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.

scholarly journals Comparative Assessment of Tubular Ceramic, Spiral Wound, and Hollow Fiber Membrane Microfiltration Module Systems for Milk Protein Fractionation

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 692
Author(s):  
Roland Schopf ◽  
Florian Schmidt ◽  
Johanna Linner ◽  
Ulrich Kulozik
Keyword(s):  
Hollow Fiber ◽  
Milk Protein ◽  
Hollow Fiber Membrane ◽  
Comparative Assessment ◽  
Transmission Factor ◽  
Transmembrane Pressure ◽  
Protein Fractionation ◽  
Flow Conditions ◽  
Local Pressure ◽  
Spiral Wound

The fractionation efficiency of hollow fiber membranes (HFM) for milk protein fractionation was compared to ceramic tubular membranes (CTM) and spiral wound membranes (SWM). HFM combine the features of high membrane packing density of SWM and the more defined flow conditions and better control of membrane fouling in the open flow channel cross-sections of CTM. The aim was to comparatively analyze the effect of variations in local pressure and flow conditions while using single industrially sized standard modules with similar dimensions and module footprints (module diameter and length). The comparative assessment with varied transmembrane pressure was first applied for a constant feed volume flow rate of 20 m3 h−1 and, secondly, with the same axial pressure drop along the modules of 1.3 bar m−1, similar to commonly applied crossflow velocity and wall shear stress conditions at the industrial level. Flux, transmission factor of proteins (whey proteins and serum caseins), and specific protein mass flow per area membrane and per volume of module installed were determined as the evaluation criteria. The casein-to-whey protein ratios were calculated as a measure for protein fractionation effect. Results obtained show that HFM, which so far are under-represented as standard module types in industrial dairy applications, appear to be a competitive alternative to SWM and CTM for milk protein fractionation.

scholarly journals Optimization of protein fractionation by skim milk microfiltration: Choice of ceramic membrane pore size and filtration temperature

2016 ◽  
Vol 99 (8) ◽  
pp. 6164-6179 ◽  
Author(s):  
Camilla Elise Jørgensen ◽  
Roger K. Abrahamsen ◽  
Elling-Olav Rukke ◽  
Anne-Grethe Johansen ◽  
Reidar B. Schüller ◽  
...  
Keyword(s):  
Pore Size ◽  
Ceramic Membrane ◽  
Skim Milk ◽  
Protein Fractionation ◽  
Membrane Pore ◽  
Membrane Pore Size

Determination of total antioxidant capacity of milk by CUPRAC and ABTS methods with separate characterisation of milk protein fractions

2015 ◽  
Vol 82 (2) ◽  
pp. 177-184 ◽  
Author(s):  
Sema Demirci Çekiç ◽  
Aslı Demir ◽  
Kevser Sözgen Başkan ◽  
Esma Tütem ◽  
Reşat Apak
Keyword(s):  
Antioxidant Capacity ◽  
Total Antioxidant Capacity ◽  
Milk Protein ◽  
Skim Milk ◽  
Protein Fractions ◽  
Relative Standard Error ◽  
Antioxidant Power ◽  
Antioxidant Capacities ◽  
Relative Standard ◽  
Total Antioxidant

Most milk-applied antioxidant assays in literature are based on the isolation and quantification of individual antioxidative compounds, whereas total antioxidant capacity (TAC) gives a more holistic picture due to cooperative action of antioxidants. Recently, the cupric reducing antioxidant capacity (CUPRAC) method has been modified to measure the antioxidant capacities of thiol-containing proteins, where the classical ammonium acetate buffer – that may otherwise precipitate proteins– was replaced with concentrated urea buffer (able to expose embedded thiol groups of proteins to oxidative attack) adjusted to pH 7.0. Thus, antioxidant capacity of milk was investigated with two competing TAC assays, namely CUPRAC and ABTS (2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid))/persulphate, because only these assays were capable of evaluating protein contribution to the observed TAC value. As milk fat caused turbidity, experiments were carried out with skim milk or defatted milk samples. To determine TAC, modified CUPRAC method was applied to whole milk, separated and redissolved protein fractions, and the remaining liquid phase after necessary operations. Both TAC methods were investigated for their dilution sensitivity and antioxidant power assessment of separate milk fractions such as casein and whey. Proteins like β-lactoglobulin and casein (but not simple thiols) exhibited enhanced CUPRAC reactivity with surfactant (SDS) addition. Addition of milk protein fractions to whole skim milk produced significant ‘negative-biased’ deviations (up to −26% relative standard error) from TAC absorbance additivity in the application of the ABTS method, as opposed to that of the CUPRAC method less affected by chemical deviations from Beer's law thereby producing much smaller deviations from additivity (i.e. the property of additivity is valid when the measured TAC of a mixture is equal to the sum of individual antioxidant capacities of its constituents).

