Plate count, titratable acidity, water soluble carbonyl (WSC) levels and hexane extractable carbonyl (HEC) levels were evaluated during incubation of Streptococcus lactis 60 at 32°C in reconstituted nonfat dry milk (NDM), peanut flour (PF)/NDM or soy protein isolate (SPI)/NDM blends and a in peanut or soybean milks. Increased heat treatment decreased acid production but did not affect growth of S. lactis in NDM, PF/NDM or SPI/NDM. Differing data trends for WSC synthesis were observed in PF/NDM and SPI/NDM when compared to NDM. The rate of growth, rate of acid production and the WSC level were lower in oilseed milks than in NDM. HEC levels in soybean milk decreased slightly with S. lactis incubation while HEC levels in other products were not significantly affected.