Use Of Lactic Acid Research Articles

Synergistic Effect of Thymol and Carvacrol Combined with Chelators and Organic Acids against Salmonella Typhimurium

To identify synergistic combinations of different food additives, the antimicrobial effects of thymol and carvacrol against Salmonella Typhimurium were assessed alone and in combination with various other preservatives including EDTA, acetic acid, lactic acid, and citric acid. Overall, growth of Salmonella Typhimurium was significantly inhibited in Mueller-Hinton broth containing thymol, carvacrol, EDTA, acetic acid, lactic acid, or citric acid at concentrations of 400 mg/liter, 400 μl/liter, 300 mg/liter, 0.2% (vol/vol), 0.2% (vol/vol), and 0.2% (wt/vol), respectively. The combination of different antimicrobials such as thymol or carvacrol with EDTA, thymol or carvacrol with acetic acid, and thymol or carvacrol with citric acid all resulted in significantly reduced populations of Salmonella Typhimurium. In samples treated with combinations, these antimicrobials had synergistic effects compared with samples treated with thymol, carvacrol, EDTA, acetic acid, or citric acid alone. However, the combined use of lactic acid with thymol or carvacrol did not produce a synergistic effect against Salmonella Typhimurium. Thus, some chelators or organic acids can be used as food preservatives in combination with thymol and carvacrol to reduce the concentrations needed to produce an adequate antimicrobial effect.

海藻乳酸発酵物の水産用飼料材としての利用

海藻乳酸発酵物の水産用飼料材としての利用

Environmental aspects of silage additives: Nutritent digestibility and nitrogen retention of inoculated alfalfa haylage in sheep

During ensiling process, naturally occurring enzymes (proteases) will cause the valuable true protein to break down (McDonald et al, 1991). Prolonged fermentation in uninoculated silage allows proteolytic bacteria (eg. Clostridia) to degrade high quality plant protein and convert it into ammonia and nitrates. Therefore, it is essential that the decline in pH is as rapid as possible in the first two or three days of ensilage to stem proteolysis as true protein rather than the products of proteolysis is more readily absorbed by the intestine (by-pass protein) than the products of protein hydrolysis (Webb and Matthews. 1998). In uncontrolled silage fermentation 45% of the protein will be broken down (Carpintero et al, 1979). The use of lactic acid producing bacteria inoculants can significantly reduce the breakdown of protein, leaving higher levels of true protein in the treated forage. Reducing soluble protein levels in the rumen has been reported to improve microbial protein synthesis (Sharp et al, 1994). This overall retention of nitrogen by the animal will lead directly to improved performance, be it live-weight gain in beef animals (Mayne and Steen, 1993), significant extra milk production in dairy cows and helps sustainable development in agriculture owing to lower nitrogen content of the manure. The authors studied the effect of a biological silage additive on apparent nutrient digestibility and nitrogen-retention of alfalfa haylage in whether.

Deposition of Titanium−Vanadium Oxide Thin Films on Organic Self-Assembled Monolayers: Role of Complexing Agents

Titanium−vanadium oxide films were co-deposited from aqueous solutions on organic self-assembled monolayers (SAMs) with alkylammonium or amine surface functional groups. The chemical composition of the films was manipulated via the use of lactic acid and oxalic acid as complexing agents. From solutions with [oxalate]:[vanadium] < 1:1, titanium-enriched films were formed. However, with [oxalate]:[vanadium] > 1:1, the Ti:V ratio dropped back to that of films deposited in the absence of complexing agents. Therefore, it is concluded that oxalic acid chelates both titanium and vanadium, but preferentially vanadium. At high concentrations of oxalic acid, no films formed, indicating that both titanium and vanadium were chelated strongly. Lactic acid, in contrast, was oxidized by pentavalent vanadium. When [lactate]:[vanadium] < 1:2, the resulting V4+ increased the deposition rate of vanadium, and vanadium-rich films were formed. For [lactate]:[vanadium] > 1:2, the remaining (i.e., unoxidized) lactic acid preferentially complexed vanadium and showed effects comparable to those seen with oxalic acid. The thickness of films formed on the alkylammonium SAMs increased with increasing vanadium content in the films, whereas film composition had little or no effect on the thickness of films formed on amine SAMs.

