Total Lactic Acid Bacteria Counts Research Articles

Effect of Fermented Dough on the Organoleptic Quality and Shelf-Life of Bread

The study was carried out to determine the effect of fermented dough (sourdough) containing lactic acid bacteria on the organoleptic quality and shelf life of bread. Spontaneous fermentation of three commonly used wheat flour was carried out for 120 hours (5 days) at ambient temperature and at 33⁰ C . The average total lactic acid bacteria counts during dough fermentation were 2.0 x 107, 1.8 x 107 and 1.7 x 107cfu/g for flour A, B and C fermented doughs respectively. A total of seven Lactobacillus species were isolated; Lactobacillus fermentum, Lactobacillus sanfransicensis, Lactobacillus casei, Lactobacillus pontis, Lactobacillus brevis, Lactobacillus plantarum and Lactoacillus acidophilus. Percentage overall acceptance of the experimental bread samples was highest (79.00%) in the bread samples with 20% fermented dough concentration. The highest minimum mould-free shelf life was 8 days in both the 15% and 20% fermented dough bread as compared to the control bread baked with yeast and commercially purchased bread. Finally, the use of fermented dough in bread production was found to improve the sensory quality and shelf life of bread.

Enhanced Bioaccessibility of Curcuminoids in Buttermilk Yogurt in Comparison to Curcuminoids in Aqueous Dispersions

Curcuminoids have low bioavailability due to low aqueous solubility. We compared the bioaccessibility of curcuminoids delivered in buttermilk yogurt to that of curcuminoid powder in an aqueous dispersion. Buttermilk containing added curcuminoids (300 mg/100 g, 0.3% w/w) was used for yogurt manufacture. We measured percentage of curcuminoids remaining in yogurts after manufacture and after exposure to simulated gastrointestinal fluids, and the in vitro bioaccessibility of the curcuminoids. Curcuminoids were stable during yogurt manufacture. At the end of in vitro digestion, approximately 11% of the curcuminoids delivered in yogurt was degraded compared to <1% for curcuminoids in an aqueous dispersion. However, curcuminoids delivered in yogurt was 15-fold more bioaccessible than curcuminoids in aqueous dispersion. The small change in yogurt properties (decrease in total lactic acid bacteria counts of <1 log and increased viscosity) on addition of curcuminoids has to be balanced against the benefits of increased bioaccessibility of curcuminoids when delivered in yogurts.

Utilization of tofu whey concentrate by nanofiltration process aimed at obtaining a functional fermented lactic beverage

Tofu whey was concentrated using the nanofiltration process up to a volume reduction factor of 4.5. The concentrate was used to produce two fermented lactic beverages: (1) with 10% of concentrated tofu whey + 90% of milk; and (2) with 20% of concentrated tofu whey + 80% of milk. Both beverages were analyzed to determine the total lactic acid bacteria count and the physicochemical, rheological and functional properties during storage (30 days). It was observed that the total lactic acid bacteria count was >8 log CFU mL−1. It was observed that the total solids and protein contents of all beverages remained unchanged, but the use of concentrated tofu whey contributed to the post-acidification process. It can be verified that the viscosity was lower for beverage 2. The apparent viscosity of all samples decreased with an increase in the shear rate, indicating shear thinning and thixotropic properties. The Power Law model was successfully applied to describe the rheological behavior. The total isoflavones content was greater for beverage 2 and remained unchanged during storage, while the oligosaccharides content decreased during storage.

Microbiological studies and sensory evaluation of breadfruit and cassava co-fermented into gari analogue

This study focused on the processing of breadfruit and cassava co-fermented into gari analogue. The microbial load was determined and the microbes associated with the fermentation were identified. The shelf life of the co-fermented gari analogue samples was also determined. A portion of both mature cassava tubers and matured but unripe breadfruit (Artocarpus altilis) was co-fermented (100:0, 0:100, 80:20, 70:30, and 60:40 Cassava: Breadfruit) to obtain gari analogue. The samples were evaluated for microbial loads (total viable, total yeast and mould count and total lactic acid bacteria counts). The products were subjected to sensory analyses using a 7-point hedonic scale. Data obtained were subjected to descriptive and inferential statistics. The results showed that six bacteria species were isolated from the fermenting mash, Corynebacterium manihot, Lactobacillus plantarum, Bacillus subtilis, Bacillus coagulans, Bacillus species and Corynebacterium species. Also isolated were Saccharomyces cerevisae, Saccharomyces fragilis, Saccharomyces rouxii and Geotricum candidum. Two moulds, Aspergillus niger and Rhizopus stolonifer, were found associated with co-fermented meals of cassava and breadfruit. The sensory attributes of 100% breadfruit gari and co-processed gari samples were significantly different (p>0.05) from the control; the co-processed gari samples were however rated higher than the 100% breadfruit in terms of overall acceptability. All the gari samples retain their quality attributes during storage for six weeks, except for the gari sample with 100% breadfruit, which deteriorated after three weeks. This study established that 20% of breadfruit co-fermented with cassava yields a novel food product that compares favourably with 100% cassava gari in terms of microbial and sensory characteristics.

