Liberation Of Free Fatty Acids Research Articles

Activity of Lipase during Mashing

Lipase, which is present in the grain of both rice and barley, catalyzes the hydrolysis of triacylglycerides at a lipid-water interface to yield free fatty acids (FFA). In brewing, FFA are generally associated with negative effects, including the formation of stale/off-flavor aldehydes. The objective of this research was to determine the survival and stability of barley and rice lipase during laboratory mashing. Wort was separated from the spent grain by centrifugation at specific time intervals, and the spent grain was immediately frozen and freeze-dried. Lipase activity was determined on the freeze-dried spent grains by a cupric acetate colorimetric method. Malt and rice lipase, found in the insoluble portion of the mash, appeared to be quite thermostable. Both activities largely survived temperatures of 67°C, and the results of this study suggest that hydrolysis of triacylglycerides, and liberation of FFA, may continue through much of the mash.

Chemical Profiles of Hydrolyzed Milk Samples after Treatment with Commercial Enzymes

ABSTRACT: Commercial enzymes (protease and lipase) were used to produce highly flavored cheese‐like hydrolysates from fluid milk. Free fatty acids, free amino acids, degree of proteolysis, and volatile profiles were assessed to suggest the importance of proteolytic and lipolytic activity on cheese flavor development. Free fatty acid liberation was maximized with the combined Flavourzyme™ (protease) and Palatase ® (lipase) treatment incubated at 30°C, most likely due to synergism conferred by the protease. The Flavourzyme/Palatase samples incubated at 45°C generated the highest total concentration of volatile compounds. The addition of Flavourzyme generated free amino acids and low molecular weight peptides (< 1400 MW).

Effect of long-term storage on the concentration of albumin and free fatty acids in human sera

Stored sera from healthy persons can be used to study relationships between blood variables at the time of sampling and disease appearing several years later but storage may influence the variables. In this work we measured the concentration of albumin and free fatty acids (FFA) in samples from the JANUS serum bank of Norway. Sera from blood donors and persons participating in health screening programs have been added to the bank since 1973. The concentration of albumin and FFA was measured in 443 JANUS bank sera. The material was divided into quartiles according to the length of storage: < 3 years (n = 110), 3-6 years (n = 110), 6-12 years (n = 115) and > 12 years (n = 108). Albumin was measured colorometrically using the bromcresol green method and FFA was determined enzymatically. The serum albumin concentrations (mean - SEM) in the four groups were 55.8 - 0.6, 56.2 - 0.5, 59.9 - 0.6 and 59.5 - 0.6 g/L. The values of groups 3 and 4 were significantly higher than those of groups 1 and 2 (p< 0.001). The serum FFA concentrations in the four groups were 0.56 - 0.03, 0.64 - 0.03, 0.77 - 0.03 and 0.85 - 0.04 mmol/L, i.e. a significant storage effect. The Scheffe´multiple comparison test showed that FFA values in groups 3 and 4 were significantly higher than those in groups 1 and 2 (p< 0.001 for group 4 vs. 1 and 2, and 3 vs. 1; p< 0.04 for group 3 vs. 2). Serum FFA and albumin levels were positively associated (r = 0.489, p< 0.001). Using linear regression analysis, it was estimated that serum albumin values increased by 0.28 g/L per year (i.e. 0.5%) and FFA by 0.02 mmol/L (i.e. 3.8%). Thus, measured by standard methods, serum FFA and albumin could increase in response to several years of storage at ° - 25 C. It is suggested that the storage time dependent increase in FFA is due to FFA liberation from lipoprotein triglycerides, whereas the apparent increase in albumin concentration possibly could be attributed to an unfolding of the protein, allowing more bromcresol green to be bound.

Lipid metabolism in the elderly.

