Influence of processing temperature on flux decline during skim milk ultrafiltration

2018 ◽  
Vol 195 ◽  
pp. 322-331 ◽  
Author(s):  
Kenneth S.Y. Ng ◽  
Dave E. Dunstan ◽  
Gregory J.O. Martin
Keyword(s):  
Skim Milk ◽  
Processing Temperature ◽  
Flux Decline

scholarly journals Influence of Processing Temperature on Membrane Performance and Characteristics of Process Streams Generated during Ultrafiltration of Skim Milk

Foods ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1721
Author(s):  
Ritika Puri ◽  
Upendra Singh ◽  
James A. O’Mahony
Keyword(s):  
Inverse Relationship ◽  
Skim Milk ◽  
Biochemical Properties ◽  
Processing Temperature ◽  
Casein Micelle ◽  
Plasmin Activity ◽  
Membrane Performance ◽  
Flux Decline ◽  
Dairy Ingredients ◽  
Β Lactoglobulin

The effects of processing temperature on filtration performance and characteristics of retentates and permeates produced during ultrafiltration (UF) of skim milk at 5, 20, and 50 °C were investigated. The results indicate that despite higher flux at 50 °C, UF under these conditions resulted in greater fouling and rapid flux decline in comparison with 5 and 20 °C. The average casein micelle diameter was higher in retentate produced at 5 and 20 °C. The retentate analysed at 5 °C displayed higher viscosity and shear thinning behaviour as compared to retentate analysed at 20 and 50 °C. Greater permeation of calcium and phosphorus was observed at 5 and 20 °C in comparison with 50 °C, which was attributed to the inverse relationship between temperature and solubility of colloidal calcium phosphate. Permeation of α-lactalbumin was observed at all processing temperatures, with permeation of β-lactoglobulin also evident during UF at 50 °C. All UF retentates were shown to have plasmin activity, while lower activity was measured in retentate produced at 5 °C. The findings revealed that UF processing temperature influences the physicochemical, rheological, and biochemical properties of, and thereby govern the resulting quality and functionality of, retentate- and permeate-based dairy ingredients.

Influence of processing temperature and seasonal change in diet on lipase activity and lipolysis during the mechanical separation of bovine milk

1985 ◽  
Vol 52 (2) ◽  
pp. 255-266 ◽  
Author(s):  
Eric C. Needs ◽  
Malcolm Anderson ◽  
Stuart J. Payne ◽  
Elizabeth A. Ridout
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Seasonal Change ◽  
Lipase Activity ◽  
Bovine Milk ◽  
Skim Milk ◽  
Relative Activity ◽  
Heat Inactivation ◽  
Processing Temperature ◽  
Original Activity

SUMMARYThe effect of separating conditions on lipase activity and free fatty acid levels in preheated milk, cream and skim milk was measured on nine occasions during a 12-week period covering the seasonal change from winter feeding to summertime grazing. This change consisted of four periods each representing a different type of forage intake, namely: silage, kale, daytime grazing and 24 h grazing. Milk was separated at 30, 40, 50 and 60°C with preheating times of 10, 25 and 55 s. Results were expressed both as absolute values and in terms of changes relative to the original unheated milk. Lipase activity and free fatty acid concentration were significantly reduced as separation temperature increased but were not influenced by holding time. The loss of activity in cream was progressive so that at 60°C only 40% of the original activity remained. Up to 50°C little change occurred in preheated milk or skim milk activity, while at 60°C 83 and 76% respectively of the original activity remained. The amount of activity calculated to be associated with the fat fraction of the cream also decreased with temperature. Activity varied significantly with date; maximum values were observed during the first 3 weeks of summertime grazing. Relative activity values indicated that the susceptibility of milk lipase to heat inactivation also varied with date. Lipolysis was also significantly affected by date. Cream free fatty acid levels were lower during the period of daytime grazing and were significantly higher than those in preheated milk. The correlation between lipase activity and free fatty acid levels was generally poor, accounting for between 0 and 34% of the variance. Possible reasons for the effect of separating temperature on lipolysis in cream are discussed.

scholarly journals Mechanisms of flux decline in skim milk ultrafiltration: A review

