THE ?-N-ACETYLGLUCOSAMINIDASE ACTIVITY OF EGG WHITE. 1. Kinetics of the Reaction and Determination of the Factors Affecting the Stability of the Enzyme in Egg White

1971 ◽  
Vol 36 (1) ◽  
pp. 174-177 ◽  
Author(s):  
J. W. DONOVAN ◽  
L. U. HANSEN
Keyword(s):  
Egg White ◽  
Factors Affecting ◽  
The Stability ◽  
Kinetics Of

Factors affecting constancy of acetate concentration and correct determination of methanogenic activity in pH-stat experiments

2003 ◽  
Vol 48 (6) ◽  
pp. 111-118
Author(s):  
M. Mösche ◽  
U. Meyer
Keyword(s):  
Accurate Determination ◽  
Original Method ◽  
Experimental Conditions ◽  
Methanogenic Activity ◽  
Factors Affecting ◽  
Acetate Concentration ◽  
Correct Determination ◽  
Ph Stat ◽  
The Stability

The determination of methanogenic activity with a pH-stat titration bioassay is evaluated utilising a mathematical model of this system. For given kinetic parameters and experimental conditions the model calculates the development of titrant flow and acetate concentration during experiments. Simulations of experiments under various conditions are compared. They show that the original method inherently causes a strong drift of acetate concentration during the experiments and a misestimation of methanogenic activity. As a solution to these disadvantages the addition of sodium hydroxide to the titrant and a careful control of pH during flushing the reactor with gas prior to the experiment are recommended. In this way a better constancy of acetate concentration and a more accurate determination of methanogenic activity should be achievable. The accuracy of this method is limited by the stability of pH-electrode calibration parameters.

scholarly journals Phytochemical Molecules from the Decarboxylation of Gomphrenins in Violet Gomphrena globosa L.—Floral Infusions from Functional Food

2020 ◽  
Vol 21 (22) ◽  
pp. 8834
Author(s):  
Natalia Drobnicka ◽  
Katarzyna Sutor ◽  
Agnieszka Kumorkiewicz-Jamro ◽  
Aneta Spórna-Kucab ◽  
Michał Antonik ◽  
...  
Keyword(s):  
Citric Acid ◽  
High Resolution Mass Spectrometry ◽  
Potential Health ◽  
Gomphrena Globosa ◽  
Brewing Process ◽  
Health Promoting ◽  
The Stability ◽  
Kinetics Of ◽  
Derivatives Of

Herein, the generation of decarboxylated derivatives of gomphrenin pigments exhibiting potential health-promoting properties and the kinetics of their extraction during tea brewing from the purple flowers of Gomphrena globosa L. in aqueous and aqueous citric acid solutions were investigated. Time-dependent concentration monitoring of natural gomphrenins and their tentative identification was carried out by LC-DAD-ESI-MS/MS. The high content of acylated gomphrenins and their principal decarboxylation products, 2-, 15-, 17-decarboxy-gomphrenins, along with minor levels of their bidecarboxylated derivatives, were reported in the infusions. The identification was supported by the determination of molecular formulas of the extracted pigments by liquid chromatography coupled with high-resolution mass spectrometry (LCMS-IT-TOF). The influence of plant matrix on gomphrenins’ stability and generation of their derivatives, including the extraction kinetics, was determined by studying the concentration profiles in the primary and diluted infusions. Isolated and purified acylated gomphrenins from the same plant material were used for the preliminary determination of their decarboxylated derivatives. The acylated gomphrenins were found to be more stable than nonacylated ones. Citric acid addition had a degradative influence on natural gomphrenins mainly during the longer tea brewing process (above 15 min); however, the presence of plant matrix significantly increased the stability for betacyanins’ identification.

Factors affecting the stability and estimation of carotene in artificially dried grass and hays

1940 ◽  
Vol 30 (4) ◽  
pp. 622-638 ◽  
Author(s):  
S. K. Kon ◽  
S. Y. Thompson
Keyword(s):  
Chromatographic Analysis ◽  
Accurate Determination ◽  
Total Loss ◽  
Carotene Content ◽  
Factors Affecting ◽  
Ordinary Temperature ◽  
Initial Drop ◽  
The Difference ◽  
The Stability

