Understanding Maillard-type reactions in food processing Case study: Extrusion Nancy, September 17, 2012 Imre Blank Nestlé PTC rbe, Switzerland
Goal: Better control of the Maillard reaction cascade under food processing conditions Food processing: Extrusion Holistic approach H Food chemistry: Flavour formation C C Targeted approach 2
Extrusion with direct expansion A multi unit operation process Flour Mix (~1 H 2 ) Water, il,... Extrusion is an integrated process in which raw materials rich in starch and protein are plastified and structuremodified in a cylinder under pressure and shear at elevated temperatures followed by expansion of the die at the end of the extruder. 110 180 C 80 170 bars Steam Moisture: 1 Expansion ~15 2 Average residence time: 20 30 seconds ~5-1 3
Parameters affecting product quality Recipe Ingredients Specific precursors Concentration, ratio Catalyst ph Extrusion Heat load (T, t) Screw speed, SME Moisture Number of barrels Slurry vs. dry addition Study the effect of extrusion parameters and recipe composition on furaneol formation from rhamnose and lysine + N H 2 NH 2 H Recipe & Process parameters C H C Identify recipe and processing conditions during extrusion of rice flour favouring the formation of caramel flavour while considering physico-chemical properties of the final product 4
Experimental design: Key product attributes are affected by both recipe and extrusion parameters Mixing Recipe parameters ph 6.4 7.7 ph Ratio Rha/Lys Phosphate Rha:Lys P4 (mol/kg) 3:0 0.035 3:1 0.134 Moisture (%) 17 20 23 Extrusion Extrusion parameters SME Moisture levels Screw speed Temperature Residence time Slurry vs. dry Screw speed (rpm) Temp. ( C) Barrel length Addition 300 120 5 Dry 400 135 7 Slurry 500 150 Drying Milling Final product Product characterisation Texture Crispness Colour Flavour Acrylamide Starch degradation Granulometry Viscosity Sensory Fractional factorial design: - 32 instead of 576 trials - Determining all main effects and two-factor interactions of 3 recipe and 5 process parameters Holistic product characterisation: - Chemical, physical, sensorial - Using 16 methods 5
Flavor Texture & Appearance Sensory assessment Reconstituted products from experimental design Trained panel (14 panelists) Product Extruded powder (85%) Sugar (15%) Reconstitution 12.4g product 100mL milk at 70 C 32 Products evaluated vs. reference Parameters units Low Medium High ph 6.4 7.7 Rha:Lys 3:0 3:1 Phosphate mol/kg 0.035 0.134 Moisture % 17 20 23 Screw speed rpm 300 400 500 T C 120 135 150 length barrel short long Addition dry slurry Identification of statistically relevant trends Wide diversity of sensory perception Range of sensory attributes teasyswallow alump tsmooth Burnt Nutty adark Caramel Toasted Processy ff verall acid WholeGrain Mushroom astringent bitter aftertaste t1thick tthick tfluffy t1wettability tsemolina Cooked Milky Rice Vanilla sweet Range covered by A01-A32 (vs. REF) -6-5 -4-3 -2-1 0 1 2 3 4 5 6 6
