Isolation and characterization of acid-sensitive Lactobacillus plantarum with application as starter culture for Nham production

The aim of this study was to derive new starter culture variants that are unable to grow below pH 4.6, the desirable pH of the Thai fermented pork sausage, Nham, specified by Thailand Food Standard, and apply them in Nham fermentation. Several acid-sensitive mutants of one of the commercial Nham starter cultures, Lactobacillus plantarum BCC 9546, were isolated as spontaneous neomycin-resistant mutants. The growth of three representative mutants was characterized in MRS broth, which revealed that their cell numbers and acid production were lower than that of the wild-type. The H⁺-ATPase activities of the three mutants were found significantly lower than that of the wild-type under either neutral or acidic conditions. Consequently, internal pH values of the mutants appeared to be lower, especially in acidic environment (pH 5). The most acid-sensitive mutant was applied in experimental Nham production and the pH of Nham fermented with the mutant had significantly higher pH at the end of fermentation (3 days) and after an additional 4 days of storage at 30 °C. These results indicate that the use of acid-sensitive L. plantarum as starter culture can reduce the severity of post-acidification and increase the shelf life of Nham at ambient temperature.     

Properties and acceptability of Som-fug, a Thai fermented fish mince, inoculated with lactic acid bacteria starters

Effect of inoculation of different lactic acid bacteria (LAB) on the fermentation and quality of Som-fug from bigeye snapper was investigated. Som-fug inoculated with Pediococcus acidilactici at 10⁴ CFU/g (PA104) had a greater acceptability than those inoculated with Lactobacillus plantarum and Pediococcus pentosaceus at either 10⁴ or 10⁶ CFU/g and the control (without inoculum). During fermentation, PA104 exhibited a higher rate of fermentation than the control as indicated by the greater rate of pH drop and lactic acid production (p<0.05). Based on pH desired (pH 4.5), the fermentation was completed within 48 and 36 h for the control and PA104, respectively. Due to higher acid production rate, the textural development of PA104 was more pronounced. Som-fug inoculated with LAB generally exhibited higher hardness and adhesiveness than the control (p<0.05), when assessed by texture profile analysis (TPA). From the result, inoculation with P. acidilactici resulted in a reduction of fermentation time and improved the quality of Som-fug. Therefore, P. acidilactici can be used as a potential starter for Som-fug fermentation.     

Biogenic amine formation in Nham,a Thai fermented sausage,and the reduction by commercial starter culture, Lactobacillus plantarum BCC 9546

Biogenic amines are of concern for sausage due to their toxicological effects on nervous, blood pressure, gastric and intestinal systems. In this study, the influence of raw pork meat quality and starter culture inoculation on biogenic amines accumulation in Nham, a Thai traditional fermented pork, were studied. Before Nham processing, pork meat was stored at 30 °C for 6 h, and at 4 and −20 °C for 2 days. Formation of biogenic amines (cadaverine, putrescine, histamine and tyramine) was significantly higher in Nham processed from stored meat. Accumulation of these biogenic amines in Nham reduced significantly by the addition of Lactobacillus plantarum BCC 9546, a commercial Nham starter culture. The results highlight the importance of using fresh meat products and the inclusion of an appropriate starter culture to minimise the formation of biogenic amines during the process of Nham fermentation.     

Nonstarter lactic acid bacteria biofilms and calcium lactate crystals in Cheddar cheese

