Manufacture of a novel cultured micellar casein concentrate ingredient for emulsifying salt free process cheese products applications

Micellar casein concentrate (MCC) is a high protein ingredient that is typically produced using 3 stages of microfiltration with a 3× concentration factor and diafiltration. Acid curd is an acid protein concentrate, which can be obtained by precipitating the casein at pH 4.6 (isoelectric point) using starter cultures or direct acids without the use of rennet. Process cheese product (PCP) is a dairy food prepared by blending dairy ingredients with nondairy ingredients and then heating the mixture to get a product with an extended shelf-life. Emulsifying salts are critical for the desired functional characteristics of PCP because of their role in calcium sequestration and pH adjustment. The objectives of this study were to develop a process to produce a novel cultured micellar casein concentrate ingredient (cMCC; culture-based acid curd) and to produce PCP without emulsifying salts using different combinations of protein from cMCC and MCC in the formulations (2.0:1.0, 1.9:1.1, and 1.8:1.2). Skim milk was pasteurized at 76°C for 16 s and then microfiltered in 3 microfiltration stages using graded permeability ceramic membranes to produce liquid MCC (11.15% total protein; TPr and 14.06% total solids; TS). Part of the liquid MCC was spray dried to produce MCC powder (75.77% TPr and 97.84% TS). The rest of the MCC was used to produce cMCC (86.9% TPr and 96.4% TS). Three PCP treatments were formulated with different ratios of cMCC:MCC, including 2.0:1.0, 1.9:1.1, and 1.8:1.2 on the protein basis. The composition of PCP was targeted to 19.0% protein, 45.0% moisture, 30.0% fat, and 2.4% salt. This trial was repeated 3 times using different batches of cMCC and MCC powders. All PCP were evaluated for their final functional properties. No significant differences were detected in the composition of PCP made with different ratios of cMCC and MCC except for the pH. The pH was expected to increase slightly with elevating the MCC amount in the PCP formulations. The end apparent viscosity was significantly higher in 2.0:1.0 formulation (4,305 cP) compared with 1.9:1.1 (2,408 cP) and 1.8:1.2 (2,499 cP). The hardness ranged from 407 to 512 g with no significant differences within the formulations. However, the melting temperature showed significant differences with 2.0:1.0 having the highest melting temperature (54.0°C), whereas 1.9:1.1 and 1.8:1.2 showed 43.0 and 42.0°C melting temperature, respectively. The melting diameter (38.8 to 43.9 mm) and melt area (1,183.9 to 1,538.6 mm²) did not show any differences in different PCP formulations. The PCP made with a 2.0:1.0 ratio of protein from cMCC and MCC showed better functional properties compared with other formulations.

A review on membrane separation processes focusing on food industry environment-friendly processes

Food processing industries have led to several environmental impacts due to their high water and energy consumption, as well as soil and water bodies' contamination through improper waste disposal. Membrane Separation Processes (MSP) emerge as an important alternative to enable the adoption of sustainable processes by food industries, since satisfying the requests of innovative processes and equipment design, such as smaller, cleaner, more energy-efficient processes (mild conditions) without the usage of chemical agents. Membrane-based processes fulfill these requirements, and their potential has been broadly recognized in the last few years. This review provides a comprehensive and up-to-date overview of the application of MSP in sustainable processes in the different segments of the food industry over the last 10 years. Waste and wastewater treatment, recovery of valuable compounds and water for reuse, and alternatives to high energy consumption processes were identified as sustainable processes in this context. One trend found is the potential for adding value to production chains by obtaining valuable compounds that have not been explored yet. As a perspective for future research, this review showed that it is advisable to implement MSP in different industrial environments in order to make current processes environmentally sustainable and less polluting.

