Increase In Lactic Acid Concentration Research Articles

Effect of lactic acid treatment during processing on the sensory quality and lactic acid content of fresh broiler chickens

SummaryMicrobial decontamination by lactic acid treatment during processing of fresh broiler chickens is an effective way to produce a safer product with good keeping quality. It remained to be assessed whether such a treatment adversely affects the organoleptic quality of the product. Lactic acid treatment results in an increased acid concentration in the skin, with no increase in lactic acid concentration in the underlying muscle tissue. Differences in sensory quality were only found in appearance of the carcasses, the controls being identified as discoloured. A preference test did not show any difference in lactic acid treated and untreated grilled legs.

THE QUALITY OF MILK PRODUCED IN "FADHILIA VILLAGE" NEAR BAGHDAD IN IRAQ

A study on the quality of milk produced in "Fadhilia Village" near Baghdad extending over a period of one year, revealed that the total bacterial and coliform counts for milk samples from individual producers were 7.4x105 and 2.5x103 in summer, and 1.8x10 and 5.4x10 in winter respectively. The above counts for bulk milk samples were 3.3x10 and 1.8x101 in sumer and 5.1x10 and 3.3x103 in winter respectively. All over the year the preliminary incubation and psychrotrophic counts for both individual and bulk milk samples were strictly higher than all the proposed standards. There was a significant drop in methylene blue reduction time in summer samples compared to winter samples. A similar drop was noticed in bulk tank samples as compared to individual producer samples. Besides that a significant increase in lactic acid content in Surner samples compared to winter samples.

Concentration-dependent chemical dissolution of calcite in lactic acid

An optical study of the morphology of etch pits and a study of the etch rates at constant temperature for the controlled dissolution of calcite cleavage surfaces by lactic acid of various concentrations are presented. It is shown that the lactic acid acts preferentially at dislocations which terminate on a cleavage surface. Furthermore, it is found that isotropic and anisotropic etch rates increase with initial increases in lactic acid concentration, attain maximum values and then decrease with a further increase in lactic acid concentration. A detailed analysis of the factors which lead to this variation is presented.

The effect of some pre-ensiling treatments on silage composition and nitrogen disappearance in the rumen

Ryegrass, harvested before ear emergence, was ensiled in triplicate in laboratory silos with and without pre-ensiling treatments. These were: 4.7 M sulphuric acid (39 and 79 g kg −1 DM); formalin (28 and 58 g kg −1 DM); ‘Add-F’ (22.5 M formic acid; 36 and 71 g kg −1 DM); formalin (28 and 58 g kg −1 DM); ‘Farmline’, a commercial additive containing acids and formalin (31 g kg −1 DM); heat (30 and 60°C for 1 h); and Lactobacillus plantarum inoculum + glucose (4.6 g kg −1 DM). The ensilage period was 120 days. Samples of each silage were incubated, in artificial fibre bags, in the rumens of four Hereford-cross steers fitted with permanent rumen cannulae. Total nitrogen (TN) disappearance was measured after incubation periods of 1, 2, 4, 7, 12 and 24 h. Hydrochloric acid and the heating pre-treatments had no significant effect ( P > 0.05) on the pH, water-soluble carbohydrates and fermentation acid values compared with those of the control. Fermentation acid production was suppressed to an increasing extent by formalin (28 g kg −1 DM), sulphuric acid (79 g kg −1 DM), formic acid (36 g kg −1 DM), formalin (58 g kg −1 DM) and formic acid (71 g kg −1 DM). The application of L. plantarum + glucose increased fermentation acids from 90.3 g kg −1 DM in the control to 227 g kg −1 DM, owing to a 10-fold increase in lactic acid content from 21.7 to 202 g kg −1 DM. All treatments, with the exception of 30°C heating, produced silages with significantly ( P < 0.001) more total nitrogen as protein than the control. This ranged from 334 g kg −1 TN (60°C heating) to 748 g kg −1 TN (formalin; 58 g kg −1 DM). All treatments significantly ( P < 0.05) reduced TN loss, compared with the control silage values, after a 7-h incubation period in the rumen. After 24 h, however, TN disappearance from the treated silages was not significantly different from that of the control with the exception of the two silages treated with formalin alone. With these silages, the proportion of TN disappearing was 55.0 and 40.0% for the low and high application rates, respectively, compared with a value of 74.0% for the control.

