Lipid cereal starch

Potato starch contains fewer lipids than the cereal starches. Free latty acids in rice and maize starches result in amylose-lipid complex formation, thereby contributing to their higher transition temperatures and lower retrogradation. 

The exact quantity of protein and lipid present depends on the species and variety of starch however, typical well washed cereal starch samples contain —0.3% protein and up to 1.0% lipid, while a typical root or tuber starch may contain —0.05% protein and 0.05-0.1% lipid.63 These values result from bulk analysis of starch in reality, the actual distribution of the components is not uniform, with both protein and lipid enrichment believed to be present towards and at the granule surface.58,64,65... 

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... 

Swinkels29 collected published characterization data for tapioca starch and compared it to that for other starches of commercial significance (Table 12.4). Tapioca starch is differentiated from other starches by its low level of residual materials (fat, protein, ash), lower amylose content than for other amylose-containing starches, and high molecular weights of amylose and amylopectin. The small amount of phosphorus in tapioca starch is partially removable30 and, therefore, not bound as the phosphate ester as in potato starch. It is also common to find protein and lipid values of zero, as reported by Hicks.31 The very low protein and lipid content is an important factor which differentiates tapioca starch from the cereal starches. 

Takahashi, S., and Seib, P. A. (1988). Paste and gel properties of prime corn and wheat starches with and without lipids. Cereal Chem. 65 474-483. 

The capacity of starch to stain blue-black with iodine suggests that some of the amylose is present in the starch in the V-form. The lipids present in cereal starch would bind to amylose if it were in the V-form, and yet X-ray analysis does not show the presence of the V-polymorph in cereal starches (i.e., most of the amylose would be in the amorphous form). The conclusion is that although a significant part of the amylose is probably in the helical form, the three-dimensional order necessary to give a crystalline diffraction pattern is absent. Indeed, the crystalline nature of starch is now attributed to the presence of amylopectin and not to amylose. Starch from waxy mutants contains only amylopectin (and no amylose), but this starch has the same degree of crystallinity and the same X-ray pattern as the regular starches that contain both components. 

Cereal starches contain low levels of lipids (0.5-1%), which are generally polar lipids requiring polar solvents such as methanol-water for extraction. Lipid content increases with amylose content, and unless the granule integrity is disrupted, the lipids remain inaccessible to normal fat solvents, suggesting that they are present as an amylose inclusion complex. Noncereal starches contain essentially no lipids. 

Fig. 33.—Effect of lipid on starch retrogradation, measured as changes in the degree of gelatinization during the storage of cooked rice. Solid points, native rice open points, defatted rice solid squares, refatted rice. (Reprinted with permission from Y. Hibi, S. Kitamura, and T. Kuge, Cereal Chem., 67 (1990) 7-10.)...

Tester, R. F. and Morrison, W. R. 1990. Swelling and gelatinization of cereal starches. I. Effects of amylopectin, amylose and lipids. Cereal Chem. 67(6) 551-557. 

Complexing abihty depends on the amylose level, its binding to amylopectin, and on lipid composition. Among starches, the least able to form amylose-hpid complexes are potato starches, which contain less amylose, protein, and hpids than cereal starches. Wasserman and Meste (2000) found no amylose-lipid (stearic acid) inclusion complex during heating and coohng of a potato starch and lipid suspension, but they did report the observation that the lipids adhered to the starch granules. 

Morrison, W.R., Tester, R., Snape, C.E., Law, R., Gidley, MJ. 1993. Swelling and gelatini-zation of cereal starches. IV. Some effects of lipid-complexed amylose and free amylose in waxy and normal barley starches, Cereal Chem., 70(4), 385. 

Shamekh, S., Mustranta, A., Poutanen, K., and Forssel, P, 1998. Enzymatic hydrolysis of barley starch lipids. Cereal Chem., 75(5), 624. 

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