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Spray-drying of protein/polysaccharide complexes: dissociation of the effects of shearing and heating steps Jian Wang, Faydi Maoulida , Chedia Ben Amara, Emilie Dumas, Adem Gharsallaoui

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  1. Spray-drying of protein/polysaccharide complexes: dissociation of the effects of shearing and heating steps Jian Wang, FaydiMaoulida, Chedia Ben Amara, Emilie Dumas, Adem Gharsallaoui Univ Lyon 1, ISARA Lyon, Laboratoire BioDyMIA, Equipe Mixte d’Accueil, n°3733, IUT Lyon 1, technopole Alimentec, rue Henri de Boissieu, F-01000 Bourg en Bresse, France adem.gharsallaoui@univ-lyon1.fr EFW 2018: The 10th International Conference on Water in Food, 19–21 September 2018, Prague (Czech Republic)

  2. Introduction • Experimental design • Effect of atomization on the properties of caseinate/pectin complexes • Effect of heat treatment on the properties of caseinate/pectin complexes • Combined effect of atomization and heat treatment of complexes • Conclusion Plan

  3. 1. Introduction : Spray-drying process Air Peristaltic pump Nozzle Drying air Heating • Spray-drying : efficient and economical processwhich was widely used in food industry; • The spray-drying process can be divided into two steps: atomization and heating. • Atomization step : pulverization of the liquid into small droplets; • Heating step : the droplets come into contact with heat air  evaporation of water. Atomization

  4. 1. Introduction : About complex coacervation (in aqueous medium) + Proteins in solution Polysaccharides in solution Attractive interactions Repulsive interactions C C pH, I Soluble complexes Coacervates / Precipitation Incompatibility Co-solubility Spray-Drying PROCESS ? 4

  5. 1. Introduction

  6. 2. Experimental Design • Sodium caseinate and Low methoxyl pectin are chosen as the protein/polysaccharide system; • Zeta-potential electrostatic complexes are formed at pH 3 (oppositely charged biopolymers). 6

  7. 2. Experimental Design Pectin Final pectin concentration: 0.5 g/L, 2.0 g/L and 6.0 g/L Constant Caseinate concentration: 5.0 g/L Caseinate/Pectin complexes Caseinate/Pectin complexes after atomization Turbidity; Zeta-potential; Particle size distribution; Surface hydrophobicity. Heat treatment* Heat treatment* Caseinate Imidazole-acetate buffer (5 mM) at pH 3 Atomization *Heat treatment: water bath at 80°C for: 1 min (T1), 2 min (T2), 3 min (T3) and 4 min (T4). Control : Unheated complexes (T0). Complexes after atomizationfollowed by heattreatment Caseinate/Pectin complexes after heat treatment

  8. 3. Effect of atomization on the properties of caseinate/pectin complexes Pectin Final pectin concentration: 0.5 g/L, 2.0 g/L and 6.0 g/L Constant Caseinate concentration: 5.0 g/L Caseinate/Pectin complexes Caseinate/Pectin complexes after atomization Turbidity; Zeta-potential; Particle size distribution; Surface hydrophobicity. Heat treatment* Heat treatment* Caseinate Imidazole-acetate buffer (5 mM) at pH 3 Atomization *Heat treatment: water bath at 80°C for: 1 min (T1), 2 min (T2), 3 min (T3) and 4 min (T4). Control : Unheated complexes (T0). Complexes after atomizationfollowed by heattreatment Caseinate/Pectin complexes after heat treatment

  9. 3. Effect of atomization on the properties of caseinate/pectin complexes • Before atomization : the turbidity of complexes increasedwith increasing pectin concentration while the average size reached a peak  at 6.0 g/L of pectin, formation of small complexes but more numerous; • After atomization : partial dissociationof complexes due to shear forces and electrostatic repulsions between the pectin chains surrounding the complexes; • Complexes formed at highpectin concentrations are more sensitive to atomization.

  10. 3. Effect of atomization on the properties of caseinate/pectin complexes • Increasing pectin concentration: the electrostatic charges changed from positive to negative  adsorption of pectin and formation of electrostatic complexes; • Atomization : the dissociation of the complexes after atomization is due to: - Shear forces during their passage in the nozzle; - An increase in their overall charge favoring electrostatic repulsions.

  11. 3. Effect of atomization on the properties of caseinate/pectin complexes • Before atomization: slight decrease of the protein hydrophobicity only at high pectin concentration (6.0 g/L) •  the hydrophobic sites of caseinate would be maskedby the pectin chains; • After atomization: a significant increase of S0was observed (particularly at 2.0 g/L and 6.0 g/L pectin): Hypothesis : molecular rearrangements and unfolding of the structure of the protein exposure of hydrophobic sites.

