Gelation characteristics of the sugar beet pectin solution charged with fish oil-loaded zein nanoparticles

• Pectin solution was charged with fish oil-loaded zein nanoparticles.
• Laccase was used to gelify the particle-free and particle-charged pectin.
• Particle charging and enzymatic oxidation influenced the viscous behavior of pectin.
• Particle charging slowed down the gelation rate of pectin solution.

It is of interest to fabricate chemical- and sugar-free pectin gels by which nutraceuticals or nutraceutical-loaded particles are delivered to consumers. Fish oil, a well known source of omega-3 fatty acids, was encapsulated in zein via alcohol evaporation. The mean size of the core-free and fish oil-loaded zein particles was 69 and 83 nm, respectively. The oil-loaded zein nanoparticles were then inoculated into the sugar beet pectin solution that gelified subsequently by the action of the oxidative enzyme, laccase. It was found that nanoparticle charging and enzymatic oxidation of pectin solution changed the flow model of the solution from Newtonian to Power law. An initial gelation rate was estimated for laccase-injected pectin solutions by using the data obtained from small amplitude rheometry tests. Nanoparticle charging of pectin solution slowed down the gelation rate ∼26 folds and resulted in a much less firm final gel. Fourier transform infrared spectroscopy confirmed that ferulic acid residues of sugar beet pectin were oxidized by laccase, resulting in gel formation.

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