A sanitized cheese plant was swabbed for the presence of nonstarter lactic acid bacteria (NSLAB) biofilms. Swabs were analyzed to determine the sources and microorganisms responsible for contamination. In pilot plant experiments, cheese vats filled with standard cheese milk (lactose:protein = 1.47) and ultrafiltered cheese milk (lactose:protein = 1.23) were inoculated with Lactococcus lactis ssp. cremoris starter culture (8 log cfu/mL) with or without Lactobacillus curvatus or Pediococci acidilactici as adjunct cultures (2 log cfu/mL). Cheddar cheeses were aged at 7.2 or 10°C for 168 d. The raw milk silo, ultrafiltration unit, cheddaring belt, and cheese tower had NSLAB biofilms ranging from 2 to 4 log cfu/100 cm². The population of Lb. curvatus reached 8 log cfu/g, whereas P. acidilactici reached 7 log cfu/g of experimental Cheddar cheese in 14 d. Higher NSLAB counts were observed in the first 14 d of aging in cheese stored at 10°C compared with that stored at 7.2°C. However, microbial counts decreased more quickly in Cheddar cheeses aged at 10°C compared with 7.2°C after 28 d. In cheeses without specific adjunct cultures (Lb. curvatus or P. acidilactici), calcium lactate crystals were not observed within 168 d. However, crystals were observed after only 56 d in cheeses containing Lb. curvatus, which also had increased concentration of d(−)-lactic acid compared with control cheeses. Our research shows that low levels of contamination with certain NSLAB can result in calcium lactate crystals, regardless of lactose:protein ratio.     

Characterization of fermented silver carp sausages inoculated with mixed starter culture

To improve the characteristics and functionality, and increase the use of fish muscle, three groups mixed starter cultures (group one: Lactobacillus plantarum-15, Staphylococcus xylosus-12 and Pediococcus pentosaceus-ATCC33316 [S-PXP]; group two: Lactobacillus planatrum-15, Staphylococcus xylosus-12 and Lactobacillus casei subs casei-1.001 [S-PXC]; and group three: Staphylococcus xylosus-12, Lactobacillus casei subsp. casei-1.001 and P. pentosaceus-ATCC33316 [S-XCP]) were inoculated in minced silver carp muscle to produce a fermented fish product. During the 48 h fermentation at 30 °C, silver carp muscle inoculated with mixed starter cultures resulted in a rapid pH decrease, suppression in the increase of thiobarturic acid (TBARS) values, total volatile base nitrogen (TVB-N), trimethylamine (TMA), and the growth of spoilage bacteria and pathogens, and had higher whiteness than the control (without any starter) (P<0.05). The changes in SDS-PAGE indicated extensive hydrolysis of muscle protein occurred during fermentation. This study showed that the mixed starter cultures could substantially improve the flavor, digestibility, and nutritional value of the silver carp muscle.     

Isolation and characterisation of a novel Podoviridae-phage infecting Weissella cibaria N 22 from Nham, a Thai fermented pork sausage

A novel Podoviridae lactic acid bacteria (LAB) phage from Nham, a Thai fermented pork sausage, is reported. From a total of 36 samples, 41 isolates of LAB were obtained and employed as hosts for the isolation of phages. From these LAB, only one phage, designated Φ 22, was isolated. The lactic acid bacterial isolate named N 22, sensitive to phage Φ 22 infection was identified by an API 50 CHL kit and N 22’s complete sequence of the 16S rDNA sequence. BLASTN analysis of the 16S rDNA sequence revealed a 99% similarity to the 16S rDNA sequence of Weissella cibaria in the GenBank database. Electron micrographs indicated that the phage head was icosahedral with head size and tail length of 92 × 50 nm and 27 nm, respectively. On the basis of the morphology, this phage belongs to the family Podoviridae. Host-range determination revealed that the phage Φ 22 was not capable of infecting the other 40 isolates of LAB and referenced Weissella strains used. A one-step growth experiment showed that the latent period and burst size were estimated at 110 min and 55 phage particles/infected cell, respectively. Furthermore, the phage was infective over a wide range of pH (pH 5.0-8.0) and the D time of Φ 22 was calculated as 88 s at 70 °C and 15 s at 80 °C. Phage titers decreased below the detection limit (20 PFU/ml) after heating for more than 60 s at 80 °C, or 20 s at 90 °C or less than 10 s at 100 °C. The results from the study of Nham revealed that Φ 22 was active against the potential starter culture (W. cibaria N 22) for Nham fermentation. Phage infection could adversely affect the fermentation process of Nham by delaying acidification when using W. cibaria N 22 as a starter. However, the results from a sensory test revealed that the panelists did not detect any defects in the final products. This is the first report on the isolation of W. cibaria phage.     

