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PubMed2006

Impact of gelation conditions and structural breakdown on the physical and sensory properties of stirred yogurts.

The objectives of this research were to understand structure-function relationships between the initial yogurt gels and stirred yogurts made from these gels. Yogurt gels were made from milk preheated at 75 or 85 degrees C for 30 min and incubated at 32, 38, or 44 degrees C. Yogurt gels were sheared at 5 s(-1) for 1 min to make stirred yogurts. Small amplitude oscillatory rheology and shear rate sweeps (flow curves) were performed to determine the dynamic moduli and apparent viscosity of yogurts, respectively. Confocal scanning laser microscopy was used to examine the microstructure. The sensory properties of stirred yogurts were determined using quantitative descriptive analysis. Yogurt gels made from high preheating temperatures and low incubation temperatures tended to have an increase in storage modulus, apparent viscosity values at structural breakdown, yield stress, and a decrease in the maximum in loss tangent values and permeability. During the shearing of intact gels, there was an initial increase in apparent viscosity in the low shear rate region, because of the resistance derived from the intact network; commonly used models for stirred yogurts could not adequately describe this type of viscoelastic behavior. Increasing milk preheating temperature and decreasing incubation temperature resulted in stirred yogurts with increased apparent viscosity, oral viscosity, and sensory mouth coating attributes. Storage modulus values of the initial gels were positively correlated with the apparent viscosity at 10 s(-1) (r = 0.61), oral viscosity (r = 0.77), and mouth coating sensory attributes (r = 0.72) of stirred yogurts. A significant negative correlation was observed between maximum in loss tangent values of initial gels and shear stress values (r = -0.68) of gels at structure breakdown, and in stirred yogurts, the oral viscosity (r = -0.85), and apparent viscosity at 10 s(-1) (r = -0.78). Permeability was negatively correlated with the oral viscosity (r = -0.84) and apparent viscosity at 10 s(-1) (r = -0.82) in stirred yogurts. These highly significant correlations demonstrated that the structure of the initial gel network and structural breakdown process had a major impact on the physical and sensory attributes of stirred yogurts. The presence of a yield stress and the elastic nature of gels at low strains resulted in commonly used models that could not adequately predict the behavior in the very low shear rate region, although they were able to predict the remainder of the flow profile.

Animals↗
PubMed1997

Manufacture and quality of iron-fortified yogurt.

Yogurts (nonfat and low fat) were manufactured and fortified with 10, 20, and 40 mg of iron/kg of yogurt. Growth of starter culture bacteria and nonstarter culture bacteria as well as lipid oxidation of the yogurts were monitored over 30 d of storage at 4 degrees C. Sensory characteristics of the yogurts were determined during that time by a trained panel of judges, and consumer panels were used to test acceptability of iron-fortified yogurt. Counts of Lactobacillus delbrueckii ssp. bulgaricas and Streptococcus thermophilus after 1 d of storage in iron-fortified skim yogurts were 7.0 x 10(8) cfu/ml, which were not significantly different from numbers in unfortified yogurts. Counts decreased to 2.5 x 10(8) and 1.9 x 10(8) cfu/ml for L. delbrueckii ssp. bulgaricus and S. thermophilus, respectively, after 30 d of storage. Fortifying yogurt with iron did not support the growth of Pseudomonas fluorescens or Escherichia coli. No significant increases in chemical oxidation, as measured using the thiobarbituric acid assay, were detected as a consequence of iron fortification. Trained panelists scored all yogurts for oxidized, metallic, bitter, and other off-flavors in the range of "not perceptible" to "very slightly perceptible". Iron-fortified yogurts had slightly higher oxidized flavor scores than did the control yogurt. There was no increase in metallic, bitter, or other off-flavors. The consumer panel did not detect any significant differences in the appearance, mouthfeel, flavor, or overall quality between fortified and unfortified flavored yogurts. All yogurt samples were liked by the consumer panelists, suggesting that yogurt is a suitable vehicle for iron fortification.

