Effect of combinations of high-pressure treatment and bacteriocin-producing lactic acid bacteria on the survival of Listeria monocytogenes in raw milk cheese

The combined effect of high-pressure (HP) treatment and bacteriocin-producing lactic acid bacteria (BP-LAB) on the survival of Listeria monocytogenes Scott A in cheeses made from raw milk that was inoculated with the pathogen at 4.80 log cfu mL⁻¹, a commercial starter and one of seven strains of BP-LAB was investigated. On day 3, the counts of L. monocytogenes were 7.03 log cfu g⁻¹ in a control cheese (without BP-LAB, not HP treated), 6.06–6.74 log cfu g⁻¹ in cheeses with BP-LAB, 6.13 log cfu g⁻¹ in a cheese without BP-LAB and treated on day 2 at 300 MPa, 2.01 log cfu g⁻¹ in a cheese without BP-LAB and treated on day 2 at 500 MPa, 3.83–5.43 log cfu g⁻¹ in cheeses with BP-LAB and treated on day 2 at 300 MPa, and 1.81 log cfu g⁻¹ or less in cheeses with BP-LAB and treated on day 2 at 500 MPa. HP treatment was more effective on day 51 than on day 2.     

Survival of Listeria monocytogenes in Galotyri,a traditional Greek soft acid-curd cheese,stored aerobically at 4°C and 12°C

Galotyri is a traditional Greek soft acid-curd cheese, which is made from ewes’ or goats’ milk and is consumed fresh. Because cheese processing may allow Listeria monocytogenes post-process contamination, this study evaluated survival of the pathogen in fresh cheese during storage. Portions (0.5 kg) of two commercial types (<2% salt) of Galotyri, one artisan (pH 4.0±0.1) and the other industrial (pH 3.8±0.1), were inoculated with ca. 3 or 7 log cfu g⁻¹ of a five-strain cocktail of L. monocytogenes and stored aerobically at 4°C and 12°C. After 3 days, average declines of pathogen's populations (PALCAM agar) were 1.3–1.6 and 3.7–4.6 log cfu g⁻¹ in cheese samples for the low and high inocula, respectively. These declines were independent (P>0.05) of the cheese type or the storage temperature. From day 3, however, declines shifted to small or minimal to result in 1.4–1.8 log cfu g⁻¹ of survivors at 28 days of storage of all cheeses at 4°C, indicating a strong “tailing” independent of initial level of contamination. Low (1.2–1.7 log cfu g⁻¹) survival of L. monocytogenes also occurred in cheeses at 12°C for 14 days, which were prone to surface yeast spoilage. When ca. 3 log cfu g⁻¹ of L. monocytogenes were inoculated in laboratory scale prepared Galotyri of pH ≅4.4 and ≅3% salt, the pathogen died off at 14 and 21 days at 12°C and 4°C, respectively, in artisan type cheeses fermented with the natural starter. In contrast, the pathogen survived for 28 days in cheeses fermented with the industrial starter. These results indicate that L. monocytogenes cannot grow but may survive during retail storage of Galotyri despite its low pH of or slightly below 4.0. Although contamination of Galotyri with L. monocytogenes may be expected low (<100 cfu g⁻¹) in practice, that long-term survival of the pathogen in commercial cheeses was shown to be unaffected by the artificial contamination level (3 or 7 logs) and the storage temperature (4°C or 12°C), which should be a concern.     