Key parameters Colour development Modulation of colour in product through recipe Sensory impact Colour generation Browning reactions ph 6 Rha/Lys 3:0 ph 7 Rha/Lys 3:1 ph 6 ph 7 Rha:Lys 3:0 Rha:Lys 3:1 Phosphate low Phosphate high 17% H2 2 H2 23% H2 300rpm 400rpm 500rpm 120 C-Long 120 C 135 C 150 C Dry Slurry Light Colour (C) High ph * ** Lysine Dark -6-4 -2 0 2 4 6 teasyswallow alump tsmooth Burnt Nutty adark Caramel Toasted Processy ff verall acid WholeGrain Mushroom astringent bitter aftertaste t1thick tthick tfluffy t1wettability tsemolina Cooked Milky Rice Vanilla sweet Range covered by A01-A32 (vs. REF) -6-5 -4-3 -2-1 0 1 2 3 4 5 6 7
Furaneol formation Free amino acids, moisture, T and phosphate are most critical Furaneol ext / mol% Furaneol dry / mol% -6-4 -2 0 2 4 6 H ph 6.4 ph 7.7 Rha:Lys 3:0 Rha:Lys 3:1 Phosphate 0.035 mol/kg Phosphate 0.134 mol/kg 17% H2 2 H2 23% H2 Conversion of rhamnose to furaneol can be modulated through 1. changes of extrusion and/or 2. recipe parameters 300 1/min 400 1/min 500 1/min 120 C-Long 120 C 135 C 150 C Dry Slurry 8
Acrylamide Temperature is most critical Furaneol ext / mol% Furaneol dry / mol% -6-4 -2 0 2 4 6 Mitigation options Acrylamide -75-50 -25 0 25 50 75 ph 6.4 ph 7.7 ph 6.4 ph 7.7 Rha:Lys 3:0 Rha:Lys 3:1 Rha:Lys 3:0 Rha:Lys 3:1 Phosphate 0.035 mol/kg Phosphate 0.134 mol/kg Phosphate 0.035 mol/kg Phosphate 0.134 mol/kg 17% H2 2 H2 23% H2 300 1/min 400 1/min 500 1/min 120 C-Long 120 C 135 C 150 C Dry Slurry H 17% H2 2 H2 23% H2 300 1/min 400 1/min 500 1/min 120 C-Long 120 C 135 C 150 C Dry Slurry NH 2 9
Structure and Texture Moisture and temperature are most critical Structure = f (SME) Texture = f (SME) Cell walls / µm -15-10 -5 0 5 10 15 ph 6.4 ph 7.7 Visco5min / mpas ViscoMax / mpas -1500-1000 -500 0 500 1000 1500 Rha:Lys 3:0 Rha:Lys 3:1 Phosphate 0.035 mol/kg Phosphate 0.134 mol/kg 17% H2 2 H2 23% H2 300 1/min 400 1/min 500 1/min 120 C-Long 120 C 135 C 150 C Dry Slurry Semolina Crispy Low High 10
Starch degradation MW = f (SME) Viscosity (mpa.s) Starch (%) SME 92 SME 35 100 Rice Flour Moisture % 8-13 80 60 Amylopectin Low MW intermediate Starch %d.b. 88-92 Total fibers %d.b. 0.3-1 Proteins %d.b. 6-9 Fat %d.b. 0.5-1 Ash %d.b. 0.3-1 Long Chain DP~50 Short Chain DP~25 40 20 0 High MW intermediate 0 50 100 SME SME 92 SME 35 High H 2 High T 6000 5000 Viscosity = f (MW) 4000 Low H 2 Low T 3000 2000 1000 0 0 2 4 6 8 10 12 Time (min) 11
%Furaneol-dry Effect of recipe/extrusion parameters ptions for flavour optimization 4 3 Rha:Lys 3:1 17% H2 Free amino acid and phosphate affect furaneol, but not SME 2 150 C 1 Phosphate high Temperature affects both furaneol and SME 150 C more viscous 0-1 300rpm 135 C Dry ph 67 120 C Slurry 2 H2 400rpm Phosphate low 500rpm Moisture affects both furaneol and SME 17% less viscous -2 120 C-Long -3-4 23% H2 Rha:Lys 3:0-20 -15-10 -5 0 5 10 15 20 SME-measured Next step: Full factorial design in a smaller space for final product optimisation 12
Goal: Better control of the Maillard reaction cascade under food process conditions Food processing: Extrusion Holistic approach H Food chemistry: Flavour formation C C Targeted approach - CAMLA 0.15 mmol [ 12 C 6 ]-glucose 0.15 mmol [ 13 C 6 ]-glucose Heating: 135 C/20min 0.1 mmol glycine or proline 1 ml 0.5 M phosphate buffer ph 5, 7 or 9 13
Glucose + Proline Furaneol 10 10 Aqueous system 10 10 Dry system 96% 10 98% Rice Model 84% 85% 8 5 5 56% 5 5 26% 18% 1 14% ph 5 ph 7 ph 9 Intact skeleton C3+C3 C2+C4 C5 +C1Glc C5 +C1Gly 1 4% 4% ph 5 ph 7 ph 9 Intact skeleton C3+C3 C2+C4 C5 +C1Glc C5 +C1Gly 1 6% 8% 1 1% ph 5 ph 7 ph 9 Intact skeleton C3+C3 C2+C4 C5 +C1Glc C5 +C1Gly Inherent prec. Rice Major pathways Aqueous systems: Intact skeleton at ph 5; recombination of C3+C3 at ph 7 and 9 Dry systems: Intact skeleton (>84%) Rice: Intact skeleton (>8), some recombination of sugar fragments at ph 7 and 9