An improved method for clearing and staining free-hand sections and whole-mount samples.

Free-hand sectioning of living plant tissues allows fast microscopic observation of internal structures. The aim of this study was to improve the quality of preparations from roots with suberized cell walls. A whole-mount procedure that enables visualization of exo- and endodermal cells along the root axis was also established. Free-hand sections were cleared with lactic acid saturated with chloral hydrate, and observed with or without post-staining in toluidine blue O or aniline blue. Both white light and UV light were used for observation. Lactic acid was also used as a solvent for berberine, and fluorol yellow for clearing and staining the samples used for suberin observation. This procedure was also applied to whole-mount roots with suberized celllayers. Clearing of sections results in good image quality to observe the tissue structure and cell walls compared with non-cleared sections. The use of lactic acid as a solvent for fluorol yellow proved superior to previously used solvents such as polyethylene glycol-glycerol. Clearing and fluorescence staining of thin roots such as those of Arabidopsis thaliana were successful for suberin visualization in endodermal cells within whole-mount roots. For thicker roots, such as those of maize, sorghum or tea, this procedure could be used for visualizing the exodermis in a longitudinal view. Clearing and staining of peeled maize root segments enabled observation of endodermal cell walls. The clearing procedure using lactic acid improves the quality of images from free-hand sections and clearings. This method enhances the study of plant root anatomy, in particular the histological development and changes of cell walls, when used in combination with fluorescence microscopy.

Effects of catholyte conditioning on electrokinetic extraction of copper from mine tailings

Effect of electrokinetic treatment on copper partitioning and distribution in mine tailings were studied. In particular the effects of catholyte enhancement by HAc-NaAc, HCl, HAc-NaAc + EDTA and lactic acid + NaOH were evaluated. The results show that conditioning the catholyte plays a very important role in improving Cu removal. When HAc-NaAc is used in the catholyte, the removal percentage of total Cu from the mine tailings sample reached 12.3% under 40 V in 15 days of treatment. The removal percentage of Cu increased to 31.2% when EDTA was used together with HAc-NaAc in the catholyte. At the same time, increasing the applied voltage and treatment time result in an increase in the Cu removal from the mine tailings. Compared with HAc-NaAc (pH = 3.52), the use of lactic acid + NaOH (pH = 3.15) in the catholyte resulted in better performance in Cu removal from the mine tailings. HCl treatment resulted in removal of about 17.5% of Cu from the mine tailings; however, it resulted in production of significant amounts of toxic chlorine gas. Copper partitioning in the mine tailings was analyzed before and after the electrokinetic treatments. The analysis was conducted using 0.25 mol/l MgCl 2 and 0.5 mol/l HCl as extractants, consequently, to assess the mobility of Cu after treatment. The results showed that lowering the pH of the mine tailings increased the exchangeable Cu fraction (or the portion extracted by MgCl 2). Accordingly, further acidification results in an increased mobility of Cu and increase in the environmental risk of mine tailings.

Use of lactic acid for extraction of fish skin gelatin

The ability of lactic acid compared to acetic acid for Dover sole ( Solea vulgaris) skin swelling and the subsequent gelatin extraction was examined. The resultant gelatins were evaluated in terms of extraction yield, amino acid composition, molecular weight distribution, gel strength, viscoelastic properties, ability to refold into triple helical structures, and aggregation phenomena. Lactic acid (25 mM) proved to be an excellent substitute for acetic acid during the skin swelling process, as the gelatin preparation thus obtained presented quite similar properties to that prepared by using 50 mM acetic acid without the negative organoleptic properties of this acid. However, the application of 50 mM lactic acid gave rise to a highly hydrolysed gelatin, with lower folding ability, gel strength and viscoelastic properties than those obtained using 25 mM lactic acid or 50 mM acetic acid.

