MPC Research. Mike Molitor Wisconsin Center for Dairy Research

Transcription

1 MPC Research Mike Molitor Wisconsin Center for Dairy Research Center for Dairy Research Solution Based Research Backed by Experience, Passion and Tradition

2 Issues with MPC Functionality MPC70 and above Slow to rehydrate especially at cold temperatures Some MPCs decrease in solubility with storage Most noticeable at storage temperatures >20C (68F) Some MPCs are more prone to sharp loss of solubility Rehydration/solubility issues can limit applications

3 Solubility of milk powders SMP MPC 56 MPC 70 MPC 85 MPC 91 Singh, 2008

4 Impact of Storage Temperature on Solubility of MPC 85 5 C 20 C 30 C Singh, 2008

5 Impact of Processing Conditions on Milk Protein Concentrate 80 Functionality Laura Rupp, Mike Molitor 2, and John Lucey 1,2 1 University of Wisconsin-Madison, Department of Food Science 2 Wisconsin Center of Dairy Research

6 Impact on Functionality Goal: Demonstrate relationships between the process and the powder attributes to help optimize MPC functionality Process parameters that were evaluated The extent of concentration using evaporation The concentration method (comparing UF only against UF finished with evaporation) The dryer s air inlet temperature Product temperature during atomization

7 Phase 4, Process flow schematic: Evaporate to three target concentrations 10% protein Concentration of UF Retentate to 19, 21 or 23% protein utilizing evaporation

8 Processing parameters UF/DF to 10% protein 30 KDa with 80 mil spacer Max temperature: 19C (66F) Inlet/Outlet Pressure: 82 / 47 psi 114 gal RO water Evaporation: Three target concentrations Max Temp: 54C (129F) Vacuum: 27.5 Spray Drying: Nozzle size: dia. Product Temp: 59C (138F) Drying conditions Feed rate (gal/ min) 19% 21% 23% Inlet Temp ( C) Outlet Temp ( C) Nozzle Pressure (psi)

9 Material and Methods Powder storage conditions: 50mL air tight plastic tubes 30 C Light exclusion Analyzed every 30 days for 6 months

10 Material and Methods Solubility test conditions: High agitation (3500 rpm) High temperature (30C/86F) Long agitation time (10 min) Foaming (5% protein solution, 20 min whipping time) % Overrun: Volume increase compared to liquid milk Stability: Time needed for half of foam drained/weight Maximum Yield stress: Rheometer, / s shear rate, Vane geometry, 300 measurement pts

11 Tapped Density 190mL 0 tapings Bulk density measured after 625 taps of experimental MPC produced from retentates with 19% ( ), 21% ( ) or 23% ( ) protein content. Powders were stored at 30 C for 6 mo. 23% protein in retentate had higher bulk density than 19% protein (P < 0.05). 130mL 625 tapings

12 Solubility due to Storage Solubility (%) Solubility of MPC powder from samples produced (n=2) with retentate protein concentrations of 19% (l ), 21% ( ) or 23% ( ), over a period of 6 mo storage at 30 C. Values are means ± SD of data from triplicate analysis. Storage time at 30 C (month) The new powder / initial solubilities were very similar to each other The solubility decreased sharply during the first two months of storage

13 Phase 3, Process flow schematic: UF combined with evaporation Or UF only Splitting of 11% Feed protein Lactose 19 % protein 19 % protein

14 Processing parameters for EV & UF UF/DF both (to 11% protein) 30 KDa with 80 mil spacer Max Temperature: 18C/64F Inlet/Outlet Pressure: 70/40 psi Part 1; Finish concentrating to 19% protein with the same UF. 30 KDa with 80 mil spacer Max temperature: 16C/61F Standardize the PDB with lactose Part 2, Use the evaporator to achieve 19% protein Max Temperature: 54C/129F Vacuum: 27.5 Spray Drying each: Nozzle size: dia. Product Temp.: 60C/140F Drying conditions EV UF Feed rate (gal/ min) Inlet Temp ( C/ F) 180/ 356 Outlet Temp ( C/ F) Nozzle Pressure (psi) / / /

15 Solubility during Storage Solubility (%) Storage time at 30 C (month) Solubility of MPC powder from samples produced with UF/DF and evaporation (l ) and from UF/DF only ( ), powders were stored over a period of 6 mo at 30 C. Values are means ±SD of data from triplicate analysis. Powder solubility was not different regardless of which process sequence was utilized

