The researchers who published their findings in Food Chemistry said the process involves a single step in which the oil is mixed with a given proportion of hexane and cooled down to temperatures between 0 ºC and 5 ºC.
Cocoa butter (CB) is extracted from the seeds of the Theobroma cacao tree, a species that only can thrive in certain locations with a tropical climate. This fact and the susceptibility of the plant to pests make the cocoa supply somewhat uncertain and variable, maintain the authors.
Furthermore, they point out, the rise in the price of CB in recent years due to increasing demands has increased the interest in developing cheaper and more readily available alternatives to this fat.
According to the researchers, three CB alternatives have been used to date: lauric fats or cocoa butter substitutes; hydrogenated oils called cocoa butter replacers; or fats known as cocoa butter equivalents (CBEs), which generally are blends of stearic acid-rich tropical butters and palm oil mid fractions.
Lauric and hydrogenated fats are known to increase the levels of LDH cholesterol and induce arteriosclerosis, said the researchers. They said that CBEs thus, due to their high oleic and stearic acid content and the fact that they do not alter the levels of plasma blood cholesterol, represent a healthier and promising alternative for confectionery companies.
And they maintain that it would make more economic sense to generate CBEs from a reliable source such as an oil crop growing in temperate climates like sunflower.
In this study, the authors said they evaluated the fractionation of high stearic and high oleic (HSHO) sunflower oils using a solvent approach.
Two different oils with 17 and 20 per cent stearic acid were used, they explained, to study the kinetics of crystallization in function of temperature and the oil/solvent ratio.
The resulting stearins were isolated and characterized chemically to compare them with CB and CBE sources like mango and shea butters, as well as also determining the melting intervals of the resulting fractions, said the Spanish researchers.
The authors found that oils with different stearic acid contents produced similar stearins but at different yields depending on their initial disaturated triacylglycerols (TAGs) content.
They said that stearins containing from 65 to 80 per cent saturated-unsaturated-saturated (SUS) displayed melting and crystallization intervals similar to CB, consistent with the characteristics of a CBE.
Furthermore, mixtures of these stearins and CB were fully compatible, demonstrating that they were indeed appropriate as CBEs.
The researchers concluded that these fats could be used as confectionery products when higher melting points are required, and could be incorporated into products to avoid chocolate blooming in temperate climates.
Source: Food Chemistry
Published online ahead of print: 10.1016/j.foodchem.2010.06.053
Title: Production of stearate-rich butters by solvent fractionation of high stearic-high oleic sunflower oil
Authors: J. J. Salas, M. A. Bootello, E. Martínez-Force, R. Garcés