Dietary supplementation with mannan oligosaccharide influences growth, digestive enzymes, gut morphology, and microbiota in juvenile striped catfish, Pangasianodon hypophthalmus

This study was conducted to evaluate the effects of mannan oligosaccharide (MOS) dietary supplementation on growth, digestive enzyme activities, gut morphology, and microbiota in striped catfish (Pangasianodon hypophthalmus). Triplicate groups of juvenile striped catfish (initial weight 20.41 ± 1.64 g) were fed twice per day at 2.5 % of body weight for 12 weeks, with 0 (control), 0.2, 0.4, 0.6, or 0.8 % MOS diets. Compared to control (0.74 ± 0.03) and fish fed low MOS concentration, those fed 0.6 % (1.01 ± 0.02) or 0.8 % (1.03 ± 0.03) MOS had significantly higher (P < 0.05) specific growth rates. Feed conversion ratio and protein efficiency ratio, respectively, significantly improved (P < 0.05) in fish fed 0.6 % (1.62 ± 0.23; 1.71 ± 0.23) or 0.8 % (1.42 ± 0.06; 1.92 ± 0.08) MOS. Further, compared to control and fish fed 0.2 % MOS, those fed 0.6 % MOS had significantly higher (P < 0.05) apparent protein and dry matter digestibilities. Amylase, protease, and lipase activities, respectively, were significantly higher (P < 0.05) in fish fed 0.6 % MOS (5.10 ± 0.97; 0.47 ± 0.08; and 5.59 ± 1.82) than in control (2.60 ± 0.53; 0.32 ± 0.05; and 3.78 ± 0.72). Histological analysis of the anterior and posterior gut showed significantly higher (P < 0.05) villus length in 0.6 and 0.8 % MOS fed fish than in the control and other treatments. The guts of fish fed different MOS concentrations showed similar total lactic acid bacteria counts, which were significantly higher (P < 0.05) than those in the control. Thus, 0.6 % MOS-supplemented diet improved growth, feed utilization, digestive enzyme activities, gut morphology, and microbiota in juvenile striped catfish.

Rheological and some physicochemical properties of probiotic boza beverage fermented with Lactobacillus casei Shirota: application of principal component analysis for the characterisation

Boza is a cereal-based fermented beverage. Lactobacillus casei Shirota, which rates among probiotic bacteria, is a member of starter culture combinations used for the production of industrial Yakult, a Japanese beverage. In this study, boza was produced using different starter culture combinations (Weisella paramesenteroides, L. casei Shirota and Lactobacillus acidophilus with two/three bacterial combinations) and principal component analysis was used for characterisation of their quality parameters. In the results, boza fermented with commercial boza (control) and with L. acidophilus + L. casei Shirota had the highest sensorial scores. Total lactic acid bacteria counts of the boza samples ranged from 9.09 to 10.48 log cfu/ml while pH was the lowest (4.08±0.02) in the boza produced with L. acidophilus + L. casei Shirota. Boza samples showed non-Newtonian pseudoplastic behaviours. Apparent viscosity values decreased with increasing shear rate. The first two principal components explain 80.71% of the total variation for measurements, with 54.90% of the total variance explained by the first principal component.