Adiposity increases with age. The size of the adipose tissue mass is determined by the balance between the recruitment of lipid substrates (ie free fatty acids) from adipose tissue and their subsequent oxidation by respiring tissues. Thus, change in the liberation of free fatty acids from adipocytes, the capacity of respiring tissue to oxidize free fatty acids or a combination of both may contribute to the age-related increase in body fat. This review focuses on studies that have examined the effect of age on free fatty acid release and the capacity of respiring tissues to oxidize fat. In vitro studies have shown that hormonal and pharmacological stimulation of lipolysis diminished with age. Despite this cellular defect, however, in vivo studies suggest that fatty acids are recruited from adipose tissue in excess of the energy demands of the body in older individuals. The capacity of respiring tissues, in particular skeletal muscle, to oxidize fat declines with age. The age-related decrease in fat oxidation is related to a reduction in both the quantity and oxidative capacity of respiring tissue. Taken together, these results suggest that an age-related decrease in the capacity of respiring tissues to oxidize fat, rather than decreased free fatty acid release, is a more likely determinant of lipid imbalance and the age-related increase in adiposity. Interventions designed to increase the mass or oxidative capacity of respiring tissue, therefore, may be effective in counteracting the age-related reduction in fat oxidation.

Electroconvulsive shock in rats: changes in superoxide dismutase and glutathione peroxidase activity

Seizures trigger a variety of biochemical processes including an influx of extracellular Ca 2+, activation of membrane phospholipases, liberation of free fatty acids, diacylglycerols, eicosanoids, lipid peroxides and free radicals. These lipid metabolites along with abnormal ion homeostasis may be involved in cell injury and cell death. The aim of this study was to determine brain antioxidant enzyme activities in rats with electroconvulsive shock (ECS)-induced seizures. ECS, single or repeated, induced a decrease in superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities in various brain regions. The most prominent changes of enzymatic activities were observed in rats that received five ECSs with 24-h recovery period between them. Decreased SOD activity was observed in the frontal cortex of all treated animals except those sacrificed 24 h after single ECS, in the cerebellum of the animals that received repeated ECSs, in the hippocampus of animals that were decapitated 2 h after a single ECS and in the pons–medulla region of rats that received five daily ECSs. Decreased GPX activity was found in all examined brain regions of the rats that received five ECSs, the cortex and hippocampus of rats that were decapitated 2 h after single ECS and the cortex of those that received 10 ECSs with 48 h between them. The results show that neither 24-h nor 48-h recovery period was sufficient for the normalisation of antioxidative enzyme activities after repeated ECS treatment.

Stimulatory effect of fatty acid treatment on glucose utilization in human erythrocytes

We previously reported that treatment of human erythrocytes with bee venom phospholipase A 2 increased the rate of lactate production from glucose. This increase was suggested to be mediated through liberation of free fatty acids from membrane phospholipids. So, in the present study we examined the mechanism of stimulation of glycolysis by fatty acids. Treatment of intact erythrocytes with most of the 15 fatty acids tested resulted in stimulation of lactate production from glucose. Among the fatty acids tested, myristoleic acid showed the highest stimulatory activity. The ratio of moles of lactate produced to those of glucose utilized was about 1.9 in both myristoleic acid-treated and untreated cells. Treatment of erythrocytes with myristoleic acid did not affect the amount of 2,3-bisphosphoglycerate. Lactate production from d-glyceraldehyde, which is thought to be phosphorylated to d-glyceraldehyde 3-phosphate and then metabolized in the glycolytic pathway, was not at all affected by treatment of cells with myristoleic acid. The cross-over plot of glycolytic intermediates suggested that the enhancement of glycolysis was induced by activation of the 6-phosphofructokinase (PFK) step. Fatty acids incorporated into erythrocytes were found to be present predominantly in the cytoplasm rather than in the plasma membrane. The PFK activity, but not the hexokinase activity, in hemolysates was clearly increased by a set of fatty acids, and myristoleic acid was again the most potent. However, partially purified human erythrocyte PFK was not activated by the acid. We conclude that fatty acids stimulate glycolysis through activation of PFK in cooperation with some other component(s) in erythrocytes.

