Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LACTIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
PubMed1991

The effect of lactic acid sprays on Campylobacter jejuni inoculated onto poultry carcasses.

Spraying poultry carcasses with 1% lactic acid 10 min after inoculation with Campylobacter jejuni, resulted in a significant reduction in the number of the bacteria after 4 h at 4 degrees C. Some of the inoculated cells, however, survived for at least 144 h. Spraying 10 min after inoculation with 2% lactic acid, totally eliminated all inoculated C. jejuni within 24 h. On the other hand, spraying 24 h after inoculation, with either 1% or 2% lactic acid did not eliminate all the bacteria. Inoculated C. jejuni on poultry carcasses not sprayed with lactic acid, survived at 4 degrees C throughout the sampling period (up to 144 h) and showed little tendency to decrease in number even when the carcasses started to deteriorate. Resident campylobacters on poultry carcasses were significantly reduced by the lactic acid treatment. Frozen and thawed chickens appeared to show a graying of the skins immediately after spraying with lactic acid, slightly stronger with 2% lactic acid, but the colour reverted to normal after 24 h. We were not able to observe any colour change on the fresh broiler chickens after lactic acid treatment. Our results indicated that lactic acid had a significant bactericidal effect on C. jejuni on both naturally and artificially contaminated poultry carcasses. This effect, however, became manifest only several hours after acid treatment.

Aerosols↗
PubMed1999

Influence of malic acid supplementation on ruminal pH, lactic acid utilization, and digestive function in steers fed high-concentrate finishing diets.

Two trials were conducted to evaluate the influence of malic acid supplementation on ruminal fermentation. In Trial 1, six Holstein steers (300 kg) with ruminal cannulas were used in a crossover design experiment to study the influence of malic acid (MA) on ruminal metabolism during glucose-induced lactic acidosis. Treatments consisted of a 77% steam-flaked barley-based finishing diet supplemented to provide 0 or 80 g/d of MA. After a 13-d dietary adjustment period, 1 kg of glucose was infused into the rumen 1 h after the morning feeding. Ruminal pH was closely associated (R2 = .70) with ruminal DL-lactate concentration. Malic acid supplementation increased (P < .01) ruminal pH 3 h after the glucose infusion. However, there were no treatment effects (P > .10) on ruminal VFA molar proportions or ruminal and plasma DL-lactate concentrations. In Trial 2, four Holstein steers (150 kg) with cannulas in the rumen and proximal duodenum were used in a crossover design experiment to evaluate the influence of MA supplementation on characteristics of digestion. Treatments consisted of an 81% steam-flaked barley-based finishing diet supplemented to provide 0 or 80 g/d of MA. There were no treatment effects (P > .10) on ruminal and total tract digestion of OM, ADF, starch, and feed N or on ruminal microbial efficiency. Malic acid supplementation increased (P < .05) ruminal pH 2 h after feeding. As with Trial 1, there were no treatment effects (P > .10) on ruminal VFA and DL-lactate concentrations. We conclude that supplementation of high-grain finishing diets with MA may be beneficial in promoting a higher ruminal pH during periods of peak acid production without detrimental effects on ruminal microbial efficiency or starch, fiber, and protein digestion. There were no detectable beneficial effects of MA supplementation on ruminal and plasma lactic acid concentrations in cattle fed high-grain diets.

Animal Feed↗
PubMed1984

The analysis of picomole amounts of L(+)- and D(-)-lactic acid in samples of dental plaque using bacterial luciferase.

L(+)-Lactic acid (5 pmol) and D(-)-lactic acid (20 pmol) were assayed by coupling the generation of NADH with the use of bacterial luciferase. The binding of NADH to L(+)-lactic dehydrogenase made it necessary to denature the protein so that the assay with bacterial luciferase was effective. The coupled luciferase assay of L(+)-lactic acid was 400 times more sensitive than the fluorometric assay. The luciferase coupled assay was used to analyze the L(+)- and D(-)-lactic acid contents of small samples of dental plaque.

Dental Plaque↗
PubMed2002

Amino acid catabolism and generation of volatiles by lactic acid bacteria.