Traditionally produced sauerkraut as source of autochthonous functional starter cultures

Spontaneous sauerkraut fermentation was performed at industrial scale in “Prehrana Inc.”, Varaždin, in order to select autochthonous lactic acid bacteria (LAB) which were evaluated according probiotic criteria and tested for their capacity as probiotic starter cultures. At the end of the spontaneous sauerkraut fermentation, total LAB counts reached 9.0×105CFU/ml. This underlines that the need for addition of the well characterised probiotic cultures, in appropriate viable cell counts, would be valuable in probiotic sauerkraut production. Phenotypic characterisation through API 50 CHL and SDS-PAGE of cell protein patterns revealed that Lactobacillus plantarum is predominant LAB strain in homofermentative phase of fermentation. Autochthonous LAB isolates SF1, SF2, SF4, SF9 and SF15 were selected based on the survival in in vitro gastrointestinal tract conditions. RAPD fingerprints indicated that the selected autochthonous LAB were distinct from one another. All of the strains efficiently inhibited the growth of indicator strains and satisfied technological properties such as acidification rate, tolerance to NaCl and viability during freeze-drying. Strains Lb. paraplantarum SF9 and Lb. brevis SF15, identified by AFLP DNA fingerprints, have shown the best properties to be applied as probiotic starter cultures, because of their highest adhesion to Caco-2 cells and expression of specific, protective S-layer proteins of 45kDa in size. With addition of these strains, probiotic attribute of the sauerkraut will be achieved, including health promoting, nutritional, technological and economic advantages in large scale industrial sauerkraut production.

Physicochemical and rheological characteristics of alcohol free probiotic boza produced using Lactobacillus casei Shirota: Estimation of apparent viscosity of boza using non-linear modeling techniques

The effects of fermentation with 2 different starter culture mixtures composed of lactic acid bacteria (LAB) on some physicochemical, microbiological, sensorial, and rheological characteristics of boza, a traditional fermented Turkish beverage, during storage for 10 days at 8 °C were investigated. Lb. casei Shirota adapted in boza well and provided the boza with a probiotic property. At the beginning of storage, the Lb. casei Shirota count of boza was 6.83 log cfu mL-1, while total LAB counts were 8.01 and 8.11 log cfu mL-1 for S1 and S2 samples, respectively. A decrease in pH values was observed when the counts of LAB and Lb. casei Shirota increased during the storage period. Sensory acceptability scores were high for all boza samples but extending storage caused a decrease in sensory scores. Adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN), 2 important nonlinear modeling techniques, were used to construct the predictive models for the estimation of apparent viscosity during storage. All boza samples showed pseudoplastic flow behavior. Apparent viscosity decreased with increasing of shear rate, storage period, and measurement temperature. ANFIS showed better fitting performance with a higher coefficient of determination (R2 = 0.995) compared to ANN (R2 = 0.980).

Kefir grain tolerance to Escherichia coli contamination—industrial advantages

Kefir grains are used in dairy plants for mother or bulk starter culture production. The aim of the study was to evaluate the possibility of the re-use of kefir grains grown at 18 °C for 24 h in pasteurized Escherichia coli contaminated milk up to 6.1 × 102 cfu.mL−1. The contamination rate was adapted to a realistic situation which may take place in plant. E. coli was enumerated in kefir grains, postharvest broth, and in milk incubated without kefir grains. Determination of the replication ability of the affected grains and acidification activity of postharvest broth was performed. The impact of milk contamination on total lactic acid bacteria (LAB), citrate-fermenting and vancomycin-tolerant LAB, and yeasts of the kefir grains and postharvest broth was evaluated. The grains separated from fermented milk and washed with water were not E. coli-contaminated. In the postharvest broth (starter culture), E. coli was found at inoculation rate, whereas in contaminated milks incubated without grains, E. coli population increased at least by 2 log. Separated from contaminated and uncontaminated milk, grains displayed similar growth dynamics in five subsequent transfers into freshly prepared milk. The postharvest broth obtained from last transfer was not contaminated and showed standard acidification milk profile. E. coli contamination of milk did not influence adversely the ratio of citrate-fermenting, vancomycin-tolerant LAB, yeasts, and total LAB counts in kefir grains and postharvest broth. These findings would have economical value for kefir producers, but it should be considered that only one strain with low contamination rate was tested.