Production of salami from beef, horse, mutton, Blesbok (Damaliscus dorcas phillipsi) and Springbok (Antidorcas marsupialis) with bacteriocinogenic strains of Lactobacillus plantarum and Lactobacillus curvatus

Lactobacillus plantarum 423, producer of bacteriocin 423, Lactobacillus curvatus DF38, producer of curvacin DF38, and a bacteriocin-negative mutant of L. plantarum 423 (423m) were evaluated as starter cultures in the production of salami from beef, horse, mutton, Blesbok (Damaliscus dorcas phillipsi) and Springbok (Antidorcas marsupialis). Growth of L. plantarum 423 and L. curvatus DF38 was best supported in Blesbok salami, as revealed by the highest growth rate during sweating, cold smoking and maturation, and final cell numbers after 70 days (1 × 10⁸ and 5 × 10⁷ cfu/g, respectively). Growth of Listeria innocua was the best suppressed in Blesbok salami fermented with L. plantarum 423 and L. curvatus DF38. Growth of L. innocua in horse salami was best suppressed when fermented with L. curvatus DF38. The final pH of salami fermented with L. plantarum 423 and L. plantarum 423m was slightly lower (4.4) compared to the pH of salami produced with L. curvatus DF38 (pH 4.7). No significant differences (P > 0.05) were recorded by a trained sensory taste panel amongst the three starter cultures regarding colour and venison like aroma. Horse, Blesbok and Springbok salami were rated significantly higher (P ? 0.05) in salami flavour than mutton salami, which was rated the lowest for this attribute. Blesbok salami was rated the highest for sour meat aroma, while beef salami was rated the lowest. Springbok salami was rated the highest in terms of oily mouth feel. Beef salami had the most compact structure and horse salami the softest structure of all meat types fermented. In general, salami produced with L. plantarum 423 yielded the best sour meat aroma, colour, texture, venison like flavour, sour meat flavour and oily mouthfeel and is considered superior to the L. plantarum mutant (strain 423m) and L. curvatus DF38.     

Novel starter cultures to inhibit biogenic amines accumulation during fish sauce fermentation

Bacteria with amine oxidase activity have become a particular interest to reduce biogenic amines concentration in food products such as meat and fish sausages. However, little information is available regarding the application of these bacteria in fish sauce. Hence, our study was aimed to investigate the effect of such starter cultures in reducing biogenic amines accumulation during fish sauce fermentation. Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05 isolated from fish sauce which possess amine oxidase activity were used as starter cultures in this study. Fermentation was held for 120 days at 35 °C. The pH value increased in all samples, while salt concentration remained constant throughout fermentation. Aerobic bacteria count was significantly lower (p < 0.05) in the control than in inoculated samples as a result of starter cultures addition. However, it decreased during fermentation due to the growth inhibition by high salt concentration. Proteolytic bacterial count decreased during fermentation with no significant difference (p > 0.05) among samples. These bacteria hydrolyzed protein in anchovy to produce free amino acid precursors for amines formation by decarboxylase bacteria. The presence of biogenic amines producing bacteria in this study was considered to be indigenous from raw material or contamination during fermentation, since our cultures were negative histamine producers. Amino acid histidine, arginine, lysine and tyrosine concentration decreased at different rates during fermentation as they were converted into their respective amines. In general, biogenic amines concentration namely histamine, putrescine, cadaverine and tyramine increased throughout fermentation. However, their concentrations were markedly higher (p < 0.05) in the control (without starter cultures) as compared to the samples treated with starter cultures. Histamine concentration was reduced by 27.7% and 15.4% by Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05, respectively. Both cultures could also reduce other amines during fermentation. After 120 days of fermentation, the overall biogenic amines concentration was 15.9% and 12.5% less in samples inoculated with Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05, respectively, as compared to control samples. These findings emphasized that application of starter cultures with amines oxidase activity in fish sauce fermentation was found to be effective in reducing biogenic amines accumulation.     

