Understanding native aroma of chocolate is important for development of food science and food industry. However, isolation of volatile compounds from chocolate is difficult due to matrix effects of cocoa butter and, so far, done using evaporation, vaporization, and distillation techniques with losing volatile compounds. The aim of this study is to develop an effective method for isolation of the volatile compounds from chocolate under mild conditions and conditions with less matrix effects. In the model study, a big gap among partition coefficients (log Pow value) of cocoa butter and volatile compounds was focused to separate volatile compounds from the matrix. Charging deodorized cocoa butter to a hexane-methanol bilayer solution enabled to perform liquid-liquid extraction and thereby push out volatile compounds into methanol layer. We named this phenomenon, the “oiling-out effect.” As a typical application, volatile compounds in dark chocolate containing 35.3% cocoa butter were extracted using liquid-liquid extraction based on the oiling-out effect. The chocolate extract was prepared under room temperature conditions and then analyzed using gas chromatography-mass spectrometry (GC-MS). Fifty-four volatile compounds from 5 g dark chocolate were identified, comprising acids, alcohols, aldehydes, esters, ketones, lactones, furans, hydrocarbons, pyrazines, pyrroles, sulfur compounds, and thiazoles. Compared with solvent extraction and headspace solid-phase micro extraction (HS-SPME), the present method, named the oiling-out assisted liquid-liquid extraction, enabled the isolation of a wide range of volatile compounds from dark chocolate. In this paper, we demonstrated the oiling-out effect as an efficient extraction method for volatile compounds in high-fat foods.
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Conflict of Interest
Daisuke Suzuki declares that he has no conflict of interest. Yuko Sato declares that she has no conflict of interest. Hiromi Nishiura declares that she has no conflict of interest. Risa Harada declares that she has no conflict of interest. Hiroshi Kamasaka declares that he has no conflict of interest. Takashi Kuriki declares that he has no conflict of interest. Hirotoshi Tamura declares that he has no conflict of interest.
This article does not contain any studies on human or animal subjects performed by any of the authors.
Chetschik I, Pedan V, Chatelain K, Kneubühl M, Hühn T (2019) Characterization of the flavor properties of dark chocolates produced by a novel technological approach and comparison with traditionally produced dark chocolates. J Agric Food Chem 67:3991–4001. https://doi.org/10.1021/acs.jafc.8b06800CrossRefGoogle Scholar
Counet C, Callemien D, Ouwerx C, Collin S (2002) Use of gas chromatography-olfactometry to identify key odorant compounds in dark chocolate. Comparison of samples before and after conching. J Agric Food Chem 50:2385–2391. https://doi.org/10.1021/jf0114177CrossRefGoogle Scholar
Mayuoni-kirshinbaum L, Tietel Z, Porat R, Ulrich D (2012) Identification of aroma-active compounds in ‘wonderful’ pomegranate fruit using solvent-assisted flavour evaporation and headspace solid-phase micro-extraction methods. Eur Food Res Technol 235:277–283. https://doi.org/10.1007/s00217-012-1757-0CrossRefGoogle Scholar
Mustakas GC (1987) Recovery of oil from soybean. In: Ericson DR, Prycle EH, Brekke OL, Mounts TL, Falb RA (eds) Handbook of soy oil processing and utilization. American Soybean Association, St. Louis, pp 49–65Google Scholar