| Meat flavor generation in extruded soy protein products via pre-extrusion addition of flavor precursors was investigated. The extrudates were comparatively examined for their sensory properties, volatile components, and their application in ground beef loaves.;The synthetic meat flavors (HH, SW) thermally generated from flavor precursor systems were found to be superior to the commercial beef samples (BV, MM, HO, GG) and comparable to the natural beef flavor (BE). The dominant nonmeaty aroma qualities of HH, HO, and BE, were "Toasted/Burnt", "Spicy/Fragrant" and "Cooked Vegetables", and "Flat/Dull", respectively and were higher than ideally desirable. The precursor system of HH and HO were selected for subsequent extrusion study.;The pre-extrusion addition of flavor precursors in the soy extrudate (15HH) resulted in a moderate, but significant improvement in "Meaty" flavor when compared to the unflavored product (UFC). No difference in meatiness was found between 15HH and the commercial beef flavored extrudate (15HO). Neither flavor systems was entirely successful in masking the off-flavors of soy protein products. Except for saltiness, no differences in "Roasted", "Sweet", "Green", "Beany" and "Bitter" notes were found among the extrudates. They were scored lower in "Meaty" flavor but higher in "Green"/"Beany" notes than ideally desirable. Subtle differences in some physicochemical properties were observed among the samples.;By gas chromatography-mass spectrometry, the volatile components of 15HH (59 identified) was found to consist mainly of aldehydes, ketones, thiols, and pyrazines, of UFC (55) was predominantly pyrazines, and of HH (29) was aldehydes, alcohols, and acids. When compared to UFC, substantial increases in 2-/3-methylbutanal, 2-pentanone, and dimethyltrisulfide and the generation of several new heterocyclics were evident in 15HH and their implications to the perceived meaty flavor were discussed.;When compared to the UFC-substituted products, substitution with 15HH at 30-60% had a significantly positive effect on the aroma and color, but a limited effect on the flavor of ground beef loaves. The juiciness and mouthfeel of the products were adversely affected by increasing levels of soy-substitution. In contrast to the all-beef control, all soy-substituted products had higher cooking yields and moisture, lower fat, and enhanced oxidative stability. |