Rapeseed lipase — pH dependent specificity for native lipid body autolysis and lipolysis of artifical oil droplets

Summary In homogenates of cotyledons from 4-day-old rapeseed ( Brassica napus L.) seedlings lipase (EC 3.1.1.3) activity is present in both the soluble cell fraction (recovery about 70 %) and the oil body fraction. In contrast to lipases and esterases of mammalian or microbial origin lipase activity from cotyledons of rapeseed seedlings is not inhibited by serine hydrolase inhibitors. Optimum activity with a triolein emulsion as substrate was found at pH 9.0. Addition of desoxycholate to the triolein substrate emulsion, which improves the stabilization of the surface of the lipid globules, shifts the apparent pH optimum to pH 8.0. In contrast, rapeseed oil emulsified in gum arabic was a poor substrate for the soluble lipase. Only after addition of desoxycholate to the emulsified rapeseed oil was the apparent activity of lipase clearly enhanced, and fatty acids, 1,2(2,3)-diacylglycerols, and monoacylglycerols were produced at such alkaline pH values. The autolysis of a crude oil body fraction demonstrating the lipolytic activity associated with these subcellular compartments by the liberation of free fatty acids from the native neutral lipids with maximum activity at pH 5.0 is taken as evidence for the presence of lipase activity in or on the surface of the oil bodies. When assayed with the standard pH-stat method the oil body fraction showed about 8 % of the total lipase activity of the crude homogenate, and the enzyme activity was found to be bound only loosely to the surface of the oil bodies. Possible misinterpretations in earlier reports about both the and properties of the rapeseed lipase are discussed.

Effects of muscarinic receptor antagonism on the phosphatidylinositol bisphosphate signal transduction pathway after experimental brain injury

Hippocampal levels of fatty acids extracted from phosphatidylinositol 4,5-bisphosphate (PIP2), free fatty acids (FFA), and lactate were measured after central fluid percussion traumatic brain injury (TBI) in rats. At 5 min after injury, there was a decrease in fatty acids extracted from PIP2 suggesting a decrease in PIP2. At the same time point, total FFA increased in saline-treated TBI rats. Levels of arachidonic acid were significantly decreased in PIP2, while at the same time arachidonic and stearic acids increased in FFA in saline-treated TBI rats. No significant alterations in PIP2-derived fatty acids or FFA were observed at 20 min after TBI. Hippocampal concentrations of lactate were significantly elevated at 5 and 20 min after injury in saline-treated rats. In general, these alterations were blunted by preinjury administration of the muscarinic antagonist, scopolamine. These results suggest that the PIP2 signal transduction pathway is activated in the hippocampus at the onset of central fluid percussion TBI and that the enhanced phospholipase C-catalyzed phosphodiestric breakdown of PIP2 is a major mechanism of liberation of FFA in these sites immediately after such injury. The blunting of PIP2 and FFA alterations in animals treated with scopolamine suggests that activation of muscarinic receptors significantly contributes to the phospholipase C (PLC) signal transduction pathophysiology in TBI. The attenuation of lactate accumulation in scopolamine-treated rats suggests that TBI-induced muscarinic receptor activation also contributes to increased glycolytic metabolism and/or ionic imbalances.

Storage Stability of Butterfish Mince (Peprilus buri) as Affected by Washing, Antioxidants, and Vacuum Packaging

Gulf of Mexico butterfish (Peprilus buri), a largely unutilized fishery resource, has been examined for its application as a food-grade marine product. Butterfish mince prewashed with sodium bicarbonate solution (0.5%) had lower lipid oxidation and free fatty acid (FFA) content than unwashed mince during a 6-month frozen storage study. Washed mince also exhibited a lower Hunter a value and had superior water retention. Addition of Tenox 2 or vacuum packaging further reduced lipid oxidation and FFA liberation. This reduction also prevented the subsequent lipid-protein interaction as indicated by increased water retention.

The role of free radicals in cold injuries.