Identification of staphylococci and dominant lactic acid bacteria in spontaneously fermented Swiss meat products using PCR-RFLP

Pathogenic, spoilage, and technologically important microorganisms were monitored in 21 spontaneously fermented Swiss meat products manufactured with meat from wildlife or animals grown in natural habitat. Thereby, PCR-restriction fragment length polymorphism (RFLP) on rpoB and 16S rRNA gene sequences provided a powerful tool for fast and accurate identification of the main microbial population. Lactobacillus sakei and Lactobacillus curvatus dominated in fermented meat products followed by Staphylococcus species, which constituted 88.2% of all Gram-positive, catalase-positive cocci (GCC⁺) with cell counts varying from 2.6 to 7.0 log cfu/g during maturation. Staphylococcus equorum was prevalent in frequency and cell counts during maturation (18.0%; 5.0-7.3 log cfu/g) and in the end products (28.4%; 1.8-6.2 log cfu/g) implicating a new presumptive starter species for meat fermentation. Nine out of 14 end products indicated safety risks to consumers due to the high incidence of Staphylococcus saprophyticus or Staphylococcus epidermidis combined with cell counts of 7.4 and 4.9 log cfu/g, respectively. This fact was supported by the detection of Staphylococcus aureus and Enterobacteriaceae in ready-to-eat products strongly exceeding the tolerable limit of 2 log cfu/g. Spontaneously fermented meat products produced from wildlife or animals grown in natural habitats not only gave rise to hygienic and safety concerns but also provided new presumptive starter strains.     

Fermentation of bighead carp (Aristichthys nobilis) surimi and the characteristics of fermented bighead carp surimi products

BACKGROUND: To improve the properties and functionality of bighead carp (Aristichthys nobilis) muscle, bighead carp surimi was inoculated with combinations of Saccharomyces cerevisiae, Lactobacillus and Monascus and fermented, and then bighead carp sausages were prepared. The characteristics of fermented bighead carp surimi and sausages were investigated. RESULTS: During the 24 h fermentation at 30 °C, bighead carp surimi inoculated with mixed starter cultures resulted in a rapid decrease of pH, and suppression in the growth of Enterobacteria. The bighead carp sausages exhibited better colour, taste, flavour and appearance than the control (P < 0.05). The changes in non‐protein nitrogen (NPN), free amino acid in the fermented bighead carp surimi and SDS–PAGE patterns indicated that severe hydrolysis of muscle protein had occurred during fermentation. The sausages inoculated with the mixed starter cultures gained higher scores for flavour and overall acceptability than the control. CONCLUSIONS: The characteristic of fermented bighead carp surimi and sausages can be significantly improved by fermentation with the combinations of yeast, Lactobacillus and Monascus. Copyright © 2008 Society of Chemical Industry     

Fermented goats’ milk produced with selected multiple starters as a potentially functional food

A screening among five lactic acid bacteria, used alone or in combination, led to select a mixed starter (Streptococcus thermophilus CR12, Lactobacillus casei LC01, Lactobacillus helveticus PR4, Lactobacillus plantarum 1288) capable to produce a fermented goats’ milk containing γ-aminobutyric acid (GABA) and angiotensin-I converting enzyme (ACE)-inhibitory peptides. The fermented milk was characterized by cell counts of lactic acid bacteria not lower than 7.0 log cfu g⁻¹, even after 45 days of storage at 4 °C. Fermentation of goats’ milk resulted in the production of ca. 28 mg kg⁻¹ of GABA. Furthermore the fermented goats’ milk had an in vitro ACE-inhibitory activity of ca. 73%. Prolonged cold storage did not significantly affect both the concentration of GABA and the ACE-inhibitory activity. Moreover, the taurine content did not significantly vary during both fermentation and the entire storage period.     

