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1.
A series of culture media were evaluated for selective enumeration of 10 commercial probiotic cultures. The media M17 and MRS 5.2 were most suitable to enumerate the yoghurt starters Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, respectively. For the enumeration of probiotic Lb. acidophilus cultures, the MRS-clindamycin medium was found to be most optimal. Selective recovery results of the tested Bifidobacterium sp. were not uniform but indicated strain-to-strain variations depending on whether NPLN or MRS-LP were used. For the enumeration of probiotic cultures of Lb. rhamnosus and Lb. paracasei, LC medium (for yoghurt products) and MRS-AC medium (for cheese products) are recommended. In conclusion, our data indicate that the choice of culture medium and methodology for selective enumeration of commercial probiotic strains in combination with starters depends strongly on the product matrix, the target group and the taxonomic diversity of the bacterial background flora in the product.  相似文献   

2.
Yoghurt is increasingly being used as a carrier of probiotic bacteria for their potential health benefits. To meet with a recommended level of ≥ 106 viable cells/g of a product, assessment of viability of probiotic bacteria in market preparations is crucial. This requires a working method for selective enumeration of these probiotic bacteria and lactic acid bacteria in yoghurt such as Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lb. acidophilus, Lb. casei and Bifidobacterium. This chapter presents an overview of media that could be used for differential and selective enumerations of yoghurt bacteria. De Man Rogosa Sharpe agar containing fructose (MRSF), MRS agar pH 5.2 (MRS 5.2), reinforced clostridial prussian blue agar at pH 5.0 (RCPB 5.0) or reinforced clostridial agar at pH 5.3 (RCA 5.3) are suitable for enumeration of Lb. delbrueckii subsp. bulgaricus when the incubation is carried out at 45 °C for 72 h. S. thermophilus (ST) agar and M17 are recommended for selective enumeration of S. thermophilus. Selective enumeration of Lb. acidophilus in mixed culture could be made in Rogosa agar added with 5-bromo-4-chloro-3-indolyl-β-d-glucopyranoside (X-Glu) or MRS containing maltose (MRSM) and incubation in a 20% CO2 atmosphere. Lb. casei could be selectively enumerated on specially formulated Lb. casei (LC) agar from products containing yoghurt starter bacteria (S. thermophilus and Lb. delbrueckii subsp. bulgaricus), Lb. acidophilus, Bifidobacterium spp. and Lb. casei. Bifidobacterium could be enumerated on MRS agar supplemented with nalidixic acid, paromomycin, neomycin sulphate and lithium chloride (MRS-NPNL) under anaerobic incubation at 37 °C for 72 h.  相似文献   

3.
This study aimed to optimize the rheological properties of probiotic yoghurts supplemented with skimmed milk powder (SMP), whey protein concentrate (WPC) and sodium caseinate (Na-Cn) by using an experimental design type simplex-centroid for mixture modeling. It included seven batches/trials: three were supplemented with each type of the dairy protein used, three corresponding to the binary mixtures and one to the ternary one in order to increase protein concentration in 1 g 100 g−1 of final product. A control experiment was prepared without supplementing the milk base. Processed milk bases were fermented at 42 °C until pH 4.5 by using a starter culture blend that consisted of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Bifidobacterium animalis subsp. lactis. The kinetics of acidification was followed during the fermentation period as well the physico-chemical analyses, enumeration of viable bacteria and rheological characteristics of the yoghurts. Models were adjusted to the results (kinetic responses, counts of viable bacteria and rheological parameters) through three regression models (linear, quadratic and cubic special) applied to mixtures. The results showed that the addition of milk proteins affected slightly acidification profile and counts of S. thermophilus and B. animalis subsp. lactis, but it was significant for L. delbrueckii subsp. bulgaricus. Partially-replacing SMP (45 g/100 g) with WPC or Na-Cn simultaneously enhanced the rheological properties of probiotic yoghurts taking into account the kinetics of acidification and enumeration of viable bacteria.  相似文献   

