Effects of Preservative Agents on Quality Attributes of Dry-Cured Fermented Sausages

Mechanisms of action of bioprotective plant extracts against the ochratoxigenic Penicillium nordicum in dry-cured sausages

Plant extracts are promising strategies to minimise the hazard associated with ochratoxin A (OTA) in dry-cured sausages. Nonetheless, their mechanisms have not been elucidated yet. The mechanisms by which rosemary (REO), thyme (TEO) and oregano (OEO) essential oils and the extract of acorn shell (AE) impact on the OTA production by Penicillium nordicum were evaluated. Their effect on the mould's gene expression, ergosterol synthesis, reactive oxygen species (ROS) production and spore germination and their potential to the OTA detoxification were in vitro studied in three mould strains. Differences at sampling time, plant extract and mould strain levels were found for all mechanisms of the antifungal agents. The relative expression of Hog1 and Rho1 genes were less affected than that of the otanps and otapks genes in treated moulds compared to the non-treated control. All treatments were able to decrease ergosterol production against one strain. Furthermore, REO 500 μL/mL, AE and OEO 50 μL/mL produced the highest fluorescence associated with ROS for another strain at the end of the incubation. Moreover, a significant detoxification of the plant extracts was only found for OEO 50 μL/mL after 24 h of incubation. Besides, spore germination was totally inhibited by TEO and OEO, obtaining the opposite effect for AE. No clear relationship was found when those findings were correlated to the OTA accumulation. Consequently, the antiochratoxigenic effect of plant extracts seems to be due to the involvement of several mechanisms of action. Finally, the plant extracts did not inhibit the potentially protective cultures against ochratoxigenic moulds.

The Overall Quality Changes of Chinese Sauced Ducks at Different Stages During Processing and Storage

This study reveals the physicochemical, microbial, flavor, and sensory changes in sauced duck from the marinating phase to the end of storage, divided into six stages (stages A-F). The changes in color, total plate count, total volatile basic nitrogen, and thiobarbituric acid reactive substance at different stages were clarified. We utilized 16S rRNA gene sequencing, GC-IMS, and GC-MS to explore the changes in bacterial flora, fatty acid composition, and flavor characteristics. The dominant bacteria identified in stages A-C included Psychrobacter, Flavobacterium, and Pseudomonas, while Lactobacillus and Staphylococcus dominated during stages D-F. Aldehydes, esters, alcohols, and ketones emerged as the main flavor compounds. Several unsaturated fatty acids significantly (p < 0.05) decreased from stage A to stage F. The sensory quality of sauced duck improved. The potential reactions were determined, and correlation analysis of sauced duck samples across different stages was performed. 3-Methy-1-butanol could be a crucial indicator of sauced duck's overall quality. This research could support the treatment optimization of sauced duck products.

Effect of Carbohydrate Formulas on Instrumental and Sensory Parameters in Dry-Fermented Iberian Pork Sausages

Dry-fermented sausages are appreciated all over the world for their sensory characteristics. Carbohydrates (sugars) are added during the production process, the type and quantity of which directly affect the quality of this product. However, there are few data on the role of sugars on instrumental and sensory parameters of sausages derived from Iberian pork. The objective was to determine the effect of different carbohydrate formulas during the ripening time on the quality of dry-fermented Iberian pork sausages. Five batches were formulated with different combinations and concentrations of carbohydrates (dextrose, dextrin and glucose syrup), making 16 sausages per batch on which to perform repeated measurements throughout the ripening process. Physicochemical characteristics, instrumental colour, textural parameters and sensory attributes were analysed. The C- batch (without any carbohydrate addition) showed unstable pH evolution and high b* values throughout the ripening process and the lowest instrumental texture values (for hardness, springiness and chewiness). The D10d5 batch also presented an unstable pH evolution but low a* values, and it was the highest rated by consumers for sensory texture attributes. This batch, made with dextrose (in higher proportion) and dextrin, differed from the other Iberian pork sausages, suggesting that this carbohydrate formula may be more appreciated by Mediterranean consumers.

In-depth characterization of food and environmental microbiomes across different meat processing plants

BACKGROUND

Processing environments can be an important source of pathogenic and spoilage microorganisms that cross contaminate meat and meat products. The aim of this study was to characterize the microbiome of raw materials, processing environments and end products from 19 facilities producing different meat products.