Microbiological conditions of moisture-enhanced pork before and after cooking

Substantial numbers of aerobic bacteria but few coliforms or Listeria spp. and no Escherichia coli were recovered from both swab samples and brines circulated in cleaned equipment used for injecting pork loins. After meat was processed for 30 or 60 min, the numbers of aerobic bacteria in brines had increased by >1 log unit, to about 4.5 log cfu ml⁻¹, but coliforms were <2 and E. coli and Listeria spp. were <1 log cfu ml⁻¹. The numbers of bacteria on the surfaces of pork loins before and after injection of the meat were similar. No bacteria were recovered from the deep tissues of the uninjected meat, but aerobic bacteria were recovered at log-mean numbers of 2.1 log cfu g⁻¹ and coliforms at log-total numbers of 1.2 log cfu 25 g⁻¹ from 25 samples of deep tissues of injected meat. Aerobic bacteria were recovered at log total numbers of 1.0 log cfu 25 g⁻¹ from 25 samples of injected pork cooked to a central temperature of 61 °C, but no bacteria were recovered from the deep tissues of meat cooked to 70 °C. The findings suggest that moisture-enhanced pork cooked to a medium rare condition can be microbiologically safe.     

Efficacy of plant extracts in inhibitingAeromonas hydrophilaandListeria monocytogenesin refrigerated,cooked poultry

Alcohol extracts of angelica root, banana purée, bay, caraway seed, carrot root, clove (eugenol), marjoram, pimento leaf and thyme were applied to cooked chicken to determine their antimicrobial activities against Aeromonas hydrophilaand Listeria monocytogenes.Skinless chicken breast meat was cooked to an internal temperature of 85°C, allowed to cool to c. 5°C, then treated by surface application with plant extracts. Low (10 cfu g⁻¹)or high (10⁵ cfu g⁻¹)populations of A. hydrophilaand L. monocytogeneswere applied and samples were stored at either 5 or 15°C for up to 14 or 7 days, respectively. Eugenol and pimento extracts were most effective in inhibiting growth of both bacteria. A. hydrophilawas the more sensitive to the two treatments, with 4 log₁₀ cfu g⁻¹less growth occurring at 14 days at 5°C on eugenol-treated breast meat than on control samples. These results suggested that plant extracts might be useful as antimicrobials in cooked, ready-to-eat chicken meat.     

The growth and survival of Escherichia coli O157:H7 on minced bison and pieces of bison meat stored at 5 and 10 °C

This study investigated the growth and survival of Escherichia coli O157:H7 on minced and whole pieces of bison meat. Growth curves of native microflora, including Pseudomonas spp. and Enterobacteriaceae were also generated. A marked E. coli O157:H7 strain was inoculated onto minced and whole pieces of bison meat at an initial level of 1.5 log₁₀ cfu g⁻¹. The inoculated meat was stored at either 5 °C for 28 days or 10 °C for 21 days. Survival, but no growth, of E. coli O157:H7 was observed on both forms of bison meat stored at 5 °C, while significant growth of the organism was observed at 10 °C. E. coli O157:H7 counts on whole pieces were generally higher than counts observed on minced bison meat, and reached their highest population by 14 days, with a total increase of 3.36 log₁₀ cfu g⁻¹ on whole pieces and 2.12 log₁₀ cfu g⁻¹on minced bison meat stored at 10 °C. Under the same storage temperature, Pseudomonas spp. and total counts displayed similar growth patterns on both pieces and minced bison meat, while the Enterobacteriaceae showed a slower growth rate. This study showed that the growth of E. coli O157:H7 on bison meat is similar to that observed in studies of beef.     

Enterobacteriaceae in beef products from retail outlets in the Republic of Ireland and comparison of the presence and counts of E. coli O157:H7 in these products

This study investigated the prevalence and numbers of Enterobacteriaceae in minced beef and beef burgers purchased from supermarkets and butcher shops in the Republic of Ireland (RoI). Samples (n=1303) collected between June 2001 and April 2002 from every county in the RoI (∼60 per county) were examined for the presence of Enterobacteriaceae using method BS 5763. Overall, in the 43 beef products in which E. coli O157:H7 was present the Enterobacteriaceae counts ranged from 0.52 to 6.98 log₁₀ cfu g⁻¹. There was no correlation between the number of Enterobacteriaceae and the presence of E. coli O157:H7. There were no significant differences between Enterobacteriaceae numbers in fresh, unpackaged, minced beef samples from butcher shops and supermarkets, or in fresh, unpackaged, beef burgers from butcher shops and supermarkets. However, there were significant differences among the numbers of Enterobacteriaceae detected in different minced beef products. The numbers of Enterobacteriaceae in fresh, unpackaged, minced beef (6.54–6.98 log₁₀ cfu g⁻¹) were considerably higher than in preprepared or prepackaged minced beef (2.95–3.62 log₁₀ cfu g⁻¹).     

