Investigating the effect of commercial starter cultures on the physicochemical and microbiological properties of Merguez, an artisanal Moroccan sausage

Aims@#This study aims to examine the effect of commercial starter cultures on traditional Merguez sausages proprieties throughout the fermentation and ripening process, aiming to produce safe and high-quality products. @*Methodology and results@#Three batches of sausages were produced, including a control batch with spontaneous fermentation (CO), a batch with Staphylococcus xylosus + Pediococcus acidilactici (SP) and a batch with Lactobacillus sakei + Staphylococcus carnosus (LS). The microbiological counts, physicochemical characteristics and chemical composition of Merguez were determined during the fermentation and ripening period. During the 18-day processing period, the microbial counts revealed a significant reduction (p<0.05) in Enterobacteriaceae counts, approximately 2 log CFU/g, in sausages inoculated with LS. Conversely, the control and SP batches exhibited comparatively higher counts. The physicochemical properties of the sausages were not significantly (p>0.05) impacted by starter cultures, except for lower pH values observed in the LS batch. SP batches showed a significant difference (p<0.05) in fat and protein content compared to LS and CO batches. Moreover, LS batches showed fat content significantly (p<0.05) different from CO and SP.@*Conclusion, significance and impact of study@#The use of starter cultures had distinct impacts on fermented Merguez sausages' safety, sensory properties and nutritional profile. The LS culture notably improved safety and sensory properties, while the SP culture increased fat content. These findings highlight the potential of using specific starter cultures to tailor Merguez sausages' safety and nutritional profile, thereby boosting their market potential.

Selection of potential lactic acid bacteria from fermented Sumbawa mare’s milk as starter cultures

Aims@#The aim of this study was to screen lactic acid bacteria (LAB) isolates from fermented Sumbawa mare‘s milk that meet the requirements as starter cultures, and to evaluate the effect of the selected starter culture in improving the organoleptic quality of mare‘s milk fermentation. @*Methodology and results@#The LAB isolates (13 isolates) derived from naturally fermented Sumbawa mare‘s milk were firstly screened for acidification activity. Afterwards, the selected isolates were evaluated for the starter culture criteria such as technological properties (proteolytic test, lipolytic test, and exopolysaccharide production), food safety test (hemolytic test and antibiotic sensitivity test), antimicrobial activity test. The selected culture (SC) together with yogurt starter cultures (YC) and combination between the selected isolate and a mixture of both (MC) were used to ferment fresh mare’s milk. Six LAB isolates (DB7, BC10, DC4, BC9, DC10, and BC7) were obtained from the acidification screening. Isolate BC10 was the most potential isolate as starter culture due to its ability in terms of acidification and proteolytic activity, lack of lipolytic activity, no indication of pathogenic potency, as well as able to inhibit the growth of Escherichia coli ATCC 25922. However, this isolate was resistant to antibiotics kanamycin, trimethoprim, and cinoxacin. The isolate BC10 presented 99.99% sequence similarity with respect to Lactobacillus plantarum.@*Conclusion, significance and impact of study@#The selected starter culture (isolate BC10) was able to improve the organoleptic quality of fermented mare‘s milk especially aroma compared to the other starter cultures. Therefore, L. plantarum BC10 is a potential isolate to be used as starter culture for mare’s milk fermentation.

Selection of starter cultures for the production of sour cassava starch in a pilot-scale fermentation process

ABSTRACT Sour cassava starch (Polvilho azedo) is obtained from a spontaneous fermentation conducted by microorganisms from raw materials and fermentation tanks. This product is traditionally used in the baking industry for the manufacture of biscuits and Brazilian cheese breads. However, the end of fermentation is evaluated empirically, and the process occurs without standardization, which results in products of inconsistent quality. Predominant microbiota from a cassava flour manufacturer was isolated in order to select starter cultures for the production of sour cassava starch in a pilot-scale fermentation process. Lactic acid bacteria and yeasts were isolated, enumerated and grouped by Restriction Fragment Length Polymorphism, and PCR fingerprinting, respectively. One isolate of each molecular profile was identified by sequencing of the rRNA gene. LAB were prevalent throughout the entire process. Lactobacillus brevis (21.5%), which produced the highest values of acidity, and Lactobacillus plantarum (13.9%) were among the most frequent species. Pichia scutulata (52.2%) was the prevalent yeast and showed amylolytic activity. The aforementioned species were tested as single and mixed starter cultures in a pilot-scale fermentation process for 28 days. L. plantarum exhibited better performance as a starter culture, which suggests its potential for the production of sour cassava starch.