Production and storage stability of concentrated micellar casein

Concentrated micellar casein (CMC) is a high-protein ingredient that can be used in process cheese product formulations. The objectives of this study were to develop a process to produce CMC and to evaluate the effect of sodium chloride and sodium citrate on its storage stability. Skim milk was pasteurized at 76°C for 16 s and cooled to ≤4°C. The skim milk was heated to 50°C using a plate heat exchanger and microfiltered with a graded permeability (GP) ceramic microfiltration (MF) membrane system (0.1 μm) in a continuous feed-and-bleed mode (flux of 71.43 L/m² per hour) using a 3× concentration factor (CF) to produce a 3× MF retentate. Subsequently, the retentate of the first stage was diluted 2× with soft water (2 kg of water: 1 kg of retentate) and again MF at 50°C using a 3× CF. The retentate of the second stage was then cooled to 4°C and stored overnight. The following day, the retentate was heated to 63°C and MF in a recirculation mode until the total solids (TS) reached approximately 22% (wt/wt). Subsequently, the MF system temperature was increased to 74°C and MF until the permeate flux was <3 L/m² per hour. The CMC was then divided into 3 aliquots (approximately 10 kg each) at 74°C. The first portion was a control, whereas 1% of sodium chloride was added to the second portion (T1), and 1% of sodium chloride plus 1% of sodium citrate were added to the third portion (T2). The CMC retentates were transferred hot to sterilized vials and stored at 4°C. This trial was repeated 3 times using separate lots of skim milk. The CMC at d 0 (immediately after manufacturing) contained 25.41% TS, 21.65% true protein (TP), 0.09% nonprotein nitrogen (NPN), and 0.55% noncasein nitrogen (NCN). Mean total aerobic bacterial counts (TBC) in control, T1, and T2 at d 0 were 2.6, 2.5, and 2.8 log cfu/mL, respectively. The level of proteolysis (NCN and NPN values) increased with increasing TBC during 60 d of storage at 4°C. This study determined that CMC with >25% TS and >95% casein as percentage of TP can be manufactured using GP MF ceramic membranes and could be stored up to 60 d at 4°C. The effects of the small increase in NCN and NPN, as well as the addition of sodium chloride or sodium citrate in CMC during 60 d of storage on process cheese characteristics, will be evaluated in subsequent studies.

Cold Microfiltration as an Enabler of Sustainable Dairy Protein Ingredient Innovation

Classically, microfiltration (0.1–0.5 µm) of bovine skim milk is performed at warm temperatures (45–55 °C), to produce micellar casein and milk-derived whey protein ingredients. Microfiltration at these temperatures is associated with high initial permeate flux and allows for the retention of the casein fraction, resulting in a whey protein fraction of high purity. Increasingly, however, the microfiltration of skim milk and other dairy streams at low temperatures (≤20 °C) is being used in the dairy industry. The trend towards cold filtration has arisen due to associated benefits of improved microbial quality and reduced fouling, allowing for extended processing times, improved product quality and opportunities for more sustainable processing. Performing microfiltration of skim milk at low temperatures also alters the protein profile and mineral composition of the resulting processing streams, allowing for the generation of new ingredients. However, the use of low processing temperatures is associated with high mechanical energy consumption to compensate for the increased viscosity, and thermal energy consumption for inline cooling, impacting the sustainability of the process. This review will examine the differences between warm and cold microfiltration in terms of membrane performance, partitioning of bovine milk constituents, microbial growth, ingredient innovation and process sustainability.

Optimization of Spiral-Wound Microfiltration Process Parameters for the Production of Micellar Casein Concentrate

A systematic selection of different transmembrane pressures (TMP) and levels of diafiltration (DF) was studied to optimize these critical process parameters during the manufacturing of micellar casein concentrate (MCC) using spiral-wound polymeric membrane filtration. Three TMPs (34.5, 62.1, and 103.4 kPa) and four DF levels (0, 70, 100, and 150%) were applied in the study. The effect of the TMP and DF level on flux rates, serum protein (SP) removal, the casein-to-total-protein ratio, the casein-to-true-protein ratio, and the rejection of casein and SP were evaluated. At all transmembrane pressures, the overall flux increased with increases in the DF level. The impact of DF on the overall flux was more pronounced at lower pressures than at higher pressures. With controlled DF, the instantaneous flux was maintained within 80% of the initial flux for the entire process run. The combination of 34.5 kPa and a DF level of 150% resulted in 81.45% SP removal, and a casein-to-true-protein ratio of 0.96. SP removal data from the lab-scale experiments were fitted into a mathematical model using DF levels and the square of TMPs as factors. The model developed in this study could predict SP removal within 90-95% of actual SP removal achieved from the pilot plant experiments.

