P Havea & P Watkinson

Transcription

1 Whey protein a realistic approach designed products for the food industry P Havea & P Watkinson Fonterra Research Centre, Palmerston North, New Zealand

2 Introduction Use of whey protein so far dominated by functional applications. Technology driven made whey products (WPC) find a way to use them. Industry demand ability to tailor-make products. Research accumulate knowledge ŁBased on model systems, both pure and low protein ŁHard to translate to commercial reality and of limited commercial value 2

3 Functions drive uses of whey protein Fundamental knowledge reality = commercial Realistic approach key requirements ŁControlled process ŁLow cost ŁConsistent delivery of the desired functions Functional performance dictated by protein interactions in food systems. Current presentation review protein interactions and the functional performance of whey proteins in food systems. 3

4 Better understanding of protein interactions Native Changes & interactions Functional performance What happen here that produce the function? Can we control these for our advantage? 4

5 Example types of interactions Native proteins Appropriate conditions Non-covalent interactions Covalent bonding -S-S- -S-S- 5

6 Two categories of protein interactions Two broad categories of interactions Ł Covalent (-S S-) strong, few per molecule, form slowly in a heated protein system. Ł Non-covalent (hydrophobic, ionic etc.) weak, many reactive sites per molecule, form quickly. Experiments with heating under different conditions Ł Control (water) both covalent and non-covalent interactions. Ł SDS (1%) covalent (disulphide bonds only). Ł DTT (10 mm) no disulphide bonding, non-covalent only. Ł NEM (1:1 molar ratio) no new disulphide bonds only those pre-existing in the system, interactions are noncovalent only. 6

7 Manipulation of protein interactions control SDS NEM DTT disulfide non-covalent 7

8 Protein interactions and gel properties G' (Pa) ºC ºC ºC 20 ºC DTT NEM Control DTT NEM Control 5000 SDS Time (min) 12% protein, ph 6.9, 80ºC, 30 min SDS 8

9 Effect of protein interactions on texture Texture mapping 70 Brittle NEM Tough Fracture Stress (kpa) DTT Water SDS 30 Mushy Rubbery Fracture Strain 12% protein, ph 6.9, 80ºC, 30 min 9

10 Modifying target -S Sinteractions Manufacturing considerations Ł Purity of protein removal of lactose, salts (e.g. Ca2+) and other non-functional components (e.g. GMP). Ł Influence of other factors in food systems to which whey protein is applied: other ingredients, processing conditions, ph, presence of salt. Ł Room for tweaking for more suitable selections. Modified whey protein products Ł How are they processed (cold-gelling WPC)? Ł How are required functional properties (thickening, water holding, emulsifying properties) preserved? 10

11 Tweaking Modified WPC80 (-S S- ) Heating at low ionic strength ŁCan achieve a variety of functional properties. ŁRetain heat-gelling function and ability to form gels at low temperatures. ŁMay apply to products such as desserts. ŁProtein functions dominated by disulphidelinked interactions. 11

12 Protein interactions and gel properties G' (Pa) 20-80ºC ºC 80 20ºC 20ºC DTT NEM Control Time (min) SDS 12% protein, ph 6.9, 80ºC, 30 min 12

13 Heating of CG WPC ºC 80ºC 80-20ºC 20ºC Reconstituted in water Storage Modulus (Pa) Time (min) 12% protein, ph

14 Heating of CG WPC ºC 80ºC 80-20ºC 20ºC Reconstituted in water Reconstituted in NEM Storage Modulus (Pa) Time (min) 12% protein, ph

15 Heating of CG WPC C 80ºC 80-20ºC 20ºC Reconstituted in water Reconstituted in NEM Reconstituted in SDS Storage Modulus (Pa) Time (min) 12% protein, ph

16 Heating of CG WPC ºC 80 ºC ºC 20 ºC Storage Modulus (Pa) Reconstituted in water Reconstituted in NEM Reconstituted in SDS Reconstituted in DTT ºC 80ºC 80-20ºC 20ºC Time (min) 12% protein, ph

17 Texture CG WPC80 Brittle NEM Tough - WPC80 water DTT SDS Mushy Rubbery 12% protein, ph 6.9, 80ºC, 30 min 17

18 Texture CG WPC80 Brittle NEM Tough - WPC80 -CGWPC80 water DTT SDS Mushy Rubbery 12% protein, ph 6.9, 80ºC, 30 min 18

19 Texture CG WPC80 Brittle NEM Tough - WPC80 -CGWPC80 water DTT SDS Mushy Rubbery 12% protein, ph 6.9, 80ºC, 30 min 19

20 Texture CG WPC80 Brittle NEM Tough - WPC80 -CGWPC80 water DTT SDS Mushy Rubbery 12% protein, ph 6.9, 80ºC, 30 min 20

21 Texture CG WPC80 Brittle NEM Tough - WPC80 -CGWPC80 water DTT SDS Mushy Rubbery 12% protein, ph 6.9, 80ºC, 30 min 21

22 Target optimised non-covalent interactions Manufacturing considerations Ł Retention of salts (e.g. Ca2+) that have a major influence on functional properties. Ł Influence of other factors in food systems to which whey protein is applied: other ingredients, processing conditions, ph, presence of salt. Modified whey protein products Ł Manipulation of processing conditions so that, upon application, interactions of protein are dominated by noncovalent associations (MWPC). Ł Main functional properties (soft-textured gels and limited emulsifying properties). Ł Protein fortification applications. 22

23 Effect of added [Ca] on texture Brittle Tough Mushy Added [Ca] g/kg = 0 = 1 = 2 = 3 = 4 = 5 = 8 Rubbery 23

24 Effect of added [Ca] on viscosity g/kg added Ca Control 1 (no added Ca) 12% protein, ph 6.9 Shear rate 250 s -1 Apparent viscosity (Pa.s) ºC 20ºC Heating time (min) 24

25 Effect of protein interactions on texture Texture mapping 70 Brittle -s-s- NEM + nc Tough Fracture Stress (kpa) 60 -s-s- Water + nc 50 nc DTT only 40 -s-s- SDS only 30 Mushy Rubbery Fracture Strain 12% protein, ph 6.9, 80ºC, 30 min 25

26 Effect of [Ca] on texture Brittle Tough Mushy Added [Ca] g/kg = 0 = 1 = 2 = 3 = 4 = 5 = 8 Rubbery 26

27 Discussion and conclusions Whey protein complex system, not easy to translate fundamental knowledge to industrial reality. Data presented demonstrate effect of protein interactions on the functional properties of whey protein gels. A better understanding of protein interactions and how they relate to functional properties in food systems is required. May be able to manipulate the processing conditions to make products with target properties suitable for specific applications. 27

28 Acknowledgement Scott Mackay for doing the work Fonterra Research Centre (Steve Taylor) IWC-2008 for the opportunity to participate 28