Quantitative investigation on the effects of chemical treatments in reducing Listeria monocytogenes populations on chicken breast meat

The effectiveness of treatments for the reduction of Listeria monocytogenes surface-inoculated in chicken breast meat was investigated. The treatments consisted of dipping breasts in chemical solutions for 15 min: buffered phosphate (control), calcium hypochlorite, trichloroisocyanuric acid, sodium acetate, sodium lactate, l-lactic acid or trisodium phosphate. The rates of inactivation observed with the chlorine compounds were similar, and in the presence of 100 mg/l of active chlorine viability decreased by 4.41 log units, compared with less than 1.0 log unit decrease observed when cells were submitted to 45 mg/l of active chlorine. Sodium lactate at 2.5% was a more effective antilisterial agent, producing a reduction of 3.88 log units. The present study extends existing findings on the importance of the use of lactic acid, sodium acetate, sodium lactate, trisodium phosphate (chemically classified as GRAS) and chlorine compounds on the inactivation of L. monocytogenes.

Rheological properties and colour evaluation of papaya during osmotic dehydration processing

Osmotic dehydration of papaya pieces using sucrose solution with additives was studied. Four types of solutions with different concentrations of sucrose, citric or lactic acid and sodium lactate or calcium chloride were employed. Water loss and sugar gain were fitted to a Fick mathematical model and showed that mass transfer increases as temperature or soaking solution concentration increases. The presence of calcium chloride in the osmotic solution seemed to improve sugar impregnation during the osmotic process. The results showed that high temperatures with the combined use of lactic acid and sodium lactate promoted faster water activity decay. The effect of osmotic dehydration on the colour parameters (luminosity and chroma) and rheological properties (stress at rupture and relaxation time) were investigated. Chroma values increased, denoting colour intensification along the process. Luminosity showed a slight increase for samples treated with CaCl 2, but for the other treatments lightness decreased in the first hour and returned for the initial values along the process. Calcium chloride showed to be effective in reinforcing tissue structure, presenting stress at fracture values for dehydrated papaya with calcium salt around three-fold higher than for other treatments. Processing at 50 °C with sodium lactate prevented over-softening of the tissue during the whole process, with greater water activity reduction.

Effect of lactic acid on Listeria monocytogenes and Edwardsiella tarda attached to catfish skin

This study evaluated the use of lactic acid to decontaminate Listeria monocytogenes andEdwardsiella tarda attached to catfish skin with or without mucus. At the highest inoculum levels (104–105cfu skin−1), lactic acid (0·5–2·0%) exposure for 10 min reduced counts of L. monocytogenes firmly attached to catfish skin by 0·9–>1·9 log10cfu skin−1and cells loosely attached by 2·7–>3·7 logs. Counts of E. tarda firmly attached to catfish skin were reduced by 0·9–>3·0 logs and cells loosely attached by 1·5–>3·5 logs. Overall bacterial numbers of lactic acid-treated cells that were firmly attached to skin with mucus were higher than on skin without mucus. Firmly attached L. monocytogenes was more resistant to lactic acid than was firmly attached E. tarda. Catfish skin mucus decreased the antimicrobial effect of lactic acid against attached L. monocytogenes and E. tarda.

Effect of Lactic Acid Administration in the Drinking Water During Preslaughter Feed Withdrawal on Salmonella and Campylobacter Contamination of Broilers

The crop is a known source of Salmonella and Campylobacter contamination. We evaluated the use of selected organic acids (0.5% acetic, lactic, or formic) in drinking water during a simulated 8-h pretransport feed withdrawal (FW). Salmonella typhimurium was recovered from 53/100 control crops and from 45/100 of crops from acetic acid-treated broilers. However, treatment with lactic acid (31/100) or formic acid (28/76) caused significant (P < 0.05) reduction in incidence. Reductions of recovered incidence were also associated with reduced numbers of S. typhimurium recovered (e.g., control, log 1.45 cfu/crop; lactic acid, 0.79 cfu/crop). In an additional commercial farm study, broilers were provided 0.44% lactic acid during a 10-h FW (4 h on the farm and 6 h transport) and pre-FW crop, post-FW crop, and pre-chill carcass wash samples were collected for Campylobacter and Salmonella detection. Crop contamination with Salmonella was significantly reduced by lactic acid treatment (6/175) as compared with controls (29/175). Importantly, Salmonella isolation incidence in prechill carcass rinses was significantly reduced by 52.4% with the use of lactic acid (26/175 vs. 55/176). Crop contamination with Campylobacter was significantly reduced by lactic acid treatment (62.3%) as compared with the controls (85.1%). Lactic acid also reduced the incidence of Campylobacter found on pre-chill carcass rinses by 14.7% compared with the controls. These studies suggest that incorporation of lactic acid in the drinking water during pretransport FW may reduce Salmonella and Campylobacter contamination of crops and broiler carcasses at processing.

