Precursors for formation of 2-pentyl pyridine in processing of soybean protein isolates

Using stable isotopic ¹³C-2,4-decadienal and ¹⁵N-ammonia, both compounds were confirmed as precursors in the formation of 2-pentyl pyridine (2-pp) in processing of soybean protein isolates (SPI). The yields of 2-pp were higher when adding 2,4-decadienal and ammonia together than the yields when adding 2,4-decadienal only for soybean cultivars Stressland, LOX null, Edison, and KS4694. Arginine, lysine, asparagine, and glutamine increased 2-pp when added together with 2,4-decadienal, whereas aspartic acid, glutamic acid, glycine, and histidine had no effects. In both buffer and defatted soybean slurry, the highest level of 2-pp was found at pH 9, followed by pH 7, then pH 4.5. The results indicate that the synthesis of 2-pp may be a spontaneous reaction.