Proteolysis during storage of UHT milk: differences between whole and skim milk

1993 ◽  
Vol 60 (3) ◽  
pp. 339-347 ◽  
Author(s):  
Rosina López-Fandiño ◽  
Agustin Olano ◽  
Nieves Corzo ◽  
Mercedes Ramos
Keyword(s):  
Free Amino ◽  
Skim Milk ◽  
Reversed Phase ◽  
Proteolytic Degradation ◽  
Process Conditions ◽  
Reversed Phase Hplc ◽  
Amino Groups ◽  
Uht Milk ◽  
Bacterial Origin

SummaryProteolysis during storage of UHT skim and whole milks processed by either direct or indirect systems has been studied. All the proteolysis indices determined (measurement of free amino groups, PAGE of caseins and PAGE and reversed-phase HPLC of the fraction soluble at pH 4·6) revealed greater proteolytic degradation during storage of skim milks compared with that of whole milks subjected to the same UHT treatments. Increased activities of both native milk proteinase and proteinases of bacterial origin were observed in skim UHT milks. The different behaviour of UHT skim and whole milks on storage would have to be taken into account in establishing the process conditions.

scholarly journals Effect of blockade of synthesis of nitric oxide by L-NAME on the level of free amino acids and biogenic amines in the brain cortex of rats with subtotal cerebral ischemia

2019 ◽  
Vol 16 (3) ◽  
pp. 291-297
Author(s):  
Y. E. Razvodovsky ◽  
V. Y. Smirnov ◽  
Ye. M. Doroshenko ◽  
N. Ye. Maksimovich ◽  
I. N. Semenenya
Keyword(s):  
Nitric Oxide ◽  
Amino Acids ◽  
Cerebral Ischemia ◽  
Free Amino Acids ◽  
Free Amino ◽  
Brain Cortex ◽  
Reversed Phase ◽  
Reversed Phase Hplc ◽  
Mechanisms Of Development ◽  
The Brain

Mechanisms of development of ischemic stroke are complex and have not been fully established. The aim of this study was to estimate the changes in the pool of free amino acids and biogenic animes in the brain cortex of rats with subtotal cerebral ischemia (SCI) and treated with L-NAME. Experiment was made on 18 rats: 12 animals were undergoing bilateral filament occlusion of arteries carotid, 6 of them were treated with L-NAME. The analyses of free amino acids levels in the blood plasma extracts were carried out by reversed phase HPLC.Concentrations of several amino acids were elevated during SCI including aspartate, b-alanine, valine and leucine. In contrast, the levels of glutamate, asparagine, treonine, gamma-aminobutiric acid, tyrosine and 5-hydroxiindolylacetate were decreased. The administration of L-NAME partially prevented the imbalance of the amino acids pool due to SCI by normalizing the levels of aspartate, glutamate, asparagine, methionine, gamma-aminobutiric acid, b-alanine, 5-hydroxiindolylacetate. However, the administration of L-NAME has induced an additional imbalance in the amino acids pool in the brain cortex (decrease in the levels of glutamine, histidine, taurine, tryptophan, phenylalanine, tyrosine (in comparison to SCI) and decrease in the levels of treonine and arginine. The imbalance of the amino acids pool induced by the administration of L-NAME during SCI is more severe than the imbalance caused by SCI.

Simultaneous analysis of free amino acids and taurine-related compounds in deep-sea mussel tissues using reversed-phase HPLC

2017 ◽  
Vol 84 (1) ◽  
pp. 127-134 ◽  
Author(s):  
Toshihiro Nagasaki ◽  
Tomoko Koito ◽  
Suguru Nemoto ◽  
Hideki Ushio ◽  
Koji Inoue
Keyword(s):  
Amino Acids ◽  
Deep Sea ◽  
Free Amino Acids ◽  
Free Amino ◽  
Reversed Phase ◽  
Simultaneous Analysis ◽  
Reversed Phase Hplc ◽  
Related Compounds

A quantitative study of changes in dried skim-milk and lactose-casein in the ‘dry’ state during storage

1963 ◽  
Vol 30 (2) ◽  
pp. 223-234 ◽  
Author(s):  
E. L. Richards
Keyword(s):  
Quantitative Study ◽  
Protein Complex ◽  
Free Amino ◽  
Skim Milk ◽  
Reducing Power ◽  
Amino Groups ◽  
Complex Change ◽  
Rapid Formation ◽  
Close Relationship

SummaryChanges in dried skim-milk and in lactose-casein in the ‘dry’ state during storage at 45 °C and 75% r.h. have been studied by the determination of free amino-N, ε-amino groups of lysine, galactose, lactulose, tagatose and 1-amino-1-deoxy-2-ketoses, and by the measurement of changes in colour, solubility and ferricyanide reducing power.In both systems there is initially a close relationship between the formation of 1-amino-1-deoxy-2-ketoses and the decrease in free amino-N. This conforms with an Amadori rearrangement of an initially formed lactose-protein complex. Change in colour is rapid only after there has been a rapid formation of 1-amino-1-deoxy-2-ketoses and a corresponding decrease in free amino-N. This conforms with browning being due to a breakdown of the Amadori rearranged complex.It is postulated that galactose and tagatose may be formed by both the basecatalysed degradation of lactose and also by breakdown of the Amadori rearranged lactose-protein complex. Lactulose is postulated to be formed only by base-catalysed degradation of lactose.

