Free Essential Amino Acids Research Articles

Proteolytic characterization of Kariesh cheese made from lactose-hydrolyzed milk

Differences in chemical and free amino acid compositions, microstructure and sensory quality during pickling were found between Kariesh cheese made from lactose-hydrolyzed milk and a control. Sodium caseinate and essential free amino acids are considered to be the proteinaceous and free amino acids components of this type of cheese. Differences in flavour between the two cheese types are assumed to be due to differences in free amino acid contents during pickling. The microstructure of the ripened experimental cheese was more homogeneous than that of the control cheese. Protein degradation, free amino acid concentration and fusion of casein micelles in the cheese protein matrix were increased, and the organoleptic quality of Kariesh cheese was improved, when β-galactosidase was added to the cheese milk before processing.

Comparison of free amino acid contents in plasma, whole blood and erythrocytes of carp, coho salmon, rainbow trout, and channel catfish.

Contents of free amino acids (FAA) and related compounds were examined in plasma, whole blood, and erythrocytes of four species of freshwater fishes: carp Cyprinus carpio, coho salmon Oncorhynchus kisutch, rainbow trout Salmo gairdnerii, and channel catfish Ictalurus punctatus. The content of each FAA in the erythrocytes washed with saline was always low in all species and about 20-60% of the calculated erythrocytes (CE) content which was estimated from the whole blood and the plasma content. This result probably indicates that FAA in the erythrocytes of fishes were washed out by rinsing. In carp, coho salmon, and rainbow trout, the total amounts of essential FAA in the CE were similar or slightly higher than those found in the plasma, while the total amounts of nonessential FAA in the CE were two to three-fold higher than those found in the plasma. In channel catfish, however, both total amounts of essential and nonessential FAA in the plasma were about one-fifth of those in the CE. The CE levels of phosphoserine, taurine, aspartate, glutamate, and ammonia were 7-30 times higher than the plasma levels. On a percentage distribution basis, the plasma contents of these compounds were only 4-16% of those in the whole blood.

ヨーロッパウナギＡｎｇｕｉｌｌａ ａｎｇｕｉｌｌａ稚魚の遊離アミノ酸含量に及ぼす飼料たんぱく質含量の影響

Free amino acids and related compounds in whole body of juvenile European eel Anguilla anguilla were determined to elucidate the relationships between levels of free amino acids and dietary protein level, protein intake or protein deposition of the fish. The eel were fed with the diets having seven levels of protein (0.3, 11.5, 21.8, 32.7, 43.8, 54.5 and 64.4%) at 25°C for six weeks. The protein source of these diets was casein fortified with L-forms of crystalline arginine, istidine, lysine, methionine, cystine, threonine and tryptophan. The total contents of free essential amino acid gradually rose as the protein intake increased, and a positive and significant correlation was observed between these parameters. On the other hand, the contents of free nonessential amino acid and ninhydrin reactive substance were more strongly correlated with the levels of protein deposition than those of dietary protein or protein intake. Free amino acids affected by the dietary treatment were as follows: threonine, α-amino-n-butylic acid, cystathionine, leucine, phenylalanine, ornithine, lysine, arginine and proline, of which the contents were positively and significantly correlated with the levels of dietary protein and protein intake. Whereas, the contents of aspartic acid, glutamic acid, alanine, methionine, tyrosine, β-alanine, histidine and asparagine showed stronger positive correlation with the levels of protein deposition than those of protein intake. Unlike these amino acids, negative and significant correlations were observed between the dietary protein levels and the serine contents, and the protein deposition levels and the taurine contents.