Biochemical and microbial changes during the storage of minimally processed cantaloupe.

The effect of storage time on pH, titratable acidity, degrees Brix, organic acids, sugars, amino acids, and color of minimally processed cantaloupe melon (Cucumis melo L. var. reticulatus Naud. cv. Mission) was determined at 4 degrees C and 20 degrees C. Changes in most of the biochemical parameters with storage time were relatively slow at the lower temperature. At 20 degrees C, a 17% loss in soluble solids and a 2-fold increase in acidity occurred after 2 days. Organic acid content also increased considerably with time at this temperature as a result of the production of lactic acid. Oxalic, citric, malic, and succinic acids were the organic acids, and glucose, fructose, and sucrose were the sugars present in the freshly cut cantaloupe. Malic acid concentration decreased concurrently with lactic acid production indicating the possible involvement of anaerobic malo-lactic fermentation along with sugar utilization by lactic acid bacteria. The effect of storage on microbial growth was determined at 4, 10, and 20 degrees C. Gram-negative stained rods grew at a slower rate at 4 degrees C and 10 degrees C than the Gram-positive mesophilic bacteria that dominated microorganism growth at 20 degrees C. Eighteen amino acids were identified in fresh cantaloupe: aspartic acid, glutamic acid, asparagine, serine, glutamine, glycine, histidine, arginine, threonine, alanine, proline, tyrosine, valine, methionine, isoleucine, leucine, phenyl alanine, and lysine. The dominant amino acids were aspartic acid, glutamic acid, arginine, and alanine. Total amino acid content decreased rapidly at 20 degrees C, but only a slight decrease occurred at 4 degrees C after prolonged storage. Changes in lightness (L), chroma, and hue at both temperatures indicate the absence of browning reactions. The results indicate the potential use of lactic acid and lactic acid bacteria as quality control markers in minimally processed fruits.

Influence of formulation on the physicochemical properties of casein microparticles

Casein microparticles (CAS/MP) have a potential clinical use for targeting drugs. However, the use of organic solvents in their preparation is undesirable. This study was designed to investigate the influence of preparation procedures in aqueous media on the formulation and physicochemical properties of CAS/MP. The first stage involved the influence of the coacervating agents (lactic acid, succinic anhydride, succinic acid and tartaric acid). The second stage studied was the influence of the ionic strength and the third, the influence of adding a thickener, hydroxypropyl cellulose or hydroxypropyl methycellulose (HPC or HPMC), and a plasticizing agent (gelatin). Some physicochemical properties of CAS/MP were evaluated. While the infrared and the thermal analysis showed that all coacervating agents were appropriate for coacervation, the scanning electron microscopy studies showed that the external morphology of the particles was more homogeneous when lactic acid was used. Utilizing lactic acid as the coacervating agent, there was a trend effect of adding NaCl implying that the increasing of the ionic strength resulted in better stability. Finally, the addition of 0.1% HPC plus either 0.25 or 0.5% gelatin resulted in homogeneous formulations. In conclusion, the use of lactic acid plus 0.1% HPC and 0.25% gelatin results in biodegradable and homogeneous CAS/MP, presenting a potentially useful drug delivery system.

Turbo-PUVA: dihydroxyacetone-enhanced photochemotherapy for psoriasis: a pilot study.

