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.

High-pressure treatment of milk: effects on casein micelle structure and on enzymic coagulation

2000 ◽  
Vol 67 (1) ◽  
pp. 31-42 ◽  
Author(s):  
ERIC C. NEEDS ◽  
ROBERT A. STENNING ◽  
ALISON L. GILL ◽  
VICTORIA FERRAGUT ◽  
GILLIAN T. RICH
Keyword(s):  
Whey Proteins ◽  
Skim Milk ◽  
Casein Micelle ◽  
Casein Micelles ◽  
Dense Networks ◽  
Protein Levels ◽  
Micelle Structure ◽  
Milk Casein ◽  
Β Lactoglobulin ◽  
Gel Network

High isostatic pressures up to 600 MPa were applied to samples of skim milk before addition of rennet and preparation of cheese curds. Electron microscopy revealed the structure of rennet gels produced from pressure-treated milks. These contained dense networks of fine strands, which were continuous over much bigger distances than in gels produced from untreated milk, where the strands were coarser with large interstitial spaces. Alterations in gel network structure gave rise to differences in rheology with much higher values for the storage moduli in the pressure-treated milk gels. The rate of gel formation and the water retention within the gel matrix were also affected by the processing of the milk. Casein micelles were disrupted by pressure and disruption appeared to be complete at treatments of 400 MPa and above. Whey proteins, particularly β-lactoglobulin, were progressively denatured as increasing pressure was applied, and the denatured β-lactoglobulin was incorporated into the rennet gels. Pressure-treated micelles were coagulated rapidly by rennet, but the presence of denatured β-lactoglobulin interfered with the secondary aggregation phase and reduced the overall rate of coagulation. Syneresis from the curds was significantly reduced following treatment of the milk at 600 MPa, probably owing to the effects of a finer gel network and increased inclusion of whey protein. Levels of syneresis were more similar to control samples when the milk was treated at 400 MPa or less.

Heat-induced interactions of β-lactoglobulin and α-lactalbumin with the casein micelle in pH-adjusted skim milk

2000 ◽  
Vol 10 (8) ◽  
pp. 509-518 ◽  
Author(s):  
David J Oldfield ◽  
Harjinder Singh ◽  
Michael W Taylor ◽  
Kevin N Pearce
Keyword(s):  
Skim Milk ◽  
Casein Micelle ◽  
Β Lactoglobulin

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 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.

scholarly journals Transmission of Major and Minor Serum Proteins during Microfiltration of Skim Milk: Effects of Pore Diameters, Concentration Factors and Processing Stages

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 888
Author(s):  
Zhibin Li ◽  
Dasong Liu ◽  
Shu Xu ◽  
Wenjin Zhang ◽  
Peng Zhou
Keyword(s):  
Serum Proteins ◽  
Skim Milk ◽  
Transmembrane Pressure ◽  
Recovery Yield ◽  
Membrane Flux ◽  
Crossflow Velocity ◽  
Inner Diameter ◽  
Concentration Factors ◽  
20 Nm ◽  
Β Lactoglobulin

