Effects of Roasting on Pyrazine Contents and Oxidative Stability of Red Pepper Seed Oil Prior to Its Extraction

Abstract

Red pepper seeds were roasted with constant stirring for 6, 9, 10, and 12 min at 210 degrees C, and oils were extracted from the roasted red pepper seeds using an expeller. The iodine values and fatty acid compositions of red pepper seed oils did not change with roasting time. The fatty acid composition of the oil obtained from the red pepper seeds roasted for 6 min was 0.24% myristic acid, 13. 42% palmitic acid, 0.33% palmitoleic acid, 2.07% stearic acid, 10. 18% oleic acid, 73.89% linoleic acid, and 0.37% linolenic acid, showing a fatty acid composition similar to that of high-linoleate safflower oil. Thirteen alkylpyrazines were identified in the roasted red pepper seed oils: 2-methylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2-ethylpyrazine, 2-ethyl-6-methylpyrazine, 2-ethyl-5-methylpyrazine, trimethylpyrazine, 2,6-diethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, tetramethylpyrazine, 2, 3-diethyl-5-methylpyrazine, 2-isobutyl-3-methylpyrazine, and 3, 5-diethyl 2-methylpyrazine. The pyrazine content increased markedly as the roasting time increased, showing 2.63, 5.01, 8.48, and 13.10 mg of total pyrazine/100 g of oils from the red pepper seeds roasted for 6, 8, 10, and 12 min, respectively, at 210 degrees C. 2, 5-Dimethylpyrazine in the roasted red pepper seed oil seemed to be the component most responsible for the pleasant nutty aroma of the oils. The oxidative stabilities of oils increased greatly as the roasting time increased.

Microwave roasting effects on the physico‐chemical composition and oxidative stability of sunflower seed oil

“…These decreases may be attributable to reductions in the number of unsaturation sites as a result of oxidation, polymerization, or breakage of the long-chain FA. However, Jung et al (32) reported that the iodine values of red pepper seed oils did not change with roasting time. In sunflower seed and peanut oils, Yoshida et al (2,33) found that roasting caused a significant decrease (P < 0.05) in molecular species containing more than four double bonds.…”

Changes in oxidative stability, antioxidant capacity and phytochemical composition of Pistacia terebinthus oil with roasting

“…However, the differences were not statistically significant (p > 0.05). Others have reported that roasting caused no significant variation in fatty acid composition of extracted oils (Jung, Bock, Baik, Lee, & Lee, 1999;Kim et al, 2002).…”

Effects of processing techniques on oxidative stability of <em>Prunus pedunculatus</em> seed oil

“…Oils, extracted from coated and unhulled seeds after microwaving, are oxidized more quickly than those from other treatments (Abou-Gharbia et al, 1997). Some studies have shown that the chemical composition of oil is independent of the roasting temperature used for its preparation (Kim et al, 2002;Jung et al, 1999).…”