Progress in micellar casein concentrate: Production and applications

Micellar casein concentrate (MCC) is a novel ingredient with high casein content. Over the past decade, MCC has emerged as one of the most promising dairy ingredients having applications in beverages, yogurt, cheese, and process cheese products. Industrially, MCC is manufactured by microfiltration (MF) of skim milk and is commercially available as a liquid, concentrated, or dried containing ≥9, ≥22, and ≥80% total protein, respectively. As an ingredient, MCC not only imparts a bland flavor but also offers unique functionalities such as foaming, emulsifying, wetting, dispersibility, heat stability, and water-binding ability. The high protein content of MCC represents a valuable source of fortification in a number of food formulations. For the last 20 years, MCC is utilized in many applications due to the unique physiochemical and functional characteristics. It also has promising applications to eliminate the cost of drying by producing concentrated MCC. This work aims at providing a succinct overview of the historical progress of the MCC, a review on the manufacturing methods, a discussion of MCC properties, varieties, and applications.

Microfiltration and Ultrafiltration Process to Produce Micellar Casein and Milk Protein Concentrates with 80% Crude Protein Content: Partitioning of Various Protein Fractions and Constituents

The objective of the study reported in this research paper was to produce micellar casein concentrate (MCC) and milk protein concentrate (MPC) with 80% crude protein relative to total solids (TS) using MF and UF processes respectively. Additionally, capillary gel electrophoresis (CGE) was used to study the protein fractions in retentate and permeate. For MCC production, 227 L of pasteurized SM was subjected to MF using 0.5-micron spiral wound polyvinylidene fluoride membrane. During the process, diafiltration (DF) water was added at six intervals, totaling 100% of the feed volume. For MPC production, 227 L of pasteurized SM from the same lot was subjected to UF using 10 kDa Polyethersulfone membranes. During the process, DF water was added at four different intervals, with a final total addition of 40% of the feed volume. Both processes used a volume reduction of five. There were significant (p < 0.05) differences in all of the compositional parameters, except fat and casein for the MF retentate (MFR) and UF retentate (UFR). UFR had a higher crude protein (CP), TS, lactose, ash and calcium content as compared to MFR and this affected the CP/TS ratio found in both the retentates. The differences in membrane pore sizes, operating pressures and level of DF used all contributed to the differences in final CP/TS ratio obtained. The CGE analysis of individual protein fractions present in the UFR and MFR showed that UFR has a β-lactaglobulin to α-lactalbumin (α-LA) ratio similar to SM, whereas the MFR has a higher ratio, indicating preferential transmission for α-LA by the MF membrane. The results from this study show that MF and UF processes could be used for production of MCC and MPC with similar CP/TS ratio with careful selection of operating parameters, and that CGE can be used for detailed analysis of various protein fractions.

Efficiency of removal of whey protein from sweet whey using polymeric microfiltration membranes

Our objective was to measure whey protein removal percentage from separated sweet whey using spiral-wound (SW) polymeric microfiltration (MF) membranes using a 3-stage, 3× process at 50°C and to compare the performance of polymeric membranes with ceramic membranes. Pasteurized, separated Cheddar cheese whey (1,080 kg) was microfiltered using a polymeric 0.3-μm polyvinylidene (PVDF) fluoride SW membrane and a 3×, 3-stage MF process. Cheese making and whey processing were replicated 3 times. There was no detectable level of lactoferrin and no intact α- or β-casein detected in the MF permeate from the 0.3-μm SW PVDF membranes used in this study. We found BSA and IgG in both the retentate and permeate. The β-lactoglobulin (β-LG) and α-lactalbumin (α-LA) partitioned between retentate and permeate, but β-LG passage through the membrane was retarded more than α-LA because the ratio of β-LG to α-LA was higher in the MF retentate than either in the sweet whey feed or the MF permeate. About 69% of the crude protein present in the pasteurized separated sweet whey was removed using a 3×, 3-stage, 0.3-μm SW PVDF MF process at 50°C compared with 0.1-μm ceramic graded permeability MF that removed about 85% of crude protein from sweet whey. The polymeric SW membranes used in this study achieve approximately 20% lower yield of whey protein isolate (WPI) and a 50% higher yield of whey protein phospholipid concentrate (WPPC) under the same MF processing conditions as ceramic MF membranes used in the comparison study. Total gross revenue from the sale of WPI plus WPPC produced with polymeric versus ceramic membranes is influenced by both the absolute market price for each product and the ratio of market price of these 2 products. The combination of the market price of WPPC versus WPI and the influence of difference in yield of WPPC and WPI produced with polymeric versus ceramic membranes yielded a price ratio of WPPC versus WPI of 0.556 as the cross over point that determined which membrane type achieves higher total gross revenue return from production of these 2 products from separated sweet whey. A complete economic engineering study comparison of the WPI and WPPC manufacturing costs for polymeric versus ceramic MF membranes is needed to determine the effect of membrane material selection on long-term processing costs, which will affect net revenue and profit when the same quantity of sweet whey is processed under various market price conditions.