Female↗
PubMedDate not supplied

[Lactose absorption and tolerance to different types of yogurts in adults with hypolactasia].

It is known that lactose is better absorbed in yogurts than in milk by lactase-deficient individuals. This fact is due to the presence of beta-galactosidase activity in the yogurts, that are different concerning the caracteristics of the products. Thus, the aim of this study was to verify the absorption and tolerance of lactose in some yogurts consumed by our population. We studied 12 hypolactasic adults who, after diagnostic confirmation, were submitted to three breath hydrogen tests after ingestion of milk and two yogurts with different levels of beta-galactosidase. These activities were determined in each sample utilized. The lactose absorption was evaluated by the measurement of H2 eliminated in the expired air and the tolerance was assessed by the symptoms reported by the participants. The medians of the H2 maximum increment were 20 ppm/min for the milk, 10.5 for yogurt X and 5.5 for the yogurt Y. The area under the curve of H2 concentration presented a median of 960 in the test with milk, 420 with yogurt X and 270 with yogurt Y. These results showed statistically significant differences for milk and the two yogurts and similar among the yogurts. The score for symptoms also were different between the milk and the two yogurts and similar among the yogurts. A statistically significant association between absorption and tolerance was not observed, because many tolerant subjects were malabsorbers of lactose. These data show that lactose in yogurts is better absorbed and better tolerated than lactose in milk, suggesting that our products are similar to those of the literature concerning their capacity of hydrolising lactose "in vivo". In spite of the differences found "in vitro" among the beta-galactosidase, there were no significant differences of absorption and tolerance between the two yogurts studied.

Adolescent↗
PubMed2006

Effects of dried dairy ingredients on physical and sensory properties of nonfat yogurt.

Physical and sensory attributes are important factors that influence food acceptance and choices. In this study, sensory and texture properties of nonfat yogurts made from reconstituted skim milk powder (SMP) fortified with SMP as a control, whey protein isolate (WPI), yogurt texture improver (TI), and sodium caseinate (NaCn) were investigated over a 12-d storage period. Viscosity and syneresis were measured as physical quality parameters. Descriptive sensory analysis was carried out for each sample to determine the profiles of the products. Consumer acceptance testing (n = 143 consumers) was also conducted to measure the acceptability of yogurts; panelists were asked to rank their preference for the different yogurt samples. Differences among physical and sensory attributes of yogurts were defined. Addition of WPI improved the physical properties of yogurts, resulting in the highest viscosity and the lowest syneresis. On the other hand, yogurt with WPI did not have desirable sensory properties. The descriptive panel indicated that yogurt with WPI had the lowest fermented flavor attribute. In general, yogurts fortified with NaCn and TI displayed better physical and sensory properties than did control and WPI-fortified yogurts. Consumer testing showed that yogurts with NaCn and TI were not different from the control with regard to their flavor acceptability. Yogurts fortified with NaCn and TI were the most preferred samples by Turkish consumers.

Caseins↗
PubMed1994

Factors affecting the ability of a high beta-galactosidase yogurt to enhance lactose absorption.

Lactose in yogurt is better absorbed by lactase-deficient subjects than is an equivalent quantity of lactose in milk, presumably because of the microbial activity of the beta-galactosidase present in yogurt. In this study, we describe a process that increases the beta-galactosidase of yogurt 5- to 6-fold and the ability of this high lactase yogurt to enhance lactose absorption in lactase-deficient subjects. These subjects ingested the yogurt meals after a 12-h fast, and lactose malabsorption was determined by measuring breath hydrogen. Breath hydrogen was reduced 39% following ingestion of high lactase yogurt from that after consumption of conventional yogurt, indicating that the high lactase yogurt enhanced lactose absorption. However, the reduction after high lactase yogurt was less than expected, given the 5- to 6-fold increment in beta-galactosidase measured in vitro. In vivo activity of beta-galactosidase requires that the enzyme resist acid denaturation in the stomach. The beta-galactosidase in high lactase yogurt was much less acid resistant than was the beta-galactosidase in conventional yogurt, and the relative inability of high lactase yogurt to enhance lactose absorption was likely due to the destruction of the beta-galactosidase in the stomach.