Métabolisme protéique de l'agneau nouveau-né. — I. Conséquences de l'ingestion de colostrum sur la glycémie, la gammaglobulinémie et les teneurs en acides aminés libres des tissus

Ten newborn lambs were divided into two groups at birth. Five of them were fed hourly with cow colostrum; the others (unfed lambs) were given saline. Jugular blood levels of glucose, urea, free amino acids and IgG1 were measured during the 10-hour period following birth. The lambs were then exsanguinated under pentobarbital anaesthesia. Free amino acid levels were determined in liver, muscle (longissimus dorsi) and skin. The glycogen contents of the liver and whole body were measured. The IgG1 levels were determined in the intestinal wall and in the contents of the abomasum and small intestine. The blood glucose levels increased after birth in both groups and did not differ significantly in either group. After colostrum feeding, hepatic glycogen and blood urea concentrations were higher in fed than in unfed lambs. Blood free essential amino acid levels which increased after birth in the fed group, were higher in that group than in the unfed one. Nonessential free amino acid levels remained nearly constant throughout the experimental period and did not differ significantly in either group (fig. 2). Free threonine and valine in the liver, skin and muscle were higher in the colostrum-fed lambs than in the others. IgG1 levels increased after birth in the blood of the fed lambs and seemed to be closely related to the intestinal contents of these compounds (fig. 3). The amount of blood free essential amino acids provided by the hydrolysis of colostral proteins was estimated at about 43% of the amount entering the small intestine.

Variations circadiennes des acides aminés libres de l'hemolymphe de Penaeus japonicus

The non-essential free amino acids of Peneaus japonicus hemolymph (asp, ser, glu, pro, gly, tyr, arg, ala, cys, tau) are more common than the essential ones: 750 pmol μl −1 of hemolymph vs 330 pmol. Under a light-dark (L-D); 12-12 photoperiod, tricircadian variations of males or tetracircadian variations of females are more pronounced for non-essential amino acids then for essential ones. In the first case, free amino acid concentrations of hemolymph can be multiplied by a factor of three, and in the second case by a factor of six; but circadian variations of females are greater than those of males. Differences between the maximum and minimum of essential free amino acid concentrations of male and female hemolymph are more frequent than for non-essential amino acids. A differences of 2 h between the minimum of essential and non-essential amino acid concentrations in males only appeared during the afternoon. The more concentrated free amino acids in P. japnicus hemolymph are glycine, proline, histidine, and alanine; the less concentrated are lysine, cysteine and glutamic acid while others, like leucine, isoleucine, phenylalanine and tyrosine can only be estimated at 10.00 and 24.00 h.

On-farm production of liquefied catfish protein

A method and the equipment used to process channel catfish ( Ictalurus punctatus) offal into a liquid catfish protein (LCP) suitable for use as an animal feedstuff component is described. This process uses the offal following cleaning of the catfish for commercial use, i.e., without additional grinding or chopping. Small amounts of either hydrochloric acid or formic acid can be used to liquefy the catfish offal in 2 h or less. The liquefaction is conducted in a drum fitted with a baffle. The drum is heated to 50°C with water from an overhead manifold while turning on a drum roller. Bones and unliquefied material are removed by screening to yield LCP at pH 4.5. Variations in the processing conditions — grinding, agitation rate, acid employed, and time — did not alter significantly the amount of crude protein or the essential amino acid profile. Acid selection altered the amount of essential free amino acids found, with hydrochloric acid producing the lesser amount. Reducing the agitation rate lowered the amount of essential free amino acids. Comparison of the essential amino acid profile of the LCP with those of catfish, menhaden and herring meals showed lower amounts of these acids but sufficient to warrant use as a feed component.

Postprandial distribution of free amino acids between plasma and erythrocytes of common carp ( Cyprinus Carpio L.)

1. 1. Free amino acid concentration in whole blood, plasma and erythrocytes washed with saline were determined in common carp of an individual weight of 500 g. 2. 2. Glutamate and aspartate have shown the highest concentrations within the erythrocytes. 3. 3. Among these amino acids which have shown the concentration ratio (erythrocyte-plasma) below unity were leucine, valine, histidine and lysine. 4. 4. Post-prandial level has shown the maximum concentration of free amino acids more or less 3 hr after feeding. 5. 5. Several amino acids have shown significant correlations between whole blood and plasma, and whole blood and erythrocyte concentrations. 6. 6. Levels of essential free amino acids in whole blood and plasma were positively correlated with their levels in the diet.