Cold injury is a tissue trauma produced by exposure to freezing temperatures and even brief exposure to a severely cold and windy environment. Rewarming of frozen tissue is associated with blood reperfusion and the simultaneous generation of free oxygen radicals. In this review is discussed the current understanding of the mechanism of action of free oxygen radicals as related to cold injury during rewarming. Decreased energy stores during ischaemia lead to the accumulation of adenine nucleotides and liberation of free fatty acids due to the breakdown of lipid membranes. On rewarming, free fatty acids are metabolized via cyclo-oxygenase and adenine nucleotides are metabolized via the xanthine oxidase pathway. These may be the source of free oxygen radicals. Leukocytes may also play a major role in the pathogenesis of cold injury. Oxygen radical scavengers, such as superoxide dismutase and catalase, may help to reduce the cold induced injury but their action is limited due to the inability readily to cross the plasma membrane. Lipid soluble antioxidants are likely to be more effective scavengers because of their presence in membranes where peroxidative reactions can be arrested.

Activation of phosphatidylinositol bisphosphate signal transduction pathway after experimental brain injury: a lipid study

Regional levels of phosphatidylinositol 4,5-biphosphate (PIP 2), diacylglycerol (DG) and free fatty acids (FFA), involved in the signal transduction pathway of the excitatory neurotransmitter system, were measured after lateral fluid percussion (FP) brain injury in rats. At 5 min postinjury, tissue PIP 2 concentrations were significantly reduced in the cortices and hippocampi of both ipsilateral and contralateral hemispheres. Only levels of stearic and arachidonic acids were substantially decreased in PIP 2 in these regions of the brain. At the same time after injury, both DG and FFA were significantly increased in the cortices and hippocampi of both hemispheres. As was true for PIP 2, only levels of stearic and arachidonic acids markedly changed in both DG and FFA in these regions of the brain. At 20 min postinjury, a significant decrease in PIP 2 concentration and significant increases in levels of DG and FFA were observed only in the injured left cortex. In addition to the increases in stearic and arachidonic acids in FFA, increased amounts of palmitic and oleic acids were also found in the injured left cortex at 20 min after injury. These results suggest that the PIP 2 signal transduction pathway is activated in the cortex and hippocampus at the onset of lateral FP brain injury and that the enhanced phospholipase C-catalyzed phosphodiestric breakdown of PIP 2 is a major mechanism of liberation of FFA in these sites immediately after such injury.

Effect of a food-grade enzyme preparation fromAspergillus oryzae on free fatty acid release in Manchego-type cheese from ovine and bovine milk

The addition of 50 mg Flavor Age (blend of lipase, proteinases and peptidases fromAspergillus oryzae) per kilogram of mixed ovine plus bovine milk for the manufacture of Manchego-type cheese caused the release of abundant free fatty acids (FFA), especially the short-chain fatty acids (C4 to C10). The effect accentuated with ripening time, the cheeses reaching a level of FFA around 2% at 120 days. The high concentration of FFA could have partially inhibited the growth of starter culture, as can be deduced from the higher residual lactose content of enzyme-treated cheeses. The results are compared and related to those obtained in a previous study on proteolysis and flavour development by the same enzyme preparation. They suggest that in the case of Man-chego-type cheese the liberation of FFA, although necessary, could be less important for flavour enhancement than the production of free amino acids.

Inhibition of the early phase of free fatty liberation during cerebral ischemia by excitatory amino acid antagonist administered

In order to ditermine the role of excitatory amino acids (EAAs) in free fatty acid (FFA) liberation during cerebral ischemia, we examined the effect on in situ adminstration of kynurenic acid, a broad-spectrum antagonist of EAA receptors, by microdialysis on the increase in FFA levels during ischemia in the rat hippocampus. A transient rapid increase in FFA levels, superimposed on a continued slow increase, was observed beginning at 1–2 min after ischemia induction. The early phase of FFA liberation. Development of massive ionic shifts during cerebral ischemia can be delayed for several minutes by kynurenic acid administered by the same procedure, suggesting a vital role for EAAs in the early appearance of anaxonic depolarization. The observed inhibition of early FFA liberation may thus be attributable to thedelay in development of massive ionic shifts and resulatant neurotransmitter release which may activate phospholipase A 2and C.

