THE "BROWNING REACTION" IN DRIED MILK POWDER

1949 ◽  
Vol 27f (11) ◽  
pp. 429-434 ◽  
Author(s):  
J. B. Moster ◽  
R. A. Chapman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Milk Powder ◽  
Amino Nitrogen ◽  
Volumetric Method ◽  
Large Excess ◽  
Browning Reaction ◽  
Titration Curves

Heated and stored dried milk powders showed a marked loss of amino nitrogen as determined by the Van Slyke volumetric method, but no loss was observed when the formol titration was used. Titration curves of the powders suggested a mechanism for the protein–sugar condensation. The heating of synthetic mixtures of amino acids and lactose resulted in intense browning, accompanied by a loss of ammo nitrogen when a large excess of lactose was employed but no loss occurred when equal parts of sugar and amino acid were present.

MATHEMATICAL MODELS FOR THE SYNTHESIS OF PLANT-BASED COMPOSITIONS WITH IMPROVED AMINO ACID COMPOSITION

2021 ◽  
Author(s):  
Irina Gaivoronskaya ◽  
Valenitna Kolpakova
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Mathematical Models ◽  
Functional Properties ◽  
Amino Nitrogen ◽  
Essential Amino Acids ◽  
Major Allergen ◽  
Structural Features ◽  
Covalent Bonds ◽  
Pea Protein

The aim of the work was to optimize the process of obtaining multicomponent protein compositions with high biological value and higher functional properties than the original vegetable protein products. Was realized studies to obtain biocomposites on the base of pea protein-oat protein and pea protein-rice protein. Developed composites were enriched with all limited amino acids. For each of the essential amino acids, the amino acid score was 100% and higher. Protein products used in these compositions are not in major allergen list, which allows to use these compositions in allergen-free products and specialized nutrition. To determine biosynthesis parameters for compositions from pea protein and various protein concentrates with the use of transglutaminase enzyme, was studied effect of concentration and exposition time on the amount of amino nitrogen released during the reaction. Decreasing of amino nitrogen in the medium indicated the occurrence of a protein synthesis reaction with the formation of new covalent bonds. Were determined optimal parameters of reaction: the hydromodule, the exposure time, the concentration of EP of the preparation, were obtained mathematical models. Studies on the functional properties of composites, the physicochemical properties of the proteins that make up their composition, and structural features will make it possible to determine the uses in the manufacture of food products based on their ability to bind fat, water, form foam, gels, and etc.

Renal Tubular Transport of Amino Acids

1971 ◽  
Vol 17 (4) ◽  
pp. 245-266 ◽  
Author(s):  
John Atherton Young ◽  
Benedict Sol Freedman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Proximal Tubule ◽  
Amino Nitrogen ◽  
High Capacity ◽  
High Specificity ◽  
Brush Borders ◽  
Tubular Transport ◽  
Renal Tubular Transport ◽  
Renal Tubular

Abstract Cushny in 1917 first remarked on the extensive amino acid reabsorption which occurs in the nephron. Although many workers since then have studied the nature and localization of the reabsorptive mechanism, progress has been slow because of the technical difficulties of micropuncture work. The bulk of filtered amino nitrogen is reabsorbed in the proximal tubule although the possibility of there being more distal reabsorptive (or secretory) sites cannot be excluded. It is also uncertain whether all segments of the proximal tubule contribute equally to the reabsorptive process. Amino acid reabsorption is an active process involving numerous illdefined steps, the first of which is binding to the brush borders. Renal amino acid transport mechanisms are of two kinds: the high-capacity low-specificity systems transport whole groups of amino acids—the acidic, basic, neutral, and imino-glycine groups—while the other, the low-capacity high-specificity systems, transport single or perhaps pairs of amino acids only.

Amino acids in muscle and kidney of potassium-deficient rats

1960 ◽  
Vol 199 (1) ◽  
pp. 39-42 ◽  
Author(s):  
Ira K. Brandt ◽  
Victor A. Matalka ◽  
Jerome T. Combs
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Nitrogen ◽  
Potassium Deficiency ◽  
Experimental Diet ◽  
Basic Amino Acids ◽  
The Relationship ◽  
Predictable Variation