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

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.

Influence of Spacer Design and Module Geometry on the Filtration Performance during Skim Milk Microfiltration with Flat Sheet and Spiral-Wound Membranes

Spacer design in spiral-wound membranes (SWMs) significantly affects the axial pressuredrop in the flow channel but also the deposit layer removal. However, the effects of the spacerdesign and feed flow distribution in the module on the filtration performance have not yet beeninvestigated during the highly fouling-susceptible fractionation of proteins from skim milk bySWMs. Therefore, a parallel spacer with no turbulence promotion and a less homogeneous feedflow distribution in the SWM was compared to a diamond spacer with regard to its impact ondeposit formation and filtration performance. The experiments were conducted in a flat sheet testcell and in SWMs. The parallel spacer induced a more homogeneous deposit layer formation.However, no difference in filtration performance could be observed in the experiments with the testcell. Even though deposit layer formation dominates the microfiltration, its amount and spatialdistribution could not be directly linked to the filtration performance. Furthermore, both spacerswere assessed in SWM. Despite the higher crossflow velocity applicable in the more open channelsof the parallel spacer, the performance of the parallel spacer was inferior to the diamond spacer.This was independent of the viscosity of the feed. Due to the high curvature of the membrane sheetsclose to the permeate collection tube, the cross-section of the flow channels in the SWM equippedwith the parallel spacer was reduced. This resulted in a distinctly lower deposit layer control andperformance, which could not be compensated by the resulting higher crossflow velocity far fromthe permeate collection tube.

Technical Concepts for the Investigation of Spatial Effects in Spiral-Wound Microfiltration Membranes

Existing works on the influence of spatial effects on flux and permeation of proteins in microfiltration (MF) have focused on ceramic membranes. There is little information on spiral-wound membranes (SWMs). Since the inner core of a SWM is practically inaccessible by non-destructive techniques, three different prototypes were constructed in this study to optimize suitability for the investigation of spatial effects on filtration performance. To measure the pressure drop, shortened SWMs 0.25, 0.50, and 0.75 times the length of a standard industrial SWM (0.96 m) were designed. Second, a sectioned membrane (0.96 m) with separated compartments on the permeate side was constructed to analyze spatial effects on flux and protein permeation along the flow path of a SWM. Three different features characterized this sectioned module: sectioned permeate pockets, a sectioned permeate collection tube, and sectioned permeate drain and measurement systems. Crossflow filtration experiments showed that these modifications did not alter the filtration performance compared to an unmodified control SWM. Thus, it can be applied to assess spatially-resolved filtration performance in SWMs. The third prototype designed was a test cell with accessible flat sheet membranes and spacer material, as in SWMs. The flow path in this test cell was designed to match the characteristics of the channels between the membrane sheets in a standard SWM as closely as possible. The flow path length and the combination of membrane material and spacer architecture were the same as in the control SWM. This test cell was designed to assess the effects of length and processing conditions on the formation of a deposit layer. The combined results of these test modules can yield new insights into the spatial distribution of flux, permeation of target components, and deposit formation.

On the Use of Ultrafiltration or Microfiltration Polymeric Spiral-Wound Membranes for Cheesemilk Standardization: Impact on Process Efficiency

Ultrafiltration (UF) and microfiltration (MF) are widely-used technologies to standardize the protein content of cheesemilk. Our previous work demonstrated that protein retention of a 0.1-µm MF spiral-wound membrane (SWM) was lower, but close to that of a 10 kDa UF one. Considering that the permeability of MF membranes is expected to be higher than that of UF ones, it was hypothesized that the former could improve the efficiency of the cheesemaking process. Consequently, the objectives of this work were to compare 0.1-µm MF and 10 kDa UF spiral-wound membranes in terms of (1) hydraulic and separation performance, (2) energy consumption and fouling behavior, (3) cheesemaking efficiency of retentates enriched with cream, and (4) economic performance in virtual cheesemaking plants. This study confirmed the benefits of using MF spiral-wound membranes to reduce the specific energy consumption of the filtration process (lower hydraulic resistance and higher membrane permeability) and to enhance the technological performance of the cheesemaking process (higher vat yield, and protein and fat recoveries). However, considering the higher serum protein retention of the UF membrane and the low price of electricity in Canada, the UF scenario remained more profitable. It only becomes more efficient to substitute the 10 kDa UF SWM by the 0.1-μm MF when energy costs are substantially higher.