2017 ◽  
Vol 523 ◽  
pp. 144-162 ◽  
Author(s):  
Kenneth S.Y. Ng ◽  
Malavika Haribabu ◽  
Dalton J.E. Harvie ◽  
Dave E. Dunstan ◽  
Gregory J.O. Martin
Keyword(s):  
Skim Milk ◽  
Flux Decline

scholarly journals Effect of Temperature-Dependent Bacterial Growth during Milk Protein Fractionation by Means of 0.1 µM Microfiltration on the Length of Possible Production Cycle Times

Membranes ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 326
Author(s):  
Simon Schiffer ◽  
Ulrich Kulozik
Keyword(s):  
Milk Protein ◽  
Skim Milk ◽  
Effect Of Temperature ◽  
Production Cycle ◽  
Processing Temperature ◽  
Microbial Count ◽  
Operational Mode ◽  
Protein Fractionation ◽  
Ph Change ◽  
Filtration Time

This study determined the maximum possible filtration time per filtration cycle and the cumulated number of operational hours per year as a function of the processing temperature during milk protein fractionation by 0.1 µm microfiltration (MF) of pasteurized skim milk. The main stopping criteria were the microbial count (max. 105 cfu/mL) and the slope of the pH change as a function of filtration time. A membrane system in a feed and bleed configuration with partial recirculation of the retentate was installed, resembling an industrial plants’ operational mode. Filtration temperatures of 10, 14, 16, 20, and 55 °C were investigated to determine the flux, pH, and bacterial count. While the processing time was limited to 420 min at a 55 °C filtration temperature, it could exceed 1440 min at 10 °C. These data can help to minimize the use of cleaning agents or mixing phase losses by reducing the frequency of cleaning cycles, thus maximizing the active production time and reducing the environmental impact.

Ultrafiltration of Skim Milk at High Temperature

1979 ◽  
Vol 42 (12) ◽  
pp. 958-960 ◽  
Author(s):  
V. K. SOOD ◽  
F. V. KOSIKOWSKI
Keyword(s):  
Alkaline Phosphatase ◽  
Protein Denaturation ◽  
Whey Proteins ◽  
Processing Condition ◽  
Microbiological Quality ◽  
Skim Milk ◽  
Processing Temperature ◽  
High Flux ◽  
Flux Rate

Raw skim milk was selectively concentrated at 60 C by ultrafiltration and diafiltration procedures in an Abcor UF-22S unit equipped with high flux membranes. The thermal effect on flux rate, microbiological quality of the retentate and whey protein denaturation were observed under this processing condition. The higher processing temperature increased flux rate, improved microbiological quality and expanded the possibility of denaturing whey proteins, particularly with diafiltration. Composition of the product was normal and alkaline phosphatase negative.

scholarly journals Effect of Ultrafiltration of Milk Prior to Fermentation on Mass Balance and Process Efficiency in Greek-Style Yogurt Manufacture

Foods ◽  
2018 ◽  
Vol 7 (9) ◽  
pp. 144 ◽  
Author(s):  
Adriana Paredes Valencia ◽  
Alain Doyen ◽  
Scott Benoit ◽  
Manuele Margni ◽  
Yves Pouliot
Keyword(s):  
Energy Consumption ◽  
Membrane Fouling ◽  
Skim Milk ◽  
Solid Content ◽  
Reduction Factor ◽  
Process Efficiency ◽  
Total Flux ◽  
Whey Permeate ◽  
Membrane Performance ◽  
Flux Decline

