The new research demonstrated the potential of a lecithin and sorbitan tri-stearate (STS) mixture to structure sunflower oil, both ingredients already commonly used as emulsifiers and crystal habit modifiers.
Writing in the journal Food Hydrocolloids, lead author Mimma Pernetti said: "The lecithin/STS organogel is a novel candidate to structure edible oil without saturated triacylglycerols (TAG)."
"The thermo-reversibility and shear-sensitivity of the resulting gel may allow several applications."The research taps into the health and nutrition trend to reduce the level of saturated fatty acids in food, reported to increase the amount of cholesterol in the blood, and increase the chance of developing heart disease.
Saturated fats are found in a wide range of common foods, including meat products, hard cheese, cream and palm oil.
"Structuring alternatives to saturated TAG hardstock are desirable, although only few are able to give structure to oil or any organic solvents," said the researchers.
Pernetti and colleagues looked at adding the two ingredients either individually or together, but found that when added separately, in concentrations between six and 20 per cent, no solidification of the sunflower oil was obtained.
When a mixture of the ingredients were added, they report a synergetic effect to form firm gels at specific ratios of lecithin:STS, between 40:60 and 60:40.
Despite the finding that the gels collapse at around 30 degrees Celsius, cooling would reverse this phenomenon and the gels would re-solidify, said Pernetti.
"From the results obtained, a model for this organogel can be proposed," said the researchers. "The building blocks for the structure are provided by STS crystals. The lecithin acts as a crystal habit modifier on the STS, stimulating needle- or plate-shaped crystals, which are more effective in building a network than other crystals.
"The secondary function of the lecithin should be to promote the formation of weak junctions between the crystals, giving a network that entangles the oil in a firm gel. The weak bounds between crystals would also explain the high shear sensitivity, observed with these gels."
Source: Food Hydrocolloids Published on-line ahead of print; doi: 10.1016/j.foodhyd.2006.10.023 "Structuring edible oil with lecithin and sorbitan tri-stearate" Authors: M. Pernetti, K. van Malssen, D. Kalnin and E. Floter