The new study, published in Food Chemistry, shows that the solubility and stability of garlic oil can be increased by up to 6.5 fold by inclusion in a beta-cyclodextrin complex. The authors said the inclusion complex also led to a controlled, temperature dependent release of garlic oil from cyclodextrin.
“Garlic oil, rich in organosulfur compounds, has a variety of antimicrobial and antioxidant activities, however, its volatility and low physicochemical stability limit its application,” said the researchers, led by senior author Dr Chengtao Wang from the Beijing Higher Institution Engineering Research Center of Food Additives and Ingredients, China.
But Dr Wang and colleagues explained that the use of cyclodextrin to form an inclusion complex with garlic oil reduces the problems associated with volatility, stability, and solubility, meaning the compound may have uses in the food industry.
Cyclodextrin
Cyclodextrins are non-toxic cyclic oligosaccharides that are widely used in the food industry as food additives, and for stabilization of flavours and the elimination of undesired tastes.
The authors said that the inclusion complexes of ‘guest’ compounds with cyclodextrins (CDs) may enhance stability, improve the aqueous solubility, protect against oxidation, light-induced decomposition, and heat-induced changes, and mask or reduce unwanted physiological effects, and reduce volatility of the ‘guest’ compound.
Wang and his colleagues explained that CDs have the ability to form inclusion complexes with a wide variety of organic compounds, noting that the most common CDs used in formulation are alpha- beta- and gamma- cyclodextrin.
“Among the CDs, beta-CD is widely used since its cavity size is suitable for common guests with molecular weights between 200 and 800 g/mol and also due to its availability and reasonable price,” said the authors.
“To the best of our knowledge, there are, so far, few reports on the inclusion complex of garlic oil and beta-CD in the scientific literature,” they added.
The new study investigated the stability, solubility, and release characterization of an inclusion complex of garlic oil and beta-cyclodextrin.
Study details
Garlic oil (containing three major constituents – 35 per cent diallyl disulfide (DADS), 42 per cent of diallyl trisulfide (DATS), and 16 per cent of diallyl sulfide) was prepared with beta-CD using co-precipitation methods.
Wang and co workers said the water solubility of garlic oil (GO) was significantly improved.
“Compared with the solubility of garlic oil in deionized water in the absence of beta-CD, there is a 6.5-fold increase in the presence of beta-CD,” said the authors.
Temperature was reported to have a “pronounced effect” on the release rate of garlic oil from the complex.
The authors observed that the complex was “very stable, and no garlic oil release from the complex was observed” at room temperature.
“An obvious increase for the release rate of GO was observed when temperature increased,” they said.
In vitro testing showed the release profile to be characterized by an initial fast release phase, followed by a delayed release which reaches the plateau level of 100 per cent, said the authors.
“The results of this study clearly demonstrated that garlic oil could be efficiently complexed with beta-CD to form an inclusion complex,” said Wang and co- workers.
Source: Food Chemistry
Published online ahead of print, doi: 10.1016/j.foodchem.2011.02.036
“Physicochemical and release characterization of garlic oil-β-cyclodextrin inclusion complexes”
Authors: J. Wang, Y. Cao, B. Sun, C. Wang