Lipids in starches

There are many cases in which alternative or modified procedures must be used. For example, butanol saturated with water appears to be the very useful solvent mixture to disrupt the inclusion complexes of lipids in starch and give the best extraction... 

Lipids in starch form 25% of total flour lipids the main components are lysophospholipids. 

Debet, M. R. and Gidley, M. J. (2007). Why do gelatinized starch granules not dissolve completely Roles of amylose, protein, and lipids in granule "ghosP integrity. /. Agric. Food Chem. 55, 4752- 760. 

In addition, to release lipids from source material, such as those in starch, fish meal, or milk, it might be necessary to treat the sample with an acid prior to lipid extraction (see Basic Protocol 4). In the case of milk, addition of ammonium hydroxide is necessary to dissolve casein prior to lipid extraction, which will release the lipids from its surrounding matrix (e.g., from the film surrounding the fat globules in milk). Furthermore, in certain cases, it is necessary to predry the sample in order to allow efficient and complete extraction of lipids. Particle size reduction is another factor that may improve lipid extraction efficacy. 

Lipids in starchy foods may occur in the free as well as bound forms. The latter being either in the form of amylose inclusion complexes or linked via ionic or hydrogen bonding to the hydroxyl groups of the starch components. Free lipids are easily extractable at ambient temperatures, while use of nonalcoholic solvents for a prolonged period or disruption of the granular structure by acid hydrolysis (see Basic Protocol 4) may be required for the efficient extraction of bound lipids. While acid hydrolysis allows the release and quantitation of lipids, the procedure leads to destruction of the starch components therefore, the alcohol extraction system involving propanol and water would be most desirable in these cases. This system removes both nonpolar and polar lipids from samples. 

Results for lipid content depends very much on the source material and the protocol used. Thus, oilseeds such as mustard, canola, and flax may contain 38% to 42% lipid, while starch may contain <1% total lipid. The content of lipids in meat and seafoods may vary from I % to 30%. Nutmeg contains 25% to 30% lipids. 

Weigh 20 mg of lipid-free starch (correct to 0.1 mg) into a round bottom screw-cap tube fitted with a Teflon-faced rubber liner in the cap. 

The carbohydrates, proteins, and lipids in foods are mostly in complex forms. For example, the carbohydrates are present as disaccharides, such as sucrose, or polysaccharides, such as starch. The first step in digestion is the breakdown of the larger, insoluble molecules into smaller, soluble forms that can be transported across the intestinal wall into the blood for delivery to the tissues. 

Changes that occur in starch on irradiation may influence the organoleptic and technological properties of flour. Several properties of cereals following irradiation have been studied, mainly on wheat. Generally the same compounds could be identified in irradiated cereals as in starch, but the presence of lipids, proteins, and other compounds present in cereals usually obscure estimations. Thus, for instance, the test for irradiation based on the reaction of malonaldehyde and thiobar-bituric acid is unsuitable.206... 

In starch chemistry and technology, extrusion is used for cooking as well as for preparation of starch complexes with such guest molecules as gluten6511 and lipids.651 Acylation of starch with cyclic anhydrides of dioic acids on extrusion has been demonstrated the reaction provides anionic starches.651... 

Substances commonly found in starch granules are amylopectin, amylose, molecules intermediate between amylose and amylopectin, lipid (including phospholipids and free fatty acids), phosphate monoester and proteins/enzymes. The contents and the structures of amylopectin and amylose play major roles in the functional properties of starch. However, lipids, phospholipids and phosphate monoester groups have significant effects on starch functional properties, even though they are minor constituents. 

Iodometric assay of amylose on cereal starches is most often done on lipid-extracted starch, and the amylose content from that assay is termed apparent amylose 145 or total amylose. 123 When the iodometric assay is performed on a lipid-extracted starch and the amylose content is corrected for interference from extra-long chains on amylopectin, the assay gives absolute amylose or real amylose. 145 Iodometric assay of starch that has not been lipid-extracted gives lipid-free (uncomplexed) amylose. Subtraction of total amylose from lipid-free amylose gives lipid-complexed amylose.123 The use of the term apparent amylose to designate lipid-free amylose is avoided in this chapter. All amylose percentages are calculated based on starch. 

Wheat starch often has a blander flavor compared to other cereal starches, presumably because of differences in lipids, ft contains around 1% lipids, which occur mainly as lysophospholipids.346,349-351 The amount of lipids in wheat starch, as determined... 

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