Differentiation of Staphylococci from Iberian dry fermented sausages by protein fingerprinting

Changes in the microbiological, physicochemical properties of Chinese traditional fermented Suan rou at ripening fermentation

This study characterized the changes in the microbiological, physicochemical properties of Suan rou during fermentation via three different techniques (Technique A is a traditional production process. Based on technique A, technique B adds a total of 200 g of sucrose to the thinly sliced meat, and technique C changes the amount of salt in the thinly sliced meat to 200 grams.). Compared to batch A, the samples from batches B and C featured more rapid reduction in pH and generated more TA. Myofibrillar proteins in batches B and C showed higher degradation rate, and several low-molecular-weight metabolites were determined on the basis of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gel lanes. The contents of thiobarbituric acid (TBARS) and total volatile base nitrogen (TVB-N) and the growth of spoilage bacteria and pathogens were suppressed in the three batches. A relatively compatible acid-salinity proportion was presented in the Suan rou of batches A and B compared with that of batch C. The results show that the Suan rou made by B technology was more palatable acid flavor and abundant nutrition.

Effect of red koji as a Starter Culture in "Wanergao": A Traditional Fermented Food in China

The objective of this study was to explore the effect of red kojis on essential indices of Wanergao. The results showed that red koji-inoculated Wanergao showed higher pH values (4.38 ± 0.06 and 4.39 ± 0.06) and lower TA values (1.61 ± 0.05 and 1.63 ± 0.05) compared to the control group. LAB and yeast in the starter culture group gradually increased to 7.57 ± 0.12, 7.64 ± 0.15 log cfu.g-1 and 8.59 ± 0.21, 8.64 ± 0.23 log cfu.g-1, respectively. During fermentation, the dominant microorganism was Lactobacillus plantarum and Saccharomyces cerevisiae. Compared to the Wanergao made using traditional backslopping, the red koji-inoculated Wanergao contained more amylases, EAA and DAA contents compared to the control sample. The red kojis and control samples presented different hardness, chewiness, and cohesiveness, as well as similar values in springiness, gumminess, and adhesiveness. Sensory analysis also showed higher chewiness aroma and resilience of Wanergao in the starter culture group than in the control group.

High-throughput sequencing-based characterization of the predominant microbial community associated with characteristic flavor formation in Jinhua Ham

Our purpose was to investigate the main bacterial microbiota and volatile profiles in the Chinese traditional dry-cured product-Jinhua ham during different processing stages and to analyze the role of the main microbiota in the formation of characteristic flavor. We determined the microbiota of Jinhua ham by using 16 S high throughput sequencing, and found that Staphylococcus constituted the predominant microbiota throughout the flavor formation process. Based on the volatile profiles of Jinhua dry-cured products from 11 different processing via SPME-GC-MS analysis, Aldehydes were the main groups of volatiles, with the most abundant ones being hexanal (13.89%) and nonanal (3.96%). To further investigate the relationship between predominant microbiota and the major volatile compounds in Jinhua ham, we screened and isolated genus Staphylococcus with high protease and lipase activities. The main Staphylococcus isolates, S. saprophyticus (53.4%) and S. equorum (31.0%) are related to the yields of aldehydes by producing hexanal, nonanal, benzaldehyde, and phenylacetaldehyde, indicating their contributions on the formation of characteristic flavor substances in Jinhua ham.

Commercial Saccharomyces cerevisiae as a starter culture in "Wanergao": A traditional fermented food in China

To explore the effect of commercial Saccharomyces cerevisiae on the quality of traditional "Wanergao" for reasonable consuming guidance, the dominant microbes, physicochemical property, free amino acid content, texture, and sensory properties during fermentation of "Wanergao" were illustrated in this paper. Compared with the samples in the control group, "Wanergao" samples in the two groups that were subjected to S. cerevisiae inoculation had weaker acidity (the pH values dropped from 4.39 ± 0.08 to 4.36 ± 0.07 and 4.36 ± 0.07 within 2 h during fermentation), higher fermenting rate (volume increased from 100 ± 1.31 to 305 ± 4.61 and 316 ± 4.93 mL separately within 3 h), and the dominant lactic acid bacteria and yeast being leukonid and S. cerevisiae. More amylose, ethanol, and free amino acid were detected in "Wanergao" produced with S. cerevisiae inoculation compared with "Wanergao" produced by sourdough. The two kinds of "Wanergao" presented various hardness (2318 ± 112, 2279 ± 103), springiness (0.76 ± 0.03, 0.71 ± 0.03), chewiness (1.43 ± 0.05, 1.41 ± 0.06), and cohesiveness (0.68 ± 0.03, 0.62 ± 0.03) after fermentation. The result of sensory analysis revealed that "Wanergao" in the S. cerevisiae group had higher elasticity, aroma, and restoring force. The experiment demonstrated that "Wanergao" produced by using S. cerevisiae is a kind of fermented rice product with rich fragrance, high amount of nutrients, and strong elasticity.