4.
The aim of this study was to develop fruit powders (apple, banana and strawberry) enriched with a probiotic strain (Lactobacillus plantarum 299v). Two methodologies were proposed: (i) drying of the fruit with probiotic culture incorporated (by convection) or (ii) drying of fruit (by convection) and addition of spray‐dried probiotic culture. In the first methodology, processing caused a notable reduction in probiotic viable counts in apple, but this reduction was lower during drying of banana and strawberry. A large reduction in viable cells was also recorded during storage. In the second methodology, the survival of L. plantarum 299v was considerably higher during spray‐drying, and fruit powders with a microbial content suitable for a probiotic food (108–10cfu g?1) were obtained. The fruit powders incorporating L. plantarum 299v can be stored at 4 °C or at room temperature, for at least 3 months. This preliminary study demonstrated that fruit powders are good carriers of probiotic cultures, but the techniques used to produce them should be carefully considered.  相似文献   

5.
Bifidobacteria are probiotic microorganisms that are widely used in the food industry. With the aim of using of Petrifilm™ Aerobic Count (AC) plates associated with selective culture media, aliquots of sterile skim milk were inoculated separately with four commercial cultures of bifidobacteria. These cultures were plated by both the conventional method and Petrifilm™AC, using the culture media NNLP and ABC. The cultures were incubated under anaerobiosis at 37 °C for 24, 48 and 72 h. No significant differences (p > 0.05) were observed between the obtained counts at 48 and 72 h. Bifidobacteria counts in ABC were usually higher than in NNLP, independent of the plating method. Subsequently, fermented milk was prepared with a Streptococcus thermophilus strain, and aliquots were inoculated with the same bifidobacteria. Then, the fermented milks were submitted to microbiological analysis for bifidobacteria enumeration using the same culture media and methodologies previously described, incubated under anaerobiosis at 37 °C for 48 h. Again, bifidobacteria counts in ABC were higher than in NNLP, with significant differences for some cultures (p < 0.05). The counts obtained by both methodologies presented significant correlations (p < 0.05). The results indicate the viability of Petrifilm™AC as an alternative method for bifidobacteria enumeration when associated to specific culture media, specially the ABC.  相似文献   

6.
Common starter cultures used in fermented mutton sausages were substituted by probiotic strains of Lactobacillus acidophilus CCDM 476 and Bifidobacterium animalis 241a. Technological properties of the traditional and the probiotic sausages were compared. The potential probiotic effect was evaluated by enumeration of bifidobacteria and lactobacilli in stool samples of 15 volunteers before and after a 14-day consumption period. The numbers of lactobacilli (107 cfu/g) and bifidobacteria (103 cfu/g) in the final product did not affect the technological properties. The use of L. acidophilus as a starter culture was found more beneficial than the use of B. animalis. Even after 60 days of storage, high counts of L. acidophilus (106 cfu/g) were detected; on the other hand, the counts of B. animalis were under the detection limit. Regarding sensory properties, the probiotic products showed better texture, and, curiously, a reduction of the typical smell of mutton. The numbers of lactobacilli in stool samples increased significantly after the consumption of the probiotic sausages.  相似文献   

7.
The effect of addition of natural sugar substitutes (stevia, erythritol or xylitol) and prebiotics (oligofructose or polydextrose) on physicochemical characteristics, probiotic survival (Lactobacillus casei) and sensory acceptance of yoghurts during storage (7 °C, 28 days) was evaluated. Yoghurts with sucrose or sucralose were also prepared. Xylitol and sucralose added yoghurts had physicochemical characteristics and sensory acceptance similar to those of the product with sucrose. Xylitol was more efficient in maintenance of textural characteristics and probiotic survival in simulated gastrointestinal conditions (SGIC) than sucralose. Addition of erythritol and stevia changed the textural parameters, reduced acceptance and decreased probiotic survival in SGIC. Addition of oligofructose or polydextrose improved texture and increased probiotic survival but decreased flavour acceptance. All formulations could be considered probiotic products during shelf life (7 °C, 28 days) with counts higher than 107 cfu mL−1 in the product and 104 cfu mL−1 after SGIC.  相似文献   