  12. 4. Effect of heat treatmenton the properties of caseinate/pectin complexes Pectin Final pectin concentration: 0.5 g/L, 2.0 g/L and 6.0 g/L Constant Caseinate concentration: 5.0 g/L Caseinate/Pectin complexes Caseinate/Pectin complexes after atomization Turbidity; Zeta-potential; Particle size distribution; Surface hydrophobicity. Heat treatment* Heat treatment* Caseinate Imidazole-acetate buffer (5 mM) at pH 3 Atomization *Heat treatment: water bath at 80°C for: 1 min (T1), 2 min (T2), 3 min (T3) and 4 min (T4). Control : Unheated complexes (T0). Complexes after atomizationfollowed by heattreatment Caseinate/Pectin complexes after heat treatment

  13. 4. Effect of heat treatmenton the properties of caseinate/pectin complexes • With increasing heat treatment duration from 0 to 4 min: • 0.5 g/L of pectin: the turbidity increased with the heating time and there was no significant effect on the size of complexes Assumption : aggregation of free caseinate molecules (protein denaturation); • 2.0 g/L: the turbidityremained stable as a function of the heating time but the size of complexes increased aggregation of complexes due to heat treatment; • 6.0 g/L: the turbidity increased and the size of the complexes decreaseddissociation of the aggregates.

  14. 4. Effect of heat treatmenton the properties of caseinate/pectin complexes • With increasing heat treatment durationfrom 0 to 4 min: • 0.5 g/L: Slight decrease in zeta-potential and increasein surface hydrophobicity: the structure of complexes changed (exposure of anionic groups of pectin and hydrophobic sites in caseinate molecules (denaturation)); • 2.0 g/L: changeof the electrostatic charge from positive to negative and a slight increase in hydrophobicity : the molecular rearrangement allowed to “protect” the protein from heat denaturation; • 6.0 g/L: S0 is almost constantas a function of heating time: protective effect of pectin at high pectin concentrations.

  15. 5. Combined effect of atomization and heat treatment of complexes Pectin Final pectin concentration: 0.5 g/L, 2.0 g/L and 6.0 g/L Constant Caseinate concentration: 5.0 g/L Caseinate/Pectin complexes Caseinate/Pectin complexes after atomization Turbidity; Zeta-potential; Particle size distribution; Surface hydrophobicity. Heat treatment* Heat treatment* Caseinate Imidazole-acetate buffer (5 mM) at pH 3 Atomization *Heat treatment: water bath at 80°C for: 1 min (T1), 2 min (T2), 3 min (T3) and 4 min (T4). Control: Unheated complexes (T0). Complexes after atomizationfollowed by heattreatment Caseinate/Pectin complexes after heat treatment

  16. 5. Combined effect of atomization and heat treatment of complexes • With increasing heat treatment duration from 0 to 4 min: • 0.5 g/L: slight increase in turbidity and constant sizeof the complexes  increase in the number of complexes due to the aggregation of free or partially complexed caseinate molecules; • 2.0 g/L: decrease in turbidity and significant increase in size association between small complexes accentuated by electrostatic charge neutralization; • 6.0 g/L: turbidity increased while the sizedid not change thermal dissociation of aggregates (already deconstructed by shearing) and formation of new complexes with free pectin chains.

  17. 6. Conclusion 6.0 g/L 2.0 g/L 0.5 g/L 2.0 g/L 6.0 g/L 0.5 g/L At low concentration of pectin, heat treatment causes the aggregation of excess caseinate; + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Heat treatment + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + • At intermediate concentration of pectin, heat treatment intensifies aggregation of complexes; • At high concentration of pectin, heat treatment favors the dissociation of the aggregates. + + + + + + + + + + + + + Atomization • Atomization causes dissociation of aggregates into smaller size complexes at all pectin concentrations. • Complexes after atomization are more sensitive to heat treatment; • A high concentration of pectin can protect the complexes against heat aggregation. + + + + + + + + + + + + Heat treatment after atomization + + + + + + + + + + + + + + + + + + + 0.5 g/L 6.0 g/L 2.0 g/L 6.0 g/L 0.5 g/L 2.0 g/L

  18. 6. Conclusion • Future works : • To better characterize the nature of the protein-polysaccharide binding, other complementary techniques like FTIR (Fourier transform infrared spectroscopy), NMR (nuclear magnetic resonance) and CD (circular dichroism) can be used for further study; • Apply caseinate/pectin system to encapsulate some bio-active molecules like essential oils by Spray-drying.

  19. THANK FOR YOUR ATTENTION

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