Bacterial Communities in Serpa Cheese by Culture Dependent Techniques, 16S rRNA Gene Sequencing and High-throughput Sequencing Analysis

Serpa cheese is one of the traditional regional Portuguese cheeses having the Protected Denomination of Origin (PDO) designation. This study investigated the bacterial community in the traditional Portuguese Serpa cheese. The microorganisms identified at the end of ripening (30 days) mainly were lactic acid bacteria (LAB). Lactobacillus paracasei/Lactobacillus casei was the main species in cheese from PDO registered industries, whereas in non-PDO registered industries Lactobacillus brevis was highlighted, among other LAB. Enterobacteriaceae species were detected at 20% to 40% of the total isolates. The results obtained by high-throughput sequencing analysis confirmed that LAB was the main microbial group, with Lactococcus genus contributing to approximately 40% to 60% of the population, followed by Leuconostoc and Lactobacillus. The Enterobacteriaceae family was also important. The differences between bacterial communities from PDO and non-PDO registered industries suggest that the lack of regulation of the cheese-making practices may influence unfavorably. The new knowledge about bacterial diversity in Serpa cheese could be useful to set up new ripening conditions, which favor the development of desirable microorganisms.

PRACTICAL APPLICATION

The control of the manufacturing process of traditional cheeses can be improved through the knowledge of the bacterial diversity that develops. Thus, the growth of desirable microorganisms can be promoted to homogenize the final product.

Antioxidant Activities of Lactic Acid Bacteria for Quality Improvement of Fermented Sausage

Lactobacillus curvatus (SR6) and Lactobacillus paracasei (SR10-1) were assessed for their antioxidant activities and inoculated into sausages to investigate their effects on quality during fermentation. The results showed that L. curvatus SR6 had better DPPH• scavenging activity (59.67% ± 6.68%) and reducing power (47.31% ± 4.62%) and L. paracasei SR10-1 had better OH• scavenging activity (285.67% ± 2.00%) and anti-lipid peroxidation capacity (63.89% ± 0.93%). The superoxide dismutase activity of the cell culture fluid was greater than 47.00 U/mL, and the catalase activity of the cell-free extracts was greater than 1.00 U/mL. In the sausage model, lactic acid bacteria rapidly became the dominant microflora and reduced the moisture content, water activity, nitrite, and pH. The bacteria significantly enhanced the antioxidant activity of the sausage extracts, which improved the sensory characteristics and safety of the sausages. These results illustrate that both strains have excellent antioxidant activities and can be used as antioxidant starters in fermented meat products.

PRACTICAL APPLICATION

The study illustrated the antioxidant and antioxidase activities of Lactobacillus curvatus SR6 and Lactobacillus paracasei SR10-1 and demonstrated the changes in the quality characteristics and antioxidant activities of fermented sausages. The findings provide valuable information for the meat industry on the application of functional starters in fermented meat products.

Characterization of microbial population of breba and main crops (Ficus carica) during cold storage: Influence of passive modified atmospheres (MAP) and antimicrobial extract application

The purpose of this work was to study the changes of bacterial and fungal population of breba fruits such as 'Banane' and 'San Antonio' as well as 'Cuello Dama Negro', 'Cuello Dama Blanco' and 'San Antonio' fig cultivars stored in passive modified atmospheres (MAP) by the use of three different microperforated films (M10 with 16 holes; M30 with five holes and M50 with three holes). Moreover the effects of the application of aqueous soy polyphenolic antimicrobial extract (APE), alone or combined with MAP, were also studied for 'Cuello Dama Negro' and 'Cuello Dama Blanco' fig cultivars. Bacteria and fungi isolates were identified by PCR-RFLP of 16S rRNA and ITS regions, respectively, and subsequently sequence of the different patterns obtained. The results indicated that Pseudomonas gessardii, Pantoea agglomerans and Enterobacter asburiae were the main species of bacteria found in all the treatments studied. The fungal species identified were Aureobasidium pulullans, Cladosporium cladosporioides and Alternaria alternata, which were found in a lower percentage in fruit stored in MAP and fruits treated with antimicrobial extracts, as this treatments allowed to reduce the microbial growth of moulds and yeasts. Thus, the application of treatments such as M30, M50 or the combination of MAP with antimicrobial extract was highly effective to control fruit spoilage in fig and breba crops.