EFFECT OF DIAFILTRATION ON PREPARATION OF FERMENTED MUNG BEANS CONCENTRATE AS PROBIOTIC SAVORY FLAVOR THROUGH ULTRAFILTRATION MEMBRANE

Diafiltration by means of the ultrafiltration system of probiotic fermented Mung beans (Phaseolus radiatus L.) concentrate has been performed to reduce or eliminate salts and smaller impurities than the nominal cut-off of the membrane of 20,000 nominal weight cut-off (NWCO). These processes have been conducted as an attempt in order to get a probiotic product with organoleptic acceptability, composition, and the optimal total lactic acid bacteria (LAB) counts because the presence of salts will affect on the viability of LAB and the cell lysis of LAB and limit its utility in food products. Concentrate of probiotic mung beans was prepared through fermentation of LAB using inoculum of LAB consisting of Lactobacillus bulgaricus and Streptococcus thermophylus (1 : 1) on fermented mung beans extract inoculated by inoculum of Rhizopus–C1 in rice substrates at salt condition. Ultrafiltration and diafiltration modes have been carried out at flow rate of 8.77 Liter/minute, room temperature and the pressure of 5 bar (0 to 79.7 minutes) and 7 bar (0-154.5 minutes) with the ratio of the volume of pure water to the volume of initial feed (number of diavolume, Nd) of 0, 0.25, 0.5, 0.75, 1.0 and 1.25, respectively. The experiment results based on total LAB counts as a probiotic product show that a high Nd can reduce the salt content but increase the total LAB counts. Nd of 1.0 results reduce the salt content which is equal to retentate, permeate, and the optimal total LAB counts. Ultrafiltration and diafiltration modes at the pressure of 7 bar and Nd of 1.0 give a retentate with total solid of 6.1355%, salt of 1.3515% and remove 86.15% of the salt from probiotic fermented mung beans concentrate and total LAB counts of 10.73 log cycles. Meanwhile, the permeate obtained at this condition results in flux value of 10.83 Liter/m 2 .hour with contents of total solid of 6.8199%, salt of 1.325% and total LAB counts of 5.49 log cycles.

Lactic acid bacteria and yeasts isolated from the starter doughs for Chinese steamed buns in Thailand

Abstract Isolation of lactic acid bacteria (LAB) and yeasts from the starter dough of Chinese steamed buns from four different commercial sources in Thailand was carried out. Thirty-one lactic acid bacteria and eight yeast strains were isolated. Total counts of LAB were from 1.8 × 10 4 to 10 8 colonies/g sample, whilst yeasts were very low from 10 to 2.3 × 10 2 colonies/g sample. The pH values of all starter doughs ranged from 3.36 to 3.52 and the Total Titratable Acidity (TTA) varied from 11.1 to 17.0 ml of 0.1 N NaOH/10 g dough. All LAB isolates were identified as Lactobacillus . The phenotypic characteristics were used to cluster all the LAB isolates into two major groups (Group A and Group B), with the B group subdivided into four groups. Phylogenetic analysis, based upon partial 16S rRNA gene sequences, showed that isolates of Group A, which all contained meso -diaminopimelic acid in their cell wall and produced dl -lactic acid, were closely related to Lactobacillus plantarum , whilst the strains of Group B that produced l -lactic acid were closely related to Lactobacillus casei . For yeasts, eight isolates based on the D1/D2 domain sequences of 26S rRNA were identified as Candida tropicalis , Pichia stipitis , Candida parapsilosis , Issatchenkia orientalis and Saccharomyces cerevisiae .

Evaluation of the role of Carnobacterium piscicola in spoilage of vacuum- and modified-atmosphere-packed cold-smoked salmon stored at 5°C

The microflora on spoiled cold-smoked salmon often consists of a mixture of lactic acid bacteria (LAB) and Gram-negative bacteria. To elucidate the role of the different groups, a storage trial was carried out in which nisin and CO 2 were used for the selective inhibition of the two bacterial groups. The shelf-life of vacuum-packed cold-smoked salmon, recorded by sensory evaluation, was four weeks at 5°C and the microflora was composed of LAB (10 6–10 7 cfu/g) with an associate Gram-negative flora in varying levels (10 5–10 7 cfu/g). The addition of nisin and/or a CO 2-atmosphere increased the shelf-life to five or six weeks and limited the level of LAB to about 10 4–10 6, 10 3–10 6 and 10 2–10 4 cfu/g, respectively. CO 2-atmosphere±nisin inhibited the growth of Gram-negative bacteria, whereas nisin had no effect on these in vacuum packages. The Gram-negative flora on vacuum-packed salmon was dominated by a Vibrio sp., resembling V. marinus, Enterobacteriaceae ( Enterobacter agglomerans, Serratia liquefaciens and Rahnella aquatilis) and occasionally Aeromonas hydrophila. Irrespective of the addition of nisin and/or CO 2-atmosphere, the LAB microflora was dominated by Carnobacterium piscicola, which was found to account for 87% of the 255 LAB isolates characterized. Whole-cell-protein patterns analysed by SDS–PAGE confirmed the Carnobacterium species identification. The spoilage potential of C. piscicola isolates was further studied by inoculation of approx. 10 6 cfu/g in cold-smoked salmon stored at 5°C. The salmon did not spoil within 4 weeks of storage in vacuum- or CO 2-atmosphere, and it is concluded that despite high levels (>10 7 cfu/g) of C. piscicola, sensory rejection was caused by autolytic changes. This was supported by the development of soft texture and sour, rancid and bitter off-flavours at the point of spoilage, irrespective of the length of shelf-life and low or high total counts of LAB and Gram-negative bacteria.

