Effect of Oil and Sugar Contents on the Surface of Dehulled-Roasted Sesame Seeds on Adhesion Between the Seeds

ABSTRACT:  The oil contents in the vicinity of the surface of adhesive and nonadhesive seeds were 0.77% and 0.43%, respectively. The total oil contents of adhesive and nonadhesive seeds were 52.2% and 51.5%, respectively. The adhesiveness of nonadhesive seeds increased from 0.02 to 0.59 when the surface oil content increased from 0.43% to 0.77% by smearing oil on the surface. The contact angle, surface tension of the oil, and surface morphology differed little between adhesive and nonadhesive sesame seeds. The mono- and oligosaccharide contents in the vicinity of the surface for adhesive and nonadhesive seeds were 0.15% and 0.064%, respectively. The adhesiveness of nonadhesive seeds increased remarkably from 0.02 to 0.99 when the surface saccharides and oil content increased from 0.064% to 0.15% and from 0.43% to 0.77%, respectively, by smearing sucrose and oil to the surface. These results suggested that surface mono- and oligosaccharides were an important factor in adhesion of dehulled-roasted seeds, and high surface oil content of the seeds caused an oil bridge to form between seeds.