Avaliação sensorial de pães de fermentação natural a partir de culturas starters inovadoras / Sensory evaluation of natural fermentation breads with innovative starter cultures

A fermentação sourdough para a produção de pães é fortemente motivada por seus efeitos benéficos quanto ao sabor, textura, vida de prateleira e pelas propriedades nutricionais dos produtos obtidos. Nesta pesquisa, estudou-se a aplicação dos micro-organismos Kluyveromyces marxianus, Dekkera bruxellensis e Lactobacillus plantarum como culturas starters alternativas na produção de pães. A partir de sete ensaios resultantes de um delineamento de mistura simplex-centroide, foram realizadas nos pães análises sensorial e instrumental. Observou-se que pães produzidos com L. plantarum apresentaram menor volume específico, enquanto que a mistura entre K. marxianus e L. plantarum exerceu influência positiva, possibilitando obter produtos de maior volume específico. A análise sensorial demonstrou a boa aceitabilidade para os pães produzidos com a mistura entre D. bruxellensis e K. marxianus e para a mistura entre os três micro-organismos. Os resultados deste trabalho demonstram a possibilidade do uso de culturas starters definidas para a fermentação sourdough, que é tradicionalmente obtida sem controle de processo.

The sourdough fermentation in bread making is strongly motivated due to its beneficial aspects on flavor, texture, shelf life, and the nutritional properties of the obtained products. In this research, the yeasts Kluyveromyces marxianus and Dekkera bruxellensis, and the bacterium Lactobacillus plantarum were used as alternative starter cultures in bread making. Experimental designs generated from simplex-centroid mixture were used in the sensorial analyses of breads. Results have shown that bread obtained with pure cultures of L. plantarum presented the smallest specific volume, while the mixture of K. marxianus and L. plantarum positively influenced the formation of good specific volume of products. Sensorial analysis showed good acceptability for breads obtained with D. bruxellensis and K. marxianus mixture, as well as for the mixture of the three microorganisms. The results obtained in this research suggest the possibility of using defined starter cultures for sourdough fermentation, which is traditionally carried out without any process controls.

Free and attached cells of Bacillus subtilis as starters for production of a soup flavouring (“ogiri egusi”)

Aims: This Bacillus subtilis has been identified to be the main fermenting bacterium during indigenous production of “ogiri egusi”; a traditional soup flavouring rich in protein. Evaluation of the use of starter and broth cultures of this bacterium in the production of ‘ogiri egusi’ was therefore undertaken with the view to improve the fermentation process and quality of product. Methodology and Results: Cowpea granules in association with Bacillus subtilis cells were developed as starter cultures for the fermentation. Results obtained showed that the starter cultures resulted in an increase in the aminonitrogen from 1.67±0.02 to 19.96±0.05 mg N/100 g dry matter in 48 h while the broth cultures increased the aminonitrogen from 1.63±0.03 to 16.54±0.05 mg N/100 g dry matter in 72 h. There was also a corresponding increase in the protease activity of the fermentation conducted with the starter cultures from 2.69±0.03 to 54.98±0.04 mg N/min in 48 h. The broth cultures produced an increase from 2.65±0.02 to 47.61±0.06 mg N/min in 72 h. Changes in these parameters for the natural process were gradual and reached their peaks at 120 h with values of 9.89±0.13 mg N/100g dry matter and 31.92±0.03 mg N/min respectively. Peroxide values for the fermentation processes increased throughout the period; however the starter cultures produced the lowest value (10.20±0.10 meq/kg) showing that rancidity may not occur in the product fermented by the starter culture. Conclusion, significance and impact of study: The starter cultures significantly reduced fermentation time from 96 – 120 h in the natural process to 48 h. Thus use of starter cultures optimized the process of fermentation and will eliminate chances of contamination of product with pathogens and spoilage organisms. This ultimately will improve product quality.

The influences of fish infusion broth on the biogenic amines formation by lactic acid bacteria

The influences of fish infusion decarboxylase broth (IDB) on biogenic amines (BA) formation by lactic acid bacteria (LAB) were investigated. BA productions by single LAB strains were tested in five different fish (anchovy, mackerel, white shark, sardine and gilthead seabream) IDB. The result of the study showed that significant differences in ammonia (AMN) and BA production were observed among the LAB strains in fish IDB (p < 0.05). The highest AMN and TMA production by LAB strains were observed for white shark IDB. The all tested bacteria had decarboxylation activity in fish IDB. The uppermost accumulated amines by LAB strains were tyramine (TYM), dopamine, serotonin and spermidine. The maximum histamine production was observed in sardine (101.69 mg/L) and mackerel (100.84 mg/L) IDB by Leuconostoc mesenteroides subsp. cremoris and Pediococcus acidophilus, respectively. Lactobacillus delbrueckii subsp. lactis and Pediococcus acidophilus had a high TYM producing capability (2943 mg/L and 1157 mg/L) in sardine IDB.

