Developing low linolenic acid, lipoxygenase-free soybean lines for improved soymilk stability and flavour
Poor oil stability and undesirable flavours in soy-based foods are associated with elevated linolenic acid levels and seed lipoxygenases. The objectives of this thesis were to produce low linolenic acid, lipoxygenase-free soybean using marker-assisted selection, and to test the effects of these traits on lipid oxidation and soymilk flavour. Large seed size and yellow hilum colour from SQ960121-7 were combined with low linolenic acid, lipoxygenase nulls from OR297. A backcross to SQ960121-7 was employed and selection of low linolenic acid level, lipoxygenase null lines was made using trait-linked markers and conventional methods. Three tofu-type, low linolenic acid, lipoxygenase-free F4 populations were produced. Soymilk prepared from OR297 (low linolenic, lipoxygenase free), OX948 (lipoxygenase free), RG10 (low linolenic), Harovinton (tofu-type) and OAC Kent (oilseed type) were evaluated by a sensory panel. Generally, OR297 was the most preferred and a significant relationship between rancidity and lipid oxidation levels was identified.