Stimulatory effect of phospholipase A 2 treatment on glucose utilization in human erythrocytes

We examined whether modification of membrane phospholipids of human erythrocytes by hydrolysis with phospholipase A 2 (PLA 2 from bee venom) would affect glucose utilization, chosen as a typical model of intracellular metabolism, and, if so, intended to clarify the mechanism of the alteration of glycolysis. Treatment of erythrocytes with PLA 2 induced a marked shape change (i.e., crenation) and significantly increased the rate of lactate production from glucose. Available evidence indicated that there is no relevance of this cell-shape change to the alteration of glycolysis. The lack of a detectable effect of papain treatment on glycolysis in PLA 2-treated cells suggested that the increase in glycolysis by PLA 2 treatment might not be caused by the conformational change of band-3 protein through modulation of membrane phospholipids. The result of the measurement of lactate production in the presence and absence of ouabain did not support the idea that hydrolysis of phospholipids by PLA 2 treatment makes plasma membranes leaky to Na + and consequently enhances glycolysis through activation of Na + K +- ATPase . The action of PLA 2 on glycolysis was abolished by extraction of free fatty acids in the cell membrane with bovine serum albumin. Loading erythrocytes with free fatty acid (oleic acid, linoleic acid, or arachidonic acid) caused a significant increase in glycolysis. Analysis of glycolytic intermediates suggested that the enhancement of glycolysis was induced by activation of 6-phosphofructokinase. The data, thus, indicate that treatment of human erythrocytes with PLA 2 significantly accelerates glucose utilization and suggest that the stimulation of glycolysis is caused by activation of 6-phosphofructokinase through liberation of free fatty acids of membrane phospholipids by PLA 2.

Nilvadipine as a neuroprotective calcium entry blocker in a rat model of global cerebral ischemia. A comparative study with nicardipine hydrochloride

The effects of two dihydropyridine type calcium entry blockers, nilvadipine and nicardipine hydrochloride (nicardipine), on the liberation of free fatty acids (FFAs) were investigated using an experimental model of global cerebral ischemia in rats, and were compared with their pharmacokinetic properties. Nilvadipine, but not nicardipine, at a dose of 100 μg/kg i.v., significantly attenuated the liberation of FFAs, particularly docosahexaenoic and arachidonic acid. Furthermore, the brain concentration of nilvadipine was higher than that of nicardipine after equivalent dosing. The results of the present study demonstrate that pharmacokinetic differences between these two calcium entry blockers might explain the difference in their pharmacological efficacy.

Evaluation of microbial chymosin from genetically engineered kluyveromyces lactis

Abstract The effects of temperature, pH, CaCl2 concentration and enzyme concentration on the milk‐clotting activity of chymosin produced by a genetically manipulated strain of Kluyveromyces lactis and Hansen's standard calf rennet were compared. Cheddar cheese was manufactured on three occasions from pasteurized whole milk in paired 1200 L vats using microbial chymosin or standard rennet. Ripening was monitored for up to 12 months by polyacrylamide gel electrophoresis, formation of water and 12% TCA soluble N and the liberation of free fatty acids; cheeses were also organoleptically assessed by professional cheese graders. Although differences in quality were observed between batches manufactured on different days, no difference was apparent between members of any pair with respect to either sensory or chemical criteria. Both enzymes behaved similarly under all environmental conditions studied.

The effects of cortisol administration on intermediary metabolism in teleost fish

1. 1. This Mini Review deals with the metabolic consequences of administration of the hormone cortisol on proteins, carbohydrates and lipids in teleost fish. 2. 2. Many effects of administered cortisol on intermediary metabolism in fish have been reported: inhibition of protein synthesis and/or catabolism of tissue protein which result in higher availability of amino acids, induction of gluconeogenesis and of liver aminotransferases, hyperglycemia and glycogen deposition in the liver, induction of gluconeogenic enzymes, liberation of free fatty acids and deposition of liver lipids. All these effects are observed to a greater or less extent. However, the experimental data show that some effects are inconsistent. 3. 3. Some explanations for the inconsistencies are given.