Inhibition of A. carbonarius growth and reduction of ochratoxin A by bacteria and yeast composites of technological importance in culture media and beverages

Five composites of yeast and six of bacterial isolates from fermented products were studied, in order to assess their ability to inhibit Aspergillus carbonarius growth and reduce OTA concentration in culture media and beverages. The antagonistic effect of the above composites against A. carbonarius growth was studied in synthetic grape medium of pH 3.5 and a_w 0.98, 0.95, 0.92 after incubation at 25 °C. Different combinations of initial inocula of bacteria or yeast composites and fungi were used (10² cfu/mL vs 10⁵ spores/mL; 10⁵ cfu/mL vs 10² spores/mL; and 10⁵ cfu/mL vs 10⁵ spores/mL). Regarding the OTA reduction experiment, 10³ and 10⁷ cfu/mL of the bacteria and yeast composites were inoculated in liquid media of different pH (3.0, 4.0, 5.0, and 6.1 or 6.5) and initial OTA concentration (50 and 100 μg/L) and incubated at 30 °C. Moreover, grape juice, red wine, and beer were supplemented with 100 μg/L of OTA and inoculated with composites of 16 yeasts (16YM) and 29 bacterial (29BM) strains (10⁷ cfu/mL) to estimate the kinetics of OTA reduction at 25 °C for 5 days. Fungal inhibition and OTA reduction were calculated in comparison to control samples. None of the bacterial composites inhibited A. carbonarius growth. The high inoculum of yeast composites (10⁵ cfu/mL) showed more efficient fungal inhibition compared to cell density of 10² cfu/mL. All yeast composites showed higher OTA reduction (up to 65%) compared to bacteria (2-25%), at all studied assays. The maximum OTA reduction was obtained at pH 3.0 by almost all yeast composites. For all studied beverages the decrease in OTA concentration was higher by yeasts (16YM) compared to bacteria (29BM). The highest OTA reduction was observed in grape juice (ca 32%) followed by wine (ca 22%), and beer (ca 12%). The present findings may assist in the control of A. carbonarius growth and OTA production in fermented foodstuffs by the use of proper strains of technological importance.     

Angiotensin-converting enzyme inhibitory activity of milk fermented by wild and industrial Lactococcus lactis strains

Angiotensin I-converting enzyme inhibitory (ACEI) activity was evaluated and compared in <3 KDa water-soluble extracts (WSE) isolated from milk fermented by wild and commercial starter culture Lactococcus lactis strains after 48 h of incubation. The highest ACEI activities were found in WSE from milk inoculated with wild L. lactis strains isolated from artisanal dairy products and commercial starter cultures. On the other hand, the lowest ACEI activities were found in WSE from milk inoculated with wild strains isolated from vegetables. Moreover, the IC₅₀ values (concentration that inhibits 50% activity) of WSE from artisanal dairy products were the lowest, indicating that these fractions were the most effective in inhibiting 50% of ACE activity. In fact, a strain isolated from artisanal cheese presented the lowest IC₅₀ (13 μg/mL). Thus, it appears that wild L. lactis strains isolated from artisanal dairy products and commercial starter cultures showed good potential for the production of fermented dairy products with ACEI properties.     

Proteomic and peptidomic insights on myofibrillar protein hydrolysis in a sausage model during fermentation with autochthonous starter cultures

The hydrolysis of myofibrillar proteins during fermentation of sausage models by an autochthonous starter culture was investigated. In order to provide a whole map of the generated products, proteomic and peptidomic were used and complemented with the amino acid profile. Beaker sausages (BS) were used as models which were inoculated or not with Lactobacillus curvatus CRL705 and Staphylococcus vitulinus GV318 as starter cultures. The hydrolysis of actin, myosin light chain 1/3 (MLC 1/3), myosin regulatory light chain-2 (MRLC-2) and myosin heavy chain (MHC) was evidenced by two-dimensional gel electrophoresis (2-DE). In addition, a total of 33 peptides arisen from troponin T, MRLC-2 and particularly from actin were identified by LC–MS/MS. These results showed that the starter culture significantly enhanced the proteolysis of the proteins named above, even when the endogenous enzymes induced a clear breakdown. L. curvatus CRL705 highly enriched both peptide pattern and amino acid concentrations. When the autochthonous starter culture was inoculated, although proteolysis was remarkably reinforced, a reduction in peptide and amino acid composition was observed. Regarding actin primary structure, three regions of this protein were highly susceptible to degradation by the starter culture. Additionally, the essential role of exopeptidases – from meat and bacteria – in diversity of actin peptides during fermentation was shown. This study improved the knowledge of the proteolysis of myofibrillar proteins and the involved enzymes, as well as, completed the previously reported degradation of sarcoplasmic proteins by the same autochthonous starter culture. The singular peptides and amino acids pattern generated might contribute to the uniqueness of produced fermented sausages while they may be used as quality markers.     

