Effects of Bleaching on the Properties of Roasted Sesame Oil

Abstract

: Improvement in quality of roasted sesame oil was studied. Roasted sesame oil was bleached at 70 °C, 85 °C, or 100 °C for 20 min with acid‐activated clay at 0.5%, 1.0%, or 3.0% (w/w) and then centrifuging at 12096 × g at 4 °C for 10 min. The color of the roasted sesame oil became lighter and the viscosity of oil decreased by bleaching. Bleaching caused a significant increase in the smoke point of the oil, from 170 °C to a range of 183 °C to 191 °C. Bleaching increased palmitic acid and decreased linoleic acid contents of roasted sesame oil. Bleaching decreased free fatty acid (FFA) and conjugated dienoic acid (CDA) contents and carbonyl values (CV) of roasted sesame oil. The more the acid clay was used, the lower were the FFA and CDA contents and CV of the oil. Amount of acid clay in bleaching of roasted sesame oil had higher effects on the color, viscosity, smoke point, FFA and CDA contents, and CV of roasted sesame oil than the bleaching temperature. Bleaching did not show a significant effect on tocopherol contents of the sesame oil. Bleaching tended to decrease sesamolin contents and increase sesamol contents in the roasted sesame oil. As the amount of acid clay and the bleaching temperature increased, the contents of sesamin and sesamolin in the oil decreased while sesamol contents increased.

Effects of sesamol, sesamin, and sesamolin extracted from roasted sesame oil on the thermal oxidation of methyl linoleate

“…Sesamol, sesamin, and sesamolin were quantified from the calibration curves of respective standard compounds. a-Tocopherol was determined by HPLC (Kim & Choe, 2005) with the same HPLC equipped with a m-porasil column (3.9 mm  300 mm; Waters Co.) and a fluorescence detector set at 300 nm for the excitation and 338 nm for the emission. The eluting solvent was isopropanol in n-hexane (0.5:99.5, v/v), and the concentration of a-tocopherol was determined from the calibration curve of standard a-tocopherol.…”

“…Methanol extracts of tea seed oil decreased the free radical autoxidation by scavenging radicals and inhibited red blood cell homolysis and low density lipoprotein oxidation (Lee & Yen, 2006). Roasted sesame oil, which is manufactured by pressing the roasted sesame seeds, is very stable to the oxidation (Chung, Lee, & Choe, 2006;Kim & Choe, 2005) and the addition of roasted sesame oil significantly decreased the oxidation of soybean oil during heating at 160 C (Chung & Choe, 2001). Sesame oil contains sesamol, sesamin, and sesamolin which decreased the autoxidation of oil and methyl linoleate at relatively low temperatures Suja, Jayalekshmy, & Arumughan, 2005).…”

Identification of key aroma‐active compounds in sesame oil from microwaved seeds using E‐nose and HS‐SPME‐GC×GC‐TOF/MS

“…The traditional fragrant sesame oil production process involves high‐temperature roasting of sesame seeds followed by the production of sesame oil by water generation or pressing (Lee & Choe, ). High‐temperature roasting produces a rich aroma of SO, but it has a deep color and poor transparency (Kim & Choe, ), and roasting of sesame seeds at 250°C can produce free fatty acids by hydrolysis of mono‐, di‐, and triacylglycerols in the seeds and these free fatty acids can accelerate oil oxidation (Choe & Min, ). Roasting of sesame seeds at 260°C can easily lead to the generation of polycyclic aromatic hydrocarbons such as benzo(a)pyrene in the sesame oil (Shin et al, ).…”

Characteristics of Structured Lipid Prepared by Lipase-Catalyzed Acidolysis of Roasted Sesame Oil and Caprylic Acid in a Bench-Scale Continuous Packed Bed Reactor

“…On the other hand, our roasted sesame oil had a shorter OSI induction period of 3.2 h at 120°C than the 6.0 h of the Codex standard at the same temperature (29) ( Table 7). This result is also due to the lower levels of sesame lignans content in our oil sample compared to those in other researchers' oil samples (7). Volatile Compounds.…”