Properties of Damaged Starch Granules. II. Crystallinity, Molecular Order and Gelatinisation of Ball-milled Starches

Wheat and maize starches were ball milled to obtain various levels of damaged starch, with corresponding losses of short-range crystalline order (measured by wide-angle X-ray diffraction) and double-helix content (measured by 13C-CP/MAS-NMR) in the dry starches. Regression analyses indicated that all damaged starch in the dry wheat and maize starches was amorphous. Order in damaged maize starches could be restored by wetting and drying the damaged starches. On wetting, the damaged portions of the granules comprised soluble material and swollen gel that were quantified together as damaged starch using an enzymic assay. The undamaged portion comprised surviving native starch granules and birefringent remnants of larger granules that had been partially damaged. Both the enthalpy and temperature of gelatinisation of the starches, and of the recovered native granules plus remnant material, decreased with increasing levels of starch damage. Starches isolated from millstreams showed the same pattern of behaviour. A model is presented to explain the observed patterns of damage. It is concluded that amorphous starch within the native granules (which does not include crystalline amylopectin) should be distinguished from amorphous damaged starch since they differ in composition and in their physical properties

The effect of the shrunken endosperm mutation shx on starch granule development in barley seeds

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Swelling and gelatinization of cereal starches. IV. Some effects of lipid-complexed amylose and free amylose in waxy and normal barley starches

Cereal Chem. 70:385-391. Amylose (AM) and lysophospholipid (LPL) contents were directly correlated in barley starches, but the linear regressions that described the relationships in waxy and nonwaxy starches were quite different. The data indicated that AM exists partially as lipid-complexed amylose (L.AM), with an LPL-to-L.AM ratio of 1:7 and partially as lipid-free amylose (F.AM). The [13]C-cross polarization/magic angle spinning-nuclear magnetic resonance (CP/MAS-NMR) spectra of the nonwaxy starches had a broad resonance with a chemical shift of 31.2 +/- 0.4 ppm, which is characteristic of midchain methylene carbons of fatty acids in the solid state or in V-amylose (V-AM) complexes. The extracted lipid was a viscous liquid that, when mixed with seven parts AM, did not give a discernible peak under the conditions used to acquire the solid- state spectra. However, when the lipid was complexed with AM, it gave a typical V-AM spectrum and a broad resonance at 31.8 ppm. This proves lipid complexed with L.AM existed in the native starches and was not an artifact formed subsequently from free LPL and F.AM. The intensity of the resonance was consistent with the LPL content of the starches. Independent supporting evidence was obtained by differential scanning calorimetry that showed a constant enthalpy for disordering of amylopectin, DeltaH(AP), for all waxy and nonwaxy starches, regardless of L.AM content and, hence, no exothermic formation of L.AM during starch gelatinization. Twelve waxy barley starches used in this study contained 0.8-4.0% L.AM and 0.9-6.4% F.AM; six nonwaxy starches contained 6.1-7.2% L.AM and 23.1-25.0% F.AM. All starches had essentially identical AP structures, as show by the chain lengths of debranched starches fractionated by gel-permeation chromatography and high-performance liquid chromatography. L.AM and F.AM appeared to have quite different effects on starch gelatinization behavior. Peak gelatinization temperature (Tp) of the waxy starches was p ositively correlated with L.AM content; because the Tp of the nonwaxy starches was much lower than predicted from the regression equation for the waxy starches, we concluded that F.AM lowered Tp. Swelling of starches at 80 C is essentially a property of AP content that is inhibited by LPL, but the relationship is not strictly linear. An improved equation to describe swelling properties assumed that 80% of the F.AM swelled with the AP fraction, although swelling was inhibited by L.AM0.485

Use of slow release starch (SRS) to treat hypoglycaemia in type 1 diabetics

The purpose of this paper is to evaluate if slow release starch (SRS) could be used to control/limit hypoglycaemia in type 1 diabetics. Ten type-1 diabetic volunteers were fitted with continuous glucose monitors for two periods of 3 days when undertaking their normal routine or when consuming 60?g SRS before sleep. The average number of nocturnal hypoglycaemic episodes where no SRS was consumed over 3 days was 2.7?±?2.0 but only 0.7?±?1.1 after SRS consumption before sleep. The duration of these events was equivalent to 318?±?282 and 140?±?337?min, respectively. Average nocturnal blood glucose concentration was 7.9?±?1.4?mmol?l-1 without SRS consumption but increased to 9.7?±?2.7?mmol?l-1 when SRS was consumed. These data were highly significant when subjected to analysis of variance (ANOVA) test on a subject by subject basis. The SRS may be used as a cost effective therapy to avoid hypoglycaemia in patients with type-1 diabetes. This paper reports for the first time the use of a physically modified waxy maize starch (SRS) to prevent/limit the incidence of nocturnal hypoglycaemia in type 1 diabetics