Incidence of Staphylococcus aureus and associated risk factors in Nham,a Thai fermented pork product

Staphylococcus aureus is one of the most prevalent bacterial pathogens causing food-borne disease worldwide. Staphylococcal food poisoning is caused by ingestion of staphylococcal enterotoxins (SEs) pre-formed in the implicated food. In this study, the incidences of S. aureus and classical SEs (SEA-SEE) contamination in ‘Nham’, a traditional Thai fermented pork product, were determined. Among 155 Nham samples tested, as high as 39.35% of the samples were positive for S. aureus (2–3500 MPN/g), but none were positive for the SEs. The risk factors for S. aureus contamination were highly correlated with the manufacturer and the pH of the product. A predictive model determined the probability of the presence of S. aureus to be ≤0.24 at the pH ≤ 4.6. During the fermentation process, the number of S. aureus slightly increased in the first day and decreased afterward. S. aureus counts continued to decrease when Nham was stored refrigerated. The negative result for enterotoxins and low counts of S. aureus in Nham surveyed in this study, and reduction of the pathogen counts during fermentation and storage suggested that there is very low risk of staphylococcal food poisoning from consuming properly fermented Nham.     

Improvement of the quality and abatement of the biogenic amines of grass carp muscles by fermentation using mixed cultures

BACKGROUND: To improve the quality of processed grass carp (Ctenopharyngodon idellus) products and control the accumulation of hazardous substances therein, minced grass carp slices were salted for 6 h at room temperature and then inoculated with mixed starter cultures of Lactobacillus casei, Streptococcus lactis, Saccharomyces cerevisiae Hansen and Monascus anka and fermented for 12 h at 30 °C. The changes in some characteristics and biogenic amine contents of the fermented muscles were investigated. RESULTS: During the 12 h fermentation at 30 °C, muscles inoculated with mixed starter cultures showed a rapid decrease in pH from 6.0 to 5.1 and suppression of the growth of enterobacteria and pseudomonads. The fermented muscles exhibited better colour, appearance, flavour and overall acceptability than the control (P < 0.05). The changes in non‐protein nitrogen and free amino acid contents of the fermented muscles and in their sodium dodecyl sulfate polyacrylamide gel electrophoresis profiles indicated that severe hydrolysis of muscle proteins occurred during fermentation. The accumulation of biogenic amines in the muscles was efficiently reduced by fermentation with mixed starter cultures. CONCLUSION: Fermentation with mixed starter cultures of L. casei, S. lactis, S. cerevisiae Hansen and M. anka significantly improved the characteristics of grass carp muscles and controlled the accumulation of biogenic amines. Copyright © 2009 Society of Chemical Industry     

Evaluation of Leuconostoc citreum HO12 and Weissella koreensis HO20 isolated from kimchi as a starter culture for whole wheat sourdough

Leuconostoc citreum HO12 and Weissella koreensis HO20 isolated from kimchi were evaluated as starter cultures in the making of whole wheat sourdough bread. After 24 h of fermentation at 25 °C, both lactobacilli grew to the final cell numbers of ca. 10⁹ cfu/g dough, and both doughs had similar pHs and total titratable acidities. In addition, the fermentation quotient of the dough with Lc. citreum HO12 was slightly lower than that of the dough with W. koreensis HO20 (1.6 versus 2.8). Sourdoughs and bread with 50% sourdough produced with the starter cultures exhibited consistent ability to retard the growth of bread spoilage fungi (Penicillium roqueforti and Aspergillus niger) and rope-forming bacterium (Bacillus subtilis). Sourdough breads underwent a significant reduction in bread firming during storage. It seems that both lactobacilli have the potential to improve the shelf-life of wheat bread. The results indicate that the selected lactobacilli have unique fermentation characteristics and produce sourdough breads with overall satisfactory quality.     

