Effects Of Wheat Flour Lipids On Dough Properties And Noodle Quality

This study used medium-strength Hour and low-strength Hour as raw material, using separation and rccombinanl methods to change free lipid content and its components’ relative content and lipids’ polarity, to study the effects on farinograph characteristics, pasting and kneading mixed properties, and different types of Chinese noodle quality, such as color, texture, tensile and cooking quality;meanwhile, the microstructure of dough and raw noodles were investigated by scanning electron microscopy to explore the mechanism of free lipids on dough properties and noodle texture. The conclusions were as follows:The gluten and farinograph characteristics of Hour defatted and recombined by petroleum ether changed significantly less little than by chloroform treatment.With the increase of free lipids content in Hour, the water absorption of Hour decreased significantly while the stability time increased significantly. The kneading mixed experimental results showed that the increase of the free lipids content in wheat Hour made midline peak height of flour reduced while width at peak increased gradually, width at8.00increased significantly in3%of the lipids content, and midline peak time extended. The increasing of free lipids content made peak viscosity of Hour changed insignificantly, but trough viscosity, final viscosity and peak time reduced significantly.The increase in proportion of non-polar lipid fractions of free lipids made the stability time of dough prolonged significantlyWith the increase of free lipids content, the brightness values (L*) of raw noodle decreased gradually, while the red value (a*) and yellowness value (b*) increased significantly. For while salt noodles, the increasing of lipids content made the hardness of raw and cooked noodles increased gradually, the stretch distance prolonged significantly which would help to improve the extension of noodles:The right amount of fat (1%of free lipid content) had a good effect on cohcsiveness and resilience of raw noodles while too much fat had a bad effect on its TPA textural properties except for hardness:The increasing of free lipids content made cohesiveness and resilience of cooked noodles reduced significantly, but had no significant effect on cooking characteristics. Compared to while salt noodles, the increase of free lipids content had no significant effect on TPA texture (except for hardness) of unsalled raw noodles, the effects on texture of unsalted cooked noodles were similar to white salt noodles.The study on quality of high added water noodles showed:right amount of free lipids (1%) improved texture and tensile force of raw noodles;the increasing of free lipids content had no significant effect on TPA textural characteristics (except for hardness), but was unfavorable for extension of cooked noodles (the tensile distance shorten);the rate of dry matter loss and protein loss in2%of free lipids content were the least.When the relative content of polar lipid in free lipids was60%,cohesiveness and resilience of raw and cooked white salted noodles were the best, the distance of raw noodles was increased significantly; the increase in the proportion of polar lipid can improved characteristics of cooked noodles. The research adding the same amount of four different polar lipid (soybean powder lecithin, monoglycerides, free lipids of flour, non-polar lipids of flour) to defatted flour found that adding monoglycerides can make springiness and cohesiveness of raw noodles increased significantly, adding non-polar lipids can improve the hardness, cohesiveness and resilience of cooked noodles, while adding soy powder lecithin can reduce cooking loss of white salt noodle significantly.The SEM results showed:With the increase of free lipids content, the starch granules in dough were from more exposed to the outside of the protein initially to deeply bury in the protein, and gluten network organization increased. The starch granules within raw noodles made by defatted flour were more exposed to the outside of the protein and the structure was loose; after adding1%free lipids, the starch granules dispersed between the protein and protein were linked closely together; after adding3%free lipids, the starch granules were more buried in protein but the internal structure is uneven. Adding soybean powder phospholipids and hydrophilic monoglyceride to defatted flour made starch granules of dough larger and more dispersed in the protein periphery; and more closely in the internal structure of the raw noodles. While adding free fat and non-polar lipid made starch granules exposed on the protein periphery, surrounded by a small amount of protein film; and loose structure in the internal structure of the raw noodles, surrounded by a small number of protein film.