Antimicrobial activity of pediocin-producing Lactococcus lactis on Listeria monocytogenes,Staphylococcus aureus and Escherichia coli O157:H7 in cheese

The antimicrobial activity of two pediocin-producing transformants obtained from wild strains of Lactococcus lactis on the survival of Listeria monocytogenes, Staphylococcus aureus and Escherichia coli O157:H7 during cheese ripening was investigated. Cheeses were manufactured from milk inoculated with the three pathogens, each at approximately 6 log cfu mL⁻¹. Pediococcus acidilactici 347 (Ped⁺), Lc. lactis ESI 153, Lc. lactis ESI 515 (Nis⁺) and their respective pediocin-producing transformants Lc. lactis CL1 (Ped⁺) and Lc. lactis CL2 (Nis⁺, Ped⁺) were added at 1% as adjuncts to the starter culture. After 30 d, L. monocytogenes, S. aureus and E. coli O157:H7 counts were 5.30, 5.16 and 4.14 log cfu g⁻¹ in control cheese made without adjunct culture. On day 30, pediocin-producing derivatives Lc. lactis CL1 and Lc. lactis CL2 lowered L. monocytogenes counts by 2.97 and 1.64 log units, S. aureus by 0.98 and 0.40 log units, and E. coli O157:H7 by 0.84 and 1.69 log units with respect to control cheese. All cheeses made with nisin-producing LAB exhibited bacteriocin activity throughout ripening. Pediocin activity was only detected throughout the whole ripening period in cheese with Lc. lactis CL1. Because of the antimicrobial activity of pediocin PA-1, its production in situ by strains of LAB growing efficiently in milk would extend the application of this bacteriocin in cheese manufacture.     

Microbiological and chemical changes during the manufacture of Kefir made from cows’ milk,using a commercial starter culture

The counts of total aerobic mesophilic bacteria, lactic acid bacteria (in three different culture media, M17 agar, MSE agar, and Rogosa agar) and yeasts, and some biochemical parameters (levels of lactose, glucose, galactose, L(+)- and D(−)-lactic acids, ethanol, titratable acidity and pH) were determined during 196 h of fermentation in five batches of Kefir made from cows’ milk using a commercial starter culture. Lactococcus spp. predominated during the first 48 h of fermentation (∼8 log₁₀ cfu g⁻¹); Lactobacillus spp. became the predominant species after 48 h (∼8.5 log₁₀ cfu g⁻¹). During the first 24 h of fermentation, the lactose content decreased from a mean value of 4.92% (w/w) to 4.02% (w/w); the concentration of L(+)-lactic acid increased from 0.01% to 0.76% (w/w) and the pH decreased to 4.24 over the same period. After 24 h of fermentation, the changes in the levels of lactose and L(+)-lactic acid, and in pH, occurred more slowly. Neither glucose nor galactose were detected during fermentation. The production of ethanol was limited, reaching a mean final value of 0.018% (w/w).     

