The molecular structure and some physicochemical properties of starches from two high‐amylose cultivars of barley, high‐amylose Glacier A (HAG‐A) and N (HAG‐N), were examined and compared with those of a normal cultivar, Normal Glacier (NG). The true amylose contents of HAG‐A, HAG‐N, and NG were 41.0, 33.4, and 23.0%, respectively. Iodine affinities before and after defatting of starch, and thermograms of differential scanning calorimetry, indicated that HAG‐A and HAG‐N starches had a higher proportion of amylose‐lipid complex than did NG starch. The amylopectins from HAG‐A and HAG‐N were similar to NG amylopectin in average chain length (18–19), β‐amylolysis limit (β‐AL 56–57%), number‐average degrees of polymerization (DPn 6,000–7,500) and chain length distribution. Very long chains (1–2%) were found in amylopectins from all cultivars. HAG‐A amylopectin had a larger amount of phosphorus (214 ppm) than the others. The amyloses from HAG‐A and HAG‐N resembled NG amylose in DPn (950–1,080) and β‐AL (70–74%). However, HAG‐A and HAG‐N had a larger number of chains per molecule (NC 2.4–2.7) than NG amylose (1.8) and contained the branched amylose with a higher NC (9.5–10.6) than that of NG amylose (5.8), although molar fractions of the branched amylose (15–20%) were similar.

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(1-21-24, Korimoto, Kagoshima 890-0065, Japan)The molecular structure and pasting properties of the starches from seven normal cultivars of barley were examined and compared with those of normal maize, rice and wheat starches. The bar ley starches had an actual amylose content of 24.3-27.9%. The starches had different pasting prop erties, such as maximum viscosity and breakdown, and different amylose gelatinization. A positive correlation was found between the maximum viscosity and the gelatinization degree of amylose, suggesting that low amylose gelatinization restrains the swelling of starch granules. The amylopec tins had a low iodine affinity (0.42-0.70 g/100 g) and resembled each other in chain-length distri bution with the individual peaks of B 1 and A chains. The amyloses had DPn of 810-1410 with 3.6-5.2 chains per molecule, indicating that barley amyloses differed in molecular structure with the cultivars. Among the cereal starches, barley starches were similar to wheat starch in amylose content and molecular structure, especially molecular size of amylose and chain-length distribution of amylopectin.Barley is one of the major cereals along with maize, rice and wheat, and is mainly used for livestock feed and raw material for the production of alcoholic beverages. Recently, barley has also been used as food, such as a rice substitute, and in breads and noodles. Starch is the main component of barley grains (65% by wet weight).1) However, structural characteristics of barley starches have been less well established compared with those of other major cereals such as maize,2,3) rice4-6) and wheat.7,8) We recently examined the molecular structure of starches from some barley cultivars with different amylose content, one waxy (0% amylose), two low-amylose (2 and 11% amylose), two normal (23 and 25% amylose) and two high amylose (33 and 41% amylose) barley starches.9,10) The barley amylopectins from starches with differ ent amylose content were similar in molecular structure, while the amyloses had different molecu lar structures. The amyloses from the normal culti vars were similar in size to those of high-amylose cultivars but smaller than those of low-amylose cultivars. To date there is only limited literature in which the molecular structure of normal barley starches is examined9-12) although many varieties are cultivated. Moreover, in most studies,13-18) their structural analyses were conducted using whole starch. In this study, seven normal barley starches were characterized in molecular structure of frac tionated amylose and amylopectin and starch pasting properties in order to elucidate both similarities and differences among the normal varieties.

The molecular structures and pasting properties of four legume starches (white Dutch runner; WDR, adzuki bean, pea and common bean) were examined. The apparent amylose content (27 .0-30.0%) was 3.9-9.4% higher than the actual amylose content (17.6-25.5%) due to the high iodine affinity (IA) of the legume amylopectins. The crystalline type of pea starch was of Cb and those of the others were of the Cc. Adzuki bean starch had the highest maximum viscosity and breakdown. No breakdown was observed for pea starch. The legume amylopectins had IA of 1.32-2.28 g/100 g and number-average chain-length of 21-22. The phosphorus content of amylopectin varied be tween 13 and 820 ppm with WDR amylopectin having the highest content. All the legume amylo pectins had 1-4% of long-chain fraction, being consistent with their high IA. Compared with starches of cereal amylopectins, the legume amylopectins seemed to contain a relatively small amount of A-chain fraction. Distribution pattern for chains of degree of polymerization (DP) 6-8 was similar to those of potato and sweet potato amylopectins in which the amount of these chains decreased with an increase in DP. The legume amyloses had number-average DP of 820-1350 and comprised 2.4-4.7 chains per molecule, being similar to cereal amyloses. Among the legume amy loses, adzuki bean amylose was the largest and most branched molecule.