Plasma free amino acids in trauma: Clinical and therapeutic implications

The aim of this study was to evaluate the plasma free amino acid patterns in patients suffering from traumatic shock. Changes found in the behaviour of single free amino acids appear to indicate that the nutritional infusate solutions should not contain glutamic acid, high concentrations of arginine or a ratio of essential free amino acids to total nitrogen of more than 3.2.

Importance of Sensory Evaluation in the Stability Testing of a Medical Food

ABSTRACTA medical food was formulated as a dry powder product containing free essential amino acids, fat and carbohydrates. Samples were stored at 4°C, 25°C, and 40°C and evaluated periodically during storage. Proximate analysis, pH, amino acid analysis, osmolarity, emulsion stability, Hunter color difference, and sensory evaluation tests were performed. Changes could not be detected by the chemical tests employed, but were manifested in sensory analysis. This study indicated that sensory testing of medical foods is a critical tool in the assessment of product stability and must be considered an integral part of any medical food stability program. Chemical analysis alone will not provide sufficient data to allow prediction of either patient acceptance or product integrity.

The physiological and biochemical responses of broilers exposed to short-term thermal stress

1. 1. Exposure of cockerels to heat stress (42°C) for 15 min resulted in a reduction of both the total free and essential free amino acids in plasma with simultaneous elevation in the levels of the total free and essential free amino acids in liver as compared to the pre-stress level. 2. 2. The reduction in the plasma free amino acid pools was accompanied by a decrease in total proteins and alkaline phosphatase concentrations, with a simultaneous elevation in albumin, glucose, uric acid, plasma free fatty acids, lactate dehydrogenase and creatine kindase. 3. 3. During the recovery period both the total plasma and hepatic free amino acids returned to prestress levels but the levels of the essential plasma free amino acids in heat-stressed birds remained low while the hepatic essential free amino acids remained high. 4. 4. At the end of a 30 min recovery period at 21°C, the glucose content substantially decreased with free fatty acids and uric acid still remaining at high levels. 5. 5. There was a significant reduction in nitrogen retention in heat-stressed birds determined during the 24 hr recovery period mainly due to an increase in the excretion of nitrogen in uric acid form. 6. 6. In birds exposed to cold (4°C), the only significant changes were an increase in the hepatic essential free amino acids and an increase in uric acid excretion. 7. 7. The results indicate that short-term heat stress affects protein metabolism in growing chickens.

Plasma amino acid changes in rainbow trout Salmo gairdneri force-fed casein and a corresponding amino acid mixture.

The sequence of appearance of free amino acids in the plasma of rainbow trout at 0, 3, 6, 12, 24, 36, 48, 72, and 96 hours after force-feeding casein and a corresponding amino acid mixture was examined. Most of the free essential amino acids in the plasma of rainbow trout after force-feeding casein did not appreciably changed from their fasting levels during the initial 12 hours, but thereafter increased in concentration to attain maximum levels between 24 and 36 hours after force-feeding, and then declined to the fasting levels after 72 to 96 hours. In contrast, most of the plasma free essential amino acids increased immediately after force-feeding the amino acid mixture and reached mean peak levels at 12 hours, returning to their fasting levels by 48 hours. Compared with the fish which were force-fed casein, those force-fed the amino acid mixture showed higher essential amino acid concentrations in plasma at their maximum levels. Also, examination of the stomach contents of the fish at these same intervals after force-feeding revealed the amino acid mixture to be emptied from the stomach more rapidly than the casein.

Effect of Proteolytic Bacteria in the Natural Fermentation of Corn to Increase its Nutritive Value

ABSTRACTThere was no significant difference in % relative nutritive value, lysine or tryptophan levels between natural lactic fermentations of Costa Rican corn meal fermented with tap water of pH 7.2 and 5.3 However, the fermented values were all significantly (P<0.05) higher than nonfermented values. Most of the increase in % relative nutritive value occurred in the first 48 hr. Free essential amino acids increased and the amino acid balance changed during typical fermentations. Proteolytic bacteria decreased after 3 days of the fermentation and declined to a few cells per ml by the 4th day. Proteolysis decreased by the second day of natural lactic fermentation.