Muscle and kidney taken from rats with potassium-deficiency alkalosis contained a higher concentration of lysine, histidine and arginine than tissue taken from pair-fed control animals. The concentration of anserine, carnosine and alpha-amino nitrogen did not differ in the two groups. Although the concentration of virtually all of the above substances varied with the length of time that the animal had been receiving the experimental diet, the relationship between the data obtained from potassium-deficient animals and from the pair-fed controls remained constant. The results suggest that a mechanism other than replacement of lost potassium as cation may bring about the increase in the basic amino acids during potassium-deficiency alkalosis and that starvation is associated with a predictable variation in some of the amino acid constituents of the tissues.

scholarly journals Metabolism of heat-damaged proteins in the rat

1971 ◽  
Vol 26 (2) ◽  
pp. 311-322 ◽  
Author(s):  
J. E. Ford ◽  
C. Shorrock
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Total Amino Acid ◽  
Carbohydrate Complex ◽  
Urinary Peptide

1. Freeze-dried cod muscle and casein were subjected to various conditions of heat treat-ment. Diets containing the different products, or the unheated materials, were given to a group of four adult male rats during successive 48 h periods, and urine was collected during the second 24 h of each 48 h period. A further collection of urine was made from the rats after they had been given protein isolated from heated skim-milk powder. The content and amino acid composition of the ‘peptide’ and ‘free amino acids’ in the urines were determined.2. Heat damage to the cod-fillet protein increased the total urinary excretion of peptide-bound amino acids, from 18·6 to 48·8 µmol/rat.d. The composition of the peptide also changed, and in particular there was a marked increase in lysine, from 2·98 to 20·30 µmol %. Three amino acids - lysine, aspartic acid and glutamic acid - together comprised nearly 70 % of the total amino acid residues. There was a corresponding increase in urinary excretion of free amino acids, from 53·7 to I 14·4 µmol/rat.d. The combined losses of lysine in urinary peptide and free amino acids were 1·5 % of the total lysine ingested, as against 0·3 % for the unheated cod fillet.3. The effects of similar heat treatment of casein on the composition of the urinary peptide and free amino acids were less marked. There was no increase in total urinary peptide excretion and there was a smaller increase in the lysine content of the peptide.4. In urine of rats given protein isolated from heated skim-milk powder, the peptide hydro-lysate was rich in lysine and in furosine, which together comprised 41 mol % of the total amino acid composition. These compounds were presumably formed, together with a smaller quantity of pyridosine, from lysine-carbohydrate complex in the urine. It is probable that, as compared with free lysine, the lysine-carbohydrate complex was absorbed relatively in-efficiently from the rat intestine.5. The findings are discussed in relation to the wider question of the metabolism of the ‚unavailable peptide’ that is released in the course of digestion of heat-damaged protein.

Renal responses to amino acids in the sheep fetus

1996 ◽  
Vol 270 (6) ◽  
pp. R1226-R1230 ◽  
Author(s):  
L. L. Woods ◽  
A. R. Hohimer ◽  
L. E. Davis
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Protein Intake ◽  
Amino Nitrogen ◽  
Maternal Plasma ◽  
Fetal Sheep ◽  
Acid Infusion ◽  
Amino Acid Infusion ◽  
Nitrogen Levels ◽  
Amino Acid Levels

Adult animals and humans are known to increase renal blood flow and glomerular filtration rate (GFR) in response to an acute protein load or amino acid infusion; however, the ontogeny of this phenomenon is not known. This study was designed to test the hypothesis that, despite normally high baseline amino acid levels in the fetus, increases in plasma amino acids stimulate increases in GFR before birth. Eight chronically instrumented fetal sheep (126 +/- 1 days gestation) were infused with a mixture of amino acids (0.15 and 0.30 mmol . kg-1 . min-1 i.v.). Plasma alpha-amino nitrogen levels increased significantly from 7.1 +/- 0.3 to 13.0 +/- 0.9 and 25.5 +/- 2.1 mg/dl, respectively, in response to the two doses, and GFR increased significantly from 3.2 +/- 0.4 to 4.0 +/- 0.5 and 4.6 +/- 0.5 ml/min, respectively. Arterial pressure did not change. Renal amino acid reabsorption was significantly increased at all time points during the amino acid infusion, reaching a value nearly five times that of control by the last clearance period. Na+ reabsorption was also increased throughout the infusion. Na+, K+, and Cl- excretions increased significantly only at the very last time point. These data indicate that the mechanism or mechanisms responsible for amino acid-induced hyperfiltration are present and functional even before birth in the sheep. Because maternal eating patterns and protein intake are known to change maternal plasma amino acid levels and amino acids are actively transported across the placenta, our findings suggest that both acute and chronic changes in maternal protein intake may alter fetal renal function.

