Colloidal structures of phospholipids in vegetable oil and their potential usage in surface treatment of nanocellulose for food applications

Research output: ThesisLicenciate's thesis

Abstract

The aim of the licentiate’s thesis was to understand the colloidal behaviour of phospholipids in vegetable oils and to study the adsorption of phospholipid nanostructures onto the surface of cellulose nanofibrils. Water concentration, temperature and free fatty acid had an effect on the formation of reverse micelles of phospholipids in vegetable oil. At low water concentration, phospholipids formed solubilized reverse cylindrical micelles above critical micelle concentration (cmc) in the oil. Increasing temperature decreased the cmc of phospholipids in oil. Addition of moderate amount of water into oil caused solubilized phospholipids to form lamellar liquid crystal structures that were precipitated from the oil and formed separate phase. Oleic acid in rapeseed oil increased the solubility of lecithin and suppressed the formation of phospholipid reverse micelles at low water content. In presence of more water, the oleic acid stabilized the reverse micelles and consequently more water was needed to induce the phase separation. Thus it could be concluded that moderate amounts of oleic acid (5 wt.-%, 10 wt.-% and 20 wt.-%) in the oil delayed the removal of phospholipid reverse micelles upon addition of water, and the formation of lamellar structures required more water. This was caused by the increased solubility of lecithin into oil due to the co-solvent effect of oleic acid. Nanocellulose has shown many potential applications in foods, such as emulsifiers, fillers, structuring agents and cholesterol binders. An interesting application for nanocellulose would be the replacement of saturated fats in foods to decrease the fat content and the energy content of the products. To increase the compatibility of nanocellulose with the vegetable oil, the adsorption of phospholipid nanostructures was studied by immersing cellulose nanofibril film into the oily liquid containing phospholipid lamellar structures. The contact angle measurement seemed not to be an optimal way to measure the adsorption of phospholipids onto the surface of nanocellulose due to the variation in the results. Some of the contact angle measurement results indicated that the addition of the oily liquid containing phospholipid lamellar structures onto the surface of nanocellulose decreased the hydrophilicity of the surface after rinsing it with chloroform. In addition, two measurements indicated that the addition of oily liquid containing phospholipid lamellar structures decreased the hydrophilicity of the surface.
Original languageEnglish
QualificationLicentiate's degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Rojas Gaona, Orlando, Supervising Professor
  • Bai, Long, Thesis Advisor
  • Hokkanen, Sanna, Thesis Advisor
Publisher
Publication statusPublished - 2019
MoE publication typeG3 Licentiate thesis

Keywords

  • Reverse micelles
  • Phospholipides
  • Vegetable oil
  • Cellulose nanofibrils

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