Effect of defatted soybean flour on the flavour of extruded mixtures with wheat flour
2002
Pokorny, J. | Farouk Mansour, A. | Pudil, F. | Janda, V. (Vysoka Skola Chemicko-technologicka, Prague (Czech Republic). Ustav Chemie a Analyzy Potravin)
Mixtures of wheat semolina, 5 % glucose and 0-30 % defatted soybean flour were used for the preparation of extruded samples using a pilot plant single screw extruder, maximum temperature being 140 deg C. Volatile substances were isolated using a SPME procedure and separated using a Fisons GLC 8000 apparatus equipped with a mass spectrometer. Organoleptic analysis was carried out by trained analysts. Only moderate browning reactions were observed. The increase of soybean flour concentration led to the changes in the sensory profile, increased odour intensity and improved sensory acceptability. Among the flavour active volatiles, pyrazines were the most prominent class of compounds, especially methyl and ethyl substituted derivatives. Pyrrole and furan substituted pyrazines were found only in small amounts because of the low extrusion temperature. Other furan and pyrrole derivatives had a lesser effect on flavour because of their relatively low amounts. Aldehydes, fatty acids, ketones, and other aliphatic derivatives contributed only a little to the resulting flavour. Compared to the mixtures of semolina and glucose only, the additions of defatted soybean flour moderately increased the number of substituted pyrazines detected in the extruded mixtures but increased substantially the pyrazine fraction in the total peak area.
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