RESULTS

The taxonomic profiles of the microbial communities evolved along processing, from raw materials to end products, suggesting that food contact (FC) surfaces play an important role in modulating the microbiome of final products. Some species persisted with the highest relative abundance in raw materials, food processing environments and/or in the final product, including species from the genera Pseudomonas, Staphylococcus, Brochothrix, Acinetobacter and Psychrobacter. Processing environments showed a very diverse core microbiota, partially shared with the products. Pseudomonas fragi and Pseudomonas sp. Lz4W (in all sample and facility types) and Brochothrix thermosphacta, Psychrobacter sp. and Psychrobacter sp. P11F6 (in raw materials, FC surfaces and end products) were prominent members of the core microbiota for all facilities, while Latilactobacillus sakei was found as a dominant species exclusively in end products from the facilities producing fermented sausages. Processing environments showed a higher amount of antimicrobial resistance genes and virulence factors than raw materials and end products. One thousand four hundred twenty-one medium/high-quality metagenome-assembled genomes (MAGs) were reconstructed. Of these, 274 high-quality MAGs (completeness > 90%) corresponded to 210 putative new species, mostly found in processing environments. For two relevant taxa in meat curing and fermentation processes (S. equorum and L. sakei, respectively), phylogenetic variation was observed associated with the specific processing facility under study, which suggests that specific strains of these taxa may be selected in different meat processing plants, likely contributing to the peculiar sensorial traits of the end products produced in them.

CONCLUSIONS

Overall, our findings provide the most detailed metagenomics-based perspective up to now of the microbes that thrive in meat, meat products and associated environments and open avenues for future research activities to better understand the microbiome functionality and potential contribution to meat quality and safety. Video Abstract.

Deciphering the antiochratoxigenic activity of plant extracts and Debaryomyces hansenii against Penicillium nordicum in a "chorizo"-based medium by proteomic analysis

Penicillium nordicum is the main ochratoxin A (OTA)-producing species on the surface of dry-fermented sausages, such as the "chorizo". New antifungal strategies are being developed using biocontrol agents (BCAs), such as plant extracts and native microorganisms. This work aimed to evaluate the antiochratoxigenic capacity and the causative modes of action of BCAs (rosemary essential oil (REO), acorn shell extract and the yeast Debaryomyces hansenii (Dh)) in a "chorizo"-based medium (Ch-DS). BCAs were inoculated on Ch-DS together with P. nordicum and incubated at 12 °C for 15 days to collect mycelia for OTA analyses and comparative proteomics. Both REO and Dh alone decreased OTA accumulation up to 99% and affected the abundance of P. nordicum proteins linked to cell wall organisation, synthesis of OTA-related metabolites and ergosterol synthesis. It is worth highlighting the increased abundance of an amidase by REO, matching with the decrease in OTA. The use of REO and Dh as BCAs could be an effective strategy to reduce the OTA hazard in the meat industry. Based on their not fully coincident modes of action, their combined application could be of interest in "chorizo" to maximise their potential against ochratoxigenic strains.

Effect of the Addition of Dandelion (Taraxacum officinale) on the Protein Profile, Antiradical Activity, and Microbiological Status of Raw-Ripening Pork Sausage

The study evaluated the effect of adding dandelion extract on the characteristics of raw-ripening pork sausages while reducing the nitrite addition from 150 to 80 mg/kg. The sausages were made primarily from pork ham (80%) and pork jowl (20%). The process involved curing, preparing the meat stuffing, forming the links, and then subjecting the sausages to a 21-day ripening period. Physicochemical parameters such as pH, water activity, and oxidation-reduction potential were compared at the beginning of production and after the ripening process. The study also examined the impact of ripening on protein metabolism in pork sausages and compared the protein profiles of different sausage variants. The obtained research results indicate that dandelion-leaf extract (Taraxacum officinale) were rich in phenolic acids, flavonoids, coumarins, and their derivatives (LC-QTOF-MS method). Antiradical activity test against the ABTS+* and DPPH radical, and the TBARS index, demonstrated that addition of dandelion (0.5-1%) significantly improved the oxidative stability of raw-ripening sausages with nitrite content reduction to 80 mg/kg. A microbiological evaluation of the sausages was also carried out to assess the correctness of the ripening process. The total number of viable bacteria, lactic acid bacteria, and coliforms were evaluated and subsequently identified by mass spectrometry.