Inhibition of Clostridium tyrobutyricum in cheese by Lactobacillus gasseri

A semi-hard cheese produced from milk artificially contaminated with Clostridium tyrobutyricum spores (2.5×10³ mL⁻¹) was used as a model for studying the ability of bacteriocin-producing Lactobacillus gasseri K7 (Rif^r) to inhibit clostridia. The added lactobacilli did not inhibit the primary starter culture (Streptococcus thermophilus), but inhibited non-starter mesophilic lactobacilli. Late blowing as a result of Cl. tyrobutyricum outgrowth and butyric acid fermentation occurred in all cheeses however it was reduced in cheeses with added Lb. gasseri. After 6 weeks, the average amount of butyric acid was significantly higher in cheeses without added lactobacilli (1.43 vs. 0.70 g kg⁻¹). At the end of 8-weeks ripening, 2.8×10⁷ cfu g⁻¹ of K7 (Rif^r) viable cells were detected. Using the total DNA from cheeses with added K7 (Rif^r) strain, PCR products were amplified with primers specific for Lactobacillus, Lb. gasseri and K7 bacteriocin gene.     

A combined morphologic and molecular approach for characterizing fungal microflora from a traditional Italian cheese (Fossa cheese)

Phenotypic and genotypic methods were used to identify filamentous fungi that characterize traditional Italian Fossa cheese and its ripening environment. After ageing for 60 days at a dairy, it was ripened for an additional three months in a pit. In the fully ripened cheese, moulds ranged from 3 to 3.4 log cfu g^?1 and Penicillium was the prevalent species. Pit environmental fungi ranged from 530 to 750 cfu m^?3 (air) and from 130 to 340 cfu cm^?2 (surfaces). The dominant pit strains were Alternaria spp., Aspergillus spp., Cladosporium spp. and Penicillium spp. Phylogenetic analyses of 18S rRNA gene and ITS1-5.8S-ITS2 regions highlighted Penicillium camemberti, Aspergillus nidulans and Aspergillus versicolor as traceable species occurring in both the cheese and pit environment, suggesting their involvement in the development of typical Fossa cheese characteristics. This approach may be used for the identification of microflora on other cheese varieties to better understand the fungal contribution in cheese ripening.     

The distribution of Staphylococcus sp. on bovine meat from abattoir deboning rooms

In developing countries such as South Africa, Staphylococcus aureus has been shown consistently to be one of the most important micro-organisms responsible for food poisoning outbreaks. In this study, the staphylococci in selected South African abattoirs were quantified, identified and further characterized in terms of coagulase types. The highest staphylococci counts (1.7×10⁶ cfu g⁻¹) were observed in the meat from the high throughput (Grade A) abattoir during week 3. The counts exceeded the National Guidelines (10² cfu g⁻¹) without exception and at least 50% surpassed the levels sufficient to produce toxins (10⁵ cfu g⁻¹) determined for S. aureus. Species were dominated by S. capitis, S. xylosus, S. auricularis, S. aureus and S. intermedius. In terms of the coagulase types of S. aureus, type V was the most dominant and type VI the least. It became evident that the hygiene practices implemented by the abattoirs investigated in this study were not effective enough in reducing the contamination levels of the staphylococci from carcasses. It is therefore recommended that the sampled abattoirs revise their manufacturing strategies in order to reduce the levels of staphylococcal contamination which have been shown to be transferred through food handlers, surfaces, equipment and the environment.     

Production of traditional Greek yoghurt using Lactobacillus strains with probiotic potential as starter adjuncts

Lactobacillus plantarum ACA-DC 146 and L. paracasei subsp. tolerans ACA-DC 4037 were examined for their potential application as adjuncts in the production of traditional Greek set-type yoghurt. Both strains displayed low milk acidification activity, while no inhibition was observed towards or from the yoghurt starters used. Yoghurt produced with L. paracasei subsp. tolerans ACA-DC 4037 exhibited the best sensory properties, with a rich traditional smooth taste, and the strain was selected for further trials. Yoghurt produced with this strain as an adjunct had good physicochemical properties. After 2 weeks of refrigerated storage, microbial loads (>7.0 log cfu g⁻¹) were in accordance with international recommendations and guidelines for probiotic and starter cultures in milk products. Increasing the microbial load further, using concentrated and encapsulated inocula (10–11 log cfu g⁻¹), gave yoghurt with long fermentation times and poor organoleptic properties.     