Diverse forms of stress lead to new patterns of gene expression through a common and essential metabolic pathway.

Many eukaryotic organisms respond to heat shock by synthesizing new proteins. We examined the possibility that heat shock proteins represent a particular expression of a general response to stress and that, regardless of the nature of the effective stimulus, the same proteins are synthesized. Accordingly, cardiac stress was applied in the intact rat by four methods: banding the ascending aorta, increasing body temperature to 42 degrees C, reducing body temperature to 18 degrees C, and forcing the rat to swim until exhausted. The hearts were then extirpated and analyzed for new mRNA synthesis. The extracted RNA was translated in a cell-free medium containing [35S]methionine. Translation products were resolved by two-dimensional electrophoresis and visualized by autoradiography. Lactic acid concentration in heart tissue was determined enzymatically. The results showed that two new and distinct proteins of Mr 71,000 and isoelectric points of 5.8 and 6.1 were synthesized in hearts stressed by banding and by heating but not in hearts of exhausted swimmers or in animals at reduced body temperatures. There was no significant difference in cardiac lactic acid concentration between control hearts and hearts from swimmers or cold-treated animals. However, there was a 2-fold increase in lactic acid concentration in hearts of rats with banded aortas compared to controls and a 10-fold increase in heat shocked hearts. We conclude that, under conditions in which the energy requirements of the heart are not completely met by aerobic processes, the resultant lactic acidosis creates an intracellular environment that leads to the selective activation of genes, the production of new mRNA, and the synthesis of a typical group of stress proteins.

A vena Coleoptile Segments: Hyperelongation Growth after Anaerobic Treatment

Abstract Avena sativa coleoptile segments show an anomalous increase in elongation growth following a short period of oxygen deprivation (tested between 0 and 60 min) lasting 20-30 min (Anaero-biosis-Aerobiosis transition effect = ANA effect). The increase in growth rate is 600% and is commensurate with that observable following an auxin treatment. This hyperelongation growth, in contrast to the auxin-induced growth, begins without a lag phase. The growth “burst” following anaerobiosis is similarly to auxin-induced elongation growth, and is suppressed increasingly by neutral or more alkaline buffers. Hyperelongation growth is suppressed by respiratory inhibitors and uncouplers. A complete inhibition is effected with KCN (0.5 mM) sodium azide (0.5 mM) and CCCP (1 μM); amytal (in the range 0.5 to 1 mM) and sodium arsenate (0.1 to 1 mM) are strong inhibitors. Some of these compounds (KCN, arsenate, amytal) cause a slight increase of the ANA effect in very low concentrations, which is probably due to the K+ or Na+ ions present; on their own, these ions have a strong positive influence on the ANA effect. During anaerobiosis the ATP level sinks around 75% and almost returns to the old value, following the supply of air, within one minute. The cell sap pH drops from 6.3 to 5.9 during anaerobiosis within 20 min. This lowering is mainly due to an increase in lactic acid concentration. Other acids such as citric, malic, and aspartic acids show insignificant changes in concentration. The NADH content increases during anaerobiosis, whereas that of NADPH drops almost as much. The mentioned changes in concentration of lactic acid, NADH and NADPH return to the control value within 20-30 min; thus the differences exist as long as hyperelongation growth is under way. Possible relationships between the mentioned chemical changes and hyperelongation growth are discussed. One of the possible explanations is the following: the lowering of the cytoplasmic pH (normally around pH 7) during anaerobiosis due to the formation of lactic acid causes an activation of H+-ATPases in the plasmalemma and ER, since their optimum activity occurs in a pH of 5.5 to 6.5. This activation causes a greater H+-excretion into the cell wall compartment, and thus hyperelongation growth following supply of air and of ATP.

