Flavor evaluation of crude oil to predict the quality of soybean oil

Reliable methods for evaluation of crude oils are needed to assist processing and to improve flavor quality of finished products. The quality of crude oils from soybeans of different sources and treatments was determined by sensory evaluation and by capillary gas chromatographic (GC) analyses of volatiles. Taste panelists were specially trained in using a new technique to evaluate crude oils by dilution and comparison with freshly deodorized oils. The flavor quality of crude oils from untempered soybeans was significantly poorer than that of oils from soybeans steam‐tempered at 104 C for four min. Capillary GC analyses of total volatiles and hexanal correlated well with differences in flavor quality and stability. Crude oils extracted from soybeans damaged by storage at 45 C and 13% moisture received decreasing flavor scores with prolonged storage time. Similarlly, hexanal and total volatile contents increased with storage times. Commercial crude oils from several geographic locations showed a wide range in flavor scores. However, flavor scores of crude oils showed good agreement with flavor stabilities (decrease in flavor scores after storage at 60 C) of the corresponding oils after refining, bleaching, and deodorization. Therefore, the combined use, of sensory evaluations and GC‐volatile analyses of crude oils can provide convenient, rapid, sensitive and reliable screening methods to assist in improving the quality of finished soybean oils by controlling soybean storage and processing.