Bacteriological quality and safety of raw milk in Malaysia

The microbiological safety of raw milk from 360 dairy farms in Peninsular Malaysia was determined. Milk samples were collected at 40 Milk Collection Centers (MCC) from four regions, namely, Southern (Johor/Melaka), Central (Selangor/Negeri Sembilan), Northern (Perak/Kedah) and Eastern (Kelantan/Terengganu) according to stratified random sampling design. Samples were analyzed for Total Plate Count (TPC), Staphylococcus aureus, coliform and Escherichia coli as well as the prevalence of selected pathogens such as Listeria monocytogenes, E. coli 015:H7 and Salmonella. The mean counts per ml for TPC, psychrotrophs and thermophiles were 12×10⁶, 7.5×10³ and 9.1×10³, respectively. A TPC less than 10⁶ cfu ml⁻¹ is used as a basic standard by MCC in the Price Incentive Programme. From the 930 milk samples tested, approximately 90% were contaminated by coliform bacteria and 65% were E. coli positive, with mean counts ranged from 10³ to 10⁴ cfu ml⁻¹. S. aureus was isolated from more than 60% of the samples and the mean count per ml was 12×10³. Meanwhile, E. coli 0157:H7 was also detected in 312 (33.5%) samples. However, Salmonella was only detected in 1.4% of the samples, with the Central region having the highest frequency of isolation. Thirteen Salmonella serotypes were identified, including S. muenchen, S. anatum and S. agona. A total of 47 strains of Listeria were isolated from 4.4% Listeria-positive samples including L. monocytogenes (1.9%), L. innocua (2.1%) and L. welshimeri (0.6%).     

Inactivation of Escherichia coli O157:H7 by cinnamic aldehyde purified from Cinnamomum cassia shoot

Escherichia coli O157:H7 is a pathogen, which causes the hemorrhagic colitis, hemolytic uremic syndrome and thrombotic thrombocytopenic purpura in humans. Control of the bacterial cells in foods is an important factor to reduce outbreaks of the foodborne diseases. In this study, cinnamic aldehyde possessing antimicrobial activity against the bacterial cells was purified from the extract of cinnamon (Cinnamomum cassia Blume) shoot by sequential fractionation with various solvents and silica gel column chromatography. When E. coli O157:H7 cells were incubated at 37°C for 12 h in the presence of 500 μg ml⁻¹ of the purified from cinnamic aldehyde, the viable counts decreased dramatically (from 4.9×10⁶ to 1.0×10² cfu ml⁻¹). In the presence of 1000 μg ml⁻¹ of the substance, most of the cells were killed after 2 h of incubation suggesting that the antimicrobial activity of cinnamic aldehyde is bacteriocidal in E. coli. Scanning electron microscopic observations revealed that the bacterial cells treated with the cinnamic aldehyde suffered from severe damages in their surface structure. Minimal inhibitory concentration of the cinnamic aldehyde was determined to be 250 μg ml⁻¹ against E. coli strains O157:H7 and O26 or 500 μg ml⁻¹ against strains ATCC11105 and O111.     

A comparison of the chemical,microbiological and sensory characteristics of bovine and ovine Halloumi cheese