Absorption↗
PubMed1990

In vitro antibacterial effect of yogurt on Escherichia coli.

We investigated the bactericidal and bacteriostatic effects of yogurt on three strains of Escherichia coli: human toxigenic (078:H11), rabbit pathogenic (RDEC-1) and rabbit nonpathogenic [015:K14(L):H4]. Approximately 10(6) organisms were incubated in yogurt, milk, broth, and modifications of these materials. Aliquots were removed at various intervals and plated on MacConkey's agar for enumeration of E. coli. Yogurt was bactericidal (at least 5 log10 reduction in bacterial counts) to all three strains of E. coli with less than 10 CFU/ml remaining by 9 hr. In contrast, all three strains replicated rapidly in milk and broth, reaching maximum concentrations by 9 hr. The E. coli strains survived and multiplied in milk acidified to the same pH as the yogurt. Yogurt (native pH 4.1-4.4) in which the pH was brought up to and maintained at pH 5.5 or pH 7 for 8 hr was not bactericidal to E. coli. Heat-treated yogurt and the filtered supernatant of centrifuged yogurt (both containing no yogurt bacteria) were only bacteriostatic. We conclude that both live yogurt bacteria and a pH near 4.5 are necessary for the bactericidal activity of yogurt. The possibility that yogurt ingestion could protect against infection via other foods contaminated with pathogenic E. coli merits further in vivo investigation.

Animals↗
PubMed2000

Chronic consumption of fresh but not heated yogurt improves breath-hydrogen status and short-chain fatty acid profiles: a controlled study in healthy men with or without lactose maldigestion.

BACKGROUND: Ingestion of fermented dairy products induces changes in the equilibrium and metabolism of the intestinal microflora and may thus have beneficial effects on the host. OBJECTIVE: We compared the effects of chronic consumption of yogurt with (fresh) or without (heated) live bacterial cultures (Lactobacillus bulgaricus and Streptococcus thermophilus) on plasma glucose, insulin, triacylglycerols, cholesterol, fatty acids, and short-chain fatty acids. DESIGN: Two groups of 12 healthy men with or without lactose malabsorption were selected with use of a breath-hydrogen test after a 30-g lactose load. Subjects were randomly assigned in a crossover design to 500 g/d of either fresh or heated yogurt for 2 periods of 15 d each, separated by a 15-d washout interval. RESULTS: Chronic consumption of fresh or heated yogurt had no detrimental effects on plasma glucose, insulin, or fatty acid areas under the curve in response to acute ingestion of 500 g yogurt in healthy men with or without lactose malabsorption. There were also no detectable changes in fasting plasma glucose, insulin, fatty acid, triacylglycerol, or cholesterol concentrations. In contrast, plasma butyrate was higher (P: < 0.03) and plasma propionate tended to be higher (P: = 0.059) in subjects without lactose malabsorption after fresh yogurt consumption than after heated yogurt consumption. There were no significant changes in plasma acetate. In subjects with lactose malabsorption, 15 d of fresh yogurt consumption also increased propionate production compared with values at baseline (P: < 0.04). In the same group, the production of breath hydrogen was lower after fresh yogurt consumption than after heated yogurt consumption (P: < 0.01). CONCLUSIONS: In men with lactose malabsorption, chronic consumption of yogurt containing live bacterial cultures ameliorated the malabsorption, as evidenced by lower breath-hydrogen excretion, but increased propionate concentrations. In subjects without lactose malabsorption, such yogurt tended to increase propionate and increased butyrate.

Adult↗
PubMed2006

Pretreatment with Lactobacillus- and Bifidobacterium-containing yogurt can improve the efficacy of quadruple therapy in eradicating residual Helicobacter pylori infection after failed triple therapy.

