Introduction. Natural dye beta-carotene E160a (pro-vitamin A) is part of many functional foods. Therefore, the total intake of beta-carotene must not exceed the tolerable upper intake level, i.e. 10 mg/day. E160a is also used in formulations of complex food additives. These products contain antioxidants, emulsifiers, preservatives, carriers, stabilizers, and thickeners, which makes it make difficult to isolate and determine the amount of beta-carotene. Complex food additives vary in composition, which, together with incomplete extraction and degradation of beta-carotene, results in inaccuracy of its determination. The present research reviewed various techniques of beta-carotene extraction from liquid and dry complex food additives.
Study objects and methods. The study featured commercial samples of complex food additives containing beta-carotene. It was isolated from the samples by liquid extraction methods using organic solvents and their binary mixtures. The extraction was performed in a stirring device at 120 rpm and in a Bandelin Sonorex ultrasonic bath at 128 W and 35 kHz. The extraction continued until the samples were completely discolored. The list of solvents included chloroform, petroleum ether, hexane, acetone, ethanol, and their mixes. The experiment was based on high performance thin layer chromatography with Sorbfil sheet plates. The optical density was determined by spectrophotometry using a SHIMADZU UV-1800 device.
Results and discussion. The extraction of beta-carotene from liquid samples with mechanical stirring at 120 rpm led to the formation of stable opaque emulsions, which made it difficult to determine the amount of beta-carotene. The emulsions were destroyed by ultrasound exposure for 30 min. The degree of extraction of beta-carotene from liquid emulsion systems (≥ 95%) was achieved by ultrasonic extraction with chloroform or a binary extractant based on mixes of acetone with chloroform, hexane, or petroleum ether in volumetric ratios of 1:1. When extracted from dry samples using chloroform or binary extractants, beta-carotene was not isolated or was not completely isolated. As a result, pre-dispersion of dry samples in water with stirring at 120 rpm was proposed. Ultrasonic treatment did not contribute to the dispersion of dry samples due to insufficient cavitation action. Ethanol, which is a solubilizer, increased the extractability of beta-carotene up to 98 %. The optimal results were achieved by adding a binary extractant (ethanol:chloroform in a 1:2 ratio) to an aqueous solution of the dry sample (1:3). The optimal elution systems were hexane:benzene (9.7:0.3), butanol:methyl ethyl ketone:ammonia 10 % (9:6:6), and petroleum ether:benzene:acetone:acetic acid (23.3:5.8:0.6:0.3).
Conclusion. The article offers new methods of beta-carotene isolation from liquid and dry complex food additives of various composition and elution systems for carotene identification. The methods caused no degradation of beta-carotene during extraction and can be used to prepare samples of complex food additives for beta-carotene identification and quantitative analysis.
