The study, published in Food Hydrocolloids, provides an insight into the properties of the non-toxic sugar ester sucrose monopalmitate as a food grade surfactant for use in the production of colloidal dispersions (such as micro- and- nano- emulsions) with natural flavour oils.
The researchers from the department of food science at the University of Massachusetts noted growing interest within the food and beverage industries “in the utilization of colloidal delivery systems to encapsulate functional agents, such as flavours, colours, antimicrobials, micronutrients, and nutraceuticals.”
“The focus of our study was to establish the factors that influence the formation and stability of micro-emulsions, nano-emulsions and emulsions fabricated using sucrose monopalmitate (SMP) as a surfactant and lemon oil as an oil phase,” said the authors, led by Professor Julian McClements.
McClements and his colleagues said the results of the study provide important information for optimizing the application of natural sucrose monoesters to form colloidal dispersions in food and beverage products.
Emulsions
The authors noted that micro-emulsions, nano-emulsions and emulsions “are of particular interest as colloidal delivery systems because they can easily be fabricated from food-grade ingredients using relatively simple processing operations.”
McClements and his co-workers said that one of the most important applications of micro- and nano- emulsions is to incorporate fat soluble (lipophilic) ingredients into water-based foods or beverages that need to remain transparent – for example fortified waters, soft drinks, sauces, and dips.
However, they noted that the widespread application of nano- and micro- emulsions in food and beverage products is currently limited – partly due to the limited number of food-grade surfactants currently available.
“Many of these are synthetic surfactants that are not permissible for application in all countries, or that can only be used at low levels due to regulatory, economic, or sensory issues,” wrote the authors.
In addition, they noted that it is difficult to prepare micro- or nano- emulsions from commonly used edible oils, such as fish, corn, or soybean oil.
“There has been increasing interest in the utilization of sugar esters as surfactants within the food and pharmaceutical industries, which can be attributed to their good taste and aroma profile, low toxicity, and high biodegradability compared to petrochemical-based surfactants,” noted McClements and his team.
“In addition, sugar esters can be produced from natural products, such as sucrose and vegetable oil, and therefore are perceived as being more environmentally friendly than many other synthetic surfactants,” they added.
Study details
The research investigated the formulation of lemon oil micro-emulsions, nano-emulsions, and emulsions using the sugar ester sucrose monopalmitate (SMP) as a food-grade surfactant.
McClements and his colleagues reported that emulsions or nano-emulsions could be formed at relatively low surfactant-to-oil ratios (ratios less than 1), whereas micro-emulsions could be formed at higher values (ratios above 1).
They added that relatively stable nano-emulsions could be formed at pH 6 and 7, and stable micro-emulsions were formed best at pH 5 and 6. The authors also found micro-emulsions to be relatively stable to salt addition, however nano-emulsion droplets were reported to aggregate and grow after the addition of relatively low levels of salt.
Oil composition
McClements and colleagues added that it is important to note that the compositions of commercial lemon oils may vary appreciably:
“Differences in the chemical composition of lemon oils may impact the type, stability and properties of colloidal dispersions formed,” wrote the researchers.
They added that preliminary experiments have shown that two different commercial lemon oils had different abilities to form dispersions, explaining that “at the same surfactant and oil concentration one formed a micro-emulsion but the other formed a nano-emulsion.”
Source: Food Hydrocolloids
Published online ahead of print, doi: 10.1016/j.foodhyd.2011.02.004
“Food-grade microemulsions, nanoemulsions and emulsions: Fabrication from sucrose monopalmitate & lemon oil”
Authors: J. Rao, D.J. McClements