Influence of molecular character of chitosan on the adsorption of chitosan to oil droplet interfaces in an in vitro digestion model

T. Helgason*, J. Gislason, D. J. McClements, K. Kristbergsson, J. Weiss

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)

Abstract

The relationship between the adsorption of chitosan to oil droplet interfaces (surface adsorption) and the molecular characteristics of the chitosan (molecular weight and charge density) was examined using an in vitro digestion model. This model involved adding different concentrations (3-10 wt%) of oil droplets to a 0.1 wt% chitosan solution at pH 3 to simulate consumption of an oil-containing meal after ingestion of chitosan. The pH was then incrementally raised to investigate pH variations that occur when a food material passes through the human digestive tract at an oil concentration of 3%. The amount of chitosan adsorbed to the oil droplet interface decreased with decreasing molecular weight (MW) and with increasing degree of deacetylation (DDA): ≈132, 85, and 78 g of oil per g of chitosan for MWs of 200, 500 and 750 kDa (all 90% DDA), respectively; and, 47, 65, and 78 g of oil per g of chitosan for DDAs of 40%, 70% and 90% (all 750 kDa), respectively at pH 3. In addition, the extent of droplet aggregation and the nature of the aggregates formed (strong versus weak; large versus small) also depended on chitosan characteristics. The pH dependence of the interaction between anionic oil droplets and cationic chitosan molecules depended on both MW and DDA. Microscope images showed formation of large flocculated structures at pH > 7 except for low DDA chitosan which remained soluble at all pH levels. Our results may have important consequences for understanding the bioactivity of chitosan, and for designing functional food ingredients to reduce lipid digestion and absorption.

Original languageEnglish
Pages (from-to)2243-2253
Number of pages11
JournalFood Hydrocolloids
Volume23
Issue number8
DOIs
Publication statusPublished - Dec 2009

Bibliographical note

Funding Information:
This study was supported by the AVS R&D Fund of the Ministry of Fisheries in Iceland, the Massachusetts Agricultural Experiment Station (MAS 831 & 911), and NRI grants by the US Department of Agriculture (2005-33503 & 2005-01357). We also thank Primex (Siglufjordur Iceland) for supplying the chitosan material and for good advice.

Other keywords

  • Chitosan
  • Emulsion
  • Lipid digestion
  • Surface adsorption

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