Effect of substitution of soy protein isolate on aroma volatiles, chemical composition and sensory quality of wheat cookies.

Summary Wheat flour was substituted with soy protein isolate (SPI) at levels of 0–20% and its effect on aroma volatiles and quality of cookies was evaluated. The chemical analysis showed that the moisture and protein content increased gradually by increasing the added levels of SPI whereas the carbohydrate and fat levels showed the opposite trend. The sensory characteristics, aroma, taste, crispiness and overall acceptability showed significant (P < 0.05) increase of up to 10% SPI substitution compared with cookies free of SPI. The gas chromatographic-mass spectrometric (GC-MS) analysis of aroma volatiles revealed that the sample containing 10% SPI had the highest yield (13.57%) of pyranones, the key odourants of cookies. The results of GC-MS analysis were consistent with those of the aroma sensory analysis of cookies during storage.