Twelve isolates of lactic acid bacteria, belonging to the Lactobacillus, Lactococcus, Leuconostoc, and Enterococcus genera, were previously isolated from 180-d-old Serra da Estrela cheese, a traditional Portuguese cheese manufactured from raw milk and coagulated with a plant rennet. These isolates were subsequently tested for their ability to catabolize free amino acids, when incubated independently with each amino acid in free form or with a mixture thereof. Attempts were made in both situations to correlate the rates of free amino acid uptake with the numbers of viable cells. When incubated individually, leucine, valine, glycine, aspartic acid, serine, threonine, lysine, glutamic acid, and alanine were degraded by all strains considered; arginine tended to build up, probably because of transamination of other amino acids. When incubated together, the degradation of free amino acids by each strain was dependent on pH (with an optimum pH around 6.0). The volatiles detected in ripened Serra da Estrela cheese originated mainly from leucine, phenylalanine, alanine, and valine, whereas in vitro they originated mainly from valine, phenylalanine, serine, leucine, alanine, and threonine. The wild strains tested offer a great potential for flavor generation, which might justify their inclusion in a tentative starter/nonstarter culture for that and similar cheeses.

Amino Acids↗
PubMed1990

Lactic acid and pH as indicators of spoilage for vacuum-packed cooked ring sausages.

Lactic acid production and pH changes of 206 vacuum-packed cooked ring sausages stored at 2, 4 and 12 degrees C from 21 different production runs were monitored as a function of time and of microbial growth. The total lactic acid concentrations and pH values were first at a constant level, starting to increase sharply after the lactobacilli count reached about 5 x 10(7) or 6 x 10(7) cfu/g, respectively. The lactic acid and pH changes as a function of the lactobacilli count were similar at 4 and 12 degrees C. The sharp increase at high lactobacilli counts was observed in both L-lactic acid and D-lactic acid. The variation was lesser and the increase greater in D-lactic acid formation than in L-lactic acid. Above a level of 3-4 mg lactic acid/g most of the samples were deemed unfit. The pH started to decrease from a level of approx. 6.3; below 5.8-5.9 the samples were deemed unfit. The lowest pH value observed was 4.58. Both a high lactic acid content and a low pH indicated that the sausage was spoiled. These changes, however, took place at later stages of storage, and do not give information about the early phase of spoilage.

Animals↗
PubMedDate not supplied

Effect of hyperthermia on the lactic acid and beta-hydroxybutyric acid content in tumour.

The effects of hyperthermia on the content of lactic acid and beta-hydroxybutyric acid in the SCK mammary carcinoma and the leg muscle of A/J mice were studied. The contents of lactic acid in the SCK tumour before heating was 9.32 mumol/g, and the content of beta-hydroxybutyric acid was only 0.013 mumol/g. The lactic acid content in the tumour increased to 17.5 mumol/g at 0 h after heating at 41.5 degrees C for 30 min and then decreased to the control level 3 h later. When heated at 43.5 degrees C for 30 min, the lactic acid content in the tumour increased to 24 mumol/g at the end of heating and remained elevated for 24 h. The content of beta-hydroxybutyric acid increased continuously reaching 0.45 mumol/g at 5 h after heating at 43.5 degrees C for 30 min, and then declined thereafter. The contents of lactic acid and beta-hydroxybutyric acid in the muscle also increased after heating, but these increases were far less than those observed in the tumours. The absolute amount of lactic acid in the heated tumours was far greater than that of beta-hydroxybutyric acid, and thus appeared to play the major role for the increased acidity in the heated tumours.

3-Hydroxybutyric Acid↗
PubMed2001

The aerobic stability of silages influenced by metabolites of lactic acid bacteria.

The stability of silages after opening the silo depends strongly on the products formed by the microorganism flora present during the conservation process. A silage additive developed at IFA-Tulln showed best results on different crops. In the starting phase of silage fermentation, acetic acid was formed by the heterofermentative lactic acid bacteria L. brevis from sugars. In the later stages, L. buchneri converts also lactic acid into acetic acid. Several trials involving different formulations of starters with varying amounts of single homo- and heterofermentative lactic acid bacteria were tested in laboratory and clump silos. Finally, an optimum composition of lactic acid bacteria, which reliably increases aerobic stability of silages and still guaranties highest quality, was evaluated.

Acetic Acid↗
PubMed1990

Contrary effect of lactic acid on expression of neuron-specific enolase and glial fibrillary acidic protein in human glioma cells.

We examined the effect of lactic acid on cultured human glioma cell lines expressing glial fibrillary acidic protein (GFAP), vimentin and neuron-specific enolase (NSE). The growth of the cells was inhibited by the lactic acid in a dose-dependent manner. At 56 mM of lactic acid, the surviving cells of the KNS-42-c2 cell line developed slender processes and increasingly formed bizzar giant cells. In an immunofluorescence study of the lactic acid-resistant cells, the GFAP-positive cells prominently decreased in number, while the NSE-positive cells clearly increased. The vimentin was not affected throughout the experiment. After removing lactic acid from the medium, the GFAP-positive cells gradually increased in number. The method of dot immunoassay was useful for quantifying GFAP in cellular extracts. It indicated that the amount of GFAP decreased in the cells cultured with lactate-containing media and increased to the primary values after removing the lactic acid. These results may suggest that the morphological and immunochemical diversities of glioma cells are secondarily affected by cellular microenvironments such as lactic acid.