8.
The aim of this work was to select a set of culture media to perform the enumeration of L. casei when it appears together with L. acidophilus, bifidobacteria and bacteria of lactic acid starters, in fermented dairy products. A number of L. acidophilus, Bifidobacterium and L. casei strains (8 of each) were tested for their ability to grow in two selective/differential media (LP-MRS agar and B-MRS agar). The enumeration of these bacteria using the media mentioned above was also carried out in fermented dairy products available on the market. B-MRS agar and LP-MRS agar were able to inhibit the lactic acid bacteria from the starters. B-MRS agar could be useful for the selective colony count of L. acidophilus or L. casei, or for a differential enumeration when these bacteria appear together in a fermented dairy product. In the case of bifidobacteria, a selective colony count could be performed on LP-MRS agar, even when it appears with L. casei, because a differential cell enumeration between both organisms was possible. The three probiotic bacteria could be simultaneously enumerated from dairy products that contain them along with starter bacteria using media developed in this work.  相似文献   

9.
The viability of lactic acid bacteria (LAB) from commercial fermented milks was studied during storage at 4 °C. The enumeration of total viable bacteria was assessed using fluorescence microscopy. Plate counting on selective media was used to enumerate LAB. Using LIVE/DEAD® BacLightTM viability staining, it was observed that bacterial counts decreased gradually after expiry dates, the number of viable bacteria remaining above 106 bacteria g?1 for all of the products. Viable cell counts estimated by plating onto selective media were lower than those obtained by direct microscopic counting. The viability of LAB contained in acid products decreased during their storage period at 4 °C. All products contain viable LAB ranging from 108 to 109 bacteria g?1 and could be considered as probiotic, given that the recommended minimum number of probiotic bacteria in such food products is approximately 107 bacteria mL?1 product. The number of bifidobacteria in commercial fermented milks declared to contain bifidobacteria varied from 104 to 107 bacteria mL?1. This study confirms the usefulness of fluorescent techniques for a rapid and accurate evaluation of bacterial viability in probiotic products.  相似文献   

10.
This study aimed to evaluate the vacuum impregnation (VI) and soaking methods in the addition of Lactobacillus acidophilusLA‐3 to minimally processed melon (MPM). The melons were washed, sanitised in chlorine solution (200 mg L?1), peeled and cutted into cubes. Lactobacillus acidophilusLA‐3 (1.4 × 1010 CFU g?1) were added to the MPM through both techniques. The L. acidophilusLA‐3 count in MPM was similar to those commonly found in dairy products having probiotic claim, but VI was more efficient than soaking in maintaining the viability (8.61 and 7.98 Log CFU g?1, respectively). The pH, acidity and soluble solids were not affected by probiotic culture and the incorporation technique; however, the VI affected the firmness of fruit. The MPM was within Brazilian standards for their microbiological characteristics. MPM may be used as a carrier of probiotic bacteria, being one more alternative for individuals who consume probiotic products.  相似文献   

11.
This study was aimed at investigating the fortification of probiotic yoghurt with rice bran to increase nutritional properties of the product. The different levels of rice bran (0.3%, 0.6%, 0.9% and 1.2%) were incorporated into milk. The yoghurt samples were produced after pasteurisation, addition of starter culture and 1% Lactobacillus acidophilus suspension (6 × 108 CFU mL?1) and incubation. During sample storage in refrigerator, the viability of L. acidophilus, viscosity and physicochemical and sensory properties of product were investigated. Rice bran significantly increased the viability of L. acidophilus (< 0.05). In addition, all probiotic yoghurts incorporating rice bran indicated higher viscosity and acidity and lower pH and syneresis compared to plain yoghurts. Furthermore, increments in rice bran incorporation levels resulted in a reduction in consumers' sample preferences. In general, the addition of rice bran at a suitable level could increase L. acidophilus viability and improve quality attributes of yoghurt.  相似文献   