1. The influence of storage in the light and in the dark at ordinary temperature and in a heated room at 70–80° F. on the carotene content of finely ground artificially dried grass stored in paper sacks and jute sacks was studied. There was an initial drop in carotene content from 61·1 to 46·5 mg./100 g., i.e. 23·9%, in the first month, and a total loss of 31·4% during 6 months' storage (August to February). No difference could be detected either between treatments or types of containers.2. There was a marked loss of carotene during 13 months' storage of baled artificially dried grass and of hays, amounting to 30–40% of the original value.3. Two methods of estimating carotene were compared. The method of Ferguson & Bishop (1936) gave higher results than the method of Peterson, Hughes & Freéman (1937). The difference is probably due to incomplete extraction in the latter method.4. Chromatographic analyses of “carotene” fractions from the above grasses showed the presence of coloured impurities amounting to 20·5–33·8% of the total recovered pigments.5. As these impurities are biologically inactive, chromatographic analysis or the use of special solvents are probably necessary for the accurate determination of carotene in forage.

scholarly journals Determination of critical stresses during prestressing along the entire length of a circular-cylindrical shell

2021 ◽  
Vol 262 ◽  
pp. 01030
Author(s):  
Takhir Chapaev ◽  
Nurilla Noraliev
Keyword(s):  
Circular Cylindrical Shell ◽  
Energy Criterion ◽  
External Pressure ◽  
Entire Length ◽  
Problem Solution ◽  
Friction Forces ◽  
Factors Affecting ◽  
Critical Stresses ◽  
The Stability

In the Russian Federation, there is an urgent issue of grain storage and processing to be resolved through the reconstruction of old and construction of new storage facilities. Currently, the most common construction is represented by steel granaries, erected by rolling using prestressing in shells. The relevance of the problem of stability of the wall of a granary, taking into account the main factors, affecting the strength, requires further theoretical and experimental study. One of the most frequently used in solving stability problems is the energy criterion in the form of Ritz-Timoshenko, which makes it possible to determine critical stresses in the shells. In this case, the problem solution becomes simpler, it is easier to consider the effect of such factors as initial perfection, friction forces between the shell and the winding, as well as other features of the stability problem of a prestressed shell. This article analyses the granary wall stability against lateral external pressure of prestressed winding or bandages. For large tanks, prestressing is generated along the entire length of the shell, and in vertical cylindrical granaries, prestressing is generated on a part of the length (height) of the shell.

scholarly journals Determination of solubility, stability and degradation kinetics of morin hydrate in physiological solutions

RSC Advances ◽  
2018 ◽  
Vol 8 (50) ◽  
pp. 28836-28842 ◽  
Author(s):  
Ashok Kumar Jangid ◽  
Deep Pooja ◽  
Hitesh Kulhari
Keyword(s):  
Degradation Kinetics ◽  
Morin Hydrate ◽  
The Stability ◽  
Kinetics Of

The stability of morin hydrate depends on pH, temperature, and light.

Factors Affecting the Stability and Behavior of Grassy Odors in Drinking Water

1999 ◽  
Vol 40 (6) ◽  
pp. 287-292
Author(s):  
Djanette Khiari ◽  
Connie C. Young ◽  
Ginachi Amah ◽  
Quanfang Ye ◽  
Khalil Atasi ◽  
...  
Keyword(s):  
Drinking Water ◽  
Profile Analysis ◽  
Threshold Concentration ◽  
Factors Affecting ◽  
Hexenyl Acetate ◽  
Controlling Mechanism ◽  
The Stability ◽  
And Behavior ◽  
Flavor Profile Analysis ◽  
Kinetics Of

The presence of grassy-type odors in drinking water has frequently been determined by flavor-profile analysis (FPA). Previous work (Khiari et al., 1995) has identified cis-3-hexen-1-ol and cis-3-hexenyl acetate as the causes of these odors in laboratory experiments. Both chemicals possess very similar characteristics; however, cis-3-hexenyl acetate has a much lower odor threshold concentration (OTC) than its corresponding alcohol. In this study, both chemicals were identified by both sensory and chemical analyses separately or in combination in natural and treated waters. It was also found that the sensory and chemical characteristics of samples with grassy odors have a tendency to change upon storage and shipment. Hydrolysis was determined to be a major controlling mechanism for the degradation of cis-3-hexenyl acetate and the formation of cis-3-hexen-1-ol in aqueous solution. The kinetics of the hydrolysis of cis-3-hexenyl acetate to cis-3-hexen-1-ol was evaluated in bench-scale experiments. These studies showed the concentration of cis-3-hexen-1-ol and cis-3-hexenyl acetate to be strongly pH-dependent. This study shows that preservation by refrigeration and adjustment of pH to 4.6 were important steps to be taken when quantitation of the compounds is needed. However, the samples should be analyzed as quickly as possible.

scholarly journals Multicomponent spectrometric analysis of riboflavin and photoproducts and their kinetic applications

