Mannitol and sorbitol dioctanoates in canola oil self-assemble into a crystalline network that encapsulates the oil, causing it to take on a semisolid form, which could provide alternatives to trans fats linked to obesity, coronary artery disease and diabetes, according to a new study published in the Journal of Agricultural and Food Chemistry.
Researchers at City College of New York tested two sugar alcohol-based gelators—mannitol dioctanoate (M8) and sorbitol dioctanoate (S8)—as structuring agents for four refined vegetable oils purchased at local grocery stores: canola oil, olive oil, soybean oil and grape seed oil. Both are amphiphiles (i.e. molecules that are attracted to water and fats) consisting of two octanoic acid chains (C8) appended to a sugar alcohol molecule.
The vegetable oils successfully transformed to a semisolid form using low-calorie sugars as a structuring agent. These may be alternatives to structured oil products produced using saturated/trans fatty acids, which have been linked to coronary artery disease, obesity and diabetes.
The best known structured oils are vegetable oil and margarine. Structured oils are also contained in candy and cake frosting.
“We have demonstrated the first sugar-based thickening agents for oil," said George John, professor of chemistry. The two agents meet both are both generally recognized as safe (GRAS), and can be used for food processing.
Both M8 and S8 demonstrated excellent gelation tendencies for all of the oils that were tested, and the gels remained stable for several months. When mixed with the oils, the gelation agents self-assembled into three-dimensional crystalline networks that encapsulated the oils in liquid stage. Optimal gelation was achieved at structuring agent concentrations between 3% and 5%.
However, some differences between the two agents were reported. For example, mannitol gels were opaque in appearance while those made with sorbitol were translucent. That was because M8 yields a more densely packed network while the network of S8 gels consisted of needle-like microcrystallites.
Mannitol was found to be a more efficient gelator, producing stronger gels. However, sorbitol-based gels, which have finer structures and appear more translucent, would be better suited for specific applications. “The multi-functionality and tunability of sugar-based gelators presents opportunities to develop next-generation oil thickeners," John said.