12.
An experiment using a standard strain of Lactobacillus amylovorus TISTR1110 to test for the capability of carbohydrate utilisation of nine cultivars of rice found that L. amylovorus TISTR1110 could utilise carbohydrate from all cultivars and also exhibit nonhaemolytic properties. After testing the viability of the strain under simulated gastrointestinal tract conditions by enumeration after 5 h, the results showed that the amount of L. amylovorus TISTR1110 present was 4.0 × 105 CFU/mL or a 73.78% survival rate. From the evaluation of Thai rice cultivars as carriers in probiotic products, the highest amount of probiotic bacteria was found in baked and encapsulated glutinous Luem Pua Thai sticky rice up to 4.9 × 106 CFU/g or a survival rate of 69.39 ± 0.06%. The second highest rate (4.8 × 105 CFU/g) was found in heat–moisture steamed rice of Riceberry rice cultivar or a survival rate of 59.74 ± 0.11%. After testing the capability of adherence using SEM, the results showed that glutinous Luem Pua sticky rice resulted in considerably high survival rate of probiotic bacteria compared with other rice. Additionally, the microbiological safety test reported that the amounts of contaminants were acceptable.  相似文献   

13.
The effect of inulin and/or okara flour on Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 viability in a fermented soy product (FSP) and on probiotic survival under in vitro simulated gastrointestinal conditions were investigated throughout 28 days of storage at 4 °C. Employing a 22 design, four FSP trials were produced from soymilk fermented with ABT-4 culture (La-5, Bb-12, and Streptococcus thermophilus): FSP (control); FSP-I (with inulin, 3 g/100 mL of soymilk); FSP-O (with okara, 5 g/100 mL); FSP-IO (with inulin + okara, ratio 3:5 g/100 mL). Probiotic viabilities ranged from 8 to 9 log cfu/g during the 28 days of storage, and inulin and/or okara flour did not affect the viability of La-5 and Bb-12. Bb-12 resistance to the artificial gastrointestinal juices was higher than for La-5, since the Bb-12 and La-5 populations decreased approximately 0.6 log cfu/g and 3.8 log cfu/g, respectively, throughout storage period. Even though the protective effect of inulin and/or okara flour on probiotic microorganisms was not significant, when compared to a fresh culture, the FSP matrix improved Bb-12 survival on day 1 of storage and may be considered a good vehicle for Bb-12 and could play an important role in probiotic protection against gastrointestinal juices.  相似文献   

14.
The study compared the growth capability of probiotic (Lactobacillus acidophilus La05, Lactobacillus casei Lc01 and Bifidobacterium animalis Bb12) and non-probiotic (Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus) cultures on twenty-one culture media grouped according to selectivity: non-selective agars, selective agars without antibiotics and MRS agars containing different combinations of lithium chloride, cystein, bile salts and antibiotics. Four of these media were selected for quantitative enumeration of L. acidophilus La05, L. casei Lc01, and B. animalis Bb12. The best culture media and incubation conditions for enumeration of the probiotic cultures were: B. animalis: MRS agar with dicloxacillin, 37 °C or 42 °C, anaerobiosis; L. acidophilus: MRS agar with bile salts, 37 °C or 42 °C, aerobiosis; L. casei: MRS agar with lithium chloride and sodium propionate, 37 °C or 42 °C, aerobiosis or anaerobiosis. Plating on MRS with glucose replaced by maltose, 37 °C or 42 °C, anaerobiosis, will distinguish probiotic from non-probiotic cultures. For enumeration of each probiotic in a mixed culture, the following media and incubation conditions were recommended: B. animalis: 4ABC-MRS, 42 °C, anaerobiosis, L. acidophilus: LC medium, 42 °C, aerobiosis or anaerobiosis and L. casei: LP-MRS, 42 °C, aerobiosis or anaerobiosis. In all experiments, differences in counts using pour plating or surface plating were not significant (P ≤ 0.05).  相似文献   