Epiphytic lactic acid bacteria succession during the pre‐ensiling and ensiling periods of alfalfa and maize

Epiphytic lactic acid bacteria (LAB) succession during the pre‐ensiling and ensiling periods were studied in 1989 for two cuttings of alfalfa (Medicago sativa L.), each harvested at three stages of maturity, and three whole‐plant maize (Zea mays L.) hybrids. Twenty‐three species and 306 strains were found. Epiphytic LAB counts were low and variable on the standing crops, particularly on alfalfa. Wilting increased LAB numbers slightly for alfalfa, but the chopping process increased the counts dramatically. Population shifts in LAB also took place during the pre‐ensiling period. Lactobacillus plantarum, Pediococcus pentosaceus, Enterococcus faecium, and Ent. faecalis were predominant on both standing crops. Lactobacillus brevis dominated alfalfa at the second cutting, 10% bloom, but Lact. viridescens was predominant after chopping. The changes in LAB caused by wilting or chopping were reflected mainly in proportional changes of Lact. plantarum, Ped. pentosaceus, Ent. faecium and Ent. faecalis. Once the crops were ensiled, total LAB counts increased rapidly, reached a maximum within 1 d, and then declined after 7 d of fermentation. Enterococcus species decreased sharply or disappeared entirely after the early stages of the ensiling period, and the species most involved in microbial succession through day 7 were Lact. plantarum and Ped. pentosaceus. After 7 d, more species, e.g. Lact. homohiochii, Lact. brevis and Lact. gasseri, joined the succession and became prevalent, depending on the crop. Only two of the six alfalfa silages were well preserved, whereas all three maize hybrids underwent typical fermentations for this crop. No relationship was found between adequacy of silage fermentation and epiphytic LAB numbers or species on the pre‐ensiled crops. Neither were pH changes during the fermentation explained by the epiphytic LAB count or population succession. Rather, the well fermented alfalfa silages were those ensiled at a high dry matter (DM) content (&gt; 360 g/kg) and low buffering capacity (&lt;450 meq/kg of DM). Only a few of the LAB strains were shown to be the same among the crops, thus indicating the specificity of LAB strains to an ecological niche.

Epiphytic lactic acid bacteria succession during the pre-ensiling and ensiling periods of alfalfa and corn (1992)

Twenty three species and 306 strains of epiphytic lactic acid bacteria (LAB) were found for two cuttings of alfalfa, each harvested at three stages of maturity, and three whole-plant corn hybrids. Epiphytic LAB counts were low and variable on the standing crops, particularly on alfalfa. Wilting increased LAB numbers slightly for alfalfa, but the chopping process increased counts dramatically for both crops. Lactobacillus plantarum, Pediococcus pentosaceus, Enterococcus faecium, and E. faecalis were predominant on both standing crops. The changes in LAB caused by wilting or chopping were mainly proportional changes in the four dominant species. Once the crops were ensiled, total LAB counts increased rapidly, reached a maximum within 1 day, and then declined after 7 days of fermentation. Enterococcus species decreased sharply or disappeared during the early fermentation. The species most prominent through day 7 were L. plantarum and P. pentosaceus. After 7 days, more species, i.e., L. homohiochii, L. brevis, and L. gasseri, joined the succession and became prevalent, depending on the crop. Only two of the six alfalfa silages were adequately preserved, whereas all three corn hybrids fermented normally. No relationship was found between epiphytic LAB numbers or species and adequacy of fermentation. Neither were pH changes during the fermentation explained by the epiphytic LAB count or population succession. Rather, the well-fermented alfalfa silages were those ensiled at a high dry matter (DM) content (>36%) and low buffering capacity (<450 meq/kg of DM). Only a few of the LAB strains were consistently present, thus indicating that populations changed during fermentation to fit an ecological niche.