BACKGROUND: Lactobacillus- and Bifidobacterium-containing yogurt (AB-yogurt) can suppress Helicobacter pylori. Improvement of the eradication rate by quadruple therapy of residual H. pylori after failed triple therapy is needed. OBJECTIVE: We tested whether prior treatment with AB-yogurt improved the efficacy of quadruple therapy in eradicating residual H. pylori after failed triple therapy. DESIGN: One hundred thirty-eight patients in whom triple therapy failed were enrolled for a culture study of H. pylori to assess antimicrobial resistance. These patients were then randomly assigned in equal numbers to either a yogurt-plus-quadruple therapy group or a quadruple therapy-only group. The patients received 1 wk of quadruple therapy with or without a 4-wk pretreatment with AB-yogurt (400 mL/d). In the yogurt-plus-quadruple group, excessive delta(13)CO(2)/mL values of the (13)C-urea breath test were collected before and every 2 wk during the 4-wk ingestion of yogurt. For both groups, a (13)C-urea breath test was conducted > or =6 wk after the quadruple therapy to assess the outcome of residual H. pylori eradication. RESULTS: For the patients in the yogurt-plus-quadruple therapy group infected with either antibiotic-sensitive or -resistant H. pylori, the excessive delta(13)CO(2)/mL values of the (13)C-urea breath test were significantly decreased after the 4-wk ingestion of AB-yogurt (P < 0.0001). The yogurt-plus-quadruple therapy group had a higher H. pylori eradication rate than did the quadruple therapy-only group (intention-to-treat analysis: 85% compared with 71.1%, P < 0.05; per-protocol analysis: 90.8% compared with 76.6%, P < 0.05). CONCLUSION: A 4-wk pretreatment with AB-yogurt can decrease H. pylori loads despite antimicrobial resistance, thus improving the efficacy of quadruple therapy in eradicating residual H. pylori.

Anti-Bacterial Agents↗
PubMed2003

Bioaccessibility of folic acid and (6S)-5-methyltetrahydrofolate decreases after the addition of folate-binding protein to yogurt as studied in a dynamic in vitro gastrointestinal model.

Milk products are only moderate sources of folate. Nevertheless, they are of interest due to their content of folate-binding proteins (FBP), which in some studies have been reported to increase folate bioavailability. The effect of FBP on folate bioavailability has been widely discussed. The aim of this study was to investigate the bioaccessibility of folic acid and (6S)-5-methyltetrahydrofolate (5-CH3-H4folate) from fortified yogurt using a dynamic in vitro gastrointestinal model (TIM). In addition, the effect of FBP on folate bioaccessibility and the stability of FBP added to yogurt during gastrointestinal passage were investigated. Folate bioaccessibility was 82% from yogurt fortified with folic acid and 5-CH3-H4folate. The addition of FBP to yogurt decreased (P < 0.05) folate bioaccessibility. The lowering effect of FBP was more pronounced in yogurt fortified with folic acid (34% folate bioaccessibility) than from yogurt fortified with 5-CH3-H4folate (57% folate bioaccessibility). After gastrointestinal passage, 17% of the FBP in yogurt fortified with 5-CH3-H4folate and 34% of the FBP in yogurt fortified with folic acid were recovered. No difference in folate bioaccessibility was found between folate-fortified yogurt and folate-fortified pasteurized milk (P = 0.10), whereas the lowering effect of FBP was (P < 0.05) greater in yogurt compared with pasteurized milk. In conclusion, based on the high bioaccessibility of folic acid and 5-CH3-H4folate, yogurt without active FBP can be considered to be an appropriate food matrix for folate fortification.

Animals↗
PubMed2004

Yogurt containing Lactobacillus gasseri OLL2716 exerts gastroprotective action against [correction of agaisnt] acute gastric lesion and antral ulcer in rats.