Commercial samples of fresh and mature Halloumi cheeses made from ovine or bovine milk were studied in order to establish their chemical, microbiological and sensory characteristics. Significant differences were observed between the two types of Halloumi cheese both when fresh and mature. The free volatile fatty acid (FVFA) content of the cheeses increased with maturation from 483 to 1356 mg kg⁻¹ for the ovine product, but lower values (380–1248 mg kg⁻¹) were found in the bovine cheese. During maturation for 40 days, Enterococcus faecium, which dominated the microflora of fresh ovine cheese, was replaced by lactobacilli, including a new species, Lactobacillus cypricasei, which was not found in the bovine samples. Fewer than 100 cfu g⁻¹ lactic acid bacteria (LAB) were present in the fresh bovine cheeses, but a microflora dominated by lactobacilli developed with time. Yeast counts in the mature ovine and bovine cheeses reached 2.3–2.8×10⁵ cfu g⁻¹ and, as some of the yeasts were proteolytic and/or lipolytic, it was assumed that they were having a positive impact of the flavour of the cheeses. The sensory panel distinguished significant differences in texture and flavour between the fresh and mature samples of both ovine and bovine cheeses and, overall, there was a significant preference for the ovine brand.     

Fate of enterotoxigenic Staphylococcus aureus in the presence of nisin-producing Lactococcus lactis strain during manufacture of Jben,a Moroccan traditional fresh cheese

The inhibitory effect of nisin-producing Lactococcus lactis subsp. lactis UL730 on the growth of enterotoxigenic Staphylococcus aureus J10 during manufacture of Jben, a Moroccan traditional fresh cheese prepared from recombined milk, was investigated.With an inoculum level of 10³ cfu mL⁻¹, S. aureus was absent in Jben four days after inoculation when the nisin-producing lactococcus was used as lactic starter. In contrast, it survived after that period, when the starter was non-nisin-producing. No staphylococcal thermonuclease was detected in all Jben samples made from milk inoculated with S. aureus at the level of 10³ cfu mL⁻¹.With a higher inoculum of 10⁵ cfu mL⁻¹, S. aureus was still present in Jben after manufacture and persisted during the storage of the product for 3 days in the laboratory, even when the starter used was nisin-producing. Staphylococcal thermonuclease and type C enterotoxin were detected in all Jben samples made from milk inoculated with 10⁵ cfu mL⁻¹. Thermonuclease and enterotoxin were already produced in the coagulum, at 24 h after milk inoculation with S. aureus.     

Probiotic properties of folate producing Streptococcus thermophilus strains

This study aimed at assessing the probiotic potential of two high folate producing Streptococcus thermophilus strains (RD102 and RD104) isolated from Indian fermented milk products by both in vitro and in vivo tests. These strains were able to survive at pH 2.5 and 2% bile with a good bile salt hydrolase activity, cell surface hydrophobicity and sensitivity to most of the clinically important antibiotics. On evaluation for gastrointestinal transit tolerance these showed a viable count of 5 log cfu mL^?1 and 7 log cfu mL^?1, respectively in simulated gastrointestinal juice of pH 2.0 and 2% bile. During the in vivo feeding trial in mice the strains showed a viable count of about 7 log cfu g^?1 faeces and 6 log cfu g^?1 of large intestine, respectively. These strains were hence observed to possess favorable strain specific probiotic properties and have the potential to be a source of novel probiotics.     

Effect of acidification on the activity of probiotics in yoghurt during cold storage

The viability of Lactobacillus acidophilus LAFTI^® L10, Bifidobacterium lactis LAFTI^® B94, and L. paracasei LAFTI^® L26 and their proteolytic activities were assessed in yoghurt at different termination pH of 4.45, 4.50, 4.55, and 4.60 in the presence of L. delbrueckii ssp. bulgaricus Lb1466 and Streptococcus thermophilus St1342 during 28 days of storage at 4 °C. All strains achieved the recommended level of 6.00 log cfu g⁻¹ of the product with L. acidophilus LAFTI^® L10 and L. paracasei LAFTI^® L26 exceeding the number to 8.00 and 7.00 log cfu g⁻¹, respectively. Lactobacilli strains showed a good cellular stability maintaining constant concentration throughout storage period regardless of termination pH. On the other hand, the cell counts of B. lactis LAFTI^® B94 decreased by one log cycle at the end of storage. The presence of probiotic organisms enhanced proteolysis significantly in comparison with the control batch containing L. delbrueckii ssp. bulgaricus Lb1466 and S. thermophilus St1342 only. The proteolytic activity varied due to termination pH, but also appeared to be strain related. The increased proteolysis improved survival of L. delbrueckii ssp. bulgaricus Lb1466 during storage resulting in lowering of pH and production of higher levels of organic acids, which might have caused the low cell counts for B. lactis LAFTI^® B94.     