Influence of a native strain of Staphylococcus xylosus on the microbiological, physicochemical and sensorial characteristics on milano salami type

In this work, the influence of native starter cultures on the microbiological, physicochemical and sensorial characteristics of Milano salami type was studied. Two batches of Milano salami type were produced: Batch A, with the addition of Staphylococcus xylosus U5 and Batch B (control) without the starter culture. The Milano salami type was characterized by an important microbial activity of coagulase-negative staphylococci (CNS) that resulted in substantial growth in Batch A during the ripening with an initial count of 7.60 log cfu.g-1 and reached 9.84 log CFU.g-1 after 14 days. Bacterial enzymes that showed efficient activity under the conditions found in Milano salami type were catalase, nitrite and nitrate reductase, contributing for sensory and physicochemical properties of the product. There were no significant differences in general free fatty acids composition among the batches, while the color parameters (L *, a * and b *) in the Batch A presented significantly higher values in relation to Batch B. Moreover, batch A had the higher preference in sensorial analysis.

A análise da influência de culturas iniciadoras nativas nas características microbiológicas, físicoquímicas e sensoriais de salame tipo Milano foi o objeto deste estudo. Foram produzidos dois grupos de salame tipo Milano: Grupo A - com aplicação de linhagem Staphylococcus xylosus U5 enquanto o controle, Grupo B, foi produzido sem culturas iniciadoras. O salame tipo Milano foi caracterizado pela importante atividade microbiana de estafilococos coagulase negativo (SCN), que resultou significativo crescimento no Grupo A durante a maturação, com contagem inicial de 7,60 ufc.g-1 e alcançando um crescimento de 9,84 cfu.g-1 depois de 14 dias. As enzimas bacterianas que mostraram eficiente atividade sob as condições encontradas no salame tipo Milano foram catalase, nitrito e nitrato redutase, contribuindo para as propriedades físicoquímicas e sensoriais do produto. Não houve diferenças significativas na composição geral dos ácidos graxos livres entre as amostras, enquanto os parâmetros de cor (L*, a* e b*) obtidos no salame inoculado (Grupo A) diferiram significativamente em relação ao controle (Grupo B) e foi o grupo preferido pelos degustadores.

Phenotypic and molecular characterization of Staphylococcus xylosus: technological potential for use in fermented sausage

Micrococcaceae strains are applied to fermented sausage as starter cultures, where several members of this family are naturally found. The aim of the present work was to isolate and characterize Staphylococcus xylosus from artisanal sausages produced in South Region of Brazil. From 89 isolates presenting catalase positive and coagulase negative activities, 25 strains were selected for phenotypic characterization. Nine strains identified as Staphylococcus xylosus by API-STAPH were evaluated for their nitrate reduction capacity, which showed satisfactory growth of the strains in the presence of nitrite and sodium chloride, demonstrating their potential for use as starter cultures in fermented sausage. The strains were also evaluated through genus and species-specific PCR, which showed only two as S. xylosus, differing from results found in phenotypic characterization.

Cepas de Micrococcaceae são aplicadas em embutidos cárneos fermentados como culturas iniciadoras, onde vários membros desta família são naturalmente encontrados. O objetivo deste trabalho foi isolar e caracterizar Staphylococcus xylosus de embutidos cárneos artesanais produzidos na região Sul do Brasil. Dos 89 isolados que apresentaram atividades positiva para catalase e negativa para coagulase, 25 cepas foram selecionadas para caracterização fenotípica. Nove cepas identificadas como Staphylococcus xylosus por API-STAPH foram avaliadas para capacidade de redução de nitratos e o crescimento satidfatório das cepas foi verificado na presença de nitrito e NaCl, demonstrando seu potencial para utilização como culturas iniciadoras em embutidos cárneos fermentados. As cepas foram ainda avaliadas quanto ao gênero e espécie através da reação em cadeia da polimerase e apenas duas cepas foram identificadas como S. xylosus, diferindo dos resultados encontrados na caracterização fenotípica.

Viability of Staphylococcus xylosus isolated from artisanal sausages for application as starter cultures in meat products / Viabilidade de Staphylococcus xylosus isoladas de embutidos artesanais para aplicação como cultivos iniciadores em produtos cárneos

Viability of Staphylococcus xylosus isolated from artisanal sausages for application as starter cultures in meat products Viability of Staphylococcus xylosus strains AD1 and U5isolated from natural fermented sausages was investigated as starter cultures in fermented sausages produced in the South Region of Brazil. The study demonstrated that the Staphylococcus xylosus strains AD1 and U5showed significant growth during fermentation, stability over freeze-dried process, negative reaction for staphylococcal enterotoxins and viability for using as a single-strain culture or associated with lactic acid bacteria for production of fermented sausages.

Investigamos a viabilidade de cepas de Staphylococcus xylosus (AD1 e U5) isoladas de embutidos com fermentação natural, para aplicação como cultivos iniciadores em embutidos fermentados produzidos na Região Sul do Brasil. O estudo demonstrou que cepas de Staphylococcus xylosus (AD1 e U5) apresentaram crescimento significativo durante a fermentação, estabilidade no processo de liofilização e conservação, ausência de produção de enterotoxinas e viabilidade para aplicação como cultivo iniciador simples ou associado com bactérias lácticas na elaboração de embutidos fermentados.