Cell Line↗
PubMed2002

The effect of cage stiffness on the rate of lumbar interbody fusion: an in vivo model using poly(l-lactic Acid) and titanium cages.

STUDY DESIGN: A goat interbody fusion model using poly-(L-lactic acid) and titanium cages was designed to evaluate the effect of cage stiffness on lumbar interbody fusion. OBJECTIVE: To investigate the effect of cage stiffness on the rate of interbody fusion. SUMMARY OF BACKGROUND DATA: Various types of cages considerably exceed the stiffness of vertebral bone, which ultimately may lead to postoperative complications. To avoid these complications, poly-(L-lactic acid) cages with limited stiffness have been designed. The mechanical integrity of the cages remains intact for at least 6 months. METHODS: Interbody fusions were performed at L3-L4 of 15 Dutch milk goats, and one of three cages was randomly implanted: 1) a titanium cage (n = 3), 2) a stiff poly-(L-lactic acid) cage (n = 6), or 3) a flexible poly-(L-lactic acid) cage (n = 6). Interbody fusion was assessed radiographically by three independent observers 3 and 6 months after surgery. RESULTS: At 3 months, all the poly-(L-lactic acid) specimens showed ingrowth of new bone, but with radiolucency in the fusion mass. At 6 months, solid arthrodesis was observed in four of six poly-(L-lactic acid) specimens, advanced ingrowth in one specimen, and infection in one specimen. Titanium cages showed ingrowth of bone, but with radiolucency in the fusion mass. Interbody fusion using poly-(L-lactic acid) cages showed a significantly higher rate statistically (P = 0.016) and more complete fusion than titanium cages of the same design. CONCLUSIONS: The reduced stiffness of poly-(L-lactic acid) cages showed enhanced interbody fusion, as compared with titanium cages after 6 months. Bioabsorbable poly-(L-lactic acid) cages thus may be a viable alternative to current interbody cage devices, thereby avoiding the concomitant problems related to their excessive stiffness. However, the bioabsorbability of the poly-(L-lactic acid) cages awaits investigation in a long-term study currently underway.

Absorbable Implants↗
PubMed1996

Effect of lactic acid isomers on keratinocyte ceramide synthesis, stratum corneum lipid levels and stratum corneum barrier function.

Alpha-hydroxy acids are effective agents for the treatment of skin xerosis and it is known that, following treatment with lotions containing D,L-lactic acid, the stratum corneum prevents xerosis more effectively. To date, the relative efficacy of the different isomers of lactic acid has not been evaluated and the mode of action of lactic acid in improving stratum corneum resilience is not known. The objective of the present studies was to determine the effects of lactic acid isomers on keratinocyte ceramide biosynthesis, stratum corneum barrier function and the resistance of the stratum corneum to the appearance of skin xerosis. In vitro, lactic acid enhanced the production of ceramides by keratinocytes. L-Lactic acid was more effective than the D isomer (300% increase vs 100% increase). Carbon label from lactic acid was incorporated into all keratinocyte lipid species and a greater incorporation of label into ceramides was achieved with L-lactate than with D-lactate. In vivo, lactic acid increased the levels of stratum corneum ceramides. Whereas, lotions containing L-lactic acid resulted in the greatest increase (48% increase) followed by D,L-lactic acid (25% increase), D-lactic acid had no effect on stratum corneum ceramide levels. The increases in stratum corneum ceramide levels following lactic acid treatment also led to improvements in stratum corneum barrier function, measured by transepidermal water loss following a challenge to the skin with SLS and in the regression phase of a moisturization efficacy study. Significant improvements in barrier function and resistance to the appearance of skin xerosis were observed following L-lactic acid and D,L-lactic acid, but not following D-lactic acid treatment. From these results we believe that lactic acid, particularly the L isomer, stimulates ceramide biosynthesis leading to increased stratum corneum ceramide levels which results in superior lipid barrier and a more effective resistance against xerosis.

Adult↗
PubMed2001

Lactic acid production by simultaneous saccharification and fermentation of alfalfa fiber.

