Relating physicochemical and microbiological safety indicators during processing of linguiça , a Portuguese traditional dry-fermented sausage

Variability in Physicochemical Parameters and Its Impact on Microbiological Quality and Occurrence of Foodborne Pathogens in Artisanal Italian Organic Salami

Artisanal salami is produced in small-scale production plants, where the lack of full automation might result in higher variability in food intrinsic properties. The aim of the present study was to evaluate the inter- and intra-batch variability in physicochemical parameters and its impact on microbial quality and occurrence of foodborne pathogens on 480 samples collected from six batches of an artisanal Italian production of organic salami. Relatively high total bacterial counts (TBC) were found on the surface of the table in the stuffing room (4.29 ± 0.40 log cfu/cm2). High loads of Enterobacteriaceae in the meat mixture of batch 2 and TBC in batch 5 were associated with a higher occurrence of bacterial pathogens. During ripening, water activity (aw) and pH failed to reach values lower than 0.86 and 5.3, respectively. Six Staphylococcus aureus and four Listeria monocytogenes isolates were collected from the salami meat mixture during ripening and the processing environment. A total of 126 isolates of Enterobacteriaceae were characterized at a species level, with Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Citrobacter freundii isolated from the final products. Results suggest the relevance of first steps of production in terms of the hygiene of raw materials and handling during stuffing procedures, especially when the physicochemical parameters of the final products do not reach values that represent hurdles for foodborne pathogens.

Behaviour of Listeria monocytogenes and Natural Microflora during the Manufacture of Riojano Chorizo (Spanish Dry Cured Sausage)

Riojano chorizo is a dry cured sausage manufactured with traditional technologies without adding starter cultures at low temperatures. Its characteristics differ from other types of chorizo since sugars and nitrites are no added and processing temperatures are low- This work evaluates the behaviour of Listeria monocytogenes during the processing of inoculated Riojano chorizo as well as the natural microflora that can play a technological role or be of interest as indicators. The sausage mixture was inoculated with a cocktail of three selected strains of L. monocytogenes (CECT 932, CECT 934 and CECT 4032) (4 log10 CFU/g) and after processed following the traditional production method. Samples were taken before inoculation, after inoculation, after stuffing (day 0) and on days 6, 13, 21 and 28 of processing. L. monocytogenes, mesophiles, Micrococcaceae, lactic acid bacteria, Enterobacteriaceae, S. aureus, sulfite-reducing clostridia and molds and yeast counts were evaluated. Furthermore, pH, water activity and humidity were determined. No growth of L mocytogenes was observed during the first 6 days, when the temperature of processing was 4 °C. The low temperature in the initial stages was a relevant hurdle to control L. monocytoegenes growth. A significant decrease (p ≤ 0.05) in L. monocytogenes counts was observed on day 13 compared to the initial counts. During drying (days 6 to 21) a reduction in this pathogen of 1.28 log CFU/g was observed. The low water activity below 0.92 on day 13 and 0.86 on day 21 seems to be critical for the reduction of L. monocytogenes.

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.

Modeling the behavior of Listeria innocua in Italian salami during the production and high-pressure validation of processes for exportation to the U.S

A model describing Listeria innocua evolution according to process parameters of 51 Italian salami processes and HPP in 31 companies was developed. A total of 51 challenge tests were performed. During processing a L. innocua reduction of 0.34-4.32 Log10 CFU/g was observed and HPP further reduced the count of 0.48-3.47 Log10 CFU/g; an overall reduction of 1.04-5.68 is reached. PH after acidification/drying process, a_w after seasoning, duration of the seasoning and caliber resulted associated (p < 0.05) with L. innocua decrease. HPP efficacy was associated (p < 0.05) with a_w and pH of the product: higher the pH and a_w after the acidification/drying and seasoning phases, higher resulted the L. innocua reduction after HPP. No significant association was observed between L.innocua and salt, nitrate and starter content and other characteristics of process. The model meets companies and Authorities needs and represents a useful tool to predict L. monocytogenes lethality, giving recommendations to food business operators interested in exportation to the U.S.

Effect of production process and high-pressure processing on viability of Listeria innocua in traditional Italian dry-cured coppa

In this study the effect of the application of High Pressure Treatment (HPP) combined with four different manufacturing processes on the inactivation of Listeria innocua, used as a surrogate for L. monocytogenes, in artificially contaminated coppa samples was evaluated in order to verify the most suitable strategy to meet the Listeria inactivation requirements needed for the exportation of dry-cured meat in the U.S. Fresh anatomical cuts intended for coppa production were supplied by four different delicatessen factories located in Northern Italy. Raw meat underwent experimental contamination with Listeria innocua using a mixture of 5 strains. Surface contamination of the fresh anatomical cuts was carried out by immersion into inoculum containing Listeria spp. The conditions of the HPP treatment were: pressure 593 MPa, time 290 seconds, water treatment temperature 14°C. Listeria innocua was enumerated on surface and deep samples post contamination, resting, ripening and HPP treatment. The results of this study show how the reduction of the microbial load on coppa during the production process did not vary among three companies (P>0.05) ranging from 3.73 to 4.30 log CFU/g, while it was significantly different (P<0.01) for the fourth company (0.92 log CFU/g). HPP treatment resulted in a significant (P<0.01) deep decrease of L.innocua count with values ranging between 1.63-3.54 log CFU/g with no significant differences between companies. Regarding superficial contamination, HPP treatment resulted significant (P<0.01) only in Coppa produced by two companies. The results highlight that there were processes less effective to inhibit the pathogen; in particular for company D an increase of L. innocua count was shown during processing and HPP alone cannot be able to in reaching the Listeria inactivation requirements needed for exportation of dry-cured meat in the U.S. According to the data reported in this paper, HPP treatment increases the ability of the manufacturing process of coppa in reducing Listeria count with the objective of a lethality treatment.

