Properties of aseptically packed ultra-high-temperature milk: II. Molecular weight changes of the casein components during storage

1972 ◽  
Vol 39 (3) ◽  
pp. 395-408 ◽  
Author(s):  
A. T. Andrews ◽  
G. C. Cheeseman
Keyword(s):  
Molecular Weight ◽  
High Temperature ◽  
Gel Filtration ◽  
Weight Changes ◽  
Ambient Temperatures ◽  
Uht Milk ◽  
Sediment Formation ◽  
Before And After ◽  
Polypeptide Chains ◽  
Ultra High Temperature

SummaryStorage of aseptically packed ultra-high-temperature (UHT) milk has been shown to be accompanied by pronounced changes in the molecular weight distribution of the pH 4·6 insoluble casein. These changes were both time-dependent and temperature-dependent, proceeding much more rapidly at 37 °C than at 30 °C, but even at 4 °C the changes were considerable. The proportions of high molecular weight material present before and after storage have been studied by gel filtration in dissociating solvents using Sephadex G-200. Measurements have also been made on casein material isolated from in-bottle sterilized milks and canned evaporated milk for comparison. The results of gel filtration have been compared with sedimentation coefficients recorded by ultracentrifugation and with changes in the content of amino groups titratable with trinitrobenzene-sulphonic acid. The results are compatible with the suggestion that the Maillard reaction occurred at ambient temperatures, and over a period of several months led to browning and sediment formation due to covalent cross-linking of polypeptide chains. The implications of this are discussed with reference to spoilage of UHT milk on storage and the phenomenon of gelation.

Ratio of Lactulose to Furosine as Indicator of Quality of Commercial Milks

1994 ◽  
Vol 57 (8) ◽  
pp. 737-739 ◽  
Author(s):  
NIEVES CORZO ◽  
TERESA DELGADO ◽  
ESPERANZA TROYANO ◽  
AGUSTIN OLANO
Keyword(s):  
High Temperature ◽  
Ambient Temperatures ◽  
Uht Milk ◽  
Milk Samples ◽  
Powder Milk ◽  
Reconstituted Milk ◽  
Ultra High Temperature

Storage of ultra high temperature (UHT) milk at high ambient temperatures gave rise to a decrease of the ratio of lactulose to furosine contents. The lactulose/furosine (Lu/Fu) ratio in UHT milks resulted to be around 16 times higher than in commercial powder milk samples so, the determination of the Lu/Fu ratio in freshly processed UHT milk seems to be useful to detect the presence of reconstituted milk.

scholarly journals Changes in Particle Size, Sedimentation, and Protein Microstructure of Ultra-High-Temperature Skim Milk Considering Plasmin Concentration and Storage Temperature

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2339
Author(s):  
So-Yul Yun ◽  
Jee-Young Imm
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Storage Temperature ◽  
Whey Proteins ◽  
Skim Milk ◽  
Storage Period ◽  
Sediment Analysis ◽  
Sediment Formation ◽  
And Storage ◽  
Ultra High Temperature

Age gelation is a major quality defect in ultra-high-temperature (UHT) pasteurized milk during extended storage. Changes in plasmin (PL)-induced sedimentation were investigated during storage (23 °C and 37 °C, four weeks) of UHT skim milk treated with PL (2.5, 10, and 15 U/L). The increase in particle size and broadening of the particle size distribution of samples during storage were dependent on the PL concentration, storage period, and storage temperature. Sediment analysis indicated that elevated storage temperature accelerated protein sedimentation. The initial PL concentration was positively correlated with the amount of protein sediment in samples stored at 23 °C for four weeks (r = 0.615; p < 0.01), whereas this correlation was negative in samples stored at 37 °C for the same time (r = −0.358; p < 0.01) due to extensive proteolysis. SDS-PAGE revealed that whey proteins remained soluble over storage at 23 °C for four weeks, but they mostly disappeared from the soluble phase of PL-added samples after two weeks’ storage at 37 °C. Transmission electron micrographs of PL-containing UHT skim milk during storage at different temperatures supported the trend of sediment analysis well. Based on the Fourier transform infrared spectra of UHT skim milk stored at 23 °C for three weeks, PL-induced particle size enlargement was due to protein aggregation and the formation of intermolecular β-sheet structures, which contributed to casein destabilization, leading to sediment formation.

scholarly journals Quality of ultra-high temperature treated milk available in Gazipur and Mymensingh of Bangladesh