Studies on some Egyptian foods. Part 2: The effect of protein on blood constituents of rats.

This study was undertaken to study the changes of the blood constituents of rats fed different proteins (lupinus termis, Guiza 1, 2 and balady; fenugreek seeds, raw, roasted, and germinated). The total serum protein for animals fed casein was slightly higher than those fed other proteins. Total serum protein of animals fed lupinus termis, roasted and germinated fenugreek was higher than those fed raw seeds. The albumin/globulin ratios showed a similar trend. The ratio of nonessential to essential free serum amino acids of rats fed non-protein diet was higher than those fed protein. Lupinus termis and fenugreek seeds are good sources of protein. Treatment of seeds either by heat of germination improves the nutritive value of the proteins.

Changes in the levels of circulating plasma free amino acids of carp ( Cyprinus carpio) after feeding a protein and an amino acid diet of similar composition

A protein diet containing casein as the sole nitrogen source and an amino acid diet of similar composition (except isolated amino acids represented all of the nitrogen) were fed to triplicate groups of yearling carp. The sequence of appearance of free amino acids in the plasma of carp at 0, 2, 4, 8 and 16 h after feeding the two diets was examined. The circulating levels of all plasma free essential amino acids were in highest concentrations at 4 h after feeding the casein diet, except for arginine which declined slightly from 2 to 4 h. After feeding the amino acid diet, plasma free arginine and lysine were at peak levels at 2 h after feeding, while others peaked by 4 h. Glutamic acid and aspartic acid were detected in very low concentrations in the plasma relative to their levels in the diets, while proline was found in the highest concentrations of all other amino acids. Essential amino acid levels in the plasma were found to be positively correlated with their levels in the diets, while non-essential amino acids were not.

Variations through the day of hepatic and muscular cathepsin A (carboxypeptidase A; EC 3.4.12.2), C (dipeptidyl peptidase; EC 3.4.14.1) and D (endopeptidase D; EC 3.4.23.5) activities and free amino acids of blood in rats: influence of feeding schedule.

1. Growing rats were fed either ad lib. or with six (equal) meals offered every 4 h (from 10.00 hours). Rats of each group were killed at intervals of 4 h beginning at 11.00 hours. Activities of cathepsin A (carboxypeptidase A; EC 3.4.12.2), C (dipeptidyl peptidase; EC 3.4.14.1) and D (endopeptidase D EC 3.4.23.5) were measured in liver and muscle homogenates and free amino acids in blood were determined. 2. In the rats fed ad lib. activities of carboxypeptidase A and endopeptidase D in liver and muscle showed significant variation, with maximum activity in the light period. In general, meal-feeding only caused minor differences in cathepsin activities; although significant differences occurred for carboxypeptidase A. For the later enzyme a peak in activity occurred in the dark as well as in the light period. 3. Irrespective of the feeding schedule, the lower concentration of free essential amino acids of blood occurred generally during the night period. With the controlled-feeding schedule there is an increase of essential amino acids and a slight decrease of non-essentail amino acids of blood.

Variation in the free amino acid content of skeletal muscle of Ophicephalus punctatus (Bloch)

The skeletal muscle of Ophicephalus punctatus contains nine essential free amino acids, arginine, histidine, isoleucine, leucine, methionine, phenylalanine, threonine, valine and lysine, and eight non‐essential amino acids, alanine, aspartic acid, cystine, glutamic acid, glycine, tyrosine, proline and serine. Histidine and lysine dominated the free amino acids pool. Seasonal variation was detected in the levels of histidine, arginine, leucine, phenylalanine, glycine, cystine and serine with highest values occurring in April and again in November. Changes were also detected in the concentrations of certain amino acids as the fish grew in size. Levels of free amino acids did not significantly differ between sexes. Factors effecting variation are discussed.

