Spruce galactoglucomannans act as multifunctional natural emulsion stabilizers

Transcription

1 Spruce galactoglucomannans act as multifunctional natural emulsion stabilizers Kirsi S. Mikkonen*, Mari Lehtonen, Chunlin Xu, Claire Berton-Carabin, Karin Schroën * Department of Food and Environmental Sciences, University of Helsinki

2 Outline 1) Wood hemicelluloses an attractive option for novel hydrocolloids 2) Emulsion preparation and characterization Morphology Droplet size distribution Surface charge Partitioning Lipid oxidation 3) Conclusions

3 Wood hemicelluloses 20 25% Lignin 25 35% Lignin 25 35% Hemicelluloses 25 30% Hemicelluloses 40 50% Cellulose 40 50% Cellulose Hemicelluloses represent a significant underutilized natural resource.

4 Structure of spruce galactoglucomannan GGM) Man:Glc:Gal 4:1:0.5 M w g/mol DA 15 30% Willför S, Rehn P, Sundberg A, Sundberg K, Holmbom B (2003) Tappi J 2:27 32 Von Schoultz, S Method for extracting biomass. Patent application WO 2014/ A1.

5 GGM in emulsions Hannuksela, Holmbom, J Pulp Paper Sci., 30, Mikkonen et al., LWT Food Sci. Technol., 42, 4, Xu et al, 2011 Nord Pulp Paper Res J 26:

6 Aims To stabilize emulsions with spruce GGM To understand the mechanisms of stabilization Physical & Oxidative Mikkonen et al. Food Hydrocolloids. 2016, 52, Lehtonen et al., Food Hydrocolloids. 2016, 58,

7 Four polysaccharides were compared a) GGM = spruce galactoglucomannan b) CMGGM = carboxymethyl derivative of GGM c) CFG* = corn fiber gum, arabinoxylan-rich by-product from corn to ethanol process, being commercialized in the US d) GA = gum arabic, commercial emulsifier/stabilizer *Yadav et al. Food Hydrocolloids. 2007, 21,

8 Emulsion preparation 1% polysaccharides 5% rapeseed oil Ultra-Turrax 7000 rpm for 1+5 min Microfluidizer 3 passes at 700 bar

9 Physical stability

10 GGM, CMGGM, and CFG emulsions were visually stable 2 weeks storage at RT 3 months storage at RT GGM CMGGM CFG GA GGM CMGGM CFG GA

11 Emulsion morphology after 1 day at RT GGM CMGGM CFG GA

12 Average droplet size Fresh 1 h D[3,2] of GGM and CMGGM emulsions was 400 nm D[3,2] (mm) GGM CMGGM CFG GA

13 A Volume (%) Droplet size distribution 1% GGM, 5% rapeseed oil Fresh 1 hour 1 day 1 week 1 month Droplet size (mm)

14 Droplet size distribution 1% CMGGM, 5% rapeseed oil B Volume (%) Fresh 1 hour 1 day 1 week 1 month Droplet size (mm)

15 Droplet size distribution 1% CFG, 5% rapeseed oil C Volume (%) Fresh 1 hour 1 day 1 week 1 month Droplet size (mm)

16 Droplet size distribution 1% GA, 5% rapeseed oil D Volume (%) Fresh 1 hour 1 day 1 week 1 month Droplet size (mm)

17 GGM CMGGM After storage, CMGGM emulsions showed flocculation CFG GA

18 Droplet size distribution of CMGGM emulsions mixed with SDS Large droplets were flocks and not coalesced B Volume (%) Fresh 2 weeks 2 weeks + SDS Droplet size (mm)

19 Surface charge of emulsions 1% PS, 5% oil Stabilizer ζ-potential (mv) GGM -9.4 ± 0.6 CMGGM ± 1 CFG ± 0.4 Highly negative ζ-potential of CMGGM may contribute to its good emulsifying capacity GA ± 0.9

20 Partitioning of polysaccharides in emulsion phases Relative polysaccharide content (%) Starting solution Aqueous phase Interface GGM CMGGM CFG GA Polysaccharides adsorbed on the interface

21 Carbohydrate composition of CMGGM in emulsion phases B) 70 Molar ratio Starting solution Aqueous phase Interface Carbohydrate composition was similar in both phases 0 Ara Rha Xyl GlcA GalA4-O-MeGlcAMan Gal Glc

22 High molar mass polysaccharides adsorbed on the interface Polysaccharide Molar mass (g/mol) Starting solution Aqueous phase Interface GGM CMGGM CFG GA

23 CMGGM partitioned according to the substitution pattern Position (%) C2 C3 C6 Starting solution Manp Glcp Aqueous phase Manp Glcp Interface Manp <29.5 Glcp 39.2 <

24 Oxidative stability

25 Oxidative stability Interface (hemicellulose) 2. Continuous phase (water) 3. Dispersed phase (oil) Large surface area is a risk, which makes the interface the most critical part of the dispersed system.

26 Highly increased oxidative stability x20 <10 meq/kg Plain stripped rapeseed oil 30 meq/kg oil (40 C, 4 days) (Lampi et al. 1999) Tween20 stabilized 310 meq/kg oil (25 C, 4 days) (Heinonen et al. 1997) Heinonen M, Haila K, Lampi AM, Piironen v Inhibition of Oxidation in 10% Oil-in-Water Emulsions by β-carotene with α- and γ-tocopherols. J Am Oil Chem Soc 74: Lampi AM, Kataja L, Kamal-Eldin A, Piironen V Antioxidant Activities of α- and γ-tocopherols in the Oxidation of Rapeseed Oil Triacylglycerols. J Am Oil Chem Soc 76:

27 Explanation? Phenolic residues

28 Conclusions GGM Spruce gum 1. Spruce gum is an efficient physical emulsion stabilizer. 2. Lipid oxidation is inhibited at challenging conditions. 3. Hypothesis of the mechanisms include Pickering stabilization by particles and assemblies with phenolic compounds.

29 Thank you Suvi Teräslahti and Dr. Anna-Maija Lampi, University of Helsinki Dr. Madhav Yadav, ERRC, USDA Academy of Finland The Finnish Food and Drink Industries Federation