Premium
Effects of Roasting Conditions on the Changes of Stable Carbon Isotope Ratios (δ 13 C) in Sesame Oil and Usefulness of δ 13 C to Differentiate Blended Sesame Oil from Corn Oil
Author(s) -
Seol Nam Gyu,
Jang Eun Yeong,
Kim MiJa,
Lee JaeHwan
Publication year - 2012
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2012.02987.x
Subject(s) - roasting , sesame oil , chemistry , isotope , stable isotope ratio , physics , sesamum , nuclear physics , horticulture , biology
Differentiating blended sesame oils from authentic sesame oil (SO) is a critical step in protecting consumer rights. Stable carbon isotope ratios (δ 13 C), color, fluorescence intensity, and fatty acid profiles were analyzed in SO prepared from sesame seeds with different roasting conditions and in corn oil blended with SO. Sesame seeds were roasted at 175, 200, 225, or 250 °C for 15 or 30 min at each temperature. SO was mixed with corn oil at varying ratios. Roasting conditions ranging from175 to 250 °C at the 30 min time point did not result in significant changes in δ 13 C ( P > 0.05). Values of δ 13 C in corn oil and SO from sesame seeds roasted at 250 °C for 15 min were −17.55 and −32.13 ‰, respectively. Fatty acid ratios, including (O + L)/(P × Ln) and (L × L)/O, where O, L, P, and Ln were oleic, linoleic, palmitic, and linolenic acids, respectively, showed good discriminating abilities among the SO blended with corn oil. Therefore, using different combinations of stable carbon isotope ratios and some fatty acid ratios can allow successful differentiation of authentic SO from SO blended with corn oil. Practical Application: Adulteration of sesame oil with less expensive oils such as corn oil or soybean oil to reduce cost is a common unethical practice in Korea. Due to the unique and strong flavor of sesame oils that may mask other weaker flavors, however, differentiating authentic sesame oils from blended oils is difficult. This study showed that the roasting process did not significantly affect the ratios of the stable carbon isotope (δ 13 C) in sesame oils. δ 13 C was confirmed to be a reliable parameter. Moreover, some fatty acid ratios were designed to discriminate between blended sesame oil with corn oil and authentic sesame oil.