Lipid-amylose complexes

In the presence of excess water, the transition enthalpy (AHCX) of the rye starch-lipid complex was determined to be 0.84 J/g.25 For the nine different rye starches described above, the AHCX range was 0.3-0.6 J/g.8 These values are lower than those for wheat starch, thus supporting the lower lipid content of rye starch compared to wheat starch.24 Also, there were small differences in transition temperature at a water content of 60%, the range was 100.0-106.6°C. 

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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. 

Shogren, R. L., Fanta, G. F., Felker, F. C. (2006). X-ray diffraction study of crystal transformations in spherulitic amylose/lipid complexes from jet-cooked starch. Carbohydrate Polymers, 64, 444 51. 

Lalush, I., Bar, H., Zakaria, I., Eichler, S., Shimoni, E. (2005). Utilization of amylose-lipid complexes as molecular nanocapsules for conjugated linoleic acid. Biomacromolecules, 6, 121-130. 

Figure 8.5 Schematic diagram of state and phase transitions ofstarch note the effect of moisture content and time on the various states. Tg1 Tg2 and Tg3 represent the glass transition at different moisture content levels. A-L and V-structures denote short- and long-range order of amylose-lipid complexes, whereas d.h. order corresponds to short-range B-type structures.

All wheat starches give the same A-type crystal pattern, but their degree of crystallinity is inversely proportional to amylose content. In addition, the intensity of one reflection of an amylose-lipid complex at 2 20-23° (d 4.4A) increases proportionally to the amylose level.265,271,281,284,289 The lipid content of waxy wheat starch is much lower (0.02-0.17%) than that in non-waxy wheat starch (0.6-0.7%).286,291 However, the crude fat content of waxy wheat flour is elevated by 20-40% (3-glucan and pentosan are increased by 30%.291,292 The degree of crystallinity of waxy wheat starch is reported to be 18-21% versus 13-16% for the wild type.284,289 Increases of 35% for waxy wheat starch, 23-28% for double nulls, 20-23% for single nulls and 22% for the wild type have also been reported.271... 

The high lipid content of oat starch is reflected in the high value of the transition enthalpy (AHCX) measured for the amylose-lipid complex (Table 15.4). This transition is reversible, and on a rerun greater AHCX, as well as Tcx (endotherm peak temperature), was found.26 When the oat starch was defatted, the endotherm assigned to the amylose-lipid complex disappeared from the DSC thermogram.26 Extraction at room temperature with 1-propanol water (3 lv/v) did not influence the thermogram of the starch, but if the starch was refluxed in the same solvent, a decrease in AH and a complete elimination of the endotherm ascribed to the amylose-lipid complex occurred.28 For oat starches with a lipid content of 1.1-1.7%, it was possible to... 

Table 15.4 DSC parameters for the transition of the amylose-lipid complex of oat starch in excess water...

J. Holm, I. Bjoerck, S. Ostrowska, A.C. Eliasson, N. G. Asp, K. Larsson, I. Lund-quist, Digestibility of amylose-lipid complexes in vitro and in-vivo, Starke 1983, 35, 294-297. 

Retrograded amylose Amylose-lipid complex Amylose-rich phase... 

Figure 4.3 Sketch representation of amylose-lipid complex with a saturated fatty acid chain. Amylose surround the fatty acid chain forming a helix with the hydrogen atoms oriented inwards. Each turn of the helix (8A) has six anhydroglucose units [24],...

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