Milk Protein Fractionation by Means of Spiral-Wound Microfiltration Membranes: Effect of the Pressure Adjustment Mode and Temperature on Flux and Protein Permeation

Protein fractionation by means of microfiltration (MF) is significantly affected by fouling, especially when spiral-wound membranes (SWMs) are used. We investigated the influence of the mode of transmembrane pressure (Δp_TM) increase to target level and the deposit layer pressure history on the filtration performance during skim milk MF at temperatures of 10 °C and 50 °C. Two filtration protocols were established: No. 1: Δp_TM was set directly to various target values. No. 2: Starting from a low Δp_TM, we increased and subsequently decreased Δp_TM stepwise. The comparison of both protocols tested the effect of the mode of Δp_TM increase to target level. The latter protocol alone tested the effect of the deposit layer history with regard to the Δp_TM. As expected, flux and protein permeation were both found to be functions of the Δp_TM. Further, both measures were independent of the filtration protocol as long as Δp_TM was held at a constant level or, as part of protocol No. 2, Δp_TM was increased. Thus, we can state that the mode of Δp_TM increase to target level does not affect filtration performance in SWM. We found that after completion of a full cycle of stepping Δp_TM up from 0.5 bar to 3.0 bar and back down, flux and deposit layer resistance were not affected by the deposit layer history at 10 °C, but they were at 50 °C. Protein permeation, however, was lower for both 10 °C and 50 °C, when the Δp_TM cycle was completed. The processing history had a significant impact on filtration performance due to remaining structural compression effects in the deposited layer, which occur most notably at higher temperatures. Furthermore, temperatures of 50 °C lead to deposit layer aging, which is probably due to an enhanced crosslinking of particles in the deposit layer. Apart from that, we could show that fouling resistance does not directly correlate with protein permeation during skim milk MF using SWM.

Effect of ceramic membrane channel diameter on limiting retentate protein concentration during skim milk microfiltration

Our objective was to determine the effect of retentate flow channel diameter (4 or 6mm) of nongraded permeability 100-nm pore size ceramic membranes operated in nonuniform transmembrane pressure mode on the limiting retentate protein concentration (LRPC) while microfiltering (MF) skim milk at a temperature of 50°C, a flux of 55 kg · m(-2) · h(-1), and an average cross-flow velocity of 7 m · s(-1). At the above conditions, the retentate true protein concentration was incrementally increased from 7 to 11.5%. When temperature, flux, and average cross-flow velocity were controlled, ceramic membrane retentate flow channel diameter did not affect the LRPC. This indicates that LRPC is not a function of the Reynolds number. Computational fluid dynamics data, which indicated that both membranes had similar radial velocity profiles within their retentate flow channels, supported this finding. Membranes with 6-mm flow channels can be operated at a lower pressure decrease from membrane inlet to membrane outlet (ΔP) or at a higher cross-flow velocity, depending on which is controlled, than membranes with 4-mm flow channels. This implies that 6-mm membranes could achieve a higher LRPC than 4-mm membranes at the same ΔP due to an increase in cross-flow velocity. In theory, the higher LRPC of the 6-mm membranes could facilitate 95% serum protein removal in 2 MF stages with diafiltration between stages if no serum protein were rejected by the membrane. At the same flux, retentate protein concentration, and average cross-flow velocity, 4-mm membranes require 21% more energy to remove a given amount of permeate than 6-mm membranes, despite the lower surface area of the 6-mm membranes. Equations to predict skim milk MF retentate viscosity as a function of protein concentration and temperature are provided. Retentate viscosity, retentate recirculation pump frequency required to maintain a given cross-flow velocity at a given retentate viscosity, and retentate protein determination by mid-infrared spectrophotometry were all useful tools for monitoring the retentate protein concentration to ensure a sustainable MF process. Using 6-mm membranes instead of 4-mm membranes would be advantageous for processors who wish to reduce energy costs or maximize the protein concentration of a MF retentate.