Yogurt containing Lactobacillus gasseri OLL2716 (LG21 yogurt) is reported to improve Helicobacter pylori-induced gastric mucosal inflammation in clinical studies. However, other beneficial effects of LG21 yogurt have not been clarified. Therefore, we examined whether LG21 yogurt exhibits a gastroprotective action against acute gastric lesion or antral ulcer in rats. Moreover, the mechanism of gastroprotective action was also evaluated. After fasting, acute gastric lesions were induced by 0.6 M HCl. Gastric mucosal folds were stained by oral administration of methyl violet. Antral ulcers were induced by the combined administration of diethyldithiocarbamate and HCl in refed rats after fasting. LG21 yogurt was orally administered before HCl treatment or staining the mucosal folds. LG21 yogurt significantly and dose-dependently inhibited the formation of acute gastric lesions, and this gastroprotective action was attenuated by pretreatment with indomethacin. LG21 yogurt also significantly increased prostaglandin E2 generation in the gastric mucosa. Stained length of gastric mucosal fold was reduced by LG21 yogurt. Antral ulcer formation was also significantly inhibited by LG21 yogurt. From the above results, it was found that the ingestion of LG21 yogurt is useful for the prevention of gastric ulcer. Moreover, endogenous prostaglandin was suggested to be one of the gastroprotective mechanisms of LG21 yogurt.

Animals↗
PubMed1979

Elucidation of the inhibitory factors of yogurt against Salmonella typhimurium.

The inhibitory nature of yogurt against contaminating microorganisms has been studied extensively. Nevertheless, the factors responsible for the death of Salmonella typhimurium in yogurt have not been elucidated. An understanding of these factors is important for the determination of yogurt's safety to consumer health. Yogurt fermented for 18 h at 42 C had a stable environment with the following conditions: pH 3.85, oxidation-reduction potential -80 mV, lactic acid concentration 158 mM, and acetic acid concentration 3.7 mM. Under these conditions, lactic acid was responsible for virtually all of yogurt's bactericidal activity against S. typhimurium at 37 C. Die-off rates were observed when these conditions were reproduced artificially in milk (artificial milk yogurt) and when lactic acid was added back to 18-h yogurt from which acids were removed by passage of the whey through a Dowex 1 (Cl-) anion exchange column (cationic yogurt). Factors that augmented lactic acid inhibition of S. typhimurium were low pH and low oxidation-reduction potential. The die-off rate of S. typhimurium was more rapid in yogurt whey (yogurt minus the casein fraction) than in whole yogurt, indicating that the casein fraction was partially able to protect Salmonella.

Acetates↗
PubMed1999

Effects of yogurt ingestion on mucosal and systemic cytokine gene expression in the mouse.

To assess the potential for ingestion of yogurt to modulate immunity, its effects on basal gene expression of cytokines in systemic and mucosal sites were determined in mice. Yogurts were manufactured from pasteurized nonfat dry milk using five commercial starter cultures with or without Bifidobacterium sp. and Lactobacillus acidophilus. Treatment mice were fed the AIN-93G diet mixed 1:1 with unheated yogurt or heat-treated yogurt (wt/wt) for 2 and 4 weeks, and control mice were fed the AIN-93G diet mixed 1:1 (wt/wt) with nonfat dry milk. The viability of the various bacterial groups in unheated yogurts was maintained above 10(6) CFU/g throughout the feeding period. The yogurt-feeding regimens did not significantly affect weight gain. Relative mRNA levels in spleen, mesenteric lymph nodes, or Peyer's patches for the cytokines interferon-gamma, tumor necrosis factor-alpha, interleukin-2, -4, and -6, and the "housekeeping gene" beta2-microglobulin were determined by reverse transcriptase-polymerase chain reaction in conjunction with hybridization analysis. Prolonged feeding of some yogurts decreased expression of several cytokine mRNAs, the depression of tumor necrosis factor-alpha mRNA in the spleen being the most prominent effect. Heat-treated yogurts were more effective in altering cytokine mRNA expression than were unheated yogurts containing viable organisms. Generally, yogurts either had no effect or decreased specific cytokine mRNA in the test organs, regardless of whether they contained Bifidobacterium sp. and L. acidophilus. These results suggest that, in contrast with previous studies in vitro, some yogurt formulations may reduce rather than stimulate basal cytokine expression and that these effects are most prominent in the systemic compartment.