Protective action of Lactobacillus curvatus CRL705 on vacuum-packaged raw beef. Effect on sensory and structural characteristics

Lactobacillus curvatus CRL705 was examined for its effectiveness as protective culture in the biopreservation of vacuum-packaged fresh beef stored during 60 days at 2 °C. For this purpose, L. curvatus CRL705, producer of lactocin 705 and lactocin AL705, was inoculated on the meat surface (10⁶ cfu g⁻¹). This microorganism became the dominating population throughout the storage period controlling the growth of Brochothrix thermosphacta and spoilage lactic acid bacteria naturally present on the meat. When the microstructural characteristics of the meat were evaluated using light microscopy, beef samples inoculated with the bioprotective culture showed a 10 days delay for the appearance of tissue degradation signs. Sensory analysis demonstrated that beef samples treated with L. curvatus CRL705 only developed an “acid” off-flavor after 60 days of refrigerated storage, and no undesirable off-odors were found. Therefore, inoculation with this bacteriocinogenic strain would provide an additional hurdle to improve storage life of refrigerated vacuum-packaged beef without affecting its sensory and structural characteristics.     

Studies on the low-salt Chinese potherb mustard (Brassica juncea, Coss.) pickle. I—The effect of a homofermentative l(+)-lactic acid producer Bacillus coagulans on starter culture in the low-salt Chinese potherb mustard pickle fermentation

A homofermentative l(+)-lactic acid producer Bacillus coagulans B179 has been evaluated as starter cultures for low-salt potherb mustard pickle process. This study examined the impact of inoculation by B. coagulans B179 as starter culture on the spontaneous lab-scale fermentation process of potherb mustard pickle. Three different salt concentrations trials, i.e., 5 g/100 g, 8 g/100 g and 10 g/100 g, respectively, were carried out. As a result, the addition of starter culture of B. coagulans B179 to 5 g/100 g salinity fermentation showed an inhibiting effect upon the population of non-lactic acid bacteria (LAB) and marked increase in population of LAB and production of titratable acidity but did not significantly influence the pickle end products quantity of acid produced by fermentation as compared with a treatment without inoculation. However, in the higher salt concentrations, i.e., 8 g/100 g and 10 g/100 g NaCl trials, inoculation had no impact on the fermentation of the pickle. From the standpoint of fermentation, as a functional starter culture, inoculated B. coagulans B179 can effectively improve desired native LAB growth and inhibit the growth of undesired fungi, which will thereby allow it to shorten fermentation period and enhance the pickle quality in the low-salt potherb mustard pickle production.     

The effects of Lactobacillus buchneri 40788 and Pediococcus pentosaceus R1094 on the fermentation of corn silage

The effect of inoculating whole-plant corn at the time of harvest with Lactobacillus buchneri 40788 (4 × 10⁵ cfu/g of fresh forage) combined with Pediococcus pentosaceus R1094 (1 × 10⁵ cfu/g) on the fermentation and aerobic stability of corn silage (37% dry matter) through 361 d of ensiling was investigated. Dry matter recovery was similar between treatments throughout the study except at one early time point (14 d), when treated silage had a lower recovery than untreated silage. The concentration of lactic acid was unaffected by inoculation but inoculated silages had greater concentrations of 1,2-propanediol and acetic acid from 56 to 361 d of storage. In general, inoculation decreased the concentration of water-soluble carbohydrates but increased the concentration of ethanol. The numbers of yeasts was lower in inoculated silage at 42, 56, 70, and 282 d of ensiling. However, inoculation did not consistently improve the aerobic stability of silage, suggesting that microbes other than yeasts may have been responsible for aerobic instability in this study. Even after prolonged storage (361 d), silage treated with L. buchneri 40788 and P. pentosaceus R1094 had normal silage fermentation characteristics.