Lactic acid was produced by simultaneous saccharification and fermentation (SSF) of liquid hot water (LHW)-pretreated and non-LHW-pretreated alfalfa fibers. The Lactobacillus plantarum and L. delbrueckii strains produced 0.464 and 0.354 g of lactic acid per g of dry matter of alfalfa fiber, respectively, by non-LHW pretreatment. L. xylosus and L. pentoaceticus produced lower yields of lactic acid from the same amount of alfalfa fiber, however, their acetic acid production was higher. These Lactobacillus strains did not require any additional nutrients during SSF of non-LHW-pretreated alfalfa fiber. After LHW pretreatment, the "raffinate" cellulosic fraction of alfalfa required additional nutrients for lactic acid production by SSF. Both L. plantarum and L. delbrueckii produced 0.606 and 0.59 g of lactic acid per g of dry matter of fiber, respectively. However, the "extract" soluble hemicellulosic fraction of alfalfa produced 0.38 to 0.62 g of lactic acid per g of dry matter extract during SSF and did not require nutrient supplementation. These results suggest that during the LHW pretreatment, alfalfa fiber nutrients are lost in cellulosic fractions but retained in hemicellulosic extract fractions.

Journal Article↗
PubMed1994

Effects of potassium and lactic acid on ventilation in anaesthetized cats.

Intravenous infusions of lactic acid alone, KCl alone and both together were administered to anaesthetized, spontaneously breathing cats. Ventilation (VI), end-tidal PO2 (PETO2), end-tidal PCO2 (PETCO2), arterial blood pressure and heart rate were recorded continuously. [K+]a and pHa were monitored using intravascular ion selective catheter electrodes. The increase in VI during infusion of KCl and lactic acid together was greater than that observed during infusion of lactic acid alone. The increment in VI produced by the addition of an infusion of KCl to the lactic acid infusion was greater than the increment produced by the addition of KCl to a control infusion of normal saline. The reduction in PaCO2 which occurred when KCl was added to the lactic acid infusion was similar to that when KCl was infused with NaCl. Thus the inhibition of respiration secondary to reduced PaCO2 was similar in both circumstances. These results suggest that the combined respiratory stimulant effect of elevation of [K+]a and acute lactic acidosis is more than additive.

Animals↗
PubMed1973

Stimulation of lactic acid bacteria by a micrococcus isolate: evidence for multiple effects.

Growth of, and rate of acid production by, six cultures of lactic acid bacteria were increased in the presence of Micrococcus isolate F4 or a preparation of its capsular material. Concentrations of hydrogen peroxide found in pure cultures of the lactic acid bacteria were not detectable, or were greatly reduced, in mixed culture with Micrococcus isolate F4. The capsular material was not as effective as whole cells in preventing accumulation of H(2)O(2). Catalase stimulated growth of, and the rate of acid production by, the lactic acid bacteria, but not to the same extent as Micrococcus isolate F4 in some cultures. The existence of two mechanisms for micrococcal stimulation of the lactic acid bacteria is postulated. One mechanism involves removal of H(2)O(2); the other has not been characterized.

Animals↗
PubMed2001

Lactic acid and trisodium phosphate treatment of lamb breast to reduce bacterial contamination.

Lactic acid and trisodium phosphate (TSP) were evaluated for the ability to reduce Escherichia coli and aerobic plate counts (APCs) on lamb breasts that were inoculated with a lamb fecal paste. A 90-s water rinse was applied followed by either a 9-s (55 degrees C) 2% lactic acid spray, a 60-s (55 degrees C) 12% TSP dip, or a combined treatment of both lactic acid and TSP treatments. Lactic acid reduced E. coli and APCs by 1.6 log10/cm2, and TSP caused a 1.8-log10/cm2 reduction in E. coli and a 0.7-log10/cm2 reduction in APCs. Combined reductions by the lactic acid spray followed by the TSP dip were 1.8 and 1.5 log10/cm2 for E. coli and APCs, respectively. Lactic acid and trisodium phosphate, used alone or in combination, were effective in reducing numbers of E. coli and could be useful as pathogen intervention steps in lamb slaughter processing.

Animals↗
PubMed2002

Elimination of Salmonella spp. by lactic acid.