Animals↗
PubMed1987

Lactose digestion by yogurt beta-galactosidase: influence of pH and microbial cell integrity.

Lactase-deficient subjects more effectively digest lactose in yogurt than lactose in other dairy products, apparently due to yogurt microbial beta-galactosidase (beta-gal) which is active in the GI tract. We evaluated the effects of buffering capacity of yogurt, gastric pH, and microbial cell disruption on beta-gal activity and lactose digestion. Three times more acid was required to acidify yogurt than to acidify milk. Yogurt beta-gal was stable at pH 4.0 but inactivated at lower pH. When yogurt was sonicated to disrupt microbial cell structure, only 20% activity remained after incubation at pH 4.0 for 60 min. In vivo gastric pH remained greater than 2.7 for 3 h after ingestion of yogurt. Acidified milk alone or with disrupted yogurt microorganisms caused twice as much lactose malabsorption as did acidified milk containing intact yogurt microorganisms. The results provide a possible explanation for the survival of beta-gal activity from yogurt in the GI tract.

Adult↗
PubMed1991

Lactose digestion from yogurt: influence of a meal and additional lactose.

Lactose in yogurt is better digested than lactose in other dairy foods by lactase-deficient individuals, in part because of intraintestinal activity of yogurt microbial beta-galactosidase (beta-gal). The survival and activity of yogurt beta-gal depend on gastrointestinal transit, pH, and viability of the yogurt culture. To evaluate the ability of yogurt beta-gal to digest lactose when yogurt is consumed with food or with additional lactose, 22 healthy lactose-maldigesting individuals were fed 10 test meals. Results of breath-hydrogen expiration, incidence of symptoms, and enzyme and lactose content of gastric aspirates indicate that the consumption of a meal with yogurt does not inhibit, and may slightly improve, lactose digestion from yogurt. However, yogurt beta-gal appears unable to assist in the digestion of additional lactose beyond that normally present in yogurt.

Adult↗
PubMed2004

Textural and sensory characteristics of whole and skimmed flavored set-type yogurt during long storage.

A study of refrigerated storage (10 degrees C for 91 d) of whole and skimmed flavored set-type yogurt was made. Comparison with storage at 20 degrees C for 21 d and 30 degrees C for 3 d (accelerated) was also carried out. Refrigerated storage yogurts were assessed by a trained panel and by a consumer panel. Trained-panel scores were correlated to instrumental data, and the acceptability data for long storage were studied using consumer criteria. In all cases, after-storage pH values barely changed over storage time, indicating that the yogurt samples did not develop much acidity under any of the storage conditions studied. The profile of the instrumental texture curves obtained corresponded to a firm gel, which broke after a plunger penetrated the sample, and the firmness values of the whole yogurt were lower than for the skimmed yogurt under all the storage conditions studied. From a microbiological point of view, the viability of the yogurts was adequate at the different storage times and temperatures studied, although those stored at 10 degrees C for long periods would not comply with some countries' minimum requirements. Logistic regression of the data from a 50-consumer sensory evaluation showed that the probability of the whole yogurt being accepted after 91 d storage at 10 degrees C was around 40%, whereas for the skimmed yogurt it was only 15%, largely because the skimmed yogurt developed certain negative attributes at an earlier stage of storage than the whole yogurt.

Dietary Fats↗
PubMed2006

Influence of proteins on the perception of flavored stirred yogurts.

Among yogurt dairy components, protein type is known to modify the texture of the products and the volatility of odorous volatile organic compounds. The aim of this study was to investigate the impact of 3 protein ratios (caseinate to total protein) on the sensory properties of 4% fat, strawberry-flavored stirred yogurts. A sensory methodology study was therefore investigated to choose the most efficient method in terms of sensitivity, quantification, and ease with which the panel could distinguish slight differences in olfactory property between the yogurts. Three kinds of product presentation procedures were compared: a monadic presentation, a comparative presentation, and a comparative presentation with a reference. The results showed that the 3 presentation methods emphasized some important texture differences between the yogurts in the same way. However, the comparative procedure with a reference was the only one to reveal clear olfactory property differences between the yogurts. The main effect of protein ratio variation in yogurt concerned the texture properties, which greatly differed between the 3 yogurts and was confirmed by complex viscosity measurements. Olfactory differences between the yogurts were more subtle. Overall, the flavor intensity and the fruity notes were less intense in the yogurts with the high caseinate ratio than in those with the low ratio. This result was in agreement with the physicochemical measurements, which showed a higher retention of a large majority of aroma compounds of the strawberry flavor in the yogurts with a high caseinate ratio.

