Effect of Water Content and Pectin on the Viscoelastic Improvement of Water-in-Canola Oil Emulsions

Maria Romero-Peña,Supratim Ghosh

doi:10.3390/fluids6060228

Abstract

This study aimed to investigate gelation in glycerol monooleate (GMO)-stabilized water-in-canola oil (W/CO) emulsions by increasing water content (20–50 wt.%) and the addition of low methoxyl pectin (LMP) in the aqueous phase. A constant ratio of GMO to water was used to keep a similar droplet size in all emulsions. Hydrogenated soybean oil (7 wt.%) was used to provide network stabilization in the continuous phase. All fresh emulsions with LMP in the aqueous phase formed a stable and self-supported matrix with higher viscosity and gel strength than emulsions without LMP. Emulsion viscosity and gel strength increased with an increase in water content. All emulsions showed gel-like properties (storage moduli (G’) > loss moduli (G’’)) related to the presence of LMP in the aqueous phase and increased water content. Freeze/thaw analysis using a differential scanning calorimeter showed improved stability of the water droplets in the presence of LMP in the aqueous phase. This study demonstrated the presence of LMP in the aqueous phase, its interaction with GMO at the interface, and fat crystals in the continuous phase that could support the water droplets’ aggregation to obtain stable elastic W/CO emulsions that could be used as low-fat table spreads.

Highlights

This study aimed to determine the interaction between water content, the presence of low-methoxyl pectin (LMP) in the aqueous phase, and hydrogenated soybean oil (HSO) in the continuous oil phase in order to develop the viscoelastic properties of a water-invegetable oil (W/VO) emulsion with improved gel strength
It should be mentioned that the presence of continuous phase fat crystal network is critical for W/O emulsion elasticity, as the emulsions made without HSO in the oil phase were liquid and destabilized with extensive water droplet sedimentation
glycerol monooleate (GMO)-stabilized water-in-canola-oil emulsions with self-supporting structures and highly elastic properties were developed with water content increments from 20 to 50 wt.%, LMP addition in the aqueous phase, and the presence of a minimum amount of saturated fat crystals (HSO) in the continuous phase

Summary

Introduction

Products containing water-in-oil (W/O) emulsions are widely used in the pharmaceutical, cosmetic, and food industries. W/O emulsions have been used to deliver moisture in lipsticks due to the high rigidity provided by the excess waxes and pigments [1]. Butter and margarine are W/O emulsions where water droplets are dispersed in a continuous fat phase made of semi-solid dairy or vegetable fats, respectively. A network of fat or wax crystals or Pickering particles around the water droplets are some of the mechanisms that have been studied to stabilize these emulsions [3]. The emulsifiers most commonly used to emulsify water in a continuous oil phase are non-ionic emulsifiers, due to their low hydrophilic–lipophilic balance (HLB)

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