Effect of gutting on microbiological,chemical, and sensory properties of aquacultured sea bass (Dicentrarchus labrax) stored in ice

The effect of gutting on microbiological, chemical, and sensory properties of aqua-cultured sea bass (Dicentrarchus labrax) stored in ice was studied. Pseudomonads and H₂S-producing bacteria (including Shewanella putrefaciens) were the dominant bacteria at the end of the 16-day storage period in ice for both whole ungutted and gutted sea bass. Brochothrix thermosphacta and Enterobacteriaceae were also found in the spoilage microflora of ungutted and gutted sea bass but their counts were always less than those of Pseudomonads and H₂S-producing bacteria. Bacterial counts of whole ungutted sea bass were always higher than those obtained for gutted sea bass samples. Mesophilic counts for gutted and ungutted fish exceeded 7 log cfu g⁻¹ after 9 and 15 days of ice storage, respectively. Of the chemical indicators of spoilage, TMA values of ungutted sea bass increased very slowly whereas for gutted samples higher values were obtained reaching a final value of 0.73 and 4.39 mg N 100 g⁻¹, respectively (day 16). TVB-N values showed no significant increase for whole ungutted sea bass during storage reaching a value of 27.7 mg N 100 g⁻¹ (day 16) whereas for gutted fish 36.9 mg N 100 g⁻¹ was recorded. TBA values remained low for ungutted sea bass samples until day 16 of storage, whereas for gutted fish were variable. Of the chemical indices used, none proved useful means of monitoring early ungutted and gutted sea bass freshness in ice. Sensory assessment using the EC freshness scale gave a grade E for up to 5 days for the ungutted sea bass, a grade A for a further 2 days and a grade B for an additional 4 days, after which sea bass was graded as C (unfit). Gutted sea bass was given a grade E for up to 3 days, a grade A for the 4–7th days, and a grade B for the 8–10th days of storage, whereas on day 11 it was graded as unfit. Acceptability scores for odor, taste and texture of cooked ungutted and gutted sea bass decreased with time of storage. Results of this study indicate that the shelf-life of whole ungutted and gutted sea bass stored in ice as determined by the overall acceptability sensory scores and microbiological data is 13 and 8 days, respectively.     

The protective effect of monosodium glutamate on survival of Lactobacillus rhamnosus GG and Lactobacillus rhamnosus E-97800 (E800) strains during spray-drying and storage in trehalose-containing powders

The use of trehalose as a means of preserving Lactobacillus rhamnosus GG (LGG) and L. rhamnosus E-97800 (E800) during spray-drying and the effects of incorporated monosodium glutamate (MSG) in the carrier medium on the survival rates during drying and storage were examined. E800 was more resistant to heat than LGG in 20%, w/w, trehalose; the d-values at 65 °C were 14 s and 5.1 s, respectively. An air outlet temperature of 65–70 °C was taken as optimal for the drying process, as the resultant moisture levels in trehalose containing these bacteria were 4.1% (w/w) and 3.79% (w/w) with corresponding viable counts of 3.65 × 10⁸ cfu mL^?1 and 1.80 × 10⁹ cfu mL^?1, respectively. The presence of MSG increased the final viable counts of LGG and E800 to 3.05 × 10⁹ cfu mL^?1 and 1.30 × 10⁹ cfu mL^?1, respectively. Survival of LGG and E800 remained constant at a minimum level of ～10⁸ cfu mL^?1 during storage at 25 °C in trehalose–MSG medium.