2000 Volume 33 Issue 3 Pages 372-376
Three kinds of sesame seed samples (washed and dried seeds, roasted seeds and dehulled seeds)were pulverized by a cooking mixer. The free oxalic acid in each sample was extracted into boiling water, and the total oxalic acid was extracted into 0.5 M hydrochloric acid. The concentration of oxalic acid in the extract was determined by ion chromatography. The amounts of total and free oxalic acid in 100 g of dried sesame seeds were found to be 1,750 mg and 350 mg, respectively, and 100mg and 50 mg, respectively, in 100g of dehulled sesame seeds. The difference between the total and free oxalic acid gave the content of calcium oxalate in the sesame seeds. The calcium oxalate contents per 100 g of dried and dehulled sesame seeds were respectively 2,323 mg and 83 mg as the monohydrate, this corresponding to 636 mg and 23mg of calcium. Almost all of the calcium oxalate was contained in the hulls of the dried sesame seeds. The total calcium per 100g of dried sesame seeds was determined as 1,210 mg, with 636 mg of calcium fixed as the oxalate. The remaining 574 mg of calcium are considered to be available for easy digestion. The calcium oxalate crystals in the hulls of the sesame seeds were aggregated particles composed of longish hexagonal plate crystals and were estimated as the monohydrate.