Ultrafiltration (UF) can be used to concentrate yogurt to produce Greek-style yogurt (GSY) (UF-YOG), but this generates acid whey permeate, which is an environmental issue. However, when UF is applied before fermentation (UF-MILK), a nonacidified whey permeate is generated. For this study, two model GSYs (UF-YOG and UF-MILK) were produced to compare the composition, UF performance, and energy consumption of the two processes. For UF-MILK, skim milk was ultrafiltered with a 30 kDa spiral-wound UF membrane to achieve a 3× volume reduction factor (VRF). The retentate was fermented to a pH of 4.5. The UF-YOG process was the same except that regular yogurt was ultrafiltered. Both GSYs had similar protein (~10%) and solid content (~17%). As expected, lactic acid/lactate was not detected in UF-MILK permeate, while 7.3 g/kg was recovered from the UF-YOG permeate. Permeation flux values (11.6 to 13.3 L m−2 h−1) and total flux decline (47% to 50%) were constant during UF-MILK, whereas drastic decreases in these two membrane performance indicators (average flux: 38.5 to 10.9 L m−2 h−1; total flux decline: 2% to 38%) were calculated for UF-YOG. Moreover, for UF-YOG, UF membrane performance never recovered, even when drastic and repeated cleaning steps were applied. Energy consumption was 1.6 kWh/kg GSY and remained constant for UF-MILK, whereas it increased from 0.6 to 1.5 kWh/kg GSY for UF-YOG. Our results show that, although the composition of GSYs was similar for both processes, the UF step of yogurt concentration affected process efficiency due to drastic and permanent membrane fouling.

Influence of diafiltration on flux decline during skim milk ultrafiltration

2018 ◽  
Vol 87 ◽  
pp. 67-74 ◽  
Author(s):  
Kenneth S.Y. Ng ◽  
Dave E. Dunstan ◽  
Gregory J.O. Martin
Keyword(s):  
Skim Milk ◽  
Flux Decline

Interactions Between Al and Cr Thin Films

1976 ◽  
Vol 34 ◽  
pp. 638-639
Author(s):  
R. M. Anderson ◽  
T. M. Reith ◽  
M. J. Sullivan ◽  
E. K. Brandis
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Vacuum System ◽  
Processing Temperature ◽  
Diffusion Couples ◽  
Electronic Circuits ◽  
Intermetallic Formation ◽  
Si Substrates ◽  
Aluminum Silicon

Thin films of aluminum or aluminum-silicon can be used in conjunction with thin films of chromium in integrated electronic circuits. For some applications, these films exhibit undesirable reactions; in particular, intermetallic formation below 500 C must be inhibited or prevented. The Al films, being the principal current carriers in interconnective metal applications, are usually much thicker than the Cr; so one might expect Al-rich intermetallics to form when the processing temperature goes out of control. Unfortunately, the JCPDS and the literature do not contain enough data on the Al-rich phases CrAl7 and Cr2Al11, and the determination of these data was a secondary aim of this work.To define a matrix of Cr-Al diffusion couples, Cr-Al films were deposited with two sets of variables: Al or Al-Si, and broken vacuum or single pumpdown. All films were deposited on 2-1/4-inch thermally oxidized Si substrates. A 500-Å layer of Cr was deposited at 120 Å/min on substrates at room temperature, in a vacuum system that had been pumped to 2 x 10-6 Torr. Then, with or without vacuum break, a 1000-Å layer of Al or Al-Si was deposited at 35 Å/s, with the substrates still at room temperature.

Strain analysis in composite ceramics

1986 ◽  
Vol 44 ◽  
pp. 494-497
Author(s):  
W. M. Kriven
Keyword(s):  
Strain Field ◽  
Strain Analysis ◽  
Processing Temperature ◽  
Transformation Toughening ◽  
Zirconia Ceramics ◽  
Volume Increase ◽  
Analysis Technique ◽  
Fundamental Understanding ◽  
Contrast Analysis ◽  
Elastic Strain Field

Significant progress towards a fundamental understanding of transformation toughening in composite zirconia ceramics was made possible by the application of a TEM contrast analysis technique for imaging elastic strains. Spherical zirconia particles dispersed in a large-grained alumina matrix were examined by 1 MeV HVEM to simulate bulk conditions. A thermal contraction mismatch arose on cooling from the processing temperature of 1500°C to RT. Tetragonal ZrO2 contracted amisotropically with α(ct) = 16 X 10-6/°C and α(at) = 11 X 10-6/°C and faster than Al2O3 which contracted relatively isotropically at α = 8 X 10-6/°C. A volume increase of +4.9% accompanied the transformation to monoclinic symmetry at room temperature. The elastic strain field surrounding a particle before transformation was 3-dimensionally correlated with the internal crystallographic orientation of the particle and with the strain field after transformation. The aim of this paper is to theoretically and experimentally describe this technique using the ZrO2 as an example and thereby to illustrate the experimental requirements Tor such an analysis in other systems.

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