15.
Various selective media for enumerating probiotic and cheese cultures were screened, with 6 media then used to study survival of probiotic bacteria in full-fat and low-fat Cheddar cheese. Commercial strains of Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus paracasei, or Bifidobacterium lactis were added as probiotic adjuncts. The selective media, designed to promote growth of certain lactic acid bacteria (LAB) over others or to differentiate between LAB, were used to detect individual LAB types during cheese storage. Commercial strains of Lactococcus, Lactobacillus, and Bifidobacterium spp. were initially screened on the 6 selective media along with nonstarter LAB (NSLAB) isolates. The microbial flora of the cheeses was analyzed during 9 mo of storage at 6°C. Many NSLAB were able to grow on media presumed selective for Lactococcus, Bifidobacterium spp., or Lb. acidophilus, which became apparent after 90 d of cheese storage, Between 90 and 120 d of storage, bacterial counts changed on media selective for Bifidobacterium spp., suggesting growth of NSLAB. Appearance of NSLAB on Lb. casei selective media [de man, Rogosa, and Sharpe (MRS) + vancomycin] occurred sooner (30 d) in low-fat cheese than in full-fat control cheeses. Differentiation between NSLAB and Lactococcus was achieved by counting after 18 to 24 h when the NSLAB colonies were only pinpoint in size. Growth of NSLAB on the various selective media during aging means that probiotic adjunct cultures added during cheesemaking can only be enumerated with confidence on selective media for up to 3 or 4 mo. After this time, growth of NSLAB obfuscates enumeration of probiotic adjuncts. When adjunct Lb. casei or Lb. paracasei cultures are added during cheesemaking, they appear to remain at high numbers for a long time (9 mo) when counted on MRS + vancomycin medium, but a reasonable probability exists that they have been overtaken by NSLAB, which also grow readily on this medium. Enumeration using multiple selective media can provide insight into whether it is the actual adjunct culture or a NSLAB strain that is being enumerated.  相似文献   

16.
Following the consumer demand of healthy vegetable products due to their interesting nutritional profiles and potential functionalities, the fermentation process of hazelnut milk with Lactobacillus rhamnosus GG and Sthermophilus was studied. The effect of different factors (glucose, inulin and inoculum contents) was analysed to ensure sufficient probiotic survivals in a minimum time. The shelf life of the optimised product was characterised in terms of its main physicochemical and quality parameters (probiotic survivals and sensory analysis). Results showed that the defined formulation allowed high probiotic survivals (≈10cfu mL?1) throughout cold storage and >60% survived to the in vitro digestion process (≈10cfu mL?1). Lactobacillus rhamnosus GG was no able to degrade inulin, which remained to exert health benefits in the host. The product was highly appreciated by the sensory panel during its shelf life despite the formation of a weak gel, which presented syneresis at the last storage time.  相似文献   

17.
The present study aimed to develop a probiotic soy-based product similar to petit-suisse cheese and to evaluate its perspectives regarding potential for consumer health benefits, sensory acceptability, and instrumental texture during storage. Three different trials were studied: MP (milk-based petit-suisse – control); MSP (mixed product with milk cream and soy); SP (soymilk-based product). The formulations were produced with an ABT culture, containing Lactobacillus acidophilus La-5, Bifidobacterium animalis Bb-12, and the starter Streptococcus thermophilus and stored at 4 °C for up to 28 days. Bb-12 viability remained always above 8 log cfu g−1 for all trials, whereas viability of La-5 was satisfactory at the end of storage for MP (7.56 log cfu g−1) and MSP (6.49 log cfu g−1), but only up to 21 days (6.84 log cfu g−1) for SP. The pH remained stable and was lower for MSP (p < 0.05), whereas instrumental hardness and gumminess increased in soy-based products (MSP and SP) and decreased in the control (MP). SP had the highest sensory score means (6.4) on day 21, being sensorially attractive to provide consumers with a functional food without dairy ingredients and with high viability of the probiotic microorganisms.  相似文献   

