The lipids divided into free (0.8-1.0%) and bound (0.6-1.0%) forms. They further divided into non-polar (50.9%) and polar (49.1%).
Polar lipids composed of triglycerides, diglyceride, monoglycerides, free fatty acids and sterol. The major portion of non-polar mainly lipids, phospholipids, and galactosyl glycerides.
Mono and diglycerides have weak polar head groups, their polarity also depends on the size of fatty acids chain present. Free fatty acids which composed 20% of non-starch non-polar lipids are the least non-polar in the non-polar faction.
Linoleic acid is the major unsaturated free-fatty acids and palmitic acid is the major saturated free fatty acids.
The bound lipids exist as starch inclusion complexes. The nonstarch lipids, about 85% of the total, participate in the chemical, physical and biochemical processes important for the preparation of baked goods.
Flour lipids play an important role in the dough-mixing and baking processes. They interact and form complexes with gluten protein and contribute to the stabilization of gas-cell structure, thus having significant effects on loaf and on final texture.
Some oxidation of lipids by wheat lipoxygenase occurs in dough, but more important oxidations resulting in dough improvement require soya lipoxygenase, and both contribute to the oxygen requirement of the dough.
Lipids have a positive effect on dough formation and bread volume, namely polar lipids or the free fatty acid component of the nonstarch lipids, whereas non-polar lipids have been found to have a detrimental effect on bread volume.
Lipid in Wheat Flour