The effects of starvation on the sodium, potassium, water and free amino acid content of parietal muscle from Agonus cataphractus

1. 1. The levels of the individual free amino acids, K, Na and water present in parietal muscle were measured in fish starved for periods of 3–115 days. 2. 2. The Na and water content progressively increased relative to dry weight of tissue during the starvation period whereas an initial increase in the K content up to 67 days was followed by a decrease to near the normal fed level by 115 days. The ammonia content remained essentially stable over the same period. 3. 3. The essential free amino acid content tended to follow the muscle sodium pattern while the non-essential amino acids and taurine gave results somewhat similar to those of potassium. 4. 4. The net result of these changes is that the Na, K and total free amino acid concentration is maintained within fairly narrow limits relative to the tissue water content during 11–67 days of the starvation period under the experimental conditions used.

Conversion of 14C glucose into free amino acids and peptides during metamorphosis of the blowfly, Phormia regina

The incorporation of 14C from labelled glucose into non-essential free amino acids was highest at puparium formation. The labelled amino acids declined substantially during pupal development with minor changes appearing in the pharate adult. The total amount of unlabelled free and peptide amino acids tended to exhibit a U-shaped curve during metamorphosis. Changes in the essential free amino acids correlate well with periods of tissue histolysis and protein synthesis. The non-essential free amino acids exhibit changes which indicate that these amino acids may be utilized as an energy source during early metamorphosis and contribute to protein synthesis in the pharate adult.

Amino acid imbalance in cystinuria.

After oral ingestion of a free amino acid mixture by three cystinuric patients, plasma increments of lysine and arginine were lower and those of many other amino acids were significantly higher than those found in control subjects. Similar results were obtained in control subjects after amino acid imbalance had been artificially induced by the omission of cystine, lysine, and arginine from the amino acid mixture. Especially high increments of alanine and proline provided the best evidence of amino acid imbalance caused by a temporary lysine and, to a lesser extent, arginine and cystine deficit. No such amino acid imbalance was found to occur in the cystinuric patients after ingestion of whole protein, indicating that absorption of oligopeptides produced by protein digestion provided a balanced physiological serum amino acid increment. This is considered to explain the lack of any unequivocal nutritional deficit in cystinuric patients despite poor absorption of the essential free amino acid, lysine.

Intravenous energy infusion in lambs: effects on nitrogen retentin, plasma free amino acids and plasma urea nitrogen

1. Acetate, propionate, butyrate and glucose were each administered intravenously (2.09 MJ (0.5 Mcal)/d) to lambs on either high-concentrate (HC) or high-roughage (HR) diets in two experiments with 4 × 4 Latin square design. During a control period all animals received a saline infusion.2. In lambs on the HC diet glucose was the most effective metabolite tested for improving nitrogen retention. Acetate was 51%, butyrate, 75%, propionate, 90% as effective as glucose in promoting N retention. Propionate infusion was most effective in increasing N retention in lambs on the HR diet. Acetate was 60%, butyrate, 75%, and glucose, 80% as effective as propionate. Glucose infusion did not lower plasma urea N (PUN) concentration in lambs receiving the HC diet, but the three volatile fatty acids (VFA) did lower it (P< 0.01). All energy sources significantly reduced the PUN concentrations with the HR diet, but differences between sources were not significant.3. Plasma concentrations of valine, isoleucine, leucine and phenylalanine were depressed to 57, 71, 89 and 90% of their control values during glucose, propionate, butyrate and acetate infusion. Plasma concentrations of lysine and methionine were significantly decreased from control values (P< 0.05) but there was no significant difference between energy sources. Lysine, valine, isoleucine and leucine were significantly (P< 0.01) higher in lambs given the HR diet than in lambs given the HC diet. The concentration of alanine was greater (P< 0.05) during glucose infusion than during acetate and butyrate infusions, indicating net synthesis of alanine and possibly other non-essential amino acids during glucose infusion, since the plasma free amino acid N concentration increased despite decreased concentrations of plasma essential amino acids during glucose infusion.4. The results indicated that glucose and propionate were superior to acetate and butyrate as energy sources for protein formation.5. The poor relationship between PUN and N balance and plasma free essential amino acids suggested that PUN concentration may have been inappropriate to assess the protein status under some dietary conditions.