Glucose + Glycine Furaneol 10 10 Aqueous system 10 10 Dry system 98% 96% 10 Rice Model 94% 94% 9 7 6 5 5 5 18% 26% 8% 8% 4% 4% 4% 6% 4% 4% ph 5 ph 7 ph 9 ph 5 ph 7 ph 9 ph 5 ph 7 ph 9 Intact skeleton C3+C3 Intact skeleton C3+C3 Intact skeleton C3+C3 C2+C4 C5 +C1Glc C2+C4 C5 +C1Glc C2+C4 C5 +C1Glc C5 +C1Gly C5 +C1Gly C5 +C1Gly Inherent prec. Rice Major pathways Aqueous systems: Intact skeleton at ph 5; less relevant with increasing ph Dry systems: Intact skeleton independent of ph Rice models: Intact skeleton independent of ph, only little by sugar fragmentation
Glucose + Glycine Furaneol (ph 7) 10 10 Aqueous system Dry system 10 98% 10 96% Rice Model 10 94% 94% 9 10 Extruded system 9 7 6 5 5 5 5 18% 26% 8% 8% 4% 4% ph 5 ph 7 ph 9 Intact skeleton C2+C4 C5 +C1Gly C3+C3 C5 +C1Glc 4% ph 5 ph 7 ph 9 Intact skeleton C2+C4 C5 +C1Gly C3+C3 C5 +C1Glc Aqueous system: Intact skeleton (major) and C3+C3 recombination (minor) Dry system: Intact skeleton (almost exclusive) Rice model: Intact skeleton (almost exclusive) 6% 4% 4% Extrusion: Intact skeleton (almost exclusive), about 8% from inherent precursors Intact skeleton C2+C4 C5 +C1Gly ph 5 ph 7 ph 9 C3+C3 C5 +C1Glc Inherent prec. Rice ph 7 Intact skeleton 8% Inherent prec. Rice
Formation of Furaneol CH 2 H H H,H H H H C H H - H 2 H C H H C C Acetylformoin H C N H CH Roasting: 10 Solution: 4 H C N, H 2, C 2 HDMF C C H H H C H H - H 2 H C C H C H H C N H CH Roasting: Solution: 6 H C N, H 2, C 2 HDMF C (Schieberle et al., 2003; Schieberle, 2005) Model systems: Furaneol is mainly formed from intact glucose skeleton Except in aqueous systems at weak basic ph where fragmentation is dominating Food system & extrusion: Furaneol is almost exclusively formed from the intact glucose skeleton
Conclusions & utlook Ensuring product quality by extrusion Flavour generation can be modulated and optimised with respect to other food product attributes (colour, texture, ) The holistic approach based on experimental design and a global product characterisation allows rapid optimisation of recipe and extrusion parameters This requires an integrated approach of various scientific and engineering disciplines Future focus Better understanding of chemical reactions taking place and their interactions during food processing (targeted experiments, CAMLA, ) Better understanding of material properties and transformation in Maillard systems Better integration of food physics & engineering (e.g. physical state, Tg, heat load) in our Maillard world to achieve better control 18
Thanks to Hélène Chanvrier PTC rbe Structure, texture Tomas Davidek PTC rbe Flavour, acrylamide Daniel Festring PTC rbe Flavour, processing Valérie Leloup PTC rbe Macromolecular chemistry Werner Pfaller PTC rbe Extrusion Andreas Rytz NRC Lausanne Experimental design Silke Illmann Univ. Karlsruhe Diploma work (Prof. H. Schuchmann) Rosa Delgado Sanchez Univ. Sevilla PhD thesis (Prof. F. Hidalgo) Lara S. Kirsch TU Munich Master thesis (Prof. T. Hofmann) and to you for your kind attention! 19