Occurrence of ochratoxin A in Sichuan bacon from different geographical regions and characterization and biocontrol of ochratoxigenic Aspergillus westerdijkiae strain 21G2-1A

Sichuan bacon represents the most prevalent dry-cured meat product across Southwest China, but it is vulnerable to fungal spoilage. In the present study, a total of 47 Sichuan bacons were obtained from different regions of the Sichuan Province and analyzed for the presence of ochratoxin A (OTA), yielding a positive rate of 23.4 % (11/47). All the observed OTA concentrations exceeded the maximum admissible dose in meat products (1 μg/kg) established by some EU countries, with the highest OTA concentration being 250.75 μg/kg, which raises a food safety concern and reveals the need for a standardized scientific processing protocol. Then, an OTA-producing fungus named 21G2-1A was isolated from positive samples and found to be Aspergillus westerdijkiae. Further characterization suggested a positive correlation between fungal growth and OTA production. The optimal temperature for the former was 25 °C, while it was 20 °C for the latter. Although the A. westerdijkiae strain 21G2-1A demonstrated greater mycelium growth in the presence of NaCl, OTA production was significantly dismissed when the salinity was greater than 5 %. Four lactic acid bacteria (LAB) were screened out as antagonists against the ochratoxigenic fungus. In vitro evaluation of the antagonists revealed that live cells inhibited fungal growth, and adsorption also contributed to OTA removal at different levels. This study sheds some light on OTA control in Sichuan bacon through a biological approach.

Penicillium chrysogenum: Beyond the penicillin

Almost one century after the Sir Alexander Fleming's fortuitous discovery of penicillin and the identification of the fungal producer as Penicillium notatum, later Penicillium chrysogenum (currently reidentified as Penicillium rubens), the molecular mechanisms behind the massive production of penicillin titers by industrial strains could be considered almost fully characterized. However, this filamentous fungus is not only circumscribed to penicillin, and instead, it seems to be full of surprises, thereby producing important metabolites and providing expanded biotechnological applications. This review, in addition to summarizing the classical role of P. chrysogenum as penicillin producer, highlights its ability to generate an array of additional bioactive secondary metabolites and enzymes, together with the use of this microorganism in relevant biotechnological processes, such as bioremediation, biocontrol, production of bioactive nanoparticles and compounds with pharmaceutical interest, revalorization of agricultural and food-derived wastes or the enhancement of food industrial processes and the agricultural production.

Bioprotective yeasts: Potential to limit postharvest spoilage and to extend shelf life or improve microbial safety of processed foods

Yeasts are a widespread group of microorganisms that are receiving increasing attention from scientists and industry. Their diverse biological activities and broad-spectrum antifungal activity make them promising candidates for application, especially in postharvest biocontrol of fruits and vegetables and food biopreservation. The present review focuses on recent knowledge of the mechanisms by which yeasts inhibit pathogenic fungi and/or spoilage fungi and bacteria. The main mechanisms of action of bioprotective yeasts include competition for nutrients and space, synthesis and secretion of antibacterial compounds, mycoparasitism and the secretion of lytic enzymes, biofilm formation, quorum sensing, induced systemic resistance of fruit host, as well as the production of reactive oxygen species. Preadaptation of yeasts to abiotic stresses such as cold acclimatization and sublethal oxidative stress can improve the effectiveness of antagonistic yeasts and thus more effectively play biocontrol roles under a wider range of environmental conditions, thereby reducing economic losses. Combined application with other antimicrobial substances can effectively improve the efficacy of yeasts as biocontrol agents. Yeasts show great potential as substitute for chemical additives in various food fields, but their commercialization is still limited. Hence, additional investigation is required to explore the prospective advancements of yeasts in the field of biopreservation for food.

Effect of selected agents for ochratoxin A biocontrol on the colour, texture and volatile profile of dry-cured fermented sausages

BACKGROUND

Traditional dry-cured fermented sausages favour the growth of an autochthonous microbial population, which plays an important role in their sensory aspects. However, some moulds can produce mycotoxins such as ochratoxin A (OTA). The biocontrol agents (BCAs) Debaryomyces hansenii FHSCC 253H and Staphylococcus xylosus FHSCC Sx8 have been demonstrated to reduce OTA production in dry-cured meat products, but their influence in the sensory characteristics of sausages has to be tested. The aim of this study was to evaluate the effect of these BCAs on the colour, texture and volatile profile of dry-cured fermented sausages.

RESULTS

D. hansenii caused few differences in the tested parameters with respect to the control batch. S. xylosus modified the texture and colour, although the values found were within the range expected for dry-cured fermented sausages 'salchichón'. Additionally, the volatile profile revealed the potential antioxidant effect of both BCAs and their ability to produce compounds associated with the ripened aroma that could increase product acceptability.