Amino acid release from the hindquarter and urea appearance in acute uremia

1981 ◽  
Vol 241 (6) ◽  
pp. E415-E419 ◽  
Author(s):  
W. E. Mitch
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Nitrogen ◽  
Nitrogen Release ◽  
Amino Acid Nitrogen ◽  
Appearance Rate ◽  
Urea Production ◽  
Intracellular Amino Acids ◽  
Acid Release

Hepatic urea production is increased in acutely uremic rats, but it is not known whether this is related to release of nitrogen from nonhepatic tissues. Rats with acute uremia had lower arterial concentrations of alanine, glutamine, and alpha-amino nitrogen when compared to sham-operated rats and released significantly more alpha-amino nitrogen from the hindquarter in situ. Release of alpha-amino nitrogen, alanine, and glutamine from the perfused hindquarter of acutely uremic rats was greater than that of sham-operated rats. These changes in situ and in the perfused hindquarter were more pronounced in rats deprived of food and water compared to fed animals and were not due to depletion of intracellular amino acids. In addition to increased amino acid nitrogen release, there was a higher urea appearance rate (excretion plus accumulation) in starved, uremic rats compared to sham-operated controls (244.7 +/- 11.2 vs. 182.0 +/- 12.4 mg. 100 g-1 .48 h-1); urea appearance also was suppressed partially by feeding. Both peripheral release of amino acids and diet influence waste nitrogen production in acute uremia.

scholarly journals Amino acid oxidation by young pigs receiving diets with varying levels of sulphur amino acids

1983 ◽  
Vol 50 (2) ◽  
pp. 383-390 ◽  
Author(s):  
Kyu-Il Kim ◽  
Henry S. Bayley
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Choline Chloride ◽  
Milk Powder ◽  
Skim Milk ◽  
Essential Amino Acids ◽  
Acid Oxidation ◽  
Amino Acid Requirement

1. Piglets were weaned at 3 d of age and were introduced to liquid diets in which 400 g/kg protein was supplied as skim-milk powder and the balance as a mixture of free amino acids. The skim milk contributed 2·3 g methionine and 1·4 g cystine/kg diet; the experimental diets were made by supplementing these levels with free amino acids.2. The adequacy of the test level of the amino acid in the diet was assessed by measuring the oxidation of [1−14]phenylalanine as an indicator of the partition of the essential amino acids between incorporation into protein and degradation. Radioactivity recovered as carbon dioxide was used as a measure of catabolism.3. Addition of 0·2, 0·4, 0·7, 1·2 and 1·7 g L-methione/kg to a diet containing 5 g cystine and 3 g choline chloride/kg showed that phenylalanine catabolism was minimal for the diet with 2·7 g methionine/kg indicating that this is the dietary requirement for methionine to serve as a source of methionine residues for protein synthesis.4. Addition of D-methionine to produce a series of diets with graded levels of methionine showed that the D-isomer was less effective than the L-isomer in reducing phenylalanine catabolism: the addition of 0·8 g D-methionine/kg diet was needed to produce the same effect as 0·4 g L-methionine/kg diet showing that the replacement value of D-methionine for L-methionine was 50% in the young pig.5. To investigate the influence of cystine on methionine requirement, diets with varying levels of methionine and cystine were prepared. Oxidation of [U-14C]methionine was used as an indication of an excess of methionine, and the results showed that increasing the dietary methionine level above 3·0 g/kg in diets containing 1·4 g cystine/kg provided an excess of methionine for oxidation. This indicated a sulphur amino acid requirement of 4·4 g/kg, one-third of this being supplied as cystine.

scholarly journals Jejunal absorption of an amino acid mixture simulating casein and an enzymic hydrolysate of casein prepared for oral administration to normal adults

1975 ◽  
Vol 33 (1) ◽  
pp. 95-100 ◽  
Author(s):  
D. B. A. Silk ◽  
M. L. Clark ◽  
T. C. Marrs ◽  
Jill M. Addison ◽  
D. Burston ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Oral Administration ◽  
Human Subjects ◽  
Amino Nitrogen ◽  
Casein Hydrolysate ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Amino Acid Mixtures ◽  
Percentage Absorption