MICROBIOLOGICAL ASPECTS OF SPONTANEOUS WORT FERMENTATION IN THE PRODUCTION OF LAMBIC AND GUEUZE

Lambic and Gueuze are special Belgian beers obtained by spontaneous fermentation. Micro-organisms involved in this fermentation were counted and differentiated using several selective growth media. Micro-organisms were also isolated from samples of Lambic of different age and originating from different casks and brews and identified by classical tests. The following general pattern of microbial development was observed. After 3 to 7 days the fermentation started with the development of wort Enterobacteriaceae and strains of Kloeckera apiculata. These organisms were overgrown after 3 to 4 weeks by strains of Saccharomyces cerevisiae and S. bayanus. These were responsible for the main fermentation, lasting for 3 to 4 months. This was followed by a strong bacterial activity. This period was dominated by the growth of strains of Pediococcus cerevisiae. These reached their maximal numbers during the summer months and were responsible for a fivefold increase in lactic acid concentration. In some casks they caused ropiness. After the main fermentation period Lambic is very sensitive to spoilage by acetic acid bacteria of the genus Acetomonas. The presence of air may be the determining factor for their development. After 8 months a new increase in yeast cells was noted. These belonged now mainly to the genus Brettano-myces bruxellensis and Br. lambicus. They caused a further slow decrease in residual extract and the appearance of special flavours. Oxidative yeasts of the genera Candida, Cryptococcus, Torulopsis and Pichia were also detected and may be responsible for the formation of a flim on the beer surface after the main fermentation.

Lactic acid efflux from ischaemic brain: An experimental study

The lactate acid content of venous blood draining via Labbé's vein from the lateral aspect of the two hemispheres of baboons has been compared. One hemisphere was rendered partially ischaemic by temporary occlusion of the middle cerebral artery and a significant increase in lactic acid content in the draining venous blood was found within 1 min of the occlusion. There was an accompanying significant fall in venous pH. The systemic arterial pH, pO 2 and lactate showed no significant change. It appears that the known prompt increase in cerebral lactic acid content following the establishment of ischaemia is reflected promptly in the lactate content in the draining veins of the infarct.

Lactic acid in gastric juice.

The conventional stimulants of gastric secretion (histamine, pentagastrin, and insulin) results in a fall in lactic acid concentration and usually a rise in lactic acid output. Agents that impose indirectly or directly a lactic acid load (glucose, fructose, xylitol, epinephrine) usually result in an increase in lactic acid concentration and output. It is considered that non-ionic diffusion plays little role in lactic acid secretion, and that the lactic acid content of gastric juice reflects the metabolic processes in the gastric mucosal cells.

Addendum

Aketa (1957, pp. 273-5), says there is a marked increase in lactic acid content following the fertilization of Japanese sea-urchins and that ‘This observation conflicts with those of other workers, who have been unable to detect any such change’ and that the difference may be ascribed to the fact that ‘other investigators performed their estimations at longer intervals after insemination than the author did’. Referring to the fertilization acid, Aketa says ‘it is still premature to deny the possibility of a relation between that manometric production of unknown acid and the lactic acid production shown in this paper’. On the basis of these remarks, I concluded that Aketa believed the fertilization acid was lactic acid. But in correspondence since the acceptance of this paper, Aketa told me he did not believe the the fertilization acid was lactic acid, but that it would be unwise to deny this possibility.

Lactic and pyruvic acid relations in contracting mammalian muscle.

Tetanic contraction of mammalian muscle under essentially anaerobic conditions was found to result in marked increase in the pyruvic acid content as well as in the lactic acid content. The increase in lactic acid content was proportionately greater than in the pyruvic acid content. Repeated single twitches at a rate of 1/sec., continued long enough to produce a steady state, resulted in only a slight increase in pyruvic acid content, with a marked decrease in the ratio of pyruvic to lactic acid. The pyruvic acid formed during the steady state of activity appears not to pass into the blood stream.

The Effects of Low Glycogen Content Upon the Contraction Process in Isolated Skeletal Muscle

A large series of observations has been made to check the findings of Olmsted and Coulthard,1 who report that gastrocnemius muscles in which little or no glycogen can be detected, taken from frogs rendered glycogen poor by means of insulin convulsions, contract upon electrical stimulation, and produce fatigue curves closely resembling the normal. They also report the increase in lactic acid content in such muscles upon fatiguing to be greater than can be accounted for by the disappearance of carbohydrate.Analyses of the muscles of 40 normal and insulinized frogs have been made (both bull frogs and grass frogs were used). The corresponding muscles of opposite limbs were used in the determination of resting and fatigue levels. The muscles were frozen in liquid air previous to preparation for analysis. The Pfluger method, modified as suggested by Evans2 was used in the determination of glycogen. The Friedeman, Cotonio, and Shaffer3 method was used in the determination of lactic acid.We have not been able to ...