2016 ◽  
Vol 44 (3) ◽  
pp. 132-136
Author(s):  
MY Arafat ◽  
R Habib ◽  
MSR Siddiki ◽  
MF Imam
Keyword(s):  
High Temperature ◽  
Specific Gravity ◽  
Viable Count ◽  
Total Viable Count ◽  
Total Solids ◽  
Uht Milk ◽  
Coliform Count ◽  
Milk Samples ◽  
Ultra High Temperature

This experiment was conducted to evaluate the quality of existing ultra-high temperature (UHT) treated milk available in two selected town markets of Bangladesh. A total of 27 UHT milk samples from three different brands–Pran Dairy (A), Aarong Dairy (B) and Farm Fresh (C) were collected from local markets at Mymensingh and Gazipur districts during the period of 1stSeptember to 29th November, 2014. Parameters studied in this experiment were organoleptic (flavour, consistency, colour and appearance), physic-chemical (specific gravity, acidity, total solids, solids-not-fat, fat, protein, lactose, and ash) and microbiological (Total Viable Count and Coliform Count). All the samples were similar in respect of color, flavor, taste and texture, and no significant difference was observed. However, significant differences were revealed (p<0.05) in case of specific gravity, acidity, total solids, solids-not-fat, and protein content. On the other hand, insignificant differences were found (p>0.05) in case of fat, lactose, and ash content. Total Viable Count and Coliform count were found to be nil in all the milk samples. Milk samples of Farm Fresh UHT milk were superior to other brands of UHT Milk in terms of contents of total solids (119.23±0.57 g/kg),fat (34.97±0.35g/kg), lactose (43.23±0.51g/kg), and ash (7.00±0.26g/kg). Though there were some fluctuations in all the parameters studied, all the milk samples conformed to the standard values for UHT milk, and in general all of the UHT milk samples studied in this experiment was of good quality.Bang. J. Anim. Sci. 2015. 44 (3):132-136

Comparison of milks processed by the direct and indirect methods of ultra-high-temperature sterilization: VI. Effects on sediment formation and clotting with enzymes

1973 ◽  
Vol 40 (2) ◽  
pp. 215-220 ◽  
Author(s):  
A. G. Perkin ◽  
M. J. Henschel ◽  
H. Burton
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Heat Treatments ◽  
Direct Process ◽  
Indirect Methods ◽  
Heated Milk ◽  
Sediment Formation ◽  
Sterilized Milk ◽  
Direct And Indirect Methods ◽  
Ultra High Temperature

SummaryWhen heat treatments of the same sporicidal effectiveness were given, directly heated ultra-high-temperature sterilized milk gave twice as much sediment as indirectly heated milk after storage at room temperature for 100 days. Both types of process reduced the rate of clotting of the milk with pepsin and rennin, but the effect of the indirect process was markedly greater than that of the direct process.

scholarly journals THE EFFECT OF WILD HONEY (Apis dorsata Fabr.) CONCENTRATIONS ON PH AND ORGANOLEPTIC VALUES OF ULTRA HIGH TEMPERATURE (UHT) MILK

2021 ◽  
Vol 1 (2) ◽  
pp. 142-152
Author(s):  
Selawati Palilati ◽  
Fahrullah ◽  
Ishak Korompot
Keyword(s):  
High Temperature ◽  
Ph Value ◽  
Average Score ◽  
Apis Dorsata ◽  
Significance Level ◽  
Uht Milk ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
Range Test ◽  
Ultra High Temperature

The research aims to observe the effect of addition wild honey (Apis dorsata Fabr.) on pH and organoleptic values of ultra high temperature milk (UHT). The research was  done using an experimental method using a non-factorial completely randomized design with five levels using SPSS 16. Different concentrations of wild honey (A1= control; A2= 5%; A3= 10%; A4= 15% and A5=20%) were used. The data was statistically analyzed using analysis of variance (ANOVA) with 5% significance level and further processed with Duncan's Multiple Range Test (DMRT). Organoleptic tests for colour, taste and overall preference were also done using qualitative tests (scores). The value of pH gave a significant value (P<0,01) between treatment. The higher the use of  wild honey concentration, the lower the pH value produced. The higher the concentration of wild honey, the higher the organoleptic value. The best treatment in terms of colour, taste, and level of preference was observed in the sample with the 20% honey concentration, each of which resulted in an average score of 4.

