A Comparison of the Starches From Barley and Malted Barley

Abstract

Starch has been isolated from barley and malted barley of the same sample of cereal. The malted-barley starch had a higher apparent amylose content, a higher gelatinization temperature, and smaller granules than that from the original barley. Pre-treatment of the granules of both starches with liquid ammonia was necessary to achieve complete dispersion prior to fractionation into their component amylose and amylopectin. The amylose from the malted-barley starch was smaller in molecu lar size and had a higher j3-amylolys!s limit than that from the barley. The amylo pectin fractions differed with regard to average chain length and /9-amylolysis limit, but they were of comparable molecular size. Calculation showed the two amylopectins to have similar internal chain-lengths, but different external chain-lengths, that for the malted-barley amylopectin being smaller. This suggests that the maltedbarley amylopectin had been degraded by /9-amylase to a limited extent. Subfractions ofamylose obtained on successive aqueous leaching of both granular starches showed a decrease In jff-amylolysis limit with increase in molecular size. The pro perties of the components from malted-barley starch can be satisfactorily accounted for by assuming limited /3-amylolysis of the amylopectin and very limited a-amylolysis of the amytose in the original barley starch. Introductionstarch during malting, little work has been

Effect of heat–moisture treatment on the structure and physicochemical properties of tuber and root starches

“…However, a slight degree of branching (9-20 branch [a-(1.-+6) points per molecule) has been reported in amylose from various starches (Hizukurietal.,1981). The side chains range in chain lengthfrom4toover100 (Hizukurietal.,1981;Takedaetal., 1987) and the extent of branching has been shown to increase with the molecular size of amylose (Greenwood and Thompson, 1959). Evidence of the occurrence of branching points in amylose is its incomplete conversion into maltose byã mylase: p amylolysis has been shown to vary from 73 to 95% (Morrison and Karkalas, 1990).…”

Pea Starch: Composition, Structure and Properties — A Review

“…The side chains range in length from 4 to over 100 [50,51]. The extent of branching has been shown to increase with the molecular size of amylose [52]. Evidence of the occurrence of branching points in amylose is its incomplete conversion into maltose by β-amylase.…”

Development of Starch and Other Components in Normal and High Amylose Barley

“…10 The amylose content of the sample was calculated on the assump tion that the blue values of amylose and amylopectin from barley are 1-30 and 0-05 respectively. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] In certain cases, granular starches were separated from the ground material as described earlier24 and were defatted in a The fat content of the samples was de termined using fresh material which had not previously been treated with ethanol. Each sample was dried, finely ground and left to stand overnight in diethyl ether, after which it was continuously extracted for 3 hr.…”