Effects of pore diameters (100, 50, and 20 nm), concentration factors (1–8) and processing stages (1–5) on the transmission of major serum proteins (β-lactoglobulin and α-lactalbumin) and minor serum proteins (immunoglobulin (Ig) G, IgA, IgM, lactoferrin (LF), lactoperoxidase (LPO), xanthine oxidase (XO)) during ceramic microfiltration (MF) of skim milk were studied. Holstein skim milk was microfiltered at a temperature of 50 °C, a transmembrane pressure of 110 kPa and a crossflow velocity of 6.7 m/s, using a tubular single stainless steel module that consisted of three ceramic tubes, each with 19 channels (3.5 mm inner diameter) and a length of 0.5 m. For MF with 100 nm and 50 nm pore diameters, the recovery yield of major serum proteins in permeate was 44.3% and 44.1%, while the recovery yield of minor serum proteins was slightly less by 0%–8% than 50 nm MF. MF with 20 nm pore diameters showed a markedly lower (by 12%–45%) recovery yield for both major and minor serum proteins, corresponding with its lower membrane flux. Flux sharply decreased with an increasing concentration factor (CF) up to four, and thereafter remained almost unchanged. Compared to the decrease (88%) of flux, the transmission of major and minor serum proteins was decreased by 4%–15% from CF = one to CF = eight. With increasing processing stages, the flux gradually increased, and the recovery yield of both major and minor proteins in the permeate gradually decreased and reached a considerably low value at stage five. After four stages of MF with 100 nm pore diameter and a CF of four for each stage, the cumulative recovery yield of major serum proteins, IgG, IgA, IgM, LF, LPO, and XO reached 95.7%, 90.8%, 68.5%, 34.1%, 15.3%, 39.1% and 81.2% respectively.

570. A medium for the simultaneous enumeration and preliminary identification of milk microflora

1955 ◽  
Vol 22 (1) ◽  
pp. 43-47 ◽  
Author(s):  
Kathleen O. Donovan ◽  
J. M. Vincent
Keyword(s):  
Acid Production ◽  
Skim Milk ◽  
Biochemical Properties ◽  
Viable Count ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Pasteurized Milk ◽  
Preliminary Identification

A medium has been developed that permits the viable count of milk bacteria to be combined with the determination of biochemical properties likely to be important in milk itself. This has involved the modification of standard glucose-tryptone skim-milk agar by incorporation of two indicators to detect alkali as well as acid production, substitution of lactose for glucose, and increasing the quantity of skim milk for the detection of proteolysis and casein precipitation. The medium has proved particularly valuable in the study of the thermoduric flora of pasteurized milk. The phenomenon of casein precipitation is, however, less reliably determined than are changes in hydrogen-ion concentration and proteolysis.

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 Development and Validation of a Method for the Quantification of Milk Proteins in Food Products Based on Liquid Chromatography with Mass Spectrometric Detection

2011 ◽  
Vol 94 (4) ◽  
pp. 1043-1059 ◽  
Author(s):  
Petra Lutter ◽  
Véronique Parisod ◽  
Hans Weymuth
Keyword(s):  
Milk Powder ◽  
Skim Milk ◽  
Internal Standard ◽  
Milk Proteins ◽  
Skim Milk Powder ◽  
Selected Reaction Monitoring ◽  
Validation Data ◽  
Development And Validation ◽  
Protein Rich ◽  
Β Lactoglobulin

Abstract The protection of allergic consumers is crucial to the food industry. Therefore, accurate methods for the detection of food allergens are required. Targeted detection of selected molecules by MS combines high selectivity with accurate quantifcation. A confrmatory method based on LC/selected reaction monitoring (SRM)-MS/MS was established and validated for the quantifcation of milk traces in food. Tryptic peptides of the major milk proteins β-lactoglobulin, β-casein, αS2-casein, and κ-casein were selected as quantitative markers. Precise quantifcation was achieved using internal standard peptides containing isotopically labeled amino acids. For each peptide, qualifer and quantifer fragments were selected according to Commission Decision 2002/657/EC. A simple sample preparation method was established without immunoaffnity or SPE enrichment steps for food matrixes containing different amounts of protein, such as baby food, breakfast cereals, infant formula, and cereals. Intermediate reproducibility, repeatability, accuracy, and measurement uncertainty were determined for each matrix. LOD values of 0.2–0.5 mg/kg, e.g., for β-lactoglobulin, were comparable to those obtained with ELISA kits. An LOQ of approximately 5 mg/kg, expressed as mass fraction skim milk powder, was validated in protein-rich infant cereals. The obtained validation data show that the described LC/SRM-MS/MS approach can serve as a confrmatory method for the determination of milk traces in selected food matrixes.

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