The aim of the present study was to determine the elimination of Salmonella by different lactic acid concentrations in microbiological media and on turkey carcass elements. The average bacteria counts in the control samples without lactic acid were: 1.8 x 10(8), 1.1 x 10(8) and 2.3 x 10(8), for S. Enteritidis, S. Anatum and S. Typhimurium, respectively. The concentration of lactic acid of 0.1% in the agar media completely inhibited the growth of all Salmonella strains. At 0.05% lactic acid concentration, the bacteria count was 2 log cycles lower and at a 0.03% solution it was 1 log cycle lower than that in the respective control samples. However, the examined bacteria developed in the presence of 0.02% and 0.01% lactic acid concentrations and their counts fell into the same log brackets. An analysis of the experimental results obtained from turkey carcass elements immersed in the lactic acid solution showed that the Salmonella identification rate was determined by the bacteria inoculum spread over the turkey carcass surface. The contamination of 10(1) CFU of Salmonella spread onto the turkey carcass was completely eliminated by immersing the carcasses in 1% or 2% lactic acid solutions. The contamination of turkey carcass elements with 10(2) CFU of S. Enteritidis and their immersion in 2% lactic acid solution for 15 min resulted in the reduction of the number of samples with Salmonella compared to the number of control samples with Salmonella. At contaminations of 10(3) CFU on the carcass surfaces, the immersions in 1% and 2% lactic acid solutions did not reduce Salmonella counts.

Animals↗
PubMed1999

Lactic acid bacteria and the human gastrointestinal tract.

OBJECTIVE: This review summarises the effects of lactic acid bacteria on lactose malabsorption, bacterial/viral or antibiotic associated diarrhoea, and describes the impact of lactic acid bacteria on cancer and the fermentative products in the colon. RESULTS: Eight studies (including 78 patients) demonstrated that lactase deficient subjects absorbed lactose in yogurt better than lactose in milk, while two studies (25 patients) did not support this. Two studies (22 patients) showed that unfermented acidophilus milk was absorbed better than milk, while six studies (68 patients) found no significant differences. Addition of lactose hydrolysing enzyme, lactase, to milk improved lactose malabsorption in seven studies (131 lactose malabsorbers), while one study (10 malabsorbers) demonstrated no improvement. Lactic acid bacteria alleviated travellers' diarrhoea in one study (94 individuals) while a study including 756 individuals was borderline statistically significant. One study (50 individuals) did not find an effect of lactic acid bacteria on travellers' diarrhoea. Six studies (404 infants) demonstrated a significant effect of lactic acid bacteria on infant diarrhoea, while one study (40 infants) did not. Lactic acid bacteria moderated antibiotic associated diarrhoea in three studies (66 individuals), while two studies (117 individuals) were insignificant. CONCLUSIONS: Lactase deficient subjects benefit from a better lactose absorption after ingestion of yoghurt compared with milk and from milk added lactase, whereas ingestion of unfermented acidophilus milk does not seem to improve lactose absorption. The majority of studies support that lactic acid bacteria alleviate bacterial/viral induced diarrhoea, especially in infants, while the effect on antibiotic associated diarrhoea is less clear. Experimental studies indicate an effect of lactic bacteria on human cell cancer lines, but clinical evidence is lacking. A 'stabilising' effect of lactic acid bacteria on the colonic flora has not been documented.

Colonic Neoplasms↗
PubMed2003

Lactic acid is absorbed from the small intestine of sheep.

A series of experiments was conducted in vivo on anaesthetized sheep to explore the hypothesis that lactic acid is absorbed from the small intestine of sheep. Test solutions varying in lactic acid concentration, pH, osmolarity, and with fixed physiological concentrations of volatile fatty acids (VFAs), K+, Na+, NH4 +, Cl-, and PO4 (-3), were separately introduced into clean, surgically sealed pouches. Studies were undertaken in 27 sheep, each with three pouches in the middle of the duodenum, jejunum, and ileum. Samples were taken at 15-minute intervals for 60 minutes to determine the absorption rates. The experimental results showed that L- and D-lactic acid were absorbed from the pouches of the duodenum, jejunum, and ileum throughout the 60 minutes. In the test solutions with pH 5.3, 420mOsmol/kg, and 12.5mM lactic acid that are in vivo conditions of light lactic acidosis, the mean absorption rates of D-lactic acid and L-lactic acid pooled from three pouches were similar, 0.07micro mol/cm2/min and 0.06micro mol/cm2/min, respectively, based on absorptive surface area. The mean absorption rates of DL-lactic acid from the duodenum, jejunum, and ileum pouches were almost the same, 0.14, 0.14, and 0.11micro mol/cm2/min, respectively. The absorption of lactic acid varied depending on lactic acid concentration, and there was a curvilinear relationship between lactic acid concentration and its absorption rate. A decrease in pH and osmotic pressure resulted in significant, corresponding increases in the absorption of lactic acid (P<0.0001 and P<0.05, respectively).

Animals↗