The liberation of free fatty acids in potato slices at low temperature

Free fatty acids (FFA) are liberated in the first stages of potato granule production. In this study, the liberation of FFA was examined in model experiments. Potato slices were exposed to conditions resembling the first stages of the industrial process, which was of the “add‐back type”. The slices were kept at 9°C in the dark and, after various periods of time (up to two hours), the amount and composition of the FFA liberated at the surface and in the middle of the potato slices were analyzed by gas chromatography.The liberation of FFA was more pronounced at the surface of the slices than in the middle. The polyunsaturated fatty acids, linoleic acid and linolenic acid, were liberated to a greater extent than the saturated fatty acids. The experiment was repeated at 4°C and the results obtained were very similar. The lower temperature did not decrease the rate of FFA liberation. But, in thin potato strips, which have a larger total surface of damaged membranes than the potato slices, considerably more FFA were liberated.The amount and composition of FFA also were analyzed in potato slices from the industrial process for potato granule production. Before the blanching bath (76°C for 12–15 min) only minor amounts of FFA were liberated but during the blanching there was a substantial liberation of FFA at the surface of the potato slices. After the blanching bath there were no more FFA liberated at the surface of the slices but in the middle of the potato slices the liberation of FFA continued until the potato slices reached the steamcooking bath.

Ischemia‐Induced Alterations in Lipid Metabolism of the Gerbil Cerebral Cortex: I. Changes in Free Fatty Acid Liberation

Does the impaired lipid metabolism during non-lethal transient ischemia truly recover within a few hours after recirculation? In an attempt to answer this question, we first investigated the time course of the changes in the amount and composition of free fatty acids (FFAs) accumulated during 5-min ischemia and after various postischemic recirculation durations (3 min, 1 h, 24 h, 3 days, and 6 days) in the gerbil cerebral cortex. Then those of FFAs liberated in response to the second 5-min ischemia at various recirculation intervals (3 min, 1 h, 3 days, and 6 days) following the initial one were also measured to evaluate the changes in the cellular response. The former study disclosed that the FFA levels transiently returned to the control levels at 1-h recirculation, increased again a few days after the onset of recirculation, followed by the final return to the control levels after 6-day recirculation. The latter study disclosed that the cellular response to the second ischemia was quite different from that to the initial one even after 6-day recirculation, suggesting that membrane lipid metabolism had not yet been recovered even at such a late period. We discuss the significance of the alterations in lipid metabolism.

Gastric emptying and serum insulin levels after intake of glucose-polymer solutions.

To examine the gastric emptying characteristics of four drinks varying in carbohydrate composition and concentration, five men ingested 600 ml of one of the different drinks on four separate occasions. All drinks contained Na+ 71 mmol.l-1, Cl- 60 mmol.l-1, Mg+2 5 mmol.l-1 and citrate 7 mmol.l-1; the carbohydrate component was either 3% glucose, 3% glucose-polymer (GP), 5% GP or 10% GP. With 99mTc-diethylene-triaminepenta-acetic acid (DTPA) as a marker, a scintillation camera and computer were used to measure the rate of gastric emptying. The half-emptying times (T 1/2) were inversely related to the glucose content of the solutions. The T 1/2 for 3% PG was 22.4 +/- 4.4 min (mean +/- SE) and for 10% GP 50 +/- 3.3 min (p less than 0.005). There was no significant difference in T 1/2 between the 3% glucose and 3% GP solutions. The increments in blood glucose (highest blood levels from 7.4 +/- 0.3 mmol.l-1 to 8.9 +/- 0.8 mmol.l-1), serum insulin (from 28 +/- 6 mU.l-1 to 77 +/- 13 mU.l-1) and C-peptide (from 3.6 +/- 0.4 micrograms.l-1 to 5.8 +/- 0.9 micrograms.l-1) were related to the amount of carbohydrate ingested. In all cases the serum insulin levels were high enough to inhibit the liberation of free fatty acids from the adipose tissue. It is concluded that the amount of carbohydrate in glucosyl units in the solution is a major determinant of gastric emptying.(ABSTRACT TRUNCATED AT 250 WORDS)