1. An intestinal perfusion technique was used in six normal human subjects to study absorption of sixteen individual amino acids from an amino acid mixture simulating casein and from an enzymic hydrolysate of casein, prepared for oral administration to these subjects, which consisted of a mixture of oligopeptides and free amino acids.2. Total absorption of α-amino nitrogen was greater from the casein hydrolysate than from the amino acid mixture, and the considerable variation in percentage absorption of individual amino acids from the amino acid mixture was much reduced when the enzymic hydrolysate solution was perfused, as a number of amino acids which were poorly absorbed from the amino acid mixture were absorbed to a greater extent from the casein hydrolysate.3. These findings indicate that after extensive intestinal resections or in malabsorption there might be significant nutritional advantages in the administration of protein hydrolysates rather than amino acid mixtures.

scholarly journals Some investigations dealing with the state of aggregation of matter.—Parts I-III

1910 ◽  
Vol 83 (562) ◽  
pp. 96-123 ◽  
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Amino Acid ◽  
General Equation ◽  
The State ◽  
Large Excess ◽  
Satisfactory Explanation

During the course of some investigations on the action of formaldehyde on the proteins, the observation was made that this aldehyde, when added to an aqueous solution of Witte's peptone, produces a precipitate, and that the reaction could be either partially or completely inhibited by the presence of neutral salts. This phenomenon was also noticed some years ago by T. Sollman, who offered no satisfactory explanation of the facts. The more recent investigations of Sörensen have shown that when formaldehyde reacts with amino-acids a methyleneimino-derivative is produced, which is readily hydrolysed in the presence of water, yielding the original amino-acid and formaldehyde. The reaction is therefore a reversible one, and can be represented by the general equation (NH 2 ) R·COOH + HCHO ⇌ (CH:N) R·COOH + H 2 O. The amino-acid is only completely converted into the methyleneimino-derivative in the presence of a large excess of formaldehyde, and the methyleneimino-acid thus produced is, in contrast to the amino-acid from which it was formed, so strongly acid that it can be titrated with caustic alkalis in the presence of phenolphthalein as indicator. These results are an extension and application of those which had been obtained some years before by Schiff.

scholarly journals The effect of proteolytic enzymes on the amino acid composition of the filtrate and the grain mash obtained from the shock activator disintegrating treated rye

2019 ◽  
Vol 81 (1) ◽  
pp. 99-104
Author(s):  
A. A. Sabirov ◽  
N. V. Barakova ◽  
E. A. Samodelkin
Keyword(s):  
Amino Acids ◽  
Particle Size ◽  
Amino Acid ◽  
Amino Acid Composition ◽  
Acid Composition ◽  
Proteolytic Enzymes ◽  
Average Particle Size ◽  
Control Sample ◽  
Amino Nitrogen ◽  
Average Particle

The effect of enzymes of proteolytic action on the amino acid composition of the filtrate and grains of grain wort obtained from UDA-treated rye was studied. The feasibility of using a complex of proteolytic enzymes: neutral and acid proteases is shown. The processing of rye was carried out on the disintegrator DEZI15 with different working elements: three and five-row rotors rotating at a frequency of 120 s1. A control sample of grinding was obtained in a laboratory mill with a rotor-knife working body. According to the data obtained on the Malvern Mastersizer 2000 laser analyzer, the average particle size in the grinding samples was: on a disintegrator with a three-row rotor – 167.5 microns, on a five-row rotor-knife working body – 384.278 microns. As a source of proteolytic enzymes, preparations of the fungal protease Рrо100L and the bacterial protease Protosubtilin GZх A120 were used. The determination of the content of ?-amino nitrogen in the finished wort (mg / dm3) was performed by calorimetry with ninhydrin. The concentration of amino acids was determined using the KNAUER amino acid analyzer: the calculation of aminograms was carried out by comparing the areas of the standard and the sample. It was established that the UDA-treatment allows obtaining a high content of ?-amino nitrogen in the filtrate of rye hydrolysates, and the complex introduction of acidic and neural proteases strengthens this effect. Analysis of the amino acid composition of the filtrate and grains showed the presence of all the essential amino acids in both of these products. The filtrate can be recommended as a nutrient nitrogen-containing medium for the cultivation of microorganisms, followed by the release of secondary metabolites of their vital activity, or as an intermediate in the production of sugar-containing syrups from whole grains with a high content of amino acids. The fraction of the hydrolyzate is of interest as a protein-containing feed additive, and the fine particle size distribution of such a product will allow it to be used not only for feeding cattle, but also in poultry farming.

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