Quality characteristics of sesame seeds and by-products

The chemical composition, of raw sesame seed (RS); Sesame coats 1 (SC1) and sesame coats 2 (SC2) obtained as a by-product respectively after dehulling and roasting processes during preparation of sesame paste (tehineh) for the manufacturing of Halaweh (sweetened tehineh), was determined along with the physicochemical characteristics of the oil fraction. Compared to RS, SC1 and SC2 showed higher amounts of dietary fibre, ash and polyphenol and lower amounts of oil and protein. Oil from SC1 and SC2, had a higher content of free fatty acids, chlorophylls, polyphenols and sesamol than RS oil. SC2 oil showed more intense colour, more absorbance in UV-A, UV-B and UV-C ranges and a significant higher viscosity (P < 0.05). No differences (P > 0.05) were observed for refractive index, iodine value and fatty acids composition. This latter was essentially dominated by oleic and linoleic acids. Oxidative stability of oil was investigated using a Rancimat system and in an oven test at 65 °C over 60 days. RS oil was more resistant to the thermal treatment during a long period than SC1 and SC2 oils.