Dihydroxyacetone (DHA), a colorless sugar in "sunless" tanning lotions, binds to stratum corneum to form a UV-A-protective brown pigment. Bound DHA polymer is shed faster from hyperproliferative skin sites such as psoriatic plaques. We tested the hypothesis that selective shedding of DHA pigment during psoralen-UV-A (PUVA) treatment of psoriasis may allow higher UV-A doses, thus accelerating clearing while protecting uninvolved skin. Concurrent use of lactic acid was investigated as an aid in removing scale and residual DHA from psoriatic plaques. Thirty psoriatic patients with more than 20% body surface area involvement were recruited. The 6 PUVA study groups were (1) standard American style, (2) American style plus lactic acid, (3) DHA-PUVA or "topical ultraviolet-resisting barrier to optiimize PUVA" (Turbo-PUVA), (4) Turbo-PUVA with lactic acid, (5) European style, and (6) European style plus DHA. Combinations of lactic acid and European-style treatment were not studied. Each subject received up to 30 oral PUVA treatments twice weekly 3 days apart. The DHA-PUVA groups used 15% DHA lotion twice weekly. Lactic acid groups used 7% lotion daily except on treatment days. Psoriasis area and severity index scores were recorded weekly. Turbo-PUVA allowed higher UV-A exposures with minimal burns, showed faster clearing, and required fewer treatments for 90% clearing (P<.001). Protection of uninvolved skin by DHA during PUVA treatment allows higher UV-A exposures to be tolerated, demonstrates faster clearing, and requires fewer treatments to clear psoriasis. By reducing the total body dose received, Turbo-PUVA may also reduce long-term risks.

Interactive Effects of Polylactic Acid with Different Aluminum Concentrations on Growth, Pigment Concentrations, and Carbohydrate Accumulation of Azolla

The interactive effects of 1 pLg 1-1 polylactic acid (PLA) with aluminum concentrations of 2, 4, 8, and 16 mg 1-~ on Azolla caroliniana growth, chlorophyll, carotenoid, anthocyanin, and carbohydrate accumulation were examined. Azolla growth was decreased with increases in alu- minum concentration. Furthermore, the growth reduction was less pronounced when PLA was present. Chlorophyll a and b concentrations were decreased in plants grown at Al concentrations of 4 mg 1-1 and higher. Polylactic acid reduced the influence of Al concentrations of 4, 8, and 16 mg 1-1 on chlorophyll a and b. Similarly, carotenoid concentrations were decreased as Al concen- trations increased in the growth media. Anthocyanin concentration was increased at 4.0 mg 1-1 Al without PLA and at higher Al concentrations with or without PLA. In general, carbohydrate accumulation increased as Al concentration increased. However, this increase in carbohydrates was less pronounced in the presence of PLA. In the absence of Al from the growth media, treat- ment with 1 iLg 1-1 PLA resulted in an increase in plant growth, chlorophyll, and carotenoid concentration and a decrease in carbohydrate accumulation. Aluminum (Al) toxicity is an important component of the damaging effects of acid rain in rivers and lakes. Rueter et al. (1987) reported that acid rain not only increased total soluble Al concentration, but also changed the affinity of organic and inorganic complexes with metals. Sprenger and McIntosh (1989) showed that Al concentrations were elevated in both water and submerged aquatic macrophytes (Ranunculus ololeucos J. Lloyd, Luronium natans Raf.) in acidified waters. According to Stanley (1974), an addition of 92 ,L.mol 1-1 Al to well-buffered medium inhibited 50% of the root growth of Myriophyllum spicatum L. The toxicity of Al depends upon a number of factors, including pH and organic matter content (Tan and Binger, 1986). Aluminum toxicity increases at a pH below 5 because its solubility increases considerably. Of the different species of Al, A13+ is the only significant one that is found in freshwater at a pH of 4 or less (Poleo, 1995). In general, Al has been shown to interfere with cell division, decrease respiration rates, interfere with enzymes governing the deposition of polysaccharide in cell walls, increase cell wall rigidity, and de- crease the uptake and transport of water and several elements including Ca, Mg, P, and K in plants (Foy et al., 1978). The earliest recorded use of lactic acid as a plant growth regulator was by