Adult↗
PubMed1999

Increase of intestinal Bifidobacterium and suppression of coliform bacteria with short-term yogurt ingestion.

To determine whether ingestion of yogurt would alter human intestinal bacterial composition and whether Bifidobacterium numbers would increase in the intestine, 34 healthy volunteers were studied. The experimental period was 26 d, including an initial 8 d without yogurt, 10 d with three bottles (230 ml each) of AB yogurt per day (President Enterprise Corporation, Tainan, Taiwan), and 8 d without yogurt. Stool samples were taken at 3- to 4-d intervals. The bacteria of each fresh stool sample were promptly analyzed by dilution and culture on blood, MacConkey, Center for Disease Control and NNLP agars, the agar contained nalidixic acid, neomycin sulfate, LiCl, and paromomycin sulfate for aerobes, coliforms, anaerobes, and bifidobacteria, respectively. The number of bacteria was determined as colony-forming units per gram of dried stool. Results indicated that ingestion of AB yogurt increased the counts of anaerobic bacteria, suppressed aerobic bacteria, and significantly elevated the bifidus to coliform ratio. Arbitrarily primed polymerase chain reaction was used to differentiate the identity of bifidobacteria in four volunteers before and after yogurt ingestion and confirmed that B. bifidum ingested from the yogurt survived and proliferated in the stool throughout the experiment. However, the elevated bifidus to coliform ratio gradually diminished and disappeared after yogurt consumption was discontinued. In conclusion, ingestion of yogurt increased the numbers of stool bifidobacteria and suppressed coliform bacteria. The ingested bifidobacteria survived for more than 8 d after yogurt consumption was discontinued.

Adult↗
PubMed2001

Effects of ingestion of yogurts containing Bifidobacterium and Lactobacillus acidophilus on spleen and Peyer's patch lymphocyte populations in the mouse.

Certain probiotic lactic acid bacteria have been reported to improve immune system function. Here, the effects of ingesting yogurts on lymphocyte populations in the spleens and Peyer's patches were determined in mice. Three probiotic-supplemented yogurts containing Streptococcus thermophilus, Lactobacillus bulgaricus, Bifidobacterium, and Lactobacillus acidophilus and one conventional yogurt containing only S. thermophilus and L. bulgaricus were prepared from commercial starter cultures and used in the study. B6C3F1 female mice were fed the four different types of yogurts mixed with an AIN-93G diet in a 50:50 (wt/wt) ratio. Nonfat dry milk mixed at a 50:50 (wt/wt) ratio with AIN-93G diet was used as the control. After a 14-day feeding period, spleen and Peyer's patches were removed and lymphocytes subjected to phenotype analysis by flow cytometry. Ingestion of the four yogurts had no effect on percentages of CD8+ (cytotoxic T cells), B220+ (B cells), IgA+, or IgM+ cells in spleen or Peyer's patches. The percentage of CD4+ (T helper) cells was significantly increased in the spleens from one group of mice fed a yogurt containing Bifidobacterium and L. acidophilus, and a similar trend was found in the remaining two probiotic-supplemented yogurts. Effects on CD4+ populations were not observed in spleens of mice fed conventional yogurt or in the Peyer's patches of any of the four yogurt groups. In total, the results suggested that ingestion of conventional or probiotic-supplemented yogurts for 2 weeks had very little effect on lymphocyte distribution in the systemic or mucosal immune compartments.

Animals↗