Effects of selective layer properties of ceramic multi-channel microfiltration membranes on the milk protein fractionation

2021 ◽  
Vol 259 ◽  
pp. 118050
Author(s):  
Simon Schiffer ◽  
Andreas Matyssek ◽  
Martin Hartinger ◽  
Peter Bolduan ◽  
Peter Mund ◽  
...  
Keyword(s):  
Milk Protein ◽  
Protein Fractionation ◽  
Selective Layer ◽  
Microfiltration Membranes

Survival of Borrelia burgdorferi in Whole Milk, Low Fat Milk, and Skim Milk at 34°C and in Skim Milk at 5°C

1991 ◽  
Vol 54 (7) ◽  
pp. 532-536 ◽  
Author(s):  
GERALDINE M. FARRELL ◽  
AHMED E. YOUSEF ◽  
ELMER H. MARTH
Keyword(s):  
Borrelia Burgdorferi ◽  
Milk Protein ◽  
Skim Milk ◽  
Storage Period ◽  
Most Probable Number ◽  
Low Fat ◽  
Probable Number ◽  
Whole Milk ◽  
The Mean ◽  
D Values

Autoclaved whole milk, low-fat milk, protein-fortified skim milk and regular skim milk were inoculated to contain ca. 105 to 106 Borrelia burgdorferi strains 35210, 35211, or EBNI/ml and stored at 34°C for 16 d. Similarly inoculated skim milk also was held at 5°C for 46 d. Numbers of survivors were estimated by the Most Probable Number (MPN) technique. In all instances, numbers of B. burgdorferi decreased over the storage period. At 34°C, no strain of B. burgdorferi was detected after day 12. The mean D-values, at 34°C, for strains 35210, 35211, and EBNI were 2.2, 2.4, and 2.2 d, respectively. The mean D-values, at 34°C, for all strains in whole milk, low-fat milk, protein-fortified skim milk, and regular skim milk were 2.4, 2.3, 1.9, and 2.4 d, respectively. At 5°C, spirochete numbers in regular skim milk decreased, but all three strains remained at a detectable level for 46 d. The mean D-values, at 5°C, for strains 35210, 35211, and EBNI were 12, 15, and 12 d, respectively.

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.

THE NUTRITIONAL VALUE AND TRYPSIN INHIBITOR CONTENT OF PROCESSED SOYBEANS FOR LAMB MILK REPLACERS

1974 ◽  
Vol 54 (3) ◽  
pp. 337-346 ◽  
Author(s):  
A. D. L. GORRILL ◽  
J. W. G. NICHOLSON ◽  
J. D. JONES
Keyword(s):  
Trypsin Inhibitor ◽  
Nutritional Value ◽  
Milk Protein ◽  
Skim Milk ◽  
Milk Replacer ◽  
Dietary Nitrogen ◽  
Nitrogen Intake ◽  
Rat Growth ◽  
Protein Milk ◽  
Milk Replacers

Full-fat soybean flour (FFSF) was prepared from dehulled soybeans by extraction with water and NaHCO3, colloid milling, cooking and spray-drying. The apparent destruction of soybean trypsin inhibitor (SBTI) prior to cooking was variable. A rat bioassay for SBTI was conducted with diets containing 1.6% nitrogen from cooked and uncooked FFSF. Cooking the FFSF for 1 h markedly improved rat growth (4.0 vs. 2.6 g/day, P < 0.01) and weight gain/protein intake (3.3 vs. 2.5, P < 0.01). The cooked FFSF was also used in three lamb experiments to supply 0, 30, 50 or 60% of the nitrogen in milk replacers. Apparent digestion coefficients for energy were 88, 92 and 92% (P < 0.05), and for nitrogen were 94, 95 and 92% for lambs fed milk replacers containing 0, 30 or 60% of the nitrogen from FFSF. The percent of total nitrogen intake retained was 61, 63 and 55, respectively. The lower energy digestion by lambs on the zero FFSF diet was attributed to the fat being supplied only by tallow. In another experiment, when unrefined soybean oil, equal to that supplied by FFSF, was used in place of the tallow in an all-milk protein milk replacer, energy digestion by lambs was greater than with a milk replacer containing FFSF. Milk replacers containing a mixture of spray-dried skim milk and whey powders resulted in higher nitrogen digestion and retention by lambs than did a mixture of roller-dried buttermilk and whey powders, when 50% of the nitrogen was supplied by FFSF. It was concluded that milk replacers containing up to 60% of the total dietary nitrogen from FFSF were utilized satisfactorily by milk-fed lambs.

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.

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