Influence of starter culture and a protease on the generation of ACE-inhibitory and antioxidant bioactive nitrogen compounds in Iberian dry-fermented sausage "salchichón"

The effect of the addition of an autochthonous starter culture and the protease EPg222 on the generation of angiotensin-I-converting enzyme (ACE)-inhibitory and antioxidant compounds by the dry-fermented sausage "salchichón" was investigated. Sausages were prepared with purified EPg222 and Pediococcus acidilactici MS200 and Staphylococcus vitulus RS34 as the starter culture (P200S34), separately and together, ripened for 90 days, and compared to a control batch. Among the ripening time points (20, 35, 65, 90 days) studied, batches inoculated with EPg222 had higher nitrogen compound concentrations at 63 days of ripening. ACE-inhibitory and antioxidant activities were also highest in both batches with EPg222 at 63 days of ripening, and these activities were stable in most cases after in vitro simulated gastrointestinal digestion. These activities were correlated with the most relevant compounds detected by HLPC-ESI-MS. The principal components analysis (PCA) linked the P200S34 + EPg222 batch with the major compounds identified. The antioxidant activity was higher at 63 days of ripening, especially in highly proteolytic batches, such as P200S34 + EPg222. The ACE-inhibitory activity was not associated with any of the major compounds. The use of the enzyme EPg222 in association with the starter culture P200S34 in the preparation of dry-cured meat products could be of great importance due to their demonstrated ability to produce compounds with high biological activity, such as ACE-inhibitory and antioxidant activity.

Potential antimicrobial and antiproliferative activities of autochthonous starter cultures and protease EPg222 in dry-fermented sausages

This work studied the presence of nitrogen compounds with bioactive properties in Iberian pork sausages that were manufactured using different autochthonous starter cultures and protease EPg222.

Improving the safety of Staphylococcus aureus polyvalent phages by their production on a Staphylococcus xylosus strain

Team1 (vB_SauM_Team1) is a polyvalent staphylococcal phage belonging to the Myoviridae family. Phage Team1 was propagated on a Staphylococcus aureus strain and a non-pathogenic Staphylococcus xylosus strain used in industrial meat fermentation. The two Team1 preparations were compared with respect to their microbiological and genomic properties. The burst sizes, latent periods, and host ranges of the two derivatives were identical as were their genome sequences. Phage Team1 has 140,903 bp of double stranded DNA encoding for 217 open reading frames and 4 tRNAs. Comparative genomic analysis revealed similarities to staphylococcal phages ISP (97%) and G1 (97%). The host range of Team1 was compared to the well-known polyvalent staphylococcal phages phi812 and K using a panel of 57 S. aureus strains collected from various sources. These bacterial strains were found to represent 18 sequence types (MLST) and 14 clonal complexes (eBURST). Altogether, the three phages propagated on S. xylosus lysed 52 out of 57 distinct strains of S. aureus. The identification of phage-insensitive strains underlines the importance of designing phage cocktails with broadly varying and overlapping host ranges. Taken altogether, our study suggests that some staphylococcal phages can be propagated on food-grade bacteria for biocontrol and safety purposes.

Impact of pre-selected autochthonous starter cultures on the flavor quality of Iberian dry-fermented "salchichón" sausage with different ripening processes

The purpose of this study was to investigate the impact on flavor quality of 2 autochthonous starter cultures in the manufacture of Iberian dry-fermented "sálchichón." A total of 2 strains of Pediococcus acidilactici (MS200 and MS198) were combined individually with a strain of Staphylococcus vitulus (RS34) to obtain 2 starter cultures: P200S34 and P198S34. The ability of both starter cultures to implant during 2 different manufacturing procedures of "salchichón" was evaluated by 16S rRNA gene sequence analysis. Changes due to starter culture inoculations on volatile compounds were determined by gas chromatography/mass spectrometry, and the impact on flavor quality evaluated by sensorial analysis. The implantation of starter cultures was adequate and did not significantly modify the flavor of the traditional Iberian dry-fermented "salchichón," while modulating the volatile compound profile with respect to that found in sausages with wild microbial populations. The influence of the starter cultures studied was more evident in the shorter sausage processing time. P198S34 was related with the increase in some volatile compounds deriving from lipid degradation. P200S34 contributed to the formation of several volatile compounds arising from lipid degradation, amino acid catabolism, and microbial esterase activity.

PRACTICAL APPLICATION

P200S34 and P198S34 are autochthonous starter cultures for specific use in the processing of Iberian dry-fermented sausages. The application of these starters allows obtaining Iberian dry-fermented sausages with sensorial characteristics standardized. It is greatly interesting for processing and marketing industry of these high-quality meat products.