Influence of Meat Spoilage Microbiota Initial Load on the Growth and Survival of Three Pathogens on a Naturally Fermented Sausage

Meat products are potential vehicles for transmitting foodborne pathogens like Salmonella, S. aureus, and L. monocytogenes. We aimed to evaluate (1) the effect of the meat's initial natural microbiota on Salmonella, S. aureus, and L. monocytogenes growth and survival in a batter to prepare a naturally fermented sausage, made with and without curing salts and wine (2) the effect of a lactic acid bacteria (LAB) starter culture and wine on the survival of the three pathogens during the manufacturing of a naturally fermented sausage made with meat with a low initial microbial load. The results revealed that the reduced contamination that is currently expected in raw meat is favorable for the multiplication of pathogens due to reduced competition. The inhibitory effect of nitrite and nitrate on Salmonella, S. aureus, and L. monocytogenes was confirmed, particularly when competition in meat was low. In any attempt to reduce or eliminate nitrite from naturally fermented sausages, the use of LAB starters should be considered to ensure an unfavorable competition environment for pathogens. In the experiment with naturally fermented sausage, chouriço, the reduction in aw strongly inhibited the challenged pathogens, particularly when a LAB starter culture and wine were used.

What is the Main Processing Factor Influencing Staphylococcus Species Diversity in Different Manufacturing Units?

The microbiota of traditional dry-cured sausages and industrial environment was assessed to characterize the diversity of coagulase-negative staphylococci (CNS), and establish potential relationships with hygiene level or technological characteristics. Eight processing units from South Portugal were audited according to a checklist of requirements. Environmental and products' samples at different production stages were evaluated regarding hygiene and safety criteria. CNS were recovered, characterized, and their potential use as starters evaluated. Low genetic diversity was observed for Staphylococcus xylosus, whereas Staphylococcus equorum showed diverse genetic profiles. Staphylococcus xylosus predominated in products with a long period of cold smoking, Staphylococcus saprophyticus in products with a long period of hot smoking, Staphylococcus epidermidis in products with a short period of cold smoking, and S. equorum in nonsmoked products. Most S. xylosus were resistant to tetracycline, whereas S. equorum were susceptible. Antibioresistance restricted the selection of starters due to safety recommendations. PRACTICAL APPLICATION: The present manuscript highlighted a few staphylococci strains that could potentially be used as starter cultures in fermented meat products. These selected strains do not show resistance to antimicrobials, exhibit adequate technological features, and are well adapted to the industrial environments of meat processing industries using different processing technologies. Therefore, the selected strains ready to be used in the manufacturing of traditional fermented meat products to ensure safety, standardize product properties, and shorten ripening.

Physicochemical, sensory and microbiological characterization of Asturian Chorizo, a traditional fermented sausage manufactured in Northern Spain

Industrial standardization of fermented meat products requires starter culturesto avoid random variations in the initial microbiota of food matrix. This allows to homogenize production batches regarding sensory and physicochemical characteristics. Also, starters contribute to assure safety, as they compete with pathogens or spoilage species, facilitating pH reduction and secretion of inhibitors. Asturian Chorizo is a traditional fermented sausage from Northern Spain, still produced in a traditional way, without starters. This work describes its characterization at the sensory, physicochemical and microbiological levels. In contrast to other fermented sausages, Asturian Chorizo microbiota is represented mainly by Lactobacillus plantarum, with secondary contributions from Lb. sakei and Lb. futsai. This results may path the way towards development of specific starter cultures for this product, avoiding the loss of the original characteristics of the fermented product in a traditional way, as it would happen in the case of using industrial processes with conventional starters.

Effect of starter culture on microbiological, physiochemical and nutrition quality of Xiangxi sausage

Fermented sausages have a long tradition originating from China. In this study, three starter microorganisms including Pediococcus pentosaceus (P), Staphylococcus xylosus (S), and a combination of P. pentosaceus and S. xylosus (P + S) were conducted for the manufacture of traditional Xiangxi (a city in China) fermented sausages. The physicochemical changes of the above three kinds of sausages during fermentation were studied and discussed, and also compared with these properties on the natural fermented sausage (N, i.e., control). The results revealed that five kinds of bacterial phases were existed at different fermentation stages in N, P, S and P + S fermented sausages, respectively. The microbiological data showed that an initial enterobacteria count of approximately 5.3 log CFU/g for all four batches of sausages. The enterobacteria count in the inoculated sausages of P and P + S groups decreased significantly to about 1 log CFU/g whereas group N and S had a count of about 3.3 log CFU/g after fermentation. In the early stages of fermentation, the pH rapidly decreased below 5.3. FAA and FFA were significantly increased in all groups and TBARS value in group P was higher than that of the other three groups. In conclusion, starter cultures can be used to improve the hygiene level of Xiangxi sausages without significant effects on pH, A_W, and nitrite residue.