Comparison of the Hide Powder Azure and Casein-Trinitrobenzene Sulfonic Acid Methods for Determining Proteolysis in Skim Milk

1984 ◽  
Vol 47 (6) ◽  
pp. 476-480 ◽  
Author(s):  
ROBIN C. McKELLAR
Keyword(s):  
Free Amino ◽  
Sulfonic Acid ◽  
Degradation Products ◽  
Skim Milk ◽  
Sodium Caseinate ◽  
Buffer System ◽  
Trinitrobenzene Sulfonic Acid ◽  
Insoluble Protein ◽  
Slope Ratio ◽  
Amino Groups

Three extracellular psychrotroph proteinases were assayed in a defined buffer system and in skim milk, using the insoluble protein-dye complex, hide powder azure (HPA), as well as by quantifying free amino groups released from casein with trinitrobenzene-sulfonic acid (TNBS). Apparent Km values for HPA of approximately 60 mg/ml were found for each enzyme while for sodium caseinate, the apparent Km of 9.14 mg/ml for enzyme ATCC 15456 was 3-fold greater than for enzymes 13 and 32A. Vmax values for enzyme ATCC 15456 were 3 to 3.5 and 1.6 to 2.8-fold lower than for the other two enzymes with HPA and sodium caseinate, respectively. When activities in skim milk were being determined, trichloroacetic acid (TCA) concentrations of 2 and 8% for HPA and TNBS, respectively, were chosen to maximize recovery of degradation products and minimize background. Proteolysis measurements in skim milk with the two methods were closely correlated (r = 0.903 to 0.920) for each of the three enzymes. Detectability values (obtained by dividing the standard error of estimate for each method by its slope ratio) of 0.098 and 0.093 for the HPA and TNBS methods, respectively, indicate that the two methods do not differ significantly (P>0.05) in reliability.

Application of reversed-phase HPLC to the study of proteolysis in UHT milk

1993 ◽  
Vol 60 (1) ◽  
pp. 111-116 ◽  
Author(s):  
Rosina López-Fandiño ◽  
Agustin Olano ◽  
Carmen San José ◽  
Mercedes Ramos
Keyword(s):  
Reversed Phase ◽  
Reversed Phase Hplc ◽  
Uht Milk

Casein, Fluorescein Isothiocyanate as a Substrate for Measuring Protease Production by Psychrotrophic Bacteria

1987 ◽  
Vol 50 (9) ◽  
pp. 744-749 ◽  
Author(s):  
GENEVIEVE L. CHRISTEN ◽  
M. SENICA
Keyword(s):  
Protease Activity ◽  
Free Amino ◽  
Skim Milk ◽  
Fluorescein Isothiocyanate ◽  
Enzyme Concentration ◽  
Protease Production ◽  
Amino Groups ◽  
Bacterial Populations ◽  
Psychrotrophic Bacteria ◽  
Bacterial Protease

Fluorescein isothiocyanate-labelled casein was evaluated as a substrate for measuring bacterial protease activity in milk. Using protease from Bacillus amyloliquefaciens, effects of substrate type, pH, temperature and enzyme concentration were determined. The procedure was sensitive to .012 unit of enzyme activity. The procedure was then used as a method to detect protease production by psychrotrophic bacteria growing in pasteurized skim milk at 7°C for 5 d. Three psychrotrophic bacteria were added at three different initial populations. Bacterial population, protease activity and cumulative free amino groups were monitored daily. Bacterial populations were not correlated with either protease activity or cumulative free amino groups. Pro-tease activity and cumulative free amino groups were correlated (r=.46, p=.001). Both protease activity and cumulative free amino groups peaked as the microorganisms entered the late log phase (approximately 108 colony forming units per ml). This occurred after incubation for 2 d at 7°C in two replications and after 3 d in the third. Both values decreased with continued storage.

COMPARATIVE STUDIES OF THE POTENTIATION OF CORTICOTROPHIN ACTIVITY BY SEVERAL INACTIVE DERIVATIVES

1963 ◽  
Vol 42 (2) ◽  
pp. 209-213 ◽  
Author(s):  
Arthur I. Cohen ◽  
Edward H. Frieden
Keyword(s):  
Biological Activity ◽  
Comparative Studies ◽  
Free Amino ◽  
Hormonal Activity ◽  
Amino Groups

ABSTRACT A number of corticotrophin analogues have been prepared, some of which potentiate the biological activity of the untreated hormone in vitro. The free amino groups of corticotrophin appear to be essential not only for hormonal activity, but also for the interaction of the analogues with the tissue corticotrophin inactivating system which is assumed to account for the potentiating effect.

scholarly journals FREE AMINO GROUPS OF EQUINE γ-GLOBULINS AND A SPECIFIC ANTIBODY

1955 ◽  
Vol 216 (2) ◽  
pp. 621-624
Author(s):  
Mary L. McFadden ◽  
Emil L. Smith
Keyword(s):  
Specific Antibody ◽  
Free Amino ◽  
Amino Groups ◽  
Γ Globulins

scholarly journals A Reversed-phase HPLC Study of the Complexation of Benzene Derivatives Guest Molecules with 5,17-bis(N-Tolyliminomethyl)-25,27-dipropoxycalix[4]arene in Acetonitrile–Water Solution

1999 ◽  
Vol 23 (1) ◽  
pp. 60-61
Author(s):  
O. I. Kalchenko ◽  
A. V. Solovyov ◽  
J. Lipkowski ◽  
V. I. Kalchenko
Keyword(s):  
Stability Constants ◽  
Water Solution ◽  
Reversed Phase ◽  
Benzene Derivatives ◽  
Reversed Phase Hplc ◽  
Guest Molecules ◽  
Hplc Study

Stability constants of the host–guest complexes of 5,17-bis( N-tolyliminomethyl)-25,27-dipropoxycalix[4]arene with benzene derivatives were determined by reversed-phase HPLC in acetonitrile–water solution.

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