Use of autochthonous Pediococcus acidilactici and Staphylococcus vitulus starter cultures in the production of "chorizo" in 2 different traditional industries

The present study determined how the different ripening conditions affected the growth and development of 3 autochthonous starter cultures, and the physico-chemical and sensory characteristics of chorizo. Each of 3 strains of Pediococcus acidilactici (MC184, MS198, and MS200) and one of Staphylococcus vitulus (RS34) were associated to prepare the starter cultures, P184S34, P198S34, and P200S34. Then, chorizo was prepared following 2 manufacturing procedures. The autochthonous starter cultures were able to compete and colonize the sausages in both ripening procedures. The use of the starter cultures showed evident differences by the texture analysis, with the control batches being generally tougher than the starter culture batches. Also, the highest biogenic amine (BA) levels were found in control batches and the lowest in P200S34 batches. While the use of these starter cultures does not change the sensory characteristics of these traditional fermented sausages, it improves their homogeneity and safety, except for P184S34 batch in which more BAs are detected in industry 2.

PRACTICAL APPLICATION

The 3 autochthonous starter cultures selected could be used in traditional industries because they are able to compete well and colonize the dry fermented sausages "chorizo." The use of these starter cultures improves the texture and homogeneity of traditional fermented sausages. Biogenic amines decreased in the starter cultures batches improving the safety.

Role of an autochthonous starter culture and the protease EPg222 on the sensory and safety properties of a traditional Iberian dry-fermented sausage "salchichón"

The effect of the addition of an autochthonous starter culture and the protease EPg222 on the physico-chemical and sensory characteristics of dry-fermented sausage ''salchichon" was investigated. Sausages were prepared with purified EPg222 and Pediococcus acidilactici MS200 and Staphylococcus vitulus RS34 as starter culture (P200S34), separately and together, ripened for 90 days, and compared with a control batch. Dry-fermented sausages ripened with EPg222 and starter culture showed higher amounts of AN and volatile compounds derived from amino acid catabolism than the control, especially in samples in which was added the association of enzyme and starter culture (P200S34+EPg222). There were clear differences shown by the texture analysis, with the P200S34+EPg222 batch being less hard. Especially important was the result found in biogenic amines, since the association P200S34+EPg222 reduced their accumulation compared to the EPg222 batch. The use of EPg222 may be of great interest to improve the sensory characteristics of dry-fermented sausages, but its association with the selected starter culture with low decarboxylase activity is necessary to guarantee healthiness and homogeneity.

Application of Lactobacillus fermentum HL57 and Pediococcus acidilactici SP979 as potential probiotics in the manufacture of traditional Iberian dry-fermented sausages

The purpose of this study was to investigate the potential of implanting the probiotics Lactobacillus fermentum HL57 and P. acidilactici SP979 during manufacture of Iberian dry-fermented sausages, and their effect on the sensory properties of these meat products. Microbial counts were studied in sausages inoculated with these strains and compared with a control batch. To detect the presence of probiotic strains at high counts (>7 log CFU/g) in the inoculated sausages, specific PCR and (RAPD)-PCR techniques were carried out. Changes due to probiotic inoculations on parameters and compounds related to fermentation, and nitrogen and lipid fractions were determined, and the impact on sensory quality evaluated by descriptive and hedonic tests. Iberian dry-fermented sausages inoculated with L. fermentum HL57 and P. acidilactici SP979 may be considered as functional products according to the counts of these strains found at the end of processing. However, inoculation with L. fermentum HL57 increased the amount of acetic acid and lipid degradation products such as malonaldehyde in Iberian dry-fermented sausages, resulting in a negative impact on relevant sensory parameters related to colour and taste. On the contrary, P. acidilactici SP979 did not notably modify the physicochemical parameters or the sensory quality of Iberian dry-fermented sausages when compared to the autochthonous microbial population present in the control batch.

Safety and functional aspects of pre-selected lactobacilli for probiotic use in Iberian dry-fermented sausages

The purpose of this study was to investigate lactobacilli for potential probiotic use in Iberian dry-fermented sausages. A total of 18 strains, previously selected, isolated from different sources were evaluated according to safety and functional characteristics including biogenic amines and d-lactic acid production, antibiotic susceptibility, haemolysis, cell adhesion, and antimicrobial activity against food-borne pathogens. The strains Lactobacillus reuteri PL519, L. reuteri PL542, and Lactobacillus fermentum HL57 were able to establish their self on the intestinal epithelium, and an inhibition of such pathogenic bacteria as Listeria monocytogenesin vitro. These strains were also considered safe to be used with regard to their low aminogenic potential and d-lactic acid production, antibiotic resistance pattern and haemolytic activity. Thus, they were selected as a potential probiotic meat starter culture suitable for manufacture of dry-fermented Iberian sausages.