Physicochemical properties of starch-wheat germ oil complex and its effects on water distribution and hardness of noodles

The physicochemical properties of starch-wheat germ oil complex (SWGOC) and its influences on the water distribution and hardness of noodles were investigated. The results showed that SWGOC retarded the retrogradation, lowered the breakdown value and solubility, and increased the swelling power of starch compared to the control. The T-21 (immobilized water) of starch dough made by SWGOC was lower than that of the control, however, the T-21 of raw noodles increased slightly from 0.12 ms to the maximum 0.13 ms and then decreased to 0.10 ms with the increase of SWGOC. The pasting profile of SWGOC during the holding phase (95 degrees C) suggested the dissociation of starch-lipid complexes during cooking. The released amylose predominantly induced double-helix at 0 h, resulting in the higher initial hardness of noodles, while the combination of liberated lipids and amylose occurred concomitantly but in a slower rate, reducing the firming rate during the first 2 h. Interestingly, the anti-firming effect was not proportion to the content of starch-lipid complexes, and noodles with less starch complexes seemed to be more effective in reducing firming rate. This study provides insight into the importance of starch-wheat endogenous lipids on noodle quality.