18.
This study evaluated the efficacy of whey protein isolate (WPI) as an encapsulation matrix for the maintenance of Lactobacillus rhamnosus GG viability during simulated gastro-intestinal studies. Micro-bead characteristics were investigated using microscopy, chromatography, laser diffractometry and zeta potential analysis. Heat-treated WPI (11%, w/v) blended with stationary phase cultures demonstrated an instant gelation impetus in acetate buffer (0.5 M), tempered to 35 °C in the presence of Tween-20 (0.04%). Atomic force microscopy (AFM) demonstrated that micro-bead extrusion at pH 4.6 fuelled strong cohesive interactions within protein-probiotic amalgams; an electrostatic alliance further highlighted by zeta potential analysis. Optimization of encapsulation conditions generated self-supporting structures (200 ± 1.2 μm) with high micro-bead strength and individual loading capacity of 2.7 × 104 cfu/micro-bead. Plate enumeration demonstrated that micro-bead extrusion had no detrimental effect on cell viability due to the perpetuation of stationary phase concentrations (109 cfu/mL). This finding was further validated by LIVE/DEAD microscopy staining, which visualized the homogenous distribution of live probiotics throughout micro-bead matrices. Following 3 h in vitro stomach incubation (pH 1.8; 37 °C), micro-beads laden with 1010 cfu demonstrated acid-stability and peptic-resistance, characteristics required for optimum probiotic refuge. However, enzyme-activated intestinal conditions catalysed a synergistic response engaging rapid matrix disintegration and controlled probiotic release. Matrix digestion was monitored by chromatography, which witnessed the sequential release of peptides <2 kDa after 30 min. In conclusion, this study led to the development and design of a protein encapsulation polymer based on congruent matrix interactions for reinforced probiotic protection during challenging situations for their targeted delivery to intestinal absorption sites.  相似文献   

19.
To assess Prato cheese as suitable carrier for probiotic bacteria, four cheeses were produced. Control cheese contained only starter culture, whereas the others contained starter culture and the probiotic cultures Lactobacillus acidophilus La5 and Bifidobacterium Bb12 either separately or in combination. Bacterial viability, physicochemical composition, proteolysis, and texture profile were assessed over 60 days of storage. The addition of microorganisms together or separately did not affect the characteristics of Prato cheese. On storage, the cheeses showed increased proteolysis, lower firmness, and the probiotic cheeses presented counts higher than 106 cfu g−1. The viability of probiotics during in vitro gastrointestinal simulation, including the effect of the cheese matrix, was also assessed. The probiotic bacteria showed resistance to loss of viability during in vitro gastrointestinal simulation.  相似文献   

20.
This study aimed to isolate and characterise green banana starch (GBS) and to investigate the effect of adding 0%, 1.5%, 3.0%, 4.5% and 6.0% GBS on physicochemical and sensory properties of a fermented product based on baru almond (Dipteryx alata Vogel) water extract with probiotic bacteria. GBS showed high gelatinisation temperature (73.37 °C), enthalpy (16.61 J g−1) and final viscosity (239.6 RVU). On the contrary, it showed a low tendency to retrograde (67.53 RVU), water solubility (0.02%), water absorption (1.85 g g−1) and gel hardness (6.7 N). Higher addition levels of GBS increased firmness, reduced syneresis and positively affected pH, titratable acid, soluble solids and colour of baru almond-based fermented products. The incorporation of 4.5% GBS was well accepted and preferred over the control sample (no GBS addition). GBS can be used as a natural thickener. The baru almond-based fermented product with 4.5% GBS stands out for having potential probiotic properties and for being a promising dairy alternative.  相似文献   

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