Chemical Pretreatment of Dairy Wastewater

Chemical treatment of dairy wastewater was studied, using dissolved air flotation for solids separation. Four different combinations of coagulants were tested. Total COD removal was very dependent on the influent CODF/CODT ratio, with the bigbest removal efficiencies at the lowest CODF/CODT ratios. About 60% removal of total COD could be achieved at a CODF/CODT ratio of 0.6. JKL (FeClSO4) removed 2-3% more COD than H2SO4 plus CMC (carboxy methyl cellulose), and 4-6% more COD than lactic acid plus CMC. H2SO4 plus LSA (lignosulphonic acid) bad the poorest removal efficiencies. Use of lactic acid plus CMC is a novel and promising approach. Further studies of the lactic acid plus CMC process is recommended, especially with regard to the feed value of the sludge.

Photocatalytic conversion of lactic acid to malic acid through pyruvic acid in the presence of malic enzyme and semiconductor photocatalysts

The photocatalytic fixation of CO2 in pyruvic acid to yield malic acid has been achieved in TiO2 microcrystal and CdS particle suspensions using malic enzyme as the catalyst, methyl viologen as the electron mediator and either 2-mercaptoethanol or lactic acid as the hole scavenger. The evaluation of the rate-determining step in the photocatalytic fixation reaction was made at the TiO2 microcrystal for the case of 2-mercaptoethanol as the hole scavenger. The use of lactic acid as the hole scavenger resulted in the selective photoproduction of pyruvic acid at the CdS photocatalyst, a fraction of which was then converted into malic acid by reductive CO2 fixation at the malic enzyme. However, it has been found that lactic acid causes a decrease in the catalytic activities of the enzyme, the degree depending on the relative concentrations of malic enzyme and lactic acid.

A Study on the Bactericidal Effect of Sodium Chlorite

The bactericidal effects of solutions of sodium chlorite (NaClO2) at various pH values was studied by several methods (the phenol coefficient method, available chlorine germicidal equivalent concentration method and phenol coefficient method under dirty conditions).A 2.73% NaClO2 solution at pH 8.8-9.1 showed no bactericidal effect against E. coli and S. aureus within 15min, but it destroyed them within 2.5min when the pH value was adjusted to 4.0. The bactericidal effect of the solution was increased by elevating the acidity of the solution, and the NaClO2 solution at the lowest concentration adjusted to pH 2.0, had a bactericidal effect. Even at pH 4.0, the effect of the high-concentration solution was sufficient.The bactericidal effect of NaClO2 at pH 4.0 was independent of the use of lactic acid, acetic acid or hydrochloric acid for pH adjustment. However at pH 2.0, the organic acids were superior to the inorganic acid as the pH regulator.

Hepatic blood flow and metabolism.

The relationship between liver blood flow and hepatic metabolism remains unclear. An animal model as well as a methodology that permits simultaneous assessment of both of these functions are proposed. Several fractions of inspired oxygen were used to produce arterial oxygen levels commonly seen in clinical practice; these ranged from hyperoxemia to established hypoxemia. Over this range there were no considerable changes in transhepatic blood flow, but there were considerable changes in hepatic metabolism as shown by measurements of the hepatic parenchymal pH, transhepatic oxygen consumption, and lactic acid use. Of these, the parenchymal pH seems to be the most sensitive indicator of metabolic events.

ESOPHAGEAL STENOSIS DUE TO LACTIC ACID

The recent report of Young and Smith¹has called attention to the possible caustic effect of lactic acid. These writers reported 3 deaths due to the action of this substance in feeding formulas and supported their observations with data derived from experiments with rabbits. The possibility that severe reactions may occur in infants as a result of errors in preparation of feeding formulas seems to have been generally overlooked in recent years, despite the widespread use of lactic acid. While Young and Smith were unable to find mention of this substance in any of the standard textbooks on toxicology, we found it briefly discussed under both "Caustic Acids" and "Organic Acids" in Sollmann's "Manual of Pharmacology."² We have recently encountered a case exhibiting the chronic effects of accidental swallowing of this substance. So far as we have been able to ascertain, the late sequelae of lactic acid in