Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Determination starch modification

The viscosity of a starch paste is often characterized differently by the starch manufacturer and by users in the paper industry. In the manufacturing plant, viscosity tests serve to control the starch modification process. As an example, the test is used to determine when to terminate a starch oxidation reaction for viscosity reduction. In the paper mill, viscosity testing is required to characterize the flow properties of starch-based coating formulations. [Pg.667]

To determine starch in the presence of dextrin, Edwards, Nanji and Chanmugam found a modification of the original method necessary ... [Pg.578]

There are five prime factors that determine the properties of starches 1. starch is a polymer of glucose (dextrose) 2. the starch polymer is of two types linear and branched 3 the linear polymeric molecules can associate with each other giving insolubility in water 4. the polymeric molecules are organized and packed into granules which are insoluble in water and 5 disruption of the granule structure is required to render the starch polymer dispersible in water. The modification of starch takes into account these factors. [Pg.176]

This is based on the method by Van Soest and Wine (1967) which has been modified according to subsequent recommendations. It is the only fibre determination suitable for non-ruminants. The residue consists of the plant cell-wall constituents cellulose, hemicellulose, lignin, cutin, NDF-insoluble tannin and ash. See the article by Cherney (2000) for current modifications these include the use of amylase to aid in the removal of starch from forages containing grain (Van Soest et al., 1991), which has been adopted by MAFF... [Pg.133]

Although simple in conception and straightforward, the standard methods for POV determination require strict observance of analytical quality to avoid interference of artifacts. For example, according to the AOCS methods , the sample dissolved in AcOH-CHCI3 (method Cd 8-53) or AcOH-isooctane (method Cd 8b-90) solvent is treated with aqueous KI and the liberated iodine is titrated with standard thiosulfate solution, using starch indicator. Similar standard methods and modifications have been reported in various countries . [Pg.657]

As indicated in Table 4.12, four regions which constitute the catalytic regions of amylolytic enzymes are conserved in the starch-branching isoenzymes of maize endosperm, rice seed and potato tuber, and the glycogen-branching enzymes of E. coli.286,281 It would be of interest to know whether the seven highly conserved amino acid residues of the a-amylase family listed in bold letters in Table 4.12 are also functional in branching enzyme catalysis. Further experiments, such as chemical modification and analysis of the three-dimensional structure of the BEs, would be needed to determine the nature of its catalytic residues and mechanism. [Pg.135]

The saccharification of potato starch with pure /3-amylase yields 61 % of maltose and not more. In a series of experiments we obtained as the mean value from the reduction, 61.1 %, and from the fermentation experiments, 60.8%. The reduction was (as in most experiments in this laboratory) determined by a modification of the iodometric method of... [Pg.262]

Fox and Robyt reported the kinetics of the acid-alcohol modifications by determining the avg. d.p. vs. time of reaction of the starch granules with 0.36 and 6.0% (w/v) HQ at 25 °C [142]. The kinetics showed that the avg. d.p. values dropped rapidly in the first 10 h and then leveled... [Pg.1460]

The well-known titrimetric method for determining oxygen in water is based on oxidizing the Mn(II) in Mn(OH)2 with oxygen. After the addition of KI and acidification of the solution with H2SO4, an equivalent amount of iodine is liberated. In the spectrophotometric modification of the method the iodine is determined either as a blue complex with starch, or after the iodine has been extracted into chloroform. [Pg.315]

Two methods were used one is the iodine method that was used to determine dextrinization or the ratio of hydrolysis of the starch, and the other is the phenolphifaalein method lhat was used to determine CD formation. Starch-dextrinizing activity was determined in accordance with Fuwa (19) and Pongasawasdi and Yagisawa (20) with slight modifications. The reaction mixture containing 100 (iL of diluted enzyme aliquot and 300 pL of 0.5% soluble starch prepared in 0.1 M acetate buffer, pH 5.5, was incubated at 55 °C for 10 min. The enzyme reaction was stopped by the addition of 4.0 mL of 0.2 M HCl solution. Then, 0.5 mL of iodine solution (0.3 g/L I2 and 3.0 g/L KI) was added to form an amylose-iodine complex with residual amylose. The final volume was adjusted to 10 mL with distilled water. The absorbance of the blue color of the amylose-iodine complex was measured by spectrophotometer at 700 nm, and a decrease in absorbance was verified, when compared to a control tube with heat-inactivated enzyme. One unit of enzyme activity was defined as the quantity of enzyme that reduces the blue color of the starch-iodine complex by 10% per minute. [Pg.136]

The formulation of starch and dextrin adhesives can be viewed more as an art than the result of rigorous scientific study. Not surprisingly, the purpose for whieh the adhesive is to be used and the method by which it will be applied greatly determine the properties needed in the resin. Factors that must be controlled inelude viseosity, solids eontent, stability, tack, slip, substrate penetration, drying rate, flexibility, water and mierobial resistance, and cost. Some of these are determined by the type of stareh or modification, while others require the addition of an additive to give the adhesive the desired properties. In the sections below we diseuss some of the most common additives that are used with starch-derived adhesives. [Pg.500]

Water is usually involved as reaction media for chemical modification of starch being an environmentally-friendly solvent ( green solvent ), even its use means a relatively low reactivity, or a reduced selectivity due to side reactions. As result of the chemical modification reactions, the crosslinking process of starch occurred, this way being an efficient approach to improve the performance of starch for different applications [57, 58]. Chemically modified starches were investigated by determination of the modification degree [55], and by infrared spectroscopy method [59,60]. [Pg.128]


See other pages where Determination starch modification is mentioned: [Pg.61]    [Pg.257]    [Pg.257]    [Pg.345]    [Pg.71]    [Pg.376]    [Pg.630]    [Pg.296]    [Pg.400]    [Pg.692]    [Pg.485]    [Pg.2]    [Pg.5]    [Pg.692]    [Pg.126]    [Pg.305]    [Pg.808]    [Pg.6]    [Pg.127]    [Pg.475]    [Pg.749]    [Pg.234]    [Pg.82]    [Pg.167]    [Pg.311]    [Pg.6]    [Pg.1770]    [Pg.865]    [Pg.107]    [Pg.318]    [Pg.372]    [Pg.118]    [Pg.129]    [Pg.542]    [Pg.59]    [Pg.330]    [Pg.467]    [Pg.135]   
See also in sourсe #XX -- [ Pg.61 ]




SEARCH



Starch modification

© 2024 chempedia.info