Patent GB-733771-A (GB)
Title: Improvements in or relating to a process for preparing starch derivatives and the products resulting therefrom
IPC: C08B31/04
Filed: 1950-08-25
Abstract: Starch derivatives of abnormally high viscosity are made by reacting commercially dry starch, or starch degradation products, in the absence of a catalyst, with from 0.01 to 0.1 mol. per molar weight of starch of a lactone <FORM:0733771/IV (b)/1> <FORM:0733771/IV (b)/2> <FORM:0733771/IV (b)/3> <FORM:0733771/IV (b)/4> or <FORM:0733771/IV (b)/5> where ROH and R1OH are starch molecules and A is H or a hydrocarbon radicle.  Under mild conditions and in the early stages at least the primary reaction will be (1) when, e.g., if where R is H or a hydrocarbon radicle and x is an integer for 1-10 hours at 50-80 DEG  C., the product being washed until substantially free from extraneous ionic material and having a viscosity substantially higher than the untreated starch.  The molar weight of starch is taken as 180.  The products may be starch ethers, starch esters or compounds in which the carbohydrate molecules are cross-bonded by ether-ester linkages, the latter compounds yielding pastes of clarity and abnormally high viscosity.  Reactions leading to the three types are stated to proceed beta-propiolactone, the preferred lactone, is used, the product after pH adjustment to about 7-8 yields clear pastes of relatively high viscosity and long flow.  After longer reaction periods pastes of high viscosity and "short" character are obtained probably via reaction (3).  Reaction (2) is mainly influenced by the reactivity of the lactone used, lactones with large, stable rings require high temperatures and long reaction times which are unfavourable to ether formation.  By a choice of reaction conditions products may be obtained with properties similar to those of the "long" flowing waxy starches, but with better paste clarity and higher viscosity, or clear superviscosity products with "short" flow characteristics may be obtained. Specified starches and degradation products are corn, tapioca, wheat, grain, sorghum, chemically modified starches, dextrins, e.g. a pyrodextrin which is 25 per cent cold water soluble, thin boiling starches, e.g. a 75 fluidity starch, and pregelatinized starches.  For ease and efficiency of reaction, beta- or gamma-lactones should be used.  The pH of the starch during reaction is preferably maintained at 5.5-10.5, e.g. by passing ammonia therethrough.  Purification of the products may be effected by pH adjustment and washing with water or alcohol.  The products may be used in the food industry, particularly as fruit pie fillings, cf. Group VI, in textile printing pastes and as alkaline dry cell fillers.  In examples, corn starch is treated with beta-propioloactone and gamma-valerolactone at various temperatures and concentrations.  Specification 675,793 is referred to.ALSO:A starch thickening agent of abnormally high viscosity for use in pie fillings, especially fruit pies, canned foods, salad dressings and mayonnaise is made by reacting commercially dry starch, or a starch degradation product, in the absence of a catalyst, with from 0.01 to 0.1 mol. per molar weight of starch of a lactone <FORM:0733771/VI/1> where R is H or a hydrocarbon radicle and x is an integer for 1-10 hours at 50-80 DEG  C., the product being washed until substantially free from extraneous ionic material and having a viscosity substantially higher than the untreated starch.  The molar weight of starch is taken as 180.  The nature of the products and details of the reaction are described in Group IV (b).  Specified starches and degradation products are corn, tapioca, wheat, grain, sorghum, chemically modified starches, dextrins, e.g. a pyrodextrin which is 25 per cent cold water soluble, thin-boiling starches, e.g. a 75 fluidity starch, and pregelatinized starches.  Reaction with beta or gamma lactones is preferred.  In examples corn starch is treated with beta-propiolactone and gamma-valerolactone at various temperatures and concentrations.  Specification 675,793, [Group IV (a)], is referred to.