Nutritional and physicochemical evaluations of tahina (sesame butter) prepared from heat-treated sesame seeds

Dehulled sesame seeds were roasted using different heat treatments. The eff ects of roasting treatments on the nutritive value, physicochemical propert ies and sensory properties of produced tahina were studied. Resultant tahin a contained 586-594 g kg(-1) crude oil, 219-226 g kg(-1) crude protein and <30 g kg(-1) crude fibre and ash. Crude protein, crude fibre, ash and N-fre e extract in tahina samples were not affected by roasting treatments. Howev er, crude oil was decreased by steam roasting and hot plate roasting. Hot p late roasting was more effective in reducing raffinose content than other r oasting treatments, whereas vacuum roasting was less effective in reducing raffinose content than other roasting treatments. Tahinas were good sources of essential amino acids, especially sulphur-containing amino acids, aroma tic amino acids and tryptophan. Hot air roasted tahina followed by vacuum r oasted tahina had higher total essential amino acid contents than steam roa sted and hot plate roasted tahinas. Lysine was the first limiting amino aci d in tahinas. Tahinas had a relatively high in vitro protein digestibility (over 83%). Tahina is a good source of niacin. Hot air roasted tahina had t he highest content of B group vitamins compared with other tahina samples. Resultant tahinas had relatively high amounts of Na, Mg, K, Cu, Zn and Fe a nd a low amount of Ca. Roasting treatments did not affect the mineral conte nts. All roasted samples had a typical protein spectrum with a maximum abso rption at 280 nm and minimum at 260 nm. However, the spectrum of hot air ro asted tahina proteins was sharper than the spectra of other tahina proteins . Size exclusion HPLC fractionated tahina proteins into two fractions for h ot roasted and vacuum roasted tahinas and three fi actions for steam roaste d and hot plate roasted tahinas. The gel filtration pattern of tahina prote ins contained four peaks with identical elution volumes but different propo rtions. Hot air roasted and vacuum roasted tahinas had higher panel scores than steam roasted and hot plate roasted tahinas for all tested sensory pro perties. (C) 2000 Society of Chemical Industry.