2014 ◽  
Vol 12 (6) ◽  
pp. 635-642 ◽  
Author(s):  
Muhammad Sheraz ◽  
Sadia Kazi ◽  
Sofia Ahmed ◽  
Kiran Qadeer ◽  
Marium Khan ◽  
...  
Keyword(s):  
Simultaneous Determination ◽  
Spectrometric Analysis ◽  
Factors Affecting ◽  
Kinetics Of Degradation ◽  
Analytical Procedures ◽  
Kinetics Of ◽  
Kinetic Treatment ◽  
Visible Spectrometry

AbstractRiboflavin (RF) is a light sensitive compound and is known to form a number of photoproducts. These photoproducts possess the same nucleus and may interfere in the analysis of RF by UV and visible spectrometry. Therefore, it is necessary to apply the methods of multicomponent spectrometric analysis to quantify the vitamin and its photoproducts accurately. Such methods are useful in the study of the kinetics of photodegradation reactions of RF to obtain accurate and reliable results. Any interference in these methods due to linear or nonlinear irrelevant absorption of the minor unknown products can be accounted for by the application of appropriate correction procedures prior to kinetic treatment. Various factors affecting the accuracy, precision and selectivity of these analytical procedures are also discussed. This review highlights the principles and applications of multicomponent spectrometric methods and their application to the simultaneous determination of RF and its major photoproducts in degraded solutions to evaluate the kinetics of degradation.

scholarly journals A study of the factors affecting the foaming properties of egg white – a review

2011 ◽  
Vol 24 (No. 3) ◽  
pp. 110-118 ◽  
Author(s):  
K. Lomakina ◽  
K. Míková
Keyword(s):  
Egg White ◽  
Foaming Properties ◽  
Factors Affecting ◽  
Foaming Ability ◽  
New Methods ◽  
The Stability ◽  
White Foam

Many foods are prepared using egg white, most of them being based on the foaming properties of egg white which are due to albumen proteins ability to encapsulate and retain air. Therefore, many scientists aim to find new methods to improve the volume and the stability of egg white foam. This paper is a review of various factors affecting the foaming ability of egg white.  

Identification and Photodegradation of Red Pigment from Serratia marcesce zl3

2015 ◽  
Vol 737 ◽  
pp. 349-352
Author(s):  
Lin Zhou ◽  
Shuang Zhu ◽  
Xin Huai Dong
Keyword(s):  
Light Intensity ◽  
Silica Gel ◽  
Column Chromatography ◽  
White Light ◽  
Red Pigment ◽  
Effect Of Ph ◽  
Factors Affecting ◽  
Light Stability ◽  
The Stability

Present study was aimed to identify and isolate the red pigment from Serratia marcesce zl3, and to investigate the factors affecting on the light stability of the purified red pigment. Silica gel and Sephadex LH-20 column chromatography were used for purification, identification was done by TLC, UV, FTIR and HPLC-MS techniques. The effect of pH and light intensity on the light stability of the purified red pigment prodigiosin was analyzed by TLC, UV and HPLC. The stability of identified prodigiosin pigment at pH 1, 3, 5 was superior to that at pH 7, 10, 14 according to the determination of OD535. Significant level of degradation of the prodigiosin was observed for 24 h, using 10 klx continuous white light. The effect of pH to the stability of prodidgiosin was partly reversible, while the degradation of prodigiosin under 4, 10, 20 klx white light was irreversible.

Extraction of dithiocarbamic acids from solutions of their salts

1982 ◽  
Vol 47 (11) ◽  
pp. 2876-2881 ◽  
Author(s):  
Drahomír Oktavec ◽  
Bohumil Síleš ◽  
Ján Remeň ◽  
Václav Konečný ◽  
Ján Garaj
Keyword(s):  
Aqueous Phase ◽  
Time Dependent ◽  
Absorption Bands ◽  
Decomposition Reactions ◽  
Maximum Extraction ◽  
The Stability ◽  
Kinetics Of ◽  
Alkali Salts ◽  
Nm Range

The extraction of dithiocarbamic acids with chloroform from aqueous phase containing their alkali salts has been investigated with regard to the fact that absorbing strongly in the 200-310 nm range, the acids interfere with the spectrophotometric determination of metals whose dithiocarbamate ligands exhibit their analytical absorption bands in that region. The amount of the dithiocarbamic acids formed depends on the kinetics of their formation and decomposition reactions and on the pH of the aqueous phase. The stability of the acids in chloroform extracts is highly time dependent. The maximum extraction of the acids (R2NCS2H) is attained at the following pH (R, pH): CH3 5.0, C2H5 5.9, C3H8 6.3, C4H9 6.8, C5H11 6.9, C6H13 6.9, iso-C3H7 7.2, iso-C4H9 6.9; for (CH3, iso-C3H7)NCS2H 7.3, C5H10NCS2H 7.2, C4H8ONCS2H 5.2.

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