16 Phase 2, Process flow schematic: Variation of the dryer s inlet air temperature RO-Water Lactose Uf/Diafiltration Concentrate: 60 C/140F 17% protein Inlet air temperature: 177, 190 or 204 C 350, 374 or 400 F

17 Processing parameters - Air Inlet Temp. UF/DF (to 17% protein) 30 KDa with 80 mil spacer Max Temperature: 22C/72F Inlet/Outlet Pressure: 70/40 psi Spray Drying: Nozzle size: dia. Product Temp: 59C/138F Drying conditions 177 C/ 351 F 190 C /374 F 204 C/ 399 F Feed rate (gal/min) Outlet Temp ( C) Nozzle Pressure (psi) Single stage spray dryer

18 How the air inlet temperature impacts the powder particle size Malvern Mastersizer: Light scattering analyzer Feed rate increases will result in higher pressure to the atomizer, which reduces the droplet size.

19 The impact of inlet air temperature on whey protein denaturation denatured whey as a % of total whey WPNI: C 190 C 204 C Inlet Air temperature + β-me STD SM SM BSA Caseins β-lg α-la Increasing the inlet air temperature results in progressively more denatured whey protein

20 Solubility during Storage Solubility (%) Solubility of MPC powder from samples produced (n=2) with inlet air temperatures of 177 C (l ), 190 C (s ), or 204 C ( ), and industrial ( ) sample. Storage time at 30 C (month) The inlet air temperature had no significant impact on MPC solubility. Solubility decreased over time (P < 0.001).

21 The Phase 1, Process flow schematic: Heating the UF concentrate to 50, 60 or 70C (122, 140, 158F) for nine minutes until going into the dryer s atomizer

22 Processing parameters UF/DF (to 13% total solids) 10 KDa with 46 mil spacer Max Temperature: 21 C Inlet / Outlet Pressure: 70/40 psi UF (to 21 % protein) 50 KDa & 130 mil spacer Max temperature: 43 C Spray Drying: Nozzle size: dia. Product Temperatures were: 50, 60 or 70 C Drying conditions Feed rate (gal/ min) 50 C 60 C 70 C Inlet Temp Outlet Temp ( C) Nozzle Pressure (psi)

23 How does the product temperature into the atomizer impact the powder particle size Density (625 taps): CT low : 0.38 ±0.03 CT med : 0.37 ±0.04 CT high : 0.38 ±0.03 Two variables work to create smaller atomizer droplets and therefore smaller powder particles: Lower viscosity due to the warmer UF concentrate Higher pressure at the atomizer due to the faster feed rate ( Doubling the flow, quadruples the pressure )

24 Concentrate temperature and whey protein denaturation % denatured whey as a % of total whey WPNI: C 60 C 70 C Retentate temperature Aggregates β-me + β-me Heating temperature (C) Confirmed that whey protein denaturation increases as the concentrate temperature is increased.

25 Solubility during Storage Concentrate heated for 9.5 min to: 50C ( ) 60C (s ) 70C ( ) Solubility (%) Storage time at 30 C (month) " MPC heated to 70 C exhibited significantly higher solubility than MPC heated to 50 C at the 0, 1, 5, and 6 month time points " Solubility decreased significantly during the 6 mo storage at 30 C (P < 0.001)

26 Key Findings Increasing protein (and solids) content: increased powder particle size and more importantly also increased bulk density did not affect solubility overall did not affect the foam stability, overrun or maximum yield stress UF only or combined with evaporation: did not affect solubility, foam stability, overrun, maximum yield stress or the powder density

27 Key Findings Increasing the inlet air temperature: decreased powder particle size because of the higher feed rate against the atomizer did not affect foam stability, overrun & maximum yield stress, density or solubility Increasing the product temperature entering the dryer atomizer: decreased the powder particle size because of the lower viscosity and higher feed rate (psi) did not affect the foam stability, overrun, maximum yield stress or powder density increased the degree of protein denaturation yet also increased the MPC powder solubility

28 Acknowledgements Graduate Students Laura Rupp Shane Crowley Staff Becky Kalscheuer Karen Smith Wisconsin Center for Dairy Research Funded by Dairy Farmers through the Wisconsin Milk Marketing Board and Dairy Management, Inc. Center for Dairy Research Solution Based Research Backed by Experience, Passion and Tradition