Amylose

About: Amylose is a research topic. Over the lifetime, 8314 publications have been published within this topic receiving 281433 citations.

Starch : chemistry and technology

Abstract: Starch: Chemistry and Technology, Second Edition focuses on the chemistry, processes, methodologies, applications, and technologies involved in the processing of starch. The selection first elaborates on the history and future expectation of starch use, economics and future of the starch industry, and the genetics and physiology of starch development. Discussions focus on polysaccharide biosynthesis, nonmutant starch granule polysaccharide composition, cellular developmental gradients, projected future volumes of corn likely to be used by the wet-milling industry, and organization of the corn wet-milling industry. The manuscript also tackles enzymes in the hydrolysis and synthesis of starch, starch oligosaccharides, and molecular structure of starch. The publication examines the organization of starch granules, fractionation of starch, and gelatinization of starch and mechanical properties of starch pastes. Topics include methods for determining starch gelatinization, solution properties of amylopectin, conformation of amylose in dilute solution, and biological and biochemical facets of starch granule structure. The text also takes a look at photomicrographs of starches, industrial microscopy of starches, and starch and dextrins in prepared adhesives. The selection is a vital reference for researchers interested in the processing of starch.

Swelling and gelatinization of cereal starches. I. Effects of amylopectin, amylose, and lipids

Abstract: A method was developed for measuring the volume of water absorbed by starch -granules heated in excess water, based on the observation that blue dextran dye (molecular weight 2 X 106) will dissolve in supernatant and interstitial water but not in the intragranular water. Swelling curves of wheat and normal and waxy barley and maize starches, determined by measuring the swelling factor (swollen volume/initial volume of airdried starch) at various temperatures up to 850C, were characterized by an initial phase of slight swelling, a second phase of rapid swelling, and a final stage of maximum swelling (not observed with high-gelatinizing starches or if granules disintegrated). With wheat starch, swelling began at 45-500C and continued to 850C; loss of birefringence and a large decrease in gelatinization enthalpy attributed to dissociation of crystalline Gelatinization in the narrowest sense is the thermal disordering of crystalline structures in native starch granules, but in the broader sense it includes related events such as swelling of the granules and leaching of soluble polysaccharides (Atwell et al 1988). Gelatinization temperature (GT) and enthalpy (AH) are conveniently measured by differential scanning calorimetry (DSC), and this aspect has received much attention in recent years because it is experimentally convenient and precise. However, in most food systems the actual temperature at which starch gelatinizes is less important than those properties that depend on swelling, such as pasting behavior and rheological properties of the partially or fully swollen starch granules. The properties of the starch-water system will, of course, be different if the swollen granules are dispersed mechanically to give a uniform gel. Historically, starch swelling has been studied by simple methods that do not distinguish between intragranular water and intergranular or interstitial water (Leach et al 1959), and the precision of measurements was not particularly good. This paper describes an improved method for measuring only intragranular water and hence the true swelling factor at a given temperature, based on the observation that blue dextran (Mr 2 X 106) does not penetrate swollen granules. The effects of amylopectin (AP), amylose (AM), and lipids on swelling behavior were then investigated using the blue dextran method. MATERIALS AND METHODS

Effects of Amylopectin Branch Chain Length and Amylose Content on the Gelatinization and Pasting Properties of Starch

Abstract: Structures and properties of starches isolated from different botanical sources were investigated. Apparent and absolute amylose contents of starches were determined by measuring the iodine affinity of defatted whole starch and of fractionated and purified amylopectin. Branch chain-length distributions of amylopectins were analyzed quantitatively using a high-performance anion-exchange chromatography system equipped with a postcolumn enzyme reactor and a pulsed amperometric detector. Thermal and pasting properties were measured using differential scanning calorimetry and a rapid viscoanalyzer, respectively. Absolute amylose contents of most of the starches studied were lower than their apparent amylose contents. This difference correlated with the number of very long branch chains of amylopectin. Studies of amylopectin structures showed that each starch had a distinct branch chain-length distribution profile. Average degrees of polymerization (dp) of amylopectin branch chain length ranged from 18...