The effect of dissolved O2 on the changes occurring in the flavour of ultra-high-temperature milk during storage

1973 ◽  
Vol 40 (2) ◽  
pp. 169-177 ◽  
Author(s):  
J. G. Zadow ◽  
R. Birtwistle
Keyword(s):  
High Temperature ◽  
Storage Temperature ◽  
Marked Decrease ◽  
Uht Milk ◽  
Noticeable Improvement ◽  
High Storage Temperature ◽  
High Storage ◽  
Dissolved O2 ◽  
Storage Temperatures ◽  
Ultra High Temperature

SummaryUltra-high-temperature (UHT)-treated milks containing a range of dissolved O2 levels were prepared using both direct and indirect UHT processes. The O2 content of directly processed UHT milk had a significant influence on the changes in the level of cooked flavour in the product during storage over a 12-week period. At storage temperatures of 2 and 20°C, a noticeable improvement in flavour could be achieved by O2 control. In general, samples with a head-space sufficient to yield an initial of 60–100 mm were most preferred. The effect of O2 control on samples stored at 38°C was only minor when compared with the marked decrease in acceptability of flavour occurring due to the high storage temperature.Directly processed samples stored at 20°C all gelled at 14 weeks while those stored at 2°C showed no evidence of gelation after 36 weeks. Storage at 38°C gave rapid flavour deterioration, bitterness at 7 weeks and gelation at 10 weeks.All indirectly processed samples were found to be severely cooked under the conditions employed, and any differences in flavour due to differing O2 contents were masked by the intensity of this flavour.

scholarly journals Purification of the Thy-1 molecule, a major cell-surface glycoprotein of rat thymocytes

1975 ◽  
Vol 151 (3) ◽  
pp. 685-697 ◽  
Author(s):  
M Letarte-Muirhead ◽  
A N Barclay ◽  
A F Williams
Keyword(s):  
Molecular Weight ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Apparent Molecular Weight ◽  
Surface Glycoprotein ◽  
Cell Surface Glycoprotein ◽  
Lentil Lectin ◽  
Polypeptide Chains

The Thy-1-molecule, which was identified by its antigenic activities, has been purified from rat thymocytes. The purification involved preparation of crude membranes and solubilization in deoxycholate, followed by gel filtration and affinity chromatography on antibody or lectin columns. In all cases the purified molecule was a glycoprotein that did not form higher polymers and was not associated with other polypeptide chains. The Thy-1 glycoprotein could be found in two forms, one binding to lentil lectin, the other not. Both forms had the same detectable antigens and were of a similar but not identical size. After sodium dodecyl sulphate-polyacrylamide-gel electrophoresis the apparent molecular weight of Thy-1 binding to lentil lectin was 25 000, whereas that not binding to the lectin was 27 000, with heterogeneity towards forms of apparently higher molecular weight.

Changes on storage in milk processed by ultra-high-temperature sterilization

1971 ◽  
Vol 38 (3) ◽  
pp. 323-332 ◽  
Author(s):  
Ruth Samel ◽  
R. W. V. Weaver ◽  
D. B. Gammack
Keyword(s):  
High Temperature ◽  
Casein Micelles ◽  
Uht Milk ◽  
Milk Samples ◽  
C Storage ◽  
Progressive Loss ◽  
Degree Of Stability ◽  
The Stability ◽  
High Degree ◽  
Ultra High Temperature

SummarySamples of commercially processed ultra-high-temperature (UHT) milk were stored at 4, 20, 30 and 37°C for up to 2 years or until gelation occurred.The stability of the proteins to ethanol, calcium ions and rennet decreased with time of storage. However, preliminary autoclaving of the UHT milk induced a high degree of stability.The extent of protein decomposition that had occurred in the UHT milk samples depended on the time and temperature of storage. There was negligible decomposition when the samples had been autoclaved before storage at 4 and 20°C. Storage at 37°C led to significant decomposition.UHT milk samples gelled after being stored for 13 months at 4, 20 and 30°C, but not at 37°C. The autoclaved milk was still fluid after being stored for 2 years at these temperatures.The time of onset of gelation did not depend on the degree of protein breakdown, and it seemed therefore that proteolysis was not the primary cause of gelation on storage.It was concluded that the proteins in UHT milk underwent several changes on storage that were apparently independent of each other and led ultimately to coagulation of the milk. These changes included proteolysis, and a progressive loss of stability under conditions that favoured aggregation of the casein micelles.

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