CONCLUSION

The results indicate that there were no inconveniences in implementing both BCAs during the processing of dry-cured fermented sausages 'salchichón'. Moreover, D. hansenii FHSCC 253H could improve the volatile profile of this product. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Avirulent Isolates of Penicillium chrysogenum to Control the Blue Mold of Apple Caused by P. expansum

Blue mold is an economically significant postharvest disease of pome fruit that is primarily caused by Penicillium expansum. To manage this disease and sustain product quality, novel decay intervention strategies are needed that also maintain long-term efficacy. Biocontrol organisms and natural products are promising tools for managing postharvest diseases. Here, two Penicillium chrysogenum isolates, 404 and 413, were investigated as potential biocontrol agents against P. expansum in apple. Notably, 404 and 413 were non-pathogenic in apple, yet they grew vigorously in vitro when compared to the highly aggressive P. expansum R19 and Pe21 isolates. Whole-genome sequencing and species-specific barcoding identified both strains as P. chrysogenum. Each P. chrysogenum strain was inoculated in apple with the subsequent co-inoculation of R19 or Pe21 simultaneously, 3, or 7 days after prior inoculation with 404 or 413. The co-inoculation of these isolates showed reduced decay incidence and severity, with the most significant reduction from the longer establishment of P. chrysogenum. In vitro growth showed no antagonism between species, further suggesting competitive niche colonization as the mode of action for decay reduction. Both P. chrysogenum isolates had incomplete patulin gene clusters but tolerated patulin treatment. Finally, hygromycin resistance was observed for both P. chrysogenum isolates, yet they are not multiresistant to apple postharvest fungicides. Overall, we demonstrate the translative potential of P. chrysogenum to serve as an effective biocontrol agent against blue mold decay in apples, pending practical optimization and formulation.

Perspectives on the Probiotic Potential of Indigenous Moulds and Yeasts in Dry-Fermented Sausages

The role of indigenous fungi in the appropriate development of sensory properties and the safety of dry-fermented sausages has been widely established. Nonetheless, their applications as probiotic agents have not been elucidated in such products yet, despite their promising functional features. Thus, it should be interesting to evaluate the probiotic potential of native Debaryomyces hansenii isolates from dry-fermented sausages and their application in the meat industry, because it is the most frequently isolated yeast species from these foodstuffs and its probiotic effects for animals as well as its possible probiotic activity for human beings have been demonstrated. Within the functional ability of foodborne yeasts, anti-inflammatory, antioxidant, antimicrobial, antigenotoxic, and immunomodulatory properties have been reported. Similarly, the use of dry-fermented sausages as vehicles for probiotic moulds remains a challenge because the survival and development of moulds in the gastrointestinal tract are still unknown. Nevertheless, some moulds have been isolated from faeces possibly from their spores as a form of resistance. Additionally, their beneficial effects on animals and humans, such as the decrease in lipid content and the anti-inflammatory activity, have been reported, although they seem to be more related to their postbiotic capacity due to the generated bioactive compounds with profunctional attributes than to their role as probiotics. Therefore, further studies providing knowledge useful for generating dry-fermented sausages with improved functionality are fully necessary.

Biocontrol of Pathogen Microorganisms in Ripened Foods of Animal Origin

Ripened foods of animal origin comprise meat products and dairy products, being transformed by the wild microbiota which populates the raw materials, generating highly appreciated products over the world. Together with this beneficial microbiota, both pathogenic and toxigenic microorganisms such as Listeria monocytogenes, Salmonella enterica, Staphylococcus aureus, Clostridium botulinum, Escherichia coli, Candida spp., Penicillium spp. and Aspergillus spp., can contaminate these products and pose a risk for the consumers. Thus, effective strategies to hamper these hazards are required. Additionally, consumer demand for clean label products is increasing. Therefore, the manufacturing sector is seeking new efficient, natural, low-environmental impact and easy to apply strategies to counteract these microorganisms. This review gathers different approaches to maximize food safety and discusses the possibility of their being applied or the necessity of new evidence, mainly for validation in the manufacturing product and its sensory impact, before being implemented as preventative measures in the Hazard Analysis and Critical Control Point programs.

Effect of a Selected Protective Culture of Lactilactobacillus sakei on the Evolution of Volatile Compounds and on the Final Sensorial Characteristics of Traditional Dry-Cured Fermented "Salchichón"

BACKGROUND

In this work, the effect of a selected starter culture of Lactilactobacillus sakei 205 on the evolution of volatile compounds throughout the ripening process and on the final sensorial characteristics of traditional dry-cured fermented "salchichón" was evaluated.

METHODS

"Salchichón" sausages were prepared, inoculated with L. sakei 205, and ripened for 90 days. Volatile compounds were analyzed throughout the ripening by GC-MS. In the final product, instrumental texture and color were determined. In addition, sensorial analysis was performed by a semi-trained panel.

RESULTS

The inoculation of L. sakei 205 does not influence the texture and color parameters of ripened "salchichón". However, an increase in volatile compounds derived from amino acid catabolism and microbial esterification and a decrease in compounds derived from lipid oxidation, mainly hexanal, were observed throughout the ripening time as a consequence of L. sakei inoculation, which could have a positive effect on the flavor development of the dry-cured fermented "salchichón".

CONCLUSIONS

The use of selected strains of lactic acid bacteria (LAB) such as L. sakei 205 as a protective culture could be recommended to improve the quality of traditional "salchichón".

Effects of Five Filamentous Fungi Used in Food Processes on In Vitro and In Vivo Gut Inflammation

Food processes use different microorganisms, from bacteria to fungi. Yeast strains have been extensively studied, especially Saccharomyces cerevisiae. However, to date, very little is known about the potential beneficial effects of molds on gut health as part of gut microbiota. We undertook a comprehensive characterization of five mold strains, Penicillium camemberti, P. nalgiovense, P. roqueforti, Fusarium domesticum, and Geotrichum candidum used in food processes, on their ability to trigger or protect intestinal inflammation using in vitro human cell models and in vivo susceptibility to sodium dextran sulfate-induced colitis. Comparison of spore adhesion to epithelial cells showed a very wide disparity in results, with F. domesticum and P. roqueforti being the two extremes, with almost no adhesion and 20% adhesion, respectively. Interaction with human immune cells showed mild pro-inflammatory properties of all Penicillium strains and no effect of the others. However, the potential anti-inflammatory abilities detected for G. candidum in vitro were not confirmed in vivo after oral gavage to mice before and during induced colitis. According to the different series of experiments carried out in this study, the impact of the spores of these molds used in food production is limited, with no specific beneficial or harmful effect on the gut.

Antifungal Metabolites as Food Bio-Preservative: Innovation, Outlook, and Challenges

Perishable food spoilage caused by fungi is a major cause of discomfort for food producers. Food sensory abnormalities range from aesthetic degeneration to significant aroma, color, or consistency alterations due to this spoilage. Bio-preservation is the use of natural or controlled bacteria or antimicrobials to enhance the quality and safety of food. It has the ability to harmonize and rationalize the required safety requirements with conventional preservation methods and food production safety and quality demands. Even though synthetic preservatives could fix such issues, there is indeed a significant social need for "clean label" foods. As a result, consumers are now seeking foods that are healthier, less processed, and safer. The implementation of antifungal compounds has gotten a lot of attention in recent decades. As a result, the identification and characterization of such antifungal agents has made promising advances. The present state of information on antifungal molecules, their modes of activity, connections with specific target fungi varieties, and uses in food production systems are summarized in this review.

Effect of the Dry-Cured Fermented Sausage "Salchichón" Processing with a Selected Lactobacillus sakei in Listeria monocytogenes and Microbial Population

In the present work, the effect of processing of dry-cured fermented sausage “salchichón” spiked with the selected Lactobacillus sakei 205 was challenge-tested with low and high levels of L. monocytogenes. The evolution of the natural microbial population throughout the “salchichón” ripening was also evaluated. For this, a total of 150 “salchichón” were elaborated and divided into six equal cases which were inoculated with different levels of L. monocytogenes, and L. sakei 205. Afterwards, sausages were ripened for 90 days according to a typical industrial process. Moisture content (%) and water activity (a_w) decreased throughout the ripening up to values around 26% and 0.78, respectively. No differences for moisture content, a_w, pH, NaCl and nitrite concentration were observed between the analyzed cases. Lactic acid bacteria counts in the L. sakei 205 inoculated cases were always higher than 6 log CFU g⁻¹ during ripening. Enterobacteriaceae counts were reduced during ripening until non-detectable levels at the end of processing. Reductions in L. monocytogenes counts ranged from 1.6 to 2.2 log CFU g⁻¹; therefore, the processing of “salchichón” itself did not allow the growth of this pathogen. Reduction in L. monocytogenes was significantly higher in the cases inoculated with L. sakei 205.