selected CRGs via qPCR. Among the 164 presumptive resistant isolates, only one strain from a liver sample, identified as Aeromonas veronii, had an ertapenem MIC of 256 µg/mL and carried a carbapenemase- (cphA) and a ß-lactamase- (blaOXA-12) encoding genes. A low incidence of CRGs was found; only nine and four faecal samples tested positive for blaNDM-1 and blaOXA-48, respectively. Overall, the importance of monitoring CPE and CRGs in livestock and their food chains should be stressed to control all potential non-human CPE and CRGs reservoirs and to determine safety levels for human health.

Tasting of traditional Polish fermented cucumbers: Microbiology, morpho-textural features, and volatilome.

In the present study, naturally fermented and unpasteurized cucumbers (Cucumis sativus L.) collected from 4 producers located in different regions of Poland were studied. The fermented cucumbers were characterized by significant nutritional features in terms of polyphenols content and antioxidant activity. Microbiological analyses revealed active bacterial populations of lactococci, thermophilic cocci, lactobacilli, and coagulase-negative cocci. The microbiological characterization of cucumber and brine samples through metataxonomic analysis allowed the dominant species to be detected, being Lactococcus and Streptococcus in cucumbers, and Lactiplantibacillus, Leuconostoc, Pediococcus, Secundilactobacillus, and Lentilactobacillus in brine. The isolation activity offered a clear picture of the main active lactic acid bacteria at the end of fermentation, being Pediococcus parvulus and Lactiplantibacillus plantarum group. All the studied isolates showed a good attitude in fermenting a cucumber-based broth, thus suggesting their potential application as starter or adjunct cultures for guided cucumber fermentation. Moreover, for the same isolates, strong aminopeptidase activity (due to leucine arylamidase and valine arylamidase) was observed, with potential effect on the definition of the final sensory traits of the product. Only a few isolates showed the ability to produce exopolysaccharides in synthetic medium. Of note, the presence of the hdcA gene in some Pediococcus ethanolidurans isolates also confirmed the need for a thorough characterization of starter candidates to avoid undesired adverse effects on consumer's health. No isolate showed the production of bacteriocins against Listeria innocua used as surrogate for Listeria monocytogenes. Based on the results of Headspace Solid-Phase Microextraction-Gas Chromatography/Mass Spectrometry analysis, a rich and complex volatilome, composed by more than 80 VOCs, was recognized and characterized. In more detail, the detected compounds belonged to 9 main classes, being oxygenated terpenes, alcohols, terpenes, ketones, acids, aldehydes, esters, sulfur, and sesquiterpenes.

Spotlight on autochthonous microbiota, morpho-textural characteristics, and volatilome of a traditional Polish cold-smoked raw sausage.

The aim of the present study was to obtain information on the bacterial diversity of traditional Polish cold-smoked raw sausages (Kielbasa polska wedzona) manufactured by two artisanal producers using different selective growth media and a metataxonomic analysis. Physico-chemical and morpho-textural characteristics were also carried out, together with Microextraction-Gas Chromatography/Mass Spectrometry (HS-SPMEGC/MS) to study the volatile organic compounds (VOCs). The results overall obtained allowed a picture of the microbiota, the morpho-textural characteristics, and the volatilome of traditional Polish cold-smoked raw sausages (Kielbasa polska wedzona) to be drawn for the first time. In more detail, viable counting revealed active populations of presumptive lactobacilli, enterococci, coagulase-negative cocci, and a few spoilage microorganisms typically occurring in raw meat products. The metataxonomic analysis revealed the dominance of Latilactobacillus sakei occurring with a relative frequency between 77% and 89%. Pediococcus pentosaceus, Weissella hellenica, and Leuconostoc carnosum were detected among the minority taxa. In the sausages herein studied, no histamine levels of concern were detected. The Principal Component Analysis (PCA) performed on the Amplicon Sequence Variants (ASVs) did not show significant differences in the microbiota composition among producers. The HS-SPMEGC/MS analysis allowed the detection and identification of more than 90 volatile components belonging to ten main classes, namely: aldehydes, ketones, esters and acetates, acids, alcohols, phenols, furans, sulphur compounds, terpenoids, and benzene derivatives. The detected VOCs originated from spices, smoke, and microbial metabolism. The PCA of volatile compounds allowed differences between the sausage samples of the two producers to be identified.

Chemical, microbiological, textural, and sensory characteristics of pilot-scale Caciofiore cheese curdled with commercial Cynara cardunculus rennet and crude extracts from spontaneous and cultivated Onopordum tauricum.

The aim of this study was the chemical, microbiological, textural, and sensory characterization of pilot-scale prototypes of an Italian ewe's raw milk cheese (Caciofiore) curdled with commercial Cynara cardunculus rennet, used as a control, and crude extracts obtained from flowers of either spontaneous or cultivated Onopordum tauricum. Hence, the control and experimental cheese prototypes produced in two rounds of cheesemaking trials were assayed, at the end of their 60-day maturation, for the following features: pH, titratable acidity, dry matter, fat, total and soluble nitrogen (TN and SN, respectively), ash, salt, protein, lactose, viable plate counts and composition of the bacterial and fungal populations, color, texture, volatile organic compounds (VOCs), and olfactory attributes by sensory analysis (the latter for the sole prototypes curdled with the commercial rennet and the extract obtained from cultivated O. tauricum). The data overall collected showed a very low impact of the type of thistle rennet on the analyzed cheese traits, with significant differences being exclusively found for SN/TN%, titratable acidity, color, and adhesiveness. By contrast, a higher impact of the cheesemaking round was seen, with significant differences being observed for salt content, load of presumptive lactobacilli, thermophilic cocci, and Escherichia coli, and levels of the following VOCs: 2,3-butanedione, 2-pentanone, 1-butanol, 2-heptanone, 3-methyl-1-butanol, 2-heptanol, 2-nonanone, dimethyl trisulfide, 2-methyl propanoic acid, butanoic acid, and 3-methyl butanoic acid. Sensory analysis revealed a strong ewe's cheese odor, accompanied by other olfactory notes, such as pungent, sour curd, sweet, and Parmesan cheese-like notes, in all the analysed cheese prototypes. Moreover, key odor active compounds, including butanoic acid, ethyl butanoate, 2,3-butanedione, 1-octen-3-one, and dimethyl trisulfide, were identified by GC-olfactometry analysis. Regarding the odor attributes as determined by sensory analysis, again the type of rennet had an almost negligible impact, with significant differences being only perceived for 1 or 2 out of 20 odor attributes, depending on the analytical conditions applied. Although some aspects deserve further investigation, the results herein collected confirm that O. tauricum can be regarded as an alternative source of thistle rennet for the manufacture of Caciofiore cheese, and more in general, Mediterranean ewe's milk cheeses.

Impact of Different Drying Methods on the Microbiota, Volatilome, Color, and Sensory Traits of Sea Fennel (Crithmum maritimum L.) Leaves.

Sea fennel (Crithmum maritimum L.) is a strongly aromatic herb of the Apiaceae family, whose full exploitation by the modern food industry is of growing interest. This study aimed at investigating the microbiological quality, volatile profile, and sensory traits of sea fennel spices produced using room-temperature drying, oven drying, microwave drying, and freeze drying. All the assayed methods were able to remove moisture up until water activity values below 0.6 were reached; however, except for microwave drying, none of the assayed methods were effective in reducing the loads of contaminating microorganisms. The metataxonomic analysis highlighted the presence of phytopathogens and even human pathogens, including members of the genera Bacillus, Pseudomonas, Alternaria, and Cryptococcus. When compared to fresh leaves, dried leaves showed increased L* (lightness) and c* (chroma, saturation) values and reduced hue angle. Dried leaves were also characterized by decreased levels of terpene hydrocarbons and increased levels of aldehydes, alcohols, and esters. For the sensory test, the microwave-dried samples obtained the highest appreciation by the trained panel. Overall, the collected data indicated microwave drying as the best option for producing sea fennel spices with low microbial loads, brilliant green color, and high-quality sensory traits.

Microbial Dynamics of a Specialty Italian Raw Ewe's Milk Cheese Curdled with Extracts from Spontaneous and Cultivated Onopordum tauricum Willd.

Milk coagulants prepared by maceration of flowers harvested from both spontaneous and cultivated Onopordum tauricum Willd. and a commercially available coagulant obtained from Cynara cardunculus L. (control) were assayed for small-scale manufacturing of Caciofiore, an Italian specialty raw ewe's milk cheese produced in a family run dairy farm located in the Marche region (Central Italy). The microbiota of the three thistle-based milk coagulants and their effect on the microbial dynamics of raw milk cheeses during fermentation and maturation (from day 0 up until day 60) were investigated through a combined approach based on viable counting and Illumina DNA sequencing. In both the control and experimental cheeses, despite the slight differences emerged depending on the coagulant used, Lactococcus lactis and Debaryomyces hansenii were the prevalent species among bacteria and fungi, respectively. Moreover, raw ewe's milk was the main factor affecting the evolution of both the bacterial and fungal microbiota in all cheeses. The overall similarities between control and experimental cheeses herein analyzed supports the exploitation of Onopordum tauricum Willd. as an alternative milk coagulating agent for production of Caciofiore and, more in general, raw ewe's milk cheeses.

Queijo Serra da Estrela PDO Cheese: Investigation into Its Morpho-Textural Traits, Microbiota, and Volatilome.

Queijo Serra da Estrela is a PDO Portuguese cheese produced through coagulation of raw ewe's milk using cardoon (Cynara cardunculus L.) flowers. The present research was aimed at depicting an up-to-date and comprehensive overview of the microbiota of Queijo Serra da Estrela cheese. To this end, viable counting and metataxonomic analysis were carried out on cheeses sampled from four Portuguese artisan producers. Physico-chemical and morpho-textural analyses were also performed, together with the analysis of volatile organic compounds (VOCs). Finally, non-starter lactic acid bacteria (NSLAB) isolated from the cheeses were characterized for their enzymatic activities using a semi-quantitative method. According to the metataxonomic analysis, Lactococcus lactis and Lactococcus piscium were the species occurring at the highest relative abundance. The isolates collected from the cheeses were assigned to Enterococcus durans, Enterococcus faecalis, Enterococcus faecium, Enterococcus lactis, Levilactobacillus brevis, Latilactobacillus graminis, Leuconostoc mesenteroides, and the Lacticaseibacillus casei group. The enzymatic characterization of these cultures highlighted esterase, aminopeptidase, acid phosphatase, beta-galactosidase, alpha-glucosidase, and beta-glucosidase among the major enzymatic activities. Fungal populations were dominated by Debaryomyces hansenii and Kurtzmaniella zeylanoides; however, species rarely found in cheese (e.g., Candida boidinii, Vishniacozyma victoriae, and Starmerella) were also detected. The volatile compounds characterizing the analyzed cheeses were carboxylic acids and esters, followed by carbonyl compounds and alcohols.