Starch initiation

FlG. 5.—Elution Pattern for Bovine Pancreatic Amylase from an Adsorbent of Agarose plus Enzymically Modified Starch. [Initial elution with 0.05 M sodium hydro-gencarbonate buffer, pH 8.5, containing M sodium chloride, followed by elution with 1% modified starch in 0.05 if acetate buffer, pH 5.5, and containing if sodium chloride (arrow). Absorbance at 280 nm (O—O), and alpha amylase activity ( — ) (see Ref. 14.]... 

Fig. 55.—Effect of extrusion temperature on expansion (solid points), water absorption index (open points), water solubility index (stars), and viscosity at 50°C (triangles) of tapioca starch. (Initial moisture content was 22% on dry starch basis.) (Reprinted with permission of C. Mercier, R. Charbonniere, J. Grebaut, and J. F. de la Gueriviere, Cereal Chem., 57 (1980) 4-9.)...

If excess iodic acid solution is added to aqueous sulfurous acid it is well known that iodine separates from the mixture. The reaction occurs immediately if the liquids are concentrated however, if the same liquids are used in dilute form it leads to the remarkable phenomenon that such a mixture treated with a little starch initially remains completely clear, and only after the passage of a certain amount of time suddenly becomes blue, which may require a few seconds up to minutes. Using the same amounts of the two solutions and maintaining a specific temperature, the time interval from the moment of mixing to the appearance of the blue color is entirely constant, with a value that can easily be determined with a clock. 

Native A-starch occurs predominantly in cereal grains, B-starch is found in certain tuberous plants, C-starch is a rare form found in some plants and may actually be a combination of A- and B-starches. Partial conversion of B-starch to A-starch can be accomplished by adjusting temperature and humidity conditions, but complete conversion has never been achieved. When starch is dissolved in hot water, it spontaneously undergoes gelation and subsequent crystallization in the well-known process of retrogradation.(13) The polymorphic form of retrograded starch is B starch, irrespective of the form of starch initially dissolved. 

Quasi-two-dimensional structure in CIMA reaction (chlorite - - iodide -t- malonic acid -I- starch). Initially transient yellow circles emerge and start to grow in a blue surrounding. These structures dissolve and break into dot patterns demonstrating a wide distribution of sizes. The dots evolve to a stationary structure consisting of yellow hexagons of different orientations [51, 52]. Similar structures have been observed in petri dish experiments with PA-MBO reaction [53]. 

Figure 3. SEM pictures of individual granules of potato starch initial (A) oxidized potato starch with DScho 2.84, DScooh = 0.27 (B) oxidized potato starch with DScho -30, DScooh 4.60 (C).

When polymers or other water-soluble substances are present in the sample, it is advantageous to add a small amount of chloroform to the initial reaction mixture after the subsequent addition of water, a two-phase system results which may be titrated in the usual way to a starch end point or by observing the disappearance of the iodine colour in the chloroform layer. 

Etherification and esterification of hydroxyl groups produce derivatives, some of which are produced commercially. Derivatives may also be obtained by graft polymerization wherein free radicals, initiated on the starch backbone by ceric ion or irradiation, react with monomers such as vinyl or acrylyl derivatives. A number of such copolymers have been prepared and evaluated in extmsion processing (49). A starch—acrylonitrile graft copolymer has been patented (50) which rapidly absorbs many hundred times its weight in water and has potential appHcations in disposable diapers and medical suppHes. 

Enzyme—Heat—Enzyme Process. The enzyme—heat—enzyme (EHE) process was the first industrial enzymatic Hquefaction procedure developed and utilizes a B. subtilis, also referred to as B. amjloliquefaciens, a-amylase for hydrolysis. The enzyme can be used at temperatures up to about 90°C before a significant loss in activity occurs. After an initial hydrolysis step a high temperature heat treatment step is needed to solubilize residual starch present as a fatty acid/amylose complex. The heat treatment inactivates the a-amylase, thus a second addition of enzyme is required to complete the reaction. 

Eig. 10. Saccharification of starch using amyloglucoside (AMG) ( " ) with puUulanase (-----) without puUulanase. Initial dry substance (DS) of 28% at... 

In Fig. 16.32, application of a TSK PW SEC system consisting of a combination of precolumn + PWM + 6000 + 5000 + 4000 + 3000 demonstrates a possibility for analytical purposes to change from DMSO-dissolved glucans to an aqueous solution. An initially DMSO-dissolved potato starch sample was applied to the TSK PW system and because separated with an aqueous... 

This is a highly selective process and very good results on cellulose and starch grafting have been observed. Ceric ion initiated grafting is usually carried out at lower temperatures and, therefore, wastage of monomer in chain transfer reactions is minimal. 

Recently, Li et al. [30], Yu et al. [31] reinvestigated the mechanism of graft copolymerization of vinyl monomers onto carbohydrates such as starch and cellulose initiated by the Ce(IV) ion with some new results as mentioned in Section II. Furthermore, they investigated the mechanism of model graft copolymerization of vinyl monomers onto chitosan [51]. They chose the compounds containing adjacent hydroxyl-amine structures, such as D-glucosamine, /mn5-2-amino-cyclohexanol, 2-... 

Fig. 24. Kinetics of add inactivation of a-amylase (Bac. subtilis) in solution (/, 2) and immobilized on Biocarb (3) 1) pH 2 2) and 3) pH 4. A/A0 is the value of relative enzymatic activity (compared to the initial activity A0 before inactivation), substrate — starch...

The second group includes SAHs obtained by radical grafting of acrylonitrile (AN) on natural polymers, mostly starch, under the action of cerium initiators [43 -46, 50, 51], The proper crosslinked hydrophilic polymer is formed at the stage of alkali hydrolysis of grafted polyacrylonitrile (PAN), the final characteristics depending on many factors, in particular the sort of starch